Product Training Manual Power Transmission Fundamentals for V-Belt Drive Systems • Basic calculations to assist in installation and problem-solving • Belt Drive Advantages • Product Types • Balancing Standards • Installation & Maintenance
INDEX Chapter 1 - Power Transmission Fundamentals 1.1 Calculation of the Circumference of a Circle....................................................................................................... 3 1.2 Force........................................................................................................................................................................ 5 1.2.1 Definition..............................................................................................................................................................5 1.2.2 Motion................................................................................................................................................................. 6 1.2.3 Torque Calculation.............................................................................................................................................. 7 1.3 Work........................................................................................................................................................................12 1.4 Speed and Velocity............................................................................................................................................... 14 1.5 Power......................................................................................................................................................................16 1.6 Efficiency................................................................................................................................................................19 1.7 Ratio........................................................................................................................................................................20 1.8 Service Factors .....................................................................................................................................................23
Chapter 2 - Drives: Belts, Bushings & Sheaves 2.1 What are the Advantages of a Belt Drive System?............................................................................................ 25 2.2 Belts ...................................................................................................................................................26 V-Belt Classifications ..............................................................................................................................................27 2.2.1.1 Light duty & Fractional horsepower (F.H.P) V-Belts ......................................................................................27 2.2.1.2 Classical V-Belts............................................................................................................................................28 2.2.1.3 Deep Wedge / Groove or Narrow V-Belts......................................................................................................29 2.2.1.4 Cogged / Raw-Edge V-Belts..........................................................................................................................30 2.2.1.5 Banded Belts.................................................................................................................................................30 2.2.1.6 V-Ribbed / Poly V-Belts..................................................................................................................................31 2.2.1.7 Double / Hexagonal V-Belts...........................................................................................................................31 2.2.1.8 Variable Speed Belts.....................................................................................................................................32 2.2.2 Other Belt Types............................................................................................................................................32 2.2.2.1 Standard Flat belts.........................................................................................................................................32 2.2.2.2 Standard / Trapezoidal Synchronous Belts....................................................................................................33 2.2.2.3 H.T.B. / Curvilinear Synchronous Belts..........................................................................................................34 2.2.3 Belt Length ...................................................................................................................................................35 2.2.3.1 Parallel axis, uncrossed belt drive.................................................................................................................36 2.2.3.2 Arc of contact.................................................................................................................................................37 2.3 Drive Components Materials.................................................................................................................................38 2.3.1 Gray/Cast Iron...............................................................................................................................................38 2.3.2 Ductile Iron ...................................................................................................................................................38 2.3.3 Sintered Metal................................................................................................................................................39 2.3.4 Table of Mechanical Properties......................................................................................................................39 2.4 Bushings ...................................................................................................................................................40 2.4.1 QD (Quick Detachable) Interchangeable Bushings.......................................................................................40 2.4.2 Taper-Lock / Bore Bushings...........................................................................................................................43 2.4.3 Split Taper Bushings......................................................................................................................................43
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2.5 Sheaves ...................................................................................................................................................44 2.5.1 Sheave Body.................................................................................................................................................45 2.5.2 Sheave Classifications & Terminology...........................................................................................................46 2.5.2.1 Light Duty Fixed & Bush Types......................................................................................................................46. 2.5.2.2 Adjustable/ F.H.P & Integral...........................................................................................................................47 2.5.2.3 Classical & Narrow Belt Drives......................................................................................................................50 2.5.2.4 Application Table by Classes.........................................................................................................................51 2.5.3 Balancing Standards (MPTA)........................................................................................................................52 2.5.3.1 General Information.......................................................................................................................................52 2.5.3.2 Static or Single-Plane Balancing...................................................................................................................52 2.5.3.3 Dynamic or Two-Plane Balancing..................................................................................................................55
Chapter 3 – Drive Selection Program Please see our On-line Program for this section at www.maskapulleys.com
Chapter 4 - Installation & Maintenance 4.1 Bushing Mounting..................................................................................................................................................57 4.1.1 Types of Mounting.........................................................................................................................................57 4.1.2 Tightening ...................................................................................................................................................58 4.2 V-Belts & Sheaves..................................................................................................................................................59 4.2.1 Mounting Structure........................................................................................................................................59 4.2.2 Center Distance Adjustment..........................................................................................................................59 4.2.3 V-Belt Installation...........................................................................................................................................60 4.2.4 Tensioning ...................................................................................................................................................63 4.2.4.1 Measuring Techniques...................................................................................................................................64 4.2.4.2 Run-in Period.................................................................................................................................................67 4.2.5 Idler Pulleys ...................................................................................................................................................68 4.2.6 Maintenance..................................................................................................................................................69 4.2.7 Belt Storage ...................................................................................................................................................69 4.3 Typical Problems ...................................................................................................................................................70 4.3.1 Drive Misalignment........................................................................................................................................70 4.3.2 Sheave Cracked in Hub.................................................................................................................................70 4.3.3 Vibrations ...................................................................................................................................................71 4.3.4 Over Tension..................................................................................................................................................71 4.3.5 High Ratio with Short Center to Center Distance..........................................................................................72 4.4 Couplings ...................................................................................................................................................73 4.4.1 Flexible Coupling Types.................................................................................................................................73 4.4.2 Shaft Misalignment........................................................................................................................................75 4.4.3 Elastomeric Element Couplings....................................................................................................................76
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In this first chapter we will endeavor to familiarize you with concepts related to different transmission applications. Various notions of mechanics and geometry required to make a good selection of drive components will be presented. These fundamental calculation basics are often found in engineering reference manuals but they have been included to show how they can be applied to problem-solving with belt transmission applications. You are therefore encouraged to examine this chapter and do the accompanying exercises as groundwork for calculating critical factors encountered when installing drive components.
Power Transmission Fundamentals
Chapter 1 POWER TRANSMISSION FUNDAMENTALS
1.1 Calculation of the Circumference of a Circle One of the most common basic geometric figures used when designing a power transmission component is the circle. The circle is the geometrical shape on which the entire power transmission process is based. The circumference is defined as the measurement of the circle’s contour; a simple method of obtaining this dimension is by measuring the exact length of string needed to go around the circle.
Circumference (C) Circle Center
Radius (R)
Diameter (D)
Fig. 1.1: Illustration of a Circle’s Main Geometric Parameters
To calculate a circle’s circumference, we must know that the ratio between the circumference and the diameter is a constant. This constant is named Pi (π, Greek letter). Its value is 3.1416.
3
Power Transmission Fundamentals
Formulas to calculate the circumference ( C ) of a circle are:
C=�•D
or C = 3.1416 X D
⇒
also, C = �(2R) C = 2�R knowing that D represents the diameter and R the radius of a circle (Fig. 1.1)
Example 1.1
Answer:
Calculate a circle’s circumference if the diameter is 4".
C = �D = 3.1416 X 4 = 12.566 inches
If a 4" disk was rolled on a flat surface, a distance of 12.566" would be covered with each complete turn.
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1.2.1 Definition Force is defined as the action that one body has on another body. When an applied force on an object is greater than any existing force, this can result in a displacement of a static body, accelerate and decelerate a body in movement or result in a distortion of some kind. This is referred to as action and reaction.
Power Transmission Fundamentals
1.2 Force
Force can be accurately determined when the magnitude, direction and the point of contact are indicated. In the following diagrams, the force’s direction and point of contact are represented by a vector (arrow) (see Fig. 1.2). The measurement unit of force in the English System is pound and the unit symbol is “lb�. In this example, the weight of one unit of mass is equal to one unit of force. NOTE: This principle does not apply when using the Metric System. When torque is not taken into consideration, all parallel forces can be subtracted if they are from opposing directions, or combined if they are in the same direction, to obtain a single force: resultant force. When calculating the resultant force, it is important to keep in mind the status of each applied force (+ or -) as this will directly influence the results obtained. However, reference to the positive or negative status is needed only when calculating mathematical equations (Example 1.2); it is more practical to draw a simple diagram of the applied forces. (Ref. Fig. 1.3)
Magnitude
20 lb Application point
Direction
Fig. 1.2: Diagram of a force
20 lbs
20 lbs
Resultant = 0
40 lbs
20 lbs
20 lbs
Fig. 1.3: Addition of collinear forces (Example 1.2)
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Power Transmission Fundamentals
Example 1.2
In figure 1.3, force is applied to each side of a block. (In this diagram, the arrow represents the point of application and the force’s direction) Calculate the resultant force for each diagram, assuming that there is no friction between the object and the ground.
Answer:
The left diagram has a resultant force of zero ( 20 lb. – 20 lb. = 0 ) and thus remains motionless. The law of static dictates that the total sum of forces must equal zero. The right diagram has a resultant force of 20 lb. ( 40 lb. – 20 lb. = 20 lb. ), thus pushing the block to the right. In this example, the block moves in the direction of the resultant force and only an opposing force, like friction, could stop the movement.
1.2.2 Motion Two major types of motion exist; they are linear and angular motions. The movement of a train on a railway track is an example of linear motion. On the other hand, a turning pulley is a good example of angular motion. Mechanical power transmission generally implies therefore angular motion and the usage of rotating elements, such as: shafts, couplings, gear reducers, chain drives, sheaves and belts. Motion always requires an external force or energy. However, motion can be measured without reference to the initial force. For example, you can calculate the speed of an object even if you don’t know the force used to power it. The interaction between motion and force are very important concepts to understand in any transmission drive system, as we will see later on.
Linear Motion
Angular Motion
Fig. 1.4: Linear and angular motion
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In the preceding subheading, we saw that force can cause an object to move linearly (example 1.2) but it can also make it turn. Torque corresponds to a twisting force and results from the action of an applied force on a body at a certain distance from the center axis. The distance between the point where force is applied and the rotary center is usually called the lever arm. So the tendency for any system submitted to torque is to turn on it’s rotation axis (example: tightening a nut with a wrench, pushing the pedals on a bicycle, a belt turning a pulley, etc.).
Power Transmission Fundamentals
1.2.3 Torque Calculation
Torque is calculated by multiplying the magnitude of the force by the lever arm. To calculate torque ( T ), use this formula:
T=Fxr or
T=FxR knowing that F = force and r = the lever arm (you can replace r by the radius R for a circular body, such as a pulley, when force is applied on the outer circumference). For this reason, torque is expressed in pounds-inches (lb.-in). Hence, torque results from the direction and magnitude of the applied force and the lever arm.
Important: The component force of torque must be at a 90o angle with the lever arm via the point of contact and the rotary center (Fig. 1.5).
center axis
R
T F Fig. 1.5: Diagram of torque force
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Power Transmission Fundamentals
150 lb.-in
r = 10 in
15 lbs Fig. 1.6: Virtual lever arm
Example 1.3 A 5" diameter pulley is installed on a shaft. The pulley bears a weight of 10 pounds
(Fig. 1.7). What is the induced torque?
Answer:
The lever arm measures 2.5 inches (diameter divided by two). The distance between the point of contact and the rotary center corresponds to the radius of a pulley. The weight is the only force producing torque.
T=FxR T = 10 [pounds] x 2.5 [inches] = 25 lb./ in.
Torque
D
10 pounds
Fig. 1.7: Torque from a suspended weight on a pulley (Example 1.3)
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Using the same example, suppose we want to calculate the lever arm; the force and torque are known. If the induced torque is 50 lb.-in and the same weight (10 lb.) is suspended on the pulley, how long should the lever arm be?
Answer: Use the same formula to calculate the R (lever arm) this time:
R=
T 50 [lb • in] = F 10 [lb]
Power Transmission Fundamentals
Example 1.4
R = 5" This illustrates the significance of the lever arm. The same weight suspended from a pulley twice the size (thus doubling the lever arm length), requires twice as much torque as in example 1.3.
At this point, it will be useful to examine the notion of resultant torque, as we did with resultant force. Multiple torque can be added or subtracted depending on their direction, but must be on the same center axis. The convention sign used for the direction of a torque is (+) for a clockwise direction and (-) for a counter clockwise direction (Fig. 1.8). The following example will help you to understand how resultant torque works.
Clockwise ( + )
Counter - Clockwise ( - )
Fig. 1.8: Torque convention sign
9
Power Transmission Fundamentals
Example 1.5 Calculate the torque from the rotating point of the beam in the illustration below (Fig. 1.9). After applying the weights, to which side will the beam tilt according to the resulting torque?
Answer: Torque from left weight applied on center axis (counter clockwise -):
T = F x R = 100[pounds] x 30[inches] = 3000 lb•in Torque from right weight (clockwise +):
T = F x R = 30[pounds] x 50[inches] = 1500 lb• in The resultant Torque is counter clockwise:
T = 1500[lb• in] – 3000[lb• in] = – 1500 lb• in The beam will tilt to the left.
30"
100 lb.
50"
30 lb.
Fig. 1.9: Example 1.5
Example 1.6
With reference to Fig. 1.9, at what distance from the rotary point would a 50-lb. weight have to be placed to balance the beam horizontally?
Answer:
First, example 1.5 indicated that the system has a counter clockwise resultant torque. In this case, the only way to stabilise the beam would be to place a weight to the right side of the rotary point. The total sum of all torque must equal zero to attain equilibrium, as was seen with the static law of force (example 1.2).
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Resultant Torque = 1,500[lb.• in] – 3,000[lb.• in] + 50[lb.] x d = 0
d=
3000[lb• in] - 1500[lb.• in] 50 [lb]
d = 30"
Power Transmission Fundamentals
50[lb] x d = 3000[lb • in] – 1500[lb • in]
*** Even if a body doesn’t move, it could have an induced torque.***
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Power Transmission Fundamentals
1.3 Work In the context of this manual, work signifies the action carried out when a force causes an object to move. Work equals the degree of force applied to a body, multiplied by the distance covered in movement. No work is recorded in the absence of movement. Note that energy is also considered a form of work but should not be confused with the notion of power (ref. Section 1.5.) In linear motion, work results from the degree of force applied to an object and the distance covered. On the other hand, angular motion results from the torque applied to an object and the angular movement. Work is usually expressed in ft.-lb. or in.-lb. Torque has the same units of measure, but involves the distance from the rotary center to the point of contact whereas work is calculated by measuring the total distance covered between the initial and final position. The formulas are:
Linear system:
Work resulting from a force
U=Fxd
Rotational system:
Work resulting from a torque
U=Txθ
or
knowing that U = work, F = force, T = torque and d = the distance covered by one body subjected to a given force. To calculate the work resulting from a torque, displacement is measured by the angle
( θ ) in radians (1 radian = 57.3 degrees or 1800/π ).
Example 1.7
A filing cabinet is pushed on a wooden floor (Fig. 1.10). The force applied to move the filing cabinet is 10 lb. The distance covered is 120 inches. What is the work value?
Answer:
U=Fxd U = 10 lb. x 120 in U = 1,200 in- lb.
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10 lb.
Power Transmission Fundamentals
120"
Fig. 1.10: Example 1.7
Example 1.8
You have to tighten a nut on a structure. You use a torque wrench with two arms, 6 inches long on each side. If you applied a constant force of 6 lb. to the extremity of each arm and turned the nut 900 (¼ of a turn), calculate how much work is involved.
Answer: 1. Calculating torque on one arm
T1 = F x d
T1 = 6 lb. x 6 in = 36 lb.-in 2. Calculating the resultant torque
T = T1 + T2 = 36 [ lb.- in ] + 36 [ lb.-in ] = 72 lb.-in
π rad = 180o π/2 rad = 90o
3. Calculating the work involved
U= T x θ U= 72 [ lb.-in] x (π/2) U= 72 [ lb.-in] x (1.57) = 113 lb.-in
3. Convert the angle to radians
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Power Transmission Fundamentals
1.4 Speed and Velocity Once the notion of movement has been understood, it is important to determine and quantify the speed an object moves. To do so, we have to calculate the velocity (speed) or distance that an object moves in a given unit of time. In linear motion, the displacement equals the distance covered and in angular motion the displacement is an angle. The formulas to calculate velocity are:
d
linear velocity (v): v = t where d = distance, t = time and v is expressed in in/sec or ft/sec.
θ
ω= and angular velocity (ω): t where ω is expressed in rad/sec. Another more practical formula to calculate the speed for angular motion is to count the number of revolutions per minute (rpm). However, tangential speed (vT) is another important measurement to understand when designing a belt-drive system or choosing a V-belt. It is usually expressed in feet per minute and corresponds to the belt velocity. When a belt is pulley-driven, the speed at the point of contact is different from the rotary speed of the pulley. For example, if using a bicycle on a treadmill machine you could compare the moving conveyor to a belt and the bicycle wheel to a pulley. The bicyclist does not need to know the rotary speed of the bicycle wheels to calculate the surface speed or the belt speed because as a speedometer can indicate this to him. However, when designing a belt drive system you usually have to determine the rim speed. To do so, the same method of conversion must be applied as that used by a car or bicycle speedometer. Here are several practical formulas to know in order to calculate tangential velocity or belt speed. The relation between VT and ω is:
ω [rad / min] = 2� x RPM & v T= ω x R
vT = 2� x R x RPM = � x D x RPM
With reference to a belt drive system, the formula to find belt speed is:
Belt Drive velocity [ft/min] = Pulley Diameter [in] x π x RPM x 1/12 [ft/in] or FPM = Pulley Diameter [in] x 0.2618 x RPM
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Belt speed
Power Transmission Fundamentals
Please note that the fraction 1/12 has been added to the formula to convert the pulley diameter into feet. You also need to remember that the outside diameter should not be used for calculating belt speed when working with variable pulleys, as the radial position will vary
Fig. 1.11: Belt Speed
Example1.9 Calculate the belt speed driven by a 5 inch pulley with a rotary speed of 2,000 rpm. V-belt drive [ft/min] = 5 [in] x 3.1416 x 2000 [rpm] x 1/12[ft/in] V-belt drive [ft/min] = 2,618 ft/min
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Power Transmission Fundamentals
1.5 Power In mechanical engineering, power is a measure of performance or capacity and is defined as the amount of work performed in a given time. The most work accomplished in the least amount of time, equals greater power. The formulas to calculate Power ( P ) are:
P=U t or
P=Txω
P=Fxv
Knowing that U = work, t = time, v = linear velocity, T = torque and F = Force. The units of measurement for power are usually in-lb./sec, ft.-lb./sec, but could vary depending on the units used in the formula.
Example 1.10 Calculate the power required to lift a 500 lb. weight 20 ft. in 60 seconds.(Fig. 1.12) Answer:
P=U=Fxd t t P = 500[lb] x 20 [ft] X 12 [in]= 2000 in•lb 60 [sec] [ft] sec
500 lb.
20 ft
Fig. 1.12: Example 1.10
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In the PT industry, the term horsepower is often used as a power unit, commonly called force. Even if this expression is currently used, it should not be confused with the definition of force that has already been given. In order to avoid confusion, it is better to use the correct term of power.
Power Transmission Fundamentals
Important
The formulas to calculate Power in hp are:
HP = U [ft·lb] = P[ft·lb/sec] 550·t[sec] 550 or
HP =
U [ft·lb] = P[ft·lb/min] 33000·t[min] 33000
Example1.11 Use the previous example (Fig. 1.12) to calculate power expressed in hp. Answer: HP = P [ft-lb.] 550 t [sec]
HP = 500[lb.] x 20[ft] 550 x 60 sec HP = 0.303 hp
In the case of angular motion, there is obviously a formula to calculate power as well. The previously discussed formulas of torque and angular velocity are involved.
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Power Transmission Fundamentals
Here is the formula to calculate power using speed revolution (RPM) or number of rotations a minute and torque (T):
P = 2π x T x RPM
Therefore, the power in hp (HP) can be calculated using the following formulas:
HP = T[lb·ft]·RPM 5252 or
HP = T[lb·in]·RPM 63025
Example 1.12: A V-belt driven system is powered by a 2 hp electric motor. The motor has two operational speeds: 1,140 rpm and 570 rpm. Calculate the torque at both speeds. Hint: Rewrite the equation to find the torque.
Answer:
Speed 1- 1,140 rpm HP = T[lb·ft]·RPM 5252 T[lb·ft] = 5252·HP= 5252x2 = 9.21 lb ·ft RPM 1140 Speed 2- 570 rpm T[lb·ft] = 5252·HP= 5252x2 = 18.4 lb ·ft RPM 570
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In most transmission systems, friction forces and heat dissipation account for a considerable loss of power. In the case of a V-belt driven system, a considerable loss is experienced from belt slip. Mechanical efficiency is measured in terms of input and output power, where 100% equals maximum performance or zero power loss. The formula for mechanical efficiency is:
Example 1.13 Answer:
Power Transmission Fundamentals
1.6 Efficiency
Calculate the efficiency of a transmission that has an input power of 10 hp and 9 hp at the output. Efficiency (%) = HP Output x 100 HP Input Efficiency (%) = 9 hp x 100 10 hp Efficiency (%) = 90 %
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Power Transmission Fundamentals
1.7 Ratio A ratio is a proportional factor between two similar objects of different sizes. In a belt drive system, a ratio is used to determine the speed relation between two pulleys. The speed ratio would be stable if slippage did not occur; however as belt slip is inevitable, the ratio varies. If the ratio is >1 we refer to a speed up system; if the ratio is <1 it is a speed reduction system. In both cases, the ratio is obtained using the dimensions of the input drive (driver) pulley and the output (driven) pulley.
Rs = Ď&#x2030;1 = RPM1 = D2 Ď&#x2030;2 RPM2 D1 where RS is the speed ratio, D1 diameter of driver pulley, D2 diameter of driven pulley.
***FOR V-BELT DRIVES, REPLACE DIAMETER(D) BY THE PITCH DIAMETER(PD)***
Example 1.14: Answer:
Calculate the ratio between a 2 inch driver pulley and a 5 inch driven pulley.
Rs = D2 =5 D1 2
Example 1.15:
2.5 : 1
Calculate the speed ratio between a driver pulley turning at a speed of 500 rpm and a driven pulley at 2,000 rpm. If the driving pulley is 4 inches in diameter, what is the dimension of the driven pulley ?
Rs = 500 2000
1: 4
When the driver pulley has completed one revolution, the driven has turned 4 times.
Rs = 500 = D2 2000 4"
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D2= 500 x 4" = 1" 2000
However, the diameter of the four pulleys can be calculated only in a compound drive where the speeds of the driving pulley and the driven pulley are known. In this case, see the following steps (ref. Example 1.16): 1. The first step is to form a fraction with the driving pulley speed as the numerator and the driven pulley speed as the denominator. 2. After that, reduce this fraction to its lowest terms. 3. Divide the numerator and the denominator into two pairs of factors (a pair being one factor in the numerator and one in the denominator). 4. If necessary, multiply each pair by a trial number that will give pulleys of suitable diameters (see example 1.16). This trial number has an influence on the cost, so it should be reduced as much as possible while retaining the power required.
Power Transmission Fundamentals
Ratios cannot be added or subtracted; only multiplied or divided. For example, to determine the speed ratio of a driven pulley in a compound drive with four pulleys (see Fig. 1.13), ratios are multiplied to make the connection between the input pulley D1 and output pulley D4.
D3 D2 D4
D1
Fig. 1.13: Example 1.16
Example 1.16:
(Step 1)
In the compound drive above, if the speed of pulley D1 is 575 rpm, and the speed of pulley D4 is 1,200 rpm, what is the diameter of the four pulleys?
Rs = 575 1200
(Step 2) reduce the fraction to its lowest terms
23 48
(Step 3) Divide into two fractions
23 = 1x23 48 2x24
(Step 4) multiply by trial number 8 and 1
(1x8) x (23x1) 8x23 = (2x8) x (24x1) 16x24
The values 8 and 23 in the numerator represent the diameters of the driven pulleys, D2 and D4, and the values 16 and 24 represent the diameters of the driver pulleys, D1 and D3.. The pulley diameters must respect the design. D3>D4>D1>D2; verify 24>23>16>8. Note: When the dimensions obtained are not standard manufacturer sizes, the pulleys can be reduced by dividing the diameter of each one by the same number so as to obtain a standard dimension. This signifies cost savings and a reduction in the design space required. Just be sure that they still meet the required HP rating.
21
Power Transmission Fundamentals
Example 1.17:
If the diameter of the pulleys D1=40, D2=15,, D3=36, and D4=48 and the speed of pulley D1 is 695, find the speed of the driven pulley D4.
D2 D4 RPM1 X D1 D3 = RPM4
N4 = D1 x D3 X RPM1 = 40 x 36 X 695 = 1390 rpm D2 x D4 15 x 48
Hence, the overall ratio between the input drive D1 and output drive D4 is equal to:
RPM1 695 D2 D4 X 1:2 RPM4 = 1390 = D1 D3 =
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When designing components for manufacturing industries, engineers must take into account factory induced factors such as operating times, the type of driving unit and the load. This service factor is used to adjust the horsepower requirements to reflect actual horsepower needs in order to ensure normal service life. A service factor can be compared to a safety factor or safety precaution. Manufacturing companies decided to use a formula based on production condition factors to foresee possible abuse through excessive wear and tear and adapt their transmission systems accordingly. Various tables based on production conditions are referred to when designing power transmission systems. Environmental factors (heat, abrasive dust) are not taken into consideration but certainly affect the life of a drive system. You’ll see how these service factor tables are used when designing a belt drive system in chapter 3.
Power Transmission Fundamentals
1.8 Service Factors
The formula for calculating a service factor is:
Ks = P' P Knowing that KS represents the service factor, P’ the design power and P the requirement power
Example1.18 If a belt drive system has a service factor of 1.4, and the rated (required) power is 40 hp, how much power is needed?
Answer:
Ks = P' P P' = P · Ks = 40[hp] · 1.4 = 56hp
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Hexagonal Bolt
Sheave
QD Bushing
Square Key
V-Belt
Drives: Belts, Bushings & Sheaves
Chapter 2 DRIVES: BELTS, BUSHINGS & SHEAVES / PULLEYS
2.1 What are the Advantages of a Belt Drive System ?
Drives: Belts, Bushings & Sheaves
In Chapter 1 it was illustrated that force and power can be transmitted in different manners. The most commonly used systems to transmit power from a driver shaft to a driven shaft are belt-drive systems (Fig.2.2a), geardrive systems (Fig.2.2b) and chain-drive systems (Fig.2.2c).
(a)
(b)
(c)
Fig. 2.2: Illustration of different drive systems There are a number of advantages to using a belt drive system as compared to other systems. It is also referred to as a “friction drive” as power is transmitted as a result of the belt’s adherence to the pulley. Among the different belt drive systems, the “V” belt drive is a very economical speed reducing option that is commonly used in industrial, automotive, commercial, agricultural and home appliance applications. The list below presents the advantages of a belt system when it is well-designed and used in a proper environment. Advantages of “V” belt drives are: *
Easy and economical installation.
*
No lubrication required.
*
Clean & low maintenance.
*
Elasticity of belts helps shock load dampening.
*
Quiet, smooth operation.
*
Long life expectancy when well designed.
*
Good mechanical efficiency.
In addition, should a rotational component become blocked while in operation, considerable damage can be caused to the entire power transmission system. This risk can be greatly lessened with a belt drive system,
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as a belt will slip if the system blocks, thus reducing the risk of breakage; this advantage is not available with a chain or gear system. However, this advantage is offset by the fact that standard friction drives can both slip and creep and so do not offer exact velocity ratios, nor precision timing between input and output shafts. It is thus very important to choose the right drive design based on the application.
Drives: Belts, Bushings & Sheaves
2.2 Belts Belt drives are one of the earliest power transmission systems and were popular during the Industrial Revolution. At the time flat belts were useful for conveying power over large distances and were made from leather. However, due to the demands for more powerful machinery, and the growth of large markets such as the automobile industry, new types of belts were designed. In order to meet higher standards of performance, V-belts, with a trapezoidal or “V” shape, and made from rubber, neoprene, urethane or similar synthetic materials, replaced flat belts. •
The belt’s inside surface must be made from a material that ensures adherence to the pulley groove through friction force and reduces the belt tension required to transmit torque.
•
The top part of the belt, called the tension or insulation section, contains fiber cords for increased strength as it carries the load of the traction force, whereas the bottom, or compression section, has been designed to withstand compression.
(1) PROTECTIVE COVER Generally a tough and elastic cover made from a special rubber-impregnated fabric that is slip-resistant and durable. This heat resistant layer serves to protect the belt’s inner components. (2) INSULATION SECTION This section helps holds the tension members in place and acts as a binder for greater adhesion between the cords and the other sections. In this manner, heat build-up is reduced resulting in extended belt life. (3) TENSION MEMBERS Pre-stretched cords (polyester, aramide, steel, fiberglass,..) provide high tensile strength and minimize stretch. (4) COMPRESSION SECTION Made from a tough rubber compound that exerts a wedging force against the pulley groove to increase adherence without deformation.
Fig. 2.3 V-Belt The torque obtained depends on the belt’s resistance to the applied tension and the degree of adherence to the inner walls of the pulley groove. For this reason, a belt drive system should never be lubricated as it depends on friction to transmit power, in contrast to chain or gear systems that function through pure contact pressure. The inside face of the belt should never touch the bottom of the groove (Ref. See Fig. 2.4)
26
All belt sizes are classified by cross-section and length dimensions. The belt identification number includes a letter, indicating the cross-section, followed by up to 3 digits. The cross-section indicates the top width, depth and “V” angle dimensions of V belts. Industrial belts are measured in terms of outside and inside (pitch) lengths (section 2.2.2.2). The different types of V-Belts mentioned below are in inches. To determine belt nomenclature in metric, you must refer to a belt manufacturer’s catalog.
Fig. 2.4: Sheave Cross-Section 2.2.1.1 Light duty & Fractional horsepower (F.H.P) V-Belts
Drives: Belts, Bushings & Sheaves
2.2.1 V-Belt Classifications
This type of V-belt was designed for light-duty applications of less than 1 hp, which is why they are referred to as F.H.P. or fractional horsepower. The V-shape results in improved performance for conventional speed operations in a more compact format, as compared to flat pulleys. These belts are used only with small 1-groove pulleys for single-belt power transmission.
Fig. 2.5: Light duty V-Belt Cross-sections
For this type of V-belt, the cross-section is identified by the letter “L” preceded by up to 5 figures (1 to 5), which when divided by 8 indicates the top width. This is true for all belts except the “5L”, of which the width is not 5/8 but rather 21/32. It is interesting to note that there is a corresponding height for every top width. The number that follows the letter “L” indicates the outside length multiplied by 10.
Fig. 2.6: Light duty 3D Cross-sections
Example 2.1 What are the dimensions of a 4L990 V-belt? Answer:
4/8 = ½-inch top width, 5/16-inch height and 99 inches outside length
27
2.2.1.2 Classical V-Belts Classical V-belts are used as much in heavy-duty as light duty (A & B ) applications because of the large selection of cross-sections available. They are available in different belt types and materials. All classical V-belts with identical cross-sections will operate in sheaves with grooves for that particular cross-section. Baldorâ&#x20AC;˘Maska offers a complete selection of classical sheaves.
Drives: Belts, Bushings & Sheaves
A
B
C
21/32"
1/2"
40o
40o
1 1/2" 1"
3/4"
17/32" 40o
E
1 1/4"
7/8" 13/32"
5/16"
D
40o
40o
Fig. 2.7: Classical V-Belt Cross-sections Classical V-belts are identified by 5 letters: A, B, C, D, & E. Unlike most belts, the cross-section is identified by a single letter, followed by the approximate inside length. 4L and 5L V-belts are respectively interchangeable with type A & B belts, although the B belt is slightly higher than the 5L. Type A and B belts are available in a larger variety of sizes than the 4L and 5L. Please note however that different belt types should not be combined on the same pulley with several grooves. All classical V-belts can be used alone or coupled with other identical cross-section belts to transmit up to hundreds of hp units.
28
Example 2.2
What are the dimensions of a B228 V-belt?
Answer:
21/32-inch top width, 13/32-inch thick and 228 inches inside length.
2.2.1.3 Deep Wedge / Groove or Narrow V-Belts Narrow V-belts are recommended for drive systems that require compact design, higher speed and increased horsepower. They have a more pronounced â&#x20AC;&#x153;Vâ&#x20AC;? shape and are used in applications similar to those of multiple classical V-belts. They have a greater horsepower capacity than conventional belts due to increased surface contact with the pulley wall.
3/8" 5/16"
3V
7/8"
17/32"
5V
8V
Fig. 2.8: Narrow V-Belt Cross-sections
Drives: Belts, Bushings & Sheaves
1"
5/8"
Three standard cross-sections cover the entire range of drive requirements, as compared to five for classical V-belts. This results in reduced inventory for this type of belt and pulley. 3V belts are used with A&B sheaves, 5V deals with B&C sheaves and 8V covers D&E cross-sections. Since greater horsepower capacity can be obtained, the drive system can be designed with shorter centers and smaller sheaves. Overall drive dimensions can be reduced by as much as 40%. Smaller, lightweight drive systems reflect cost savings through reduced size components or can transmit up to twice the horsepower of classical section belts within the same space. As with light duty belts, the initial number, when divided by 8, indicates the top width. The last number multiplied by ten indicates the outside circumference.
Fig 2.9: Narrow V-Belt (3D Cross-section) Fig. 2.9: Narrow V-Belt (3D Cross-section)
Example 2.3
Answer:
What is the belt identification number of a 140 inches length narrow V-belt with a 3/8 inch width? 3V1400
29
2.2.1.4 Cogged / Raw-Edge V-Belts
Drives: Belts, Bushings & Sheaves
Cogged V-belts are offered as a feature on both classical and narrow configurations. The letter “X” is added to the cross-section identification letter (ex. AX, BX, CX & 3VX, 5VX). The notches that are cut in the underside render the belt more flexible, resulting in increased surface contact. For this reason, cogged belts are especially useful for high performance, high speed applications operating with smaller sheaves. When subjected to difficult operating conditions, the use of cogged belts allows for increased surface contact, resulting in improved heat distribution. •
Used in heavy trucks and buses because of longer service life and reduced bending stress.
•
Increased torque capacity even in high-speed operations.
•
Less slippage.
Fig. 2.10: Narrow V-Belt (3D Cross-section) 2.2.1.5 Banded Belts Banded V-belts are identified by the letter “R” placed before the crosssection identification letter. The standard cross-section identification for classical banded V-belts is: RB-RC-RD. The standard crosssection identification for narrow V-belts is: R3V-R5V-R8V. The advantages of classical or deep wedge V-belts are multiplied by the strength of several belts in one.
Advantages & Features:
30
•
Recommended for applications with vertically-mounted shafts or extended center-to-center distances.
•
Assures lateral rigidity and guides the belts into the pulley walls in a straight line.
•
Designed for heavy-duty drives where shock loading is a problem and where multiple matched single belts tend to roll over or jump off.
2.2.1.6 V-Ribbed / Poly-V Belts
The belt tension must be a little higher than with classical V-belts, but performs up to 30% more power. This type of belt is recommended when drive ratios are as high as 40:1 and require small pulleys. Some crosssection V-ribbed belts are capable of transmitting up to 1,000 hp.
Advantages & Features: •
The multiple V-ribbed design provides more effective surface contact area than conventional V-belts.
•
The use of smaller, less expensive sheaves with shorter center distances.
•
Flexibility allows multi-pulley drives.
•
High speed capability in serpentine drives with limited space
Drives: Belts, Bushings & Sheaves
Fig 2.12: Poly-V Belt
V-ribbed belts are a combination design of flat and V-shaped belts. You can thus benefit from the best of both worlds – increased V-belt power transmission coupled with the flexibility of flat belts that function well at higher speeds. The multiple ribs provide much more stability than a flat belt.
Fig. 2.13: Serpentine Drive 2.2.1.7 Double / Hexagonal V-Belts Double V-belts are used on equipment where the driven shafts rotate in a direction opposite to that of the driving shaft. Usually the driver and driven shafts rotate in the same direction; an example of such an exception is that of serpentine reverse bend drives, where this type of V-belt is used. The double V-belt drives from both the top and bottom surface. The cross-sections are identical to classical V-belts but with two driving surfaces. Standard double V-belts are identified by duplicate letters in the belt code followed by the inside length.
Fig. 2.14: Doubled V-Belt cross sections
Fig. 2.15: Doubled V-Belt Double sided V-belts are generally found in agricultural and textile applications.
31
2.2.1.8
Variable-Speed Belts
Drives: Belts, Bushings & Sheaves
Variable or adjustable V-belts are uniquely designed to transmit power in applications where there is a varying speed-ratio. This is the case when working with adjustable pulleys that have been designed with two moveable flanges that can be adjusted in width.
Fig 2.16: Variable speed V-Belt Fig 2.16: Variable speed V-Belt
Variable-speed belts have cross-wise rigidity and length stability for optimum performance because of the increased width at the top of the belt in proportion to the thickness. Variable speed belts also require lengthwise flexibility to bend around small sheaves without excess strain that could shorten belt life. Advantages & Features: •
Industrial applications of variable speed V-belts are pumps, fans, blowers, conveyors, & mixers. Consumer applications include motorcycles, snowmobiles and golf carts.
•
The belt adjusts easily within the pulley groove, thus allowing for a wide range of speed ratios.
2.2.2 Other Belt Types 2.2.2.1 Standard Flat belts Flat belts have been replaced by V-belts in most industrial applications because of improved resistance and reduced size. However, the flat belt is still one of the best solutions for high speed applications as great as 15,000 ft./min. Due to their height and weight, V-belts are subject to increased centrifugal force whereas lighter flat belts, whose center of gravity is closer to the pulley’s surface, maintain better surface contact at high speeds. Pulleys used with flat belts must have a larger surface area to transmit the same amount of power. In fact, in order to attain the equivalent coefficient of friction, flat belts must be considerably larger as they are much thinner. (See Fig. below)
Flat Belts
The small bending cross-section of the flat belt causes little bending loss. This fact, together with even running and the absence of pulley wedge effects, leads to higher flat belt efficiency. The maximum efficiency attained by flat belts is 98% compare to 96% for V-belts. Advantages & Features: • Flat belts are capable of transmitting power over long distances.
Fig 2.17: Standard flat Belt sections
• They are still used because of their flexibility in serpentine drives and in applications where belts must be twisted to achieve reverse shaft rotation. • Increased flexibility results in less bending loss.
32
2.2.2.2 Standard / Trapezoidal Synchronous Belts
2.18: Synchronous belt Fig Fig 2.18: Synchronous belt These belts are found in a wide variety of precision drive applications including robots, machine tools and plotters. High-volume applications include driving and timing overhead camshafts in automotive engines. Speeds vary from a few inches per minute to more than 16,000 FPM and load carrying capacity can vary from fractional to hundreds of horsepower.
240 Belt Pitch Length (24.0 inches)
/ L / Tooth Pitch (3/8 inch)
Drives: Belts, Bushings & Sheaves
Used primarily where the motion of input and output shafts must be precisely matched, synchronous belts are also known as timing belts or positive-belts. Transmission is produced through evenly spaced teeth on the inside surface of the belt that engage mating grooves in a pulley. There is no belt slip and the speed ratio is constant and precise. Though visually similar, this type of belt is not to be confused with cogged belts. As with V-belts, there are dual-sided timing belts with teeth on both sides for reversed-motion and serpentine drives.
075 Belt width (0.75 inches)
•
Smooth engagement of belt with pulley allows high speed operations.
•
Ideal where back-lash, noise and maintenance of chain drives would be undesirable.
•
Timing belts weigh only a fraction as compared to alternative methods for the same horsepower requirements.
•
The clean operation is ideal for contamination sensitive environments, such as industrial food processing.
33
Belt Pitches
Drives: Belts, Bushings & Sheaves
On synchronous belts, pitch is the distance between the center of two adjacent teeth as measured along the pitch line. The pulley pitch line must be the same as the belt pitch line in order to be synchronized. For this reason, the pulleyâ&#x20AC;&#x2122;s pitch is the distance between groove centers, and the pulley pitch circle is measured midway between the areas of tension and compression of the belt.
Pitch Diameter
Outside Diameter
Belt Pitch Line
Sprocket Pitch Diameter
The belt pitch line (simply called pitch for narrow v-belts) is located within the tension member and coincides with the pitch circle of the pulley mating Fig 2.19: Synchronous Drive with it. The distance between the pitch line and the outside of the pulley is called the Pitch Line Differential. Any change in belt construction that alters the pitch line differential requires a corresponding change in the pulley diameters. Timing belts must be run with pulleys with an identical pitch. Belts - in order to handle a wide range of loads, speeds and applications at highest possible efficiencies - are made in five stock pitches. Consequently, when designing belt drives, as with gear or chain drives, circular pitch (usually referred to as pitch) is a fundamental consideration. 2.2.2.3 H.T.B. / Curvilinear Synchronous Belts H.T.B. is an abbreviation for High Torque Belts and follows the same drive design rules as the timing pulley. These rounded form belts allow for all the advantages that come from synchronous rubber belts on applications that previously called for roller chains and gear drives. The standard-trapezoidal tooth timing belt presented above performs poorly in high torque applications and high power drives at lower speeds. To overcome this drawback, the High Torque Belt (HTB) was developed using a more efficient tooth profile. HTB timing belts are classified by tooth profile, belt pitch length, tooth pitch and belt width in millimeters.
720 Belt Pitch Length (mm)
/ 8M / Tooth Pitch (mm)
Among the advantages are : * Higher torque transmission at lower speeds * High power transmission over a wide speed change * Improved meshing to reduce tooth jump * Higher resistance to tooth shear * Less tooth wear due to friction
Fig. 2.20: High torque belt
34
30 Belt width (mm)
2.2.3 Belt Length The belt length equals the sum of the length of both straight sections and both lengths in contact with the sheaves.
02 D2 Drives: Belts, Bushings & Sheaves
01 D1
C Fig 2.21: Diagram to calculate belt length The variables of this system are: D1 : Datum diameter of the driving pulley/sheave (in) D2 : Datum diameter of the driven pulley/sheave (in) C : Distance between sheaves’ rotary axis (center distance, in) θ1 et θ2: Arc of contact between the belt and, respectively, the driving and the driven sheaves (degree or radius (if indicated))
35
2.2.3.1 Parallel axis, uncrossed belt drive This is the most common belt system set-up in the industry. The installation method is illustrated below. (Fig. 2.21) The arc of contact for the smaller sheave is:
Drives: Belts, Bushings & Sheaves
θ1 = 2 cos-1
D2 - D1 2C
or
θ1 ≈ 180 -
60·(D2 -D1 ) C
The arc of contact for the larger sheave is:
θ2 = 360 - 2 cos-1
D2 - D1 2C
or
θ2 ≈ 180 +
60·(D2 -D1 ) C
Therefore, the formula to calculate the total length is (angles are in radians):
L=√4C 2 - (D2 -D1 )2 + 21 (D2 θ2 -D1 θ1 ) To accelerate the calculation, the following formula can also be used: 2 L≈2C + π (D2+D1 ) + (D2 -D1 ) 2 4·C
or
L≈2C + 1.57(D2+D1 )+ (D2 -D1 ) 4·C
2
The above formula applies to unequal pulleys (different diameters); the formula to calculate the belt length for equal pulleys (same diameters) is:
L≈2C + D·π 36
or
L≈2C + D·3.1416
2.2.3.2 Arc of contact The arc of contact (θ1 et θ2 Fig. 2.21) determines to a great extent a belt-drive systemâ&#x20AC;&#x2122;s capacity to transmit power. For efficient operation, the minimum belt wrap, or arc of contact, of the smallest pulley should be 120o. The maximum arc of contact that can be obtained is 180o. This is achieved when the two pulleys are of equal diameter.
Drives: Belts, Bushings & Sheaves
The formulas used in sections 2.2.3.1. illustrate that the arc of contact increases with the center to center distance. The minimum arc of contact necessary in a power transmission system thus has a direct influence on the design of the center to center distance of the pulleys.
37
2.3 Drive Components Materials Before considering the remaining principal components of a V-belt drive system, such as bushings and sheaves, we will discuss the importance of selecting the proper material when designing the part.
Drives: Belts, Bushings & Sheaves
One of the most common ferrous metals used is cast iron. This is a cost-efficient material that adapts well to the molding process, and is recommended even for complex parts. The following is a description of the mechanical and physical properties of the two main types of cast iron that Baldor•Maska works with.
2.3.1 Gray/Cast Iron The property that differentiates gray cast iron from plain carbon steel is the presence of pure graphite in the form of flakes. During the molding process, although most of the carbon mixes with iron, the remaining elements form graphite. The presence of graphite contributes to gray cast iron’s high vibration absorption and wear resistance. On the other hand, the graphite flakes create weakness planes which result in slightly reduced tensile strength. Gray iron also has greater corrosion resistance under most conditions compared to plain steel. For those reason, coupled with a wide range of casting properties, machine frames and engine blocks are Fig 2.22: Cast iron manufactured from this material. The majority of Baldor•Maska pulleys used in standard applications are manufactured from gray cast iron; however they are not recommended for operations that are at risk of experiencing excessive shock loads or high speed. For this reason, certain items are made from ductile iron for improved strength.
2.3.2 Ductile Iron Ductile iron has greater resilience and ductility, as it’s name denotes, than gray cast iron. Graphite is present in a nodular (small, round lumps) rather than flaky form. Corrosion resistance is comparable to that of gray. This stronger material is recommended for operations that could experience occasional jolting. Compared to gray, ductile iron cannot be machined as easily. It also has less vibration absorbency. However, the mechanical properties are similar to steel and it is used in the Fig 2.23: Ductile iron production of gears, crankshafts, wheel hubs, etc. In addition, other advantages of ductile iron as compared to gray, is that it allows for a reduction in size and weight of the part, and has added resistance to impact failure. Baldor•Maska is one of the only companies that offers a broad range of QD Bushings in ductile iron.
38
2.3.3 Sintered Metal
Whereas casted metals must be brought to the melting point, this raw material is a pre-determined mixture of different alloys in a fine, granular form (powder) of which small amounts undergo high pressure compacting from presses equipped with a set of matrixes and punches that determine the shape. At this stage, the part usually has the required shape, but not the mechanical resistance required. In order to acquire the necessary resilience found in casted metal, the particles need to be binded together. This is done by heating the parts over a specific period of time called sintering, at temperatures just under the melting point. The controlled temperature generates metallurgical binders within the part without altering the shape due to excessive heat. Upon coming out of the furnace, the part is a finished product, unless special machining or treatments are needed.
Drives: Belts, Bushings & Sheaves
Sintered metal processing has become very popular in the last 20 years. Easily adapted to mass production, this process has been used in the automobile industry and can produce complex parts with high tolerances and very little waste during molding. In addition, the ferrous alloys available have excellent mechanical properties at a competitive price, due to economical processing methods.
A unique advantage of this sintering process is the possibility of adjusting the basic powder â&#x20AC;&#x153;recipeâ&#x20AC;? to include special additives that can either increase corrosive resistance, improved machinability or increased part density. Although sintered metal has different mechanical properties than that of casted metal, the results are nonetheless very competitive. Baldorâ&#x20AC;˘Maska was one of the first companies to market and take advantage of sintered metal processing for certain product lines.
2.3.4 Table of Mechanical Properties
MATERIAL Grey cast iron Ductile iron Sintered Metal
GRADE
TENSILE STRENGTH MIN. ( PSI )
YIELD STRENGTH MIN. ( PSI )
ELONGATION ( PERCENT )
MODULUS OF ELASTICITY ( X 106 PSI)
30
30,000
30,000
<1.0
13-16.4
65-45-12
65,000
45,000
12
24
FC-0205-40
40,000
40,000
<1.1
17.5
39
Drives: Belts, Bushings & Sheaves
2.4 Bushings All power transmission components must either be attached or connected to a shaft. A bushing is the intermediary element used to mount or attach a sheave/pulley to a shaft. In belt transmission drive systems, the bushing is installed in the hub of the pulley and is secured with screws, thus exerting a pressure on the hub. This pressure is created by a taper geometry principle that can also be observed when a male conical object is inserted into the mating surface of the corresponding female part. The bushing has a thin slit down the side that enables it to be compressed evenly around the shaft during installation, which results from the axial force applied when fitting the bushing into the sheave hub. Most tapered bushings compensate for normal variations in shaft and component dimensional tolerances. Bushings are available in a number of different bore sizes for various shaft dimensions and safely permit power transmission as the go-between the shaft and the sheave. They greatly reduce the number of standard sheaves required or having to machine the part for every different shaft size. (Fig. 2.1)
2.4.1 QD (Quick Detachable) Interchangeable Bushings QD bushings have a straight bore with a tapered barrel on the outer surface that matches the pulley hub. QD bushings have a full split through the flange and barrel to permit a tight clamping action on the shaft. They are easy to install, eliminate fretting corrosion between the bore and the shaft and are an excellent choice for V-belt drive systems. Cap screws are used to tighten and secure the bushing onto the shaft. To assemble, the bushing and sheave are slipped over the shaft. When the tapered surfaces first meet, the fit between the bushing bore and the shaft is relatively loose. When the cap screws are tightened, the split closes partially and the bushing grips the shaft tightly.
2.24: QD Bushing Baldor•Maska offers an interchangeable QD BUSHING (QD is a registered trademark and manufactured under license).
40
•
Precision machining of the tapered bore in the hub of the QD sheave and the tapered mating surface of the bushing insure a snug and precision fit between the sheave and the bushing.
•
The split is full (not partial). As the cap screws are tightened, a tremendous pressure is generated, with a grip equivalent to that of a press fit, on the shaft.
•
Bushings should not be re-bored as the concentricity (perfect center) will be lost. However, this may be possible for applications with a very low RPM,.
•
It is very IMPORTANT not to use any type of lubricant on any surface of the bushing or mating hub.
Bushing “L” (“H” - Cross Reference)
Bushing “JA to J” Inclusive
Bushing “M to W” Inclusive
Bushing “S”
Taper 3/4" per FT on Diameter - B -
Drives: Belts, Bushings & Sheaves
Baldor•Maska, and all other M.P.T.A. members, manufacture “QD” bushings conform to standardised dimensions in order to assure total interchangeability.
Illustration of QD Bushing SD - 1 ¾ Bushing “SD” Stock Bore 1 ¾ Keyseat 3/8 x 1/8** SK - 40
Bushing “SK” Stock Bore 40 (metric system) Keyseat 12x8
In some cases, as the bore increases in diameter, a shallow keyseat is provided due to insufficient metal thickness. This does not affect the bushing’s ability to transmit the load. The rectangular key, on flat key as it is also referred to, fits into the standard keyway in the shaft. SK 1-3/4 Bushing “SK” Stock Bore 1-3/4 Keyseat 3/8X3/16 **Shallow Keyseat.
41
Drives: Belts, Bushings & Sheaves
Standard Keyseat
Shallow Keyseat
Fig. 2.26: Keyseat
Types of Keyseat Note: The metric system does not refer to keyseat or keyway dimensions, as does the Imperial system; instead, dimensions are given for the key itself, which is rectangular in shape. This meets ISO standards.
For more explanations about bushing mounting and proper wrench torque, please consult the Installation & Maintenance Chapter.
Important English System: Square key rectangular keyway
Metric System: Rectangular key square keyway
Baldorâ&#x20AC;˘Maska offers three different types of bushings. The difference is based on the shaft diameter and the number of holes in the flange. Bushings L to J have the same number of holes and tapped holes. As the number of holes increases, the admissible torque on the sheave increases. Only bushings M to S have tapped holes to secure mounting.
42
2.4.2 Taper-Lock / Bore Bushings
They are not interchangeable with QD type bushings as the taper has a different angle and tapped holes in the hub are not in the same position (a split hole on the inside of the Taper lock hub vs. complete holes in the side of the QD hub). They are installed onto the shaft with set screws instead of standard bolts, as with QD Bushings.
Fig. 2.27: Taper-Lock
Drives: Belts, Bushings & Sheaves
With more than a million presently in operation, and initially limited to Europe, many companies world-wide now consider “Taper Lock” bushings as standard mounting components in the PT industry. This type of bushing does not have a flange, resulting in a compact, neat design that is preferred in certain applications.
Taper Lock Installation 1. Line up the smooth holes of the Taper Lock bushing with the three threaded holes in the sheave hub. 2. Thread the cap screws into the sheave hub. Note: The threaded holes in the bushing are used to remove the bushing.
As the cap screws are tightened, the bushing uniformly supports the hub along the entire circumference.
*
Frequently matched with sprockets, gears and timing belts; not necessary in V-Belt drives (“over-design”)
*
Suitable when excessive torque is applied (H.T.D.). Shear forces, that act on the screws when submitted to a excessive torque, do so over a larger surface area (diameter X length) instead of acting on the screws section area, as is the case with QD bushings.
2.4.3 Split Taper Bushings As compared to QD style, Split taper bushings were designed with two different features. First, there is a keyway on both sides of the barrel; the additional key that fits into the hub bears the pressure of shearing forces when torque is applied to the pulley, rather than acting on the set screws as with QD style bushings. Secondly, the Split taper bushing, as it’s name refers, is split only through the barrel or taper, and not through the flange. Split taper bushings are available with a simple or double split barrel. Shaft tolerances on applications have to be tighter with this type of bushing, as compared to QD bushings, which have greater flexibility and more uniform clamping force.
Fig. 2.28: Split Taper-Lock
43
2.5 Sheaves
Drives: Belts, Bushings & Sheaves
A sheave is defined as a V-grooved wheel used to transmit power or motion in conjunction with a V-belt. Some terms associated with sheaves are explained and illustrated below.
Groove
Shaped portion of a sheave; width, depth and angle are determined by the belt section used. Grooves are machined to meet standard tolerances.
Face Width catalog.
Distance measured across grooves - defined as « F » dimension in the Baldor•Maska
F
Outside Diameter Dimension measured around the outer sheave diameter defined as O.D. in the Baldor•Maska catalog. Pitch Diameter
Dimension measured around the sheave where the belt pitch line meets the sheave groove wall - defined as P.D. in the Baldor•Maska catalog. (see Fig. 2.29)
O.D. P.D.
Fig. 2.29: Sheave nomenclature
Datum System A new standard for classical V-belts and sheaves has been recently established wherein the title “Datum System” replaced the designation “Pitch System”, and “Pitch Diameter” became “Datum Diameter”. With reference to classical sheaves, the new “Pitch Diameter” value equals the sheave’s outside diameter seeing as the top of the belt arrives at the same height. The only exception is that of an “A” belt fitted with a “B” sheave, as the top of the belt is below the O.D. The “Datum System” is a compromise that the MPTA chose as the most accurate approximate value of the “Pitch Line” that serves as the standard for all belt manufacturers, so as to compensate for the slight differences between the different companies.
44
2.5.1 Sheave Body
Sheaves come in several forms, being either solid, webbed or arm design, depending on the outside diameter. The type of design is indicated in the Baldor•Maska catalog in the column “T” (type). The Baldor•Maska nomenclature or listing for the three classifications is as follows:
TYPE B - Block Diameter ~ 0" to 6"
TYPE W - Web Diameter ~ 6" to 14"
TYPE A – Arm Diameter ~ Over 14"
Drives: Belts, Bushings & Sheaves
The structure of the sheave body differs with size. Larger sheaves do not need to be solid or full in order to meet the mechanical requirements. For example, a 30-inch solid sheave would be very heavy and expensive. Baldor•Maska engineers determine the amount of material necessary in the construction of each part for highquality performance and security that meets industry standards.
Fig. 2.30: Sheave body
45
2.5.2 Sheave Classifications & Terminology: Sheaves must be designed to work efficiently with belts so as to deliver the necessary power. One of the most important factors is the design of the groove, as this is the belt contact zone. Standard identification classification for pulleys include the belt cross-section, number of grooves, and diameter. All Baldor•Maska sheaves can be grouped into three family-types.
Drives: Belts, Bushings & Sheaves
2.5.2.1 Light Duty Fixed & Bush Types Typical applications for this type of sheaves are pumps, mixers, compressors, conveyors, fans and blowers driven by motors up to 10 HP. Baldor•Maska does not manufacture or distribute pulleys for 2L belts as they do not need to be made from cast iron. Part Classification Number:
MA80X1/2
1 groove fixed bore (3L) & A (4L) V-belts O.D. = 8.0 in ½ Bore size
MBL77
1 groove bush type A (4L) & B (5L) V-belts L bushing O.D. = 7.7 in.
2MA80X1/2
2 grooves fixed bore A (4L) V-belts O.D. = 8.0 in
2MBL77
2 grooves bush type A ( 4L) &B (5L) V-belts L bushing
½ Bore size
46
O.D. = 7.7 in.
2.5.2.2 Adjustable/ F.H.P & Integral
Adjustable speed sheaves have one or two grooves with flanges that can be adjusted in width, so the belt moves in a radial movement within the groove (see illustration below). The principle of the adjustable pitch sheave is that one of the discs forming the V-shaped groove (in which the belt rides) Fig. 2.31: Adjustable sheave is movable. When the disc is moved closer, the belt rides higher in the groove and the pitch diameter of the sheave is larger. When the disc is moved apart, the belt rides lower and the pitch diameter becomes smaller, thereby producing a speed and ratio change.
Drives: Belts, Bushings & Sheaves
Adjustable sheaves offer the flexibility of adapting to varying driving shaft speeds through expansion of the pulley walls. In this way, the belt pitch used varies depending on the adjusted width of the sheave, resulting in the possibility of different speed ratios.
Fig. 2.32: Ratio variation – Close and Open
Important Baldor•Maska adjustable speed sheaves are used only for static pitch drive design.
• Adjustable Light Duty (H.V.A.C.) MVL This adjustable sheave is made to accommodate “3L”, “4L”, or “5L” belts. MVL adjustable light duty sheaves are designed to be used with F.H.P. (fractional HP) motors.
47
• Adjustable Pitch V-Belt Sheaves (8000 series)
Drives: Belts, Bushings & Sheaves
Baldor•Maska variable pitch V-belt sheaves are precision machined cast to provide maximum strength, and also ensure smooth and quiet operation. Grooves are accurately machined and smoothly finished to provide proper belt seating. They are used with “4L” or “A” and “5L” or “B” V-belts.
The datum diameter of the sheave is adjusted by loosening the set screws in the hubs and turning the threaded flange to the desired setting, then re-tightening the set screws. Both single and double groove adjustable sheaves permit variations of as much as 30% in speed. Both single and double grooves of the 8000 series are suitable for drives up to 25 hp.
Fig. 2.33: 2 groove 8000 series
• Adjustable Pitch V-Belt Sheaves (MVS) The MVS sheave offers several significant advantages. This sheave is available in 6 sizes and is designed for “A”-”B” or “5V” belts. Capacities range up to 40 hp at 1,750 rpm. The speed is infinitely variable, and as only one screw controls both movable flanges, accurate groove spacing is assured at all times. No lubrication is needed.
Fig. 2.34: MVS series Adjustable Pitch V-Belt Sheaves L
H
48
F
E
OUTBOARD
O.D.
INBOARD
E
Step pulleys (MAS)
- - -
Combination of 3 steps up to 5 (equal number of possible speed ratios) Designed for A, 4L & 3L V-Belts. From 2 to 6 inch diameters. Commonly used for varying speeds with drill presses & wood lathes.
Fig. 2.35: Step pulleys
Drives: Belts, Bushings & Sheaves
-
49
2.5.2.3 Classical & Narrow Belt Drives Classical (conventional) V-Belts are available in different types and designs. All classical V-belts with the same cross-section will operate in sheaves with grooves for that particular cross-section. Baldor•Maska offers a complete selection of classical sheaves. This family includes sheaves for classical V-belts and narrow V-belts. In addition, A/B Combination (code B) sheaves can be used with either “A”(4L) or “B”(5L) V-belts.
Drives: Belts, Bushings & Sheaves
Part Designation number: 2B64-SDS
2 grooves
1-3V8.00-SDS
1 groove
A(4L)&B(5L) V-belt
3V-belt
P.D. = 6.4 in
O.D. = 8.0 in
Bushing size SDS
(P.D. = 7.95 in) Bushing size SDS
1C110-SF
1 groove
3-5V4.40-SDS
3 grooves
“C” V-belt
5V-belt
P.D. = 11 in
O.D. = 4.4 in
Bushing size SF
(P.D. = 4.30 in) Bushing size SDS
4D150-F
4 grooves
4-8V44.5-M
4 grooves
“D” V-belt
8V-belt
P.D. = 15 in
O.D. = 44.5 in
Bushing size F
(P.D. = 44.3 in) Bushing size M
Important Due to the mechanical properties of grey and ductile cast iron, parts made from gray iron can operate up to maximum rim speeds of 6,500 feet per minute. Speeds in excess of this rate MUST use parts made from ductile iron, which has a maximum safe operating speed of 9,500 feet per minute.
50
2.5.2.4 Application Table by Classes Table showing all sheave families manufactured by Baldorâ&#x20AC;˘Maska with a limited list of industrial applications.
SHEAVES
MFAL
APPLICATIONS Fans, Blowers, H.V.A.C., Wood Processing Equipment, Pumps, Conveyors, Printing Machines, Machine Tools, Mixers and Compressors Up to 3 hp
Light Duty Fixed & Bush Types MA-MB-MAL-MBL
Fans, Blowers, H.V.A.C., Wood Processing Equipment, Pumps, Conveyors, Printing Machines, Machine Tools, Mixers and Compressors
Drives: Belts, Bushings & Sheaves
FAMILY
Up to 10 hp
MVL
Fans, Pumps, Conveyors, Machine Tools, Mixers and Compressors Up to 2 hp
Adjustable/ F.H.P & Integral
8000
Fans, Pumps, Conveyors, Machine Tools, Mixers and Compressors Up to 25 hp
MVS
Wood Processing Equipment., Air Moving Equipment, Conveyors Systems, Bottling Plant Up to 40 hp
Classical & Narrow V-Belt Drives
A/B-C-D-3V-5V-8V
Pulp and Paper Mills Equipment, Saw Mill Equipment, Mining Equipment, Crushers, Pumps, Compressors Screens, Extruders Up to 500 HP
51
2.5.3 Balancing Standards (MPTA)
Drives: Belts, Bushings & Sheaves
2.5.3.1 General Information When a unit turns in a circular path, a hypothetical inertia force known as centrifugal force exerts a pulling influence on the element away from the center during the rotational movement. This can be illustrated by tying an object to one end of a rope and the other end to a rotating axis of the center of the part. As the speed increases, the object is lifted into the air until it attains a horizontal position.
M
Fig 2.36: Centrifugal force
In power transmission systems, if the mass of a rotating body is unevenly distributed around the rotation axis, the centrifugal forces will be unbalanced. This causes vibration, noise and reduced components service life. A secondary operation called balancing is carried out to minimize these effects by altering the center of gravity to correspond with the axis of rotation of the center of the part so as to be evenly distributed. Every rotating component is eventually unbalanced to some degree; parts manufactured with absolute balance would be a costly process for the consumer. For this reason, it must be determined to what degree a sheave must be balanced for the industrial application in question. We will now consider the two types of balancing in use in the industry and approved by MPTA: single-plane and double-plane operations.
2.5.3.2 Static or Single-Plane Balancing Single-plane balancing is a basic secondary operation and commonly used method that is recommended for all products. A one-plane absolute balanced system can be illustrated by a uniform disk with the center mass perfectly aligned with the shaft axis.
Balanced Force on Shaft
Axis of rotation (Shaft)
Center of gravity concentric with the axis of rotation Fig. 2.37: Balanced Force on shaft
52
However, should the disk have a hole at a certain distance from the center, the system would be unbalanced. To illustrate, if a rod with an iron ball was attached to one side of a shaft, the ball could be compared to excess weight on one side of the disk. Unbalanced Force on Shaft
Unbalanced Equivalent Mass
Drives: Belts, Bushings & Sheaves
Axis of rotation (Shaft)
Hole in Disk Shifts Center of Gravity to the Opposite Side
Fig. 2.38: Unbalanced Force on shaft As the rotational speed increases, the centrifugal force causes the shaft to feel the pull of the non-balanced disk. In order to offset the situation, a counter weight must be added directly opposite to the extra mass. In this case, an identical amount of mass must be eliminated by boring another hole opposite the first one.
Unbalanced Force on Shaft
Drilled Hole for Balanced
Unbalanced Equivalent Mass
Axis of rotation (Shaft)
Hole in Disk Shifts Center of Gravity to the Opposite Side
Balanced Mass
Fig. 2.39: Balanced Force on shaft
A
A
The method for determining where the hole should be bored in order to balance the part or sheave consists of placing it on an horizontal shaft suspended from two carefully levelled vertical supports, as illustrated in Figure 40. If the sheave is not balanced, the shaft will turn until the heavier side is on the bottom. A hole (or holes) is (are) bored until the sheave is in static balance, or remains mobile regardless of what position it is placed in.
Fig. 2.40: Balancing â&#x20AC;&#x201C; Vertical position
53
A second method that is also used to balance a sheave consists of mounting the sheave horizontally on a vertical arbor placed on table B, which is supported by a knife-edge bearing. A pendulum C is suspended from table B. To test the static balance of the sheave, it is counter-balanced until the indicator is stable in the center of the stationary scale D. There are several other devices for testing static balance that are similar in design to these standard principles.
B
Drives: Belts, Bushings & Sheaves
The nomograph below shows the maximum speed limit (in RPM) for standard statically balanced sheaves of a given diameter and face width. To use the nomograph, lay a straightedge ruler between the diameter and face width readings and take the maximum RPM recommended for standard balance where the ruler edge crosses the slanted line. If the RPM of the application exceeds the maximum recommended, two-plane balancing should be carried out.
C D
Fig 2.41: Balancing â&#x20AC;&#x201C; Horizontal position 64 60 55 50
500
40
600
640
700 800
725 35
860
30 28
1160
24
1600
20
1750
18
7 6 5 4
12 10 9 8 7 6 5 4.5 4 3.5
2200 2400 2600 2800 3000
14
8
1800 2000
16
10 9
1400
1460
22
1000 1100 1200
26
12
900
960
36 32 28 24 20 18 16 14
2900 3500
3 2.5
3400 3800
4200 4400 4600 5000
MAX RPM RECOMMENDED FOR STANDARD BALANCE
2
1.5
Fig. 2.42: Nomograph-Max RPM for one-plane balancing
54
FACE WIDTH IN INCHES
45
To determine whether dynamic balancing is recommended, the following formula can also be used:
RPM = 15500 â&#x2C6;&#x161;D â&#x20AC;˘ F
The resultant RPM is the maximum recommended operating RPM for sheaves with a single plane balance.
Example 2.4
If a 20 in. x 10 in. diameter face width sheave runs faster than 1,100 rpm, dynamic balancing is recommended. The result obtained with the formula is 1,096 rpm.
2.5.3.3 Dynamic or Two-Plane Balancing
Drives: Belts, Bushings & Sheaves
D is the Diameter in inches F is Face Width in inches
A sheave may have undergone single-plane balancing and yet not be sufficiently balanced for certain operations, such as when the sheave rotates at high speeds and has a relatively large face width. Under these conditions a different type of balancing is necessary. Two-plane balancing is an operation where balance corrections are made and measured at two planes on the component axis (Fig. 2.43). (This is not as fully dynamic balancing, but rather partially dynamic balancing.) The areas affected must be well separated to effectively produce a two-plane balance (see MPTA norm). Hence, two-plane balancing acts on non-balanced units of masses which do not lie within a narrow plane; instead they are spread along the length of the component.
Unbalanced Force on Shaft
Unbalanced Equivalent Mass -1st Plane
Axis of rotation (Shaft)
Hole in Disk Shifts Center of Gravity to the Opposite Side
Unbalanced Equivalent Mass -1nd Plane
Fig. 2.43: Unbalanced Force on shaft â&#x20AC;&#x201C; Two planes
55
Drives: Belts, Bushings & Sheaves
Factors such as the mass of the imbalance, the distance from the rotational center, the speed (RPM), and the distance between the imbalance along the axial length, all affect the degree of imbalance and must be examined in order to justify two-plane balancing. In general, the longer a component in relation to its diameter, the greater the possible need for two-plane balancing at a certain speed. Once again we will represent an equivalent situation using a rod and iron ball on each end of the shaft. When they are rotated, not only does the weight cause a pull on the first rod, but because there are two rods pulling at each end of the shaft, the rotating shaft also vibrates. In this case, the application as shown in Fig. 2.43 would appear to be in balance if submitted to only single-plane balancing operations. However, two-plane balancing would be needed with this example wherein the sheaves are balanced with reference to planes (Fig. 2.44)
In conclusion, the type of balancing required, whether it be single-plane or 2nd plane, is usually determined by the axial length of the parts. Two-plane balancing is recommended only in certain cases where the product face width is relatively large and the operational speed relatively fast, or where balance is considered very critical. Two-plane balancing is considered as an option and must be specifically requested. When non-balanced portions are at opposite ends or in different planes, balancing must be carried out so as to counteract the centrifugal force of the sheaves at high speeds. Dynamic Balancing then consists of positioning the counter-balancing weights according to their weight, their position on the axis of rotation and their angular positions.
Drilled Holes for Balanced
Unbalanced Equivalent Mass -- Balanced Mass 1st Plane
Axis of rotation (Shaft)
Hole in Disk Shifts Center of Gravity to the Opposite Side
Balanced Unbalanced Mass Equivalent Mass -1nd Plane
Fig. 2.44: Balanced Force on shaft â&#x20AC;&#x201C; 2nd planes
56
Chapter 4 INSTALLATION & MAINTENANCE 4.1 Bushing Mounting 4.1.1 Types of Mounting There are two ways to mount a bushing with a sheave onto a shaft that leaves the cap screws accessible from the outside; either way is acceptable.
Bushing flange toward machine or motor 1. Align tapped holes in bushing flange with drilled holes in sheave hub.
3. Position assembly on shaft and tighten cap screws progressively and uniformly.
To remove
Installation & Maintenance
2. Insert cap screws through drilled holes in sheave hub and thread loosely into tapped holes in bushing flange.
1. Remove cap screws and thread into tapped holes in sheave hub. Tighten progressively until bushing is free from sheave taper. 2. Remove assembly from shaft.
Bushing flange away from machine or motor 1. Align drilled holes in bushing flange with tapped holes in sheave hub. 2. Insert cap screws through drilled holes in bushing flange and thread loosely into tapped holes in sheave hub. 3. Position assembly on shaft and tighten cap screws progressively and uniformly.
To remove 1. Remove cap screws and thread into tapped holes in bushing flange. Tighten progressively until bushing is free from sheave taper. 2. Remove assembly from shaft.
57
IMPORTANT When mounting, do not use any lubricant. Tighten screws with the appropriate wrench torque.
4.1.2 Tightening Tighten screws evenly and progressively. Never allow the sheave to be drawn into contact with the bushing flange. If too much pressure is applied when tightening the screws, excess strain will be created in the hub causing it to crack. For the correct wrench torque, please refer to the following table.
Installation & Maintenance
PROPER WRENCH TORQUE TO TIGHTEN SCREWS
58
BUSHING No.
SCREW SIZE
TORQUE WRENCH
OPEN END OR SOCKET WRENCH
TORQUE CAPACITY
Inches
Ft.-Lbs.
LENGTH Inches
Pull / Lbs.
In.-Lbs.
L
1/4
6
4
18
1,200
JA
no. 10
5
4
15
1,000
SH
1/4
9
4
27
3,000
SDS-SD
1/4
9
4
27
5,000
SK
5/16
15
6
30
7,000
SF
3/8
30
6
60
11,000
E
1/2
60
12
60
20,000
F
9/16
75
12
75
30,000
J
5/8
135
15
135
45,000
M
3/4
225
15
180
85,000
N
7/8
300
15
240
150,000
P
1
450
18
300
250,000
W
1 1/8
600
24
300
375,000
S
1 1/4
750
30
300
625,000
4.2 V-Belts & Sheaves With proper installation and maintenance, V-belts will have a longer, more cost-effective service life. Main guidelines on how to correctly install a V-belt drive will now be discussed.
4.2.1 Mounting Structure Drive tensioning can impose excessive load on the structure that supports the motor, reducer, and other driven equipment. For example, a 100-hp drive that runs a 1,760-rpm motor, the force induced by belt tension can easily exceed 2,500 lb. Itâ&#x20AC;&#x2122;s important therefore to design the mounting structure in an appropriate manner to support this load without deflection under static and dynamic load conditions. Otherwise, all of the care taken during installation would be futile.
V-belt drive units should allow for an adjustment of the distance between the driving and the driven sheaves. The center distance must have a minus allowance to permit easy installation of the V-belts in order to avoid any strain or damage and a plus allowance to allow for an adjustment to the desired tension. In most cases, the minus allowance is 1.5% of the center distance and the plus allowance is 3%.
Installation & Maintenance
4.2.2 Center Distance Adjustment
Motor base or motor slide rails are the most common adjustable mechanisms for tensioning a drive. These devices are available in a variety of models, including spring-loaded versions that automatically compensate for belt elongation. For installations that do not allow for an adjustable center distance, the use of an idler pulley is recommended.
Example 4.1 If the center to center distance of a drive belt system is 40 in., calculate the allowance required for installation and removal of the belt drive.
Answer: The minus allowance = 40[in] x 1.5% = 40 x 0.05 = 2 in. The plus allowance = 40[in] x 3.0% = 40 x 0.03 = 1.2 in. The maximum value of the center to center distance should therefore be at least 42 in. and the minimum distance should be equal to or less than 38.8 in.
59
4.2.3 V-Belt Installation Step 1 : Replacing V-belts -
Reduce the center-to-center distance between the driver and the driven sheaves by moving the motor-plate inwards. This reduces tension and allows for slack in the belt between the sheaves.
-
Remove the used belts from the sheaves and examine the groove surfaces for any damage.
Installation & Maintenance
Step 2: Sheave Inspection -
Check for wear on the side walls, cracking, reinforcing nylon cords and oily surfaces.
-
The wear of the V-groove in the sheave can be measured with a “go-no-go” belt gauge available from Baldor•Maska Part No. 006346.
It’s very important to know if the V-groove walls have been subjected to excessive strain caused by improper belt tension or misalignment between the driving and the driven sheaves. If the V-groove surface has deteriorated or been damaged, the defective parts must be replaced with new ones. Worn sheaves can reduce belt life by as much as 50%. Step 3: Cleaning Sheaves -
Use a stiff brush to remove all foreign matter from the sheave that could abrade belts. Do not use brushes that could scratch the surface of the groove walls as these scratches can graze the V-belt’s outer skin when rotating, thus systematically destroying it.
-
Pulley grooves should be free from rust, oil, grease, dust and burrs.
Step 4: Sheave Alignment
Simple alignment for angular and parallel offset
The question of alignment is not as critical in V-belts drives as with other systems, for example they are inherently more forgiving of misalignment than synchronous belt drives. Nonetheless, before installing V-belts, verify that the sheaves are properly aligned and parallel as a prerequisite to proper tensioning. Poor alignment renders accurate tensioning impossible and causes a load imbalance across the belt span. The first step consists of verifying whether the drive shafts are parallel, and the sheaves are in the proper position on the axis. This procedure can by checked with sufficient accuracy through use of a machinist’s straightedge ruler, or by placing a tightly drawn piece of string, across the faces of the sheaves to see if all four points of contact are made.
60
However, if there is a difference in the side wall thickness of the sheaves, this method will not be sufficiently accurate. For this reason, this method will be effective only when the sheaves are a matched pair. When this is not the case, the sheaves must be aligned parallel by their grooves. This is the preferred alignment method with any drive. In order to determine what degree of misalignment is acceptable, and at what point it becomes excessive, alignment must be quantified and compared to the belt manufacturerâ&#x20AC;&#x2122;s recommendations for various drives. An example of this follows:
Installation & Maintenance
Fig. 4.1: Alignment â&#x20AC;&#x201C; Use of a straightedge or a string
Maximum allowable offset Type Angular offset (deg.)
V-belt 0.5
Synchronous belt 0.25
Fig. 4.2: Angular offset
61
Type Parallel offset (in. / ft. of center distance.)
V-belt
Synchronous belt
0.1
0.05
Fig. 4.3: Parallel offset
Installation & Maintenance
Example 4.2 With a 5 ft. center distance, what is the allowable parallel offset for a V-belt drive? Answer: V-belt parallel offset = 5 x 0.1 = 0.5 in. max
Other types of misalignment The preceding procedure illustrated a quick method for checking sheave alignment as seen from one angle only. This method is useful only when the engine shafts are parallel horizontally in a straight line as seen in Fig. 4.1. In fact, sheaves that have been installed on a shaft can be misaligned if the driven shaft does not have the same angle as the driver shaft (for example, dips towards the ground) as opposed to the horizontal surface (Fig. 4.4). In this case, the two shafts would have to be placed parallel to each other at this plane. To verify, you would have to look from another angle and repeat the steps for checking misalignment with a level gauge. This type of misalignment should not be confused with a 1/4th or 1/8th turn drive design.
Fig. 4.4: Other type of misalignment
62
Step 5: V-Belt Installation -
Verify that the replacement belts are of the corresponding size. The V-belt cross-section must be compatible with the V section in the groove.
As discussed in chapter 2, V-belts are made of different materials and of varied design depending on the application. In addition, similar cross-section belts from different manufacturers do not necessarily have the same features and can differ in stretch capacity and friction coefficients. For this reason, belts from the same manufacturer should be used with multiple groove sheaves.
-
Adjust the center-to-center distance in order to slide the belts over the sheaves. The motor must shift enough to allow the belts to be removed or installed without forcing them.
-
Never lever belts over the sheave grooves as this may injure the reinforcements cords.
-
Install the new belts over the sheaves so that the slack side of all belts is on the same side, either the top or the bottom of the drive. Increase the drive center distance to pre-tension the belts (see next section for correct tensioning).
-
Installation & Maintenance
Never use new and used V-belts on the same design, even if the used belts seem to be in good shape. Belts should always be installed in matched sets. If one belt needs to be changed, the whole set should be replaced. If the V-belts are not of the exact same length, it will result in rapid wear of the new belts and unequal distribution of the load, thus reducing belt life significantly.
4.2.4 Tensioning One of the most important factors that determines the efficiency of a V-belt drive is proper belt-tensioning. Insufficient belt tension will cause belt slippage, resulting in reduced pulling capacity. To increase tension, as seen earlier, we have merely to increase the center distance. However, before attempting to tension any drive, it is imperative that the sheaves be properly installed and aligned as stated in a preceding section (section 4.2.2). The effects of low tension on a synchronous belt are equally disastrous. Low tension allows the belt teeth to ride up on the sprocket teeth, thus placing severe stress on the teeth. Under heavy loads, the drive can jump teeth (ratchet), which leads to rapid belt failure. If too much tension is applied to the V-belts, the service life of belts and bearings will be considerably reduced. Drive tension that is too high can have other, far-reaching consequences. Undue stress is placed not only on the belt, but the bearings and shafting as well. Early belt failure is the norm, as excessive tension overstresses belt cords. Bearing overload also leads to early failure, and can result in motor and reducer damage.
â&#x20AC;˘ â&#x20AC;˘ â&#x20AC;˘
Incorrect tension can destroy belts and equipment. Alignment affects belt tension. Tension can be measured with a simple spring scale or acoustical instrument.
63
4.2.4.1 Measuring Techniques V-belts and synchronous belts have been greatly improved compared to only a few years ago. They deliver a lot more power in a smaller package. In order to benefit from this improvement, it is essential that they be correctly aligned and tensioned. All it takes is a few simple tools and techniques to easily and accurately tension a drive, in order to yield the high performance designed into them.
Deflection Force Method
Installation & Maintenance
The most common method for tensioning adjustment is with a tension meter or another type of spring scale tool. This tool measures the deflection force when pressed to the open span of the belt drive. Carrying out the following procedures will obtain adequate tensioning for most V-belt drive requirements: Step 1:
Following the belt installation procedure already discussed, arrange the belts so that both the top and bottom spans have about the same sag. Apply tension to the belts by increasing the center distance until the belts are snug (Fig. 4.5).
Step 2:
Operate the drive a few minutes to seat the belts in the sheave grooves. Observe the operation of the drive under the highest load condition (usually starting). A slight bowing of the slack side of the drive indicates proper tension. If the slack side remains taut during the peak load, the drive is too tight. Excessive bowing or slippage indicates insufficient tension. If this is the case, stop the drive and tighten the belts until all the slack is taken up. Further increase the tension until only a slight bow on the slack side is apparent while the drive is operating under load.
Step 3:
Stop the drive and use the meter to measure the force necessary to depress one of the center belts 1/64inch for every inch of belt span. For example a deflection for a 50 inch belt span is 50/64 or 25/32-inch. If the deflection exceeds 50/64 in. for every inch of span length, the drive needs to be tensioned higher. If the deflection is less, drive tension is excessive and should be reduced.
64
√
t = C2 -
Installation & Maintenance
Fig. 4.5: Belt Tension – Deflection force method
D1 - D2 2
The amount of force required to deflect the belt should match up with the deflection force data noted in the chart below. Note that the deflection force varies with V-belts from the initial run-in values, which are higher (reflecting higher run-in tensioning) than the normal values obtained after the run-in period.
Standard V-belt Tensioning Deflection Force Table For Baldor•Maska Blue Flex Belts Belt Cross-Section
Smaller Pulley Diameter Range (in.)
Deflection Force Run-in ( lbs )
Normal ( lbs)
A
3.0 - 3.6 3.8 - 4.8 5.0 - 7.0
3 - 3/8 4 - 1/4 5-1/8
2 - 1/4 2 - 7/8 3 - 3/8
AX
3.0 - 3.6 3.8 - 4.8 5.0 - 7.0
4 - 1/8 5 6
2 - 3/4 3 - 1/4 4
B
3.4 - 4.2 4.4 - 5.2 5.4 - 9.4
4 6 7 - 1/8
2 - 5/8 4 5 - 1/4
BX
3.4 - 4.2 4.4 - 5.2 5.4 - 9.4
5 - 1/4 7 - 1/8 9
3 - 1/2 4 - 3/4 6
C
7.0 - 9.0 9.5 - 16.0
11 - 1/4 15 - 3/4
7 - 1/2 10 - 1/2
CX
7.0 - 9.0 9.5 -16.0
13 - 1/2 17 - 1/2
9 11 - 3/4
65
D
12.0 - 16.0 18.0 - 22.0
24 â&#x20AC;&#x201C; ½ 33
16 - 1/2 22
E
21.6 - 27.0
48
32
3V
3.40 - 4.20 4.20 - 10.6
6 7
4 5
3VX
2.20 - 3.65 4.12 - 10.6
7 8
5 6
5V
7.10 - 10.9 11.8 - 16.0
16 20
8 - 12 10 - 15
5VX
4.40 - 10.9 11.8 - 16.0
18 22
10 - 14 12 - 18
8V
12.5 - 17.0 18.0 - 22.4
36 40
18 - 27 20 - 30
Installation & Maintenance
Step 4: Restart the unit and allow the belts to seat themselves in the sheave grooves.
Step 5: Stop the unit after a few hours and measure all belt tensions (Refer to Step 3). Note: During the initial run-in period, it can be expected that the belt tension will need to be re-adjusted before obtaining the correct deflection. Repeat the procedure until all of the slack is taken out of the belts. Step 6: Restart the unit. Steps 4 and 5 are often overlooked during belt installation, but re-checking the tension is a very important step in the efficient operation and maintenance of V-belts. As such, it is worth taking a little extra time to do so, as you will see in the next step. Step 7: See section 4.2.4.2 on Run-in period
Elongation method Belt tension can be measured by marking lines 10 inches apart across the beltsâ&#x20AC;&#x2122; top surfaces at 90 degrees to the length on an installed belt. Apply tension until the gap increases by the desired percentage. For 2 per cent tension, the lines on the tensioned belt would be 10.2 inches apart. Mechanical failure may result when belt tensioning is excessive; 2 to 2.5 per cent elongation should be regarded as the limit. This procedure is normally used to tension drives using banded belts that require a deflection force beyond the range of conventional equipment. The elongation method is not suitable for tensioning synchronous belts that are constructed with fiberglass or aramide cords that have almost no elasticity. This method is accurate only when using long belts; the deflection method discussed above is the standard, recommended procedure to follow.
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4.2.4.2 Run-in Period The first 48-hours following installation is the most critical time for V-belt tension verification. The initial stretch is taken out of the belt during this run-in period, and it settles deeper into the groove of the sheave after the soft rubber surface of the beltâ&#x20AC;&#x2122;s outer envelope is abraded away causing the belt to run slack. To avoid considerable slippage, frictional burning, and other irreparable damage the slack on the new belts must be taken up.
Installation & Maintenance
It is very important to verify the tension on a new drive frequently over the first few days by observing the slack side. Adjust the belt according to the normal tension data given in the chart until all signs of stretching have been eliminated. This process must be repeated until all of the stretch has been eliminated. After operating for several days, the belts will seat themselves in the sheave grooves and it may be necessary to readjust the tension so that the drive shows a slight bow on the slack side. Being vigilant at this stage will eliminate early damage and promote longer belt life. It will also improve the mechanical efficiency of the motor, and the driven mechanical equipment, by reducing wear on rotating mechanical components.
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4.2.5 Idler Pulleys The preferred location for an idler pulley is always on the slack side of the drive (Fig. 4.6). An inside idler imposes less stress on the belt, and should be located near the larger sheave to minimize the reduction in the arc of contact with the smaller sheave or sprocket. If an outside idler is the only option, locate it near the smaller sheave as this enhances the arc of contact with the smaller sheave. It is important that the idler diameter is not inferior to the smallest sheave in the drive. • •
An inside idler decreases the arc of contact on adjacent wheels. An outside idler increases the arc of contact on adjacent wheels.
slack IDLER DRIVER
tight
OUTSIDE IDLER slack IDLER DRIVER
tight
Installation & Maintenance
INSIDE IDLER Fig. 4.6: Idler – Recommended position
Idlers are occasionally used in the design of conventional V-belt and timing belt drives for various reasons: 1. 2. 3. 4. 5.
To provide take-up for fixed center drives. To clear obstructions. To subdue belt whip on long center distance. To maintain tension. To improve a poor design, such as a very small sheave driving a very large sheave.
If at all possible, the use of idlers should be avoided. They either reduce the horsepower rating or shorten belt life. However, as stated earlier, idlers should be located, if at all possible, on the slack side of the drive. This is especially true when spring loaded or weighted idlers are being used, as this keeps the spring force or the weight to a minimum.
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Make V-belt drive inspections periodically.
•
Check belt tension regularly.
•
Never apply belt dressing, as this will damage the belt and cause early failure. They often have a solvent effect upon rubber compounds, which may temporarily increase friction, but does so at the expense of rapid V-belt deterioration.
•
V-belts should be kept clean and free of oil, grease and dust.
•
For outdoor machinery, avoid exposing belts to direct sunlight.
•
Factors affecting ultimate belt life include temperature (an increase in temperature of 10°C or 18°F can cut longevity by 50%), the power pulse characteristics of the engine, abrasives and chemical contamination, abnormally tight or loose tensioning, worn pulleys, and misalignment.
•
High temperatures are harmful to long V-belt performance. For this reason, avoid tight fitting mounting and safety guards that may obstruct the ventilation openings.
Installation & Maintenance
4.2.6 Maintenance
The essential factors to watch for when using belts are: keeping them clean, any significant changes in temperature, the humidity level, and the presence of chemical products or fumes. The degree to which these elements are present directly affects belt life and performance. Many applications require belts with a resistant substance or fabric casing as a protection against acids and solvents.
4.2.7 Belt Storage Storage conditions have a direct influence on V-belt life. Inadequate storage may cause damage to belts and thus reduce belt life. •
Storing belts on sheaves saves space and is the best way of storing. Shorter belts may be stacked in single file one on top of the other, while long belts should be folded 3 or 5 times.
•
V-belts should be stored without stress i.e. without tension, pressure or any other form of deformation.
•
Damp storage rooms are unsuitable. This leads to mildew formation which deteriorates the belt’s jacket.
V-belts should be stored in a cool and dry place with temperatures varying from 10º to 20º C. A relative humidity of between 20% - 60% offers the best storage conditions as humidity may cause a fungus to form on belts. They should also be kept away from direct sunlight or arc welders and high voltage apparatus.
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4.3 Typical Problems 4.3.1 Drive Misalignment Belt drive misalignment is one of the most common causes of premature belt failure. It reduces belt drive performance and causes uneven wear to one side of the belt. A belt can be damaged in as little as one hour, to a couple of days, if the sheaves or pulleys have been improperly aligned during installation. All drive components should be checked to verify that they are all well-tightened and in place. If the misalignment comes from design, the unit should be revised in order to eliminate the problem. Misalignment may force a belt to roll over in the sheave, or it can throw the entire load onto one side of the belt, thus stretching or breaking the cords.
Installation & Maintenance
Angular misalignment (Fig. 4.1) results in accelerated belt/sheave wear and potential stability problems in single groove V-belt drives. If the same problem occurs with a multiple groove pulley, unequal load sharing results to each belt and leads to premature failure.
4.3.2 Sheave Cracked in Hub When mounting a bushing by tightening the screws, excessive torque can crack the sheave as a result of too much pressure against the hub. Never allow the sheave to be drawn into contact with the flange of the bushing, and never lubricate the bushing or the sheave (lubrication can increase the lateral forces up to seven times with the same torque values on cap screws).
Fig. 4.7: Excessive torque - High pressure against the hub
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4.3.3 Vibrations
Vibrations are the most serious problem that can develop with a drive design. There are two reasons as to why this is such a difficult problem: First of all, the cause of the problem is very tricky to discover, as all of the mechanismâ&#x20AC;&#x2122; components could be the source of the vibrations. Secondly, vibrations involve the entire drive design; the problem is thus not limited to the sheave or belt, which are easily replaced.
Installation & Maintenance
Fig. 4.8: High level of vibration
Step One involves finding the main source of vibrations â&#x20AC;&#x201C; is the entire design out of balance? Is the design inaccurate as far as the choice of components is concerned? Has there occurred a mechanical breaking of a part, etc.? The second step is to apply the required corrections. However, if the designer has to deal with a high level of vibration, then the use of specialized components should be considered (rolling joint, coupling, etc.).
4.3.4 Over Tension Over belt tension results in accelerated wear of the shaft bearings. The solution is to reduce the center distance to lower the tension, as discussed in Section 4.2.4.
Fig. 4.9: High tension â&#x20AC;&#x201C; Overloaded bearings
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4.3.5 High Ratio with Short Center to Center Distance In order to increase the arc of contact on a drive designed with a high ratio, it will be necessary to install an idler pulley. This tensioning device, as mentioned, should be installed on the slack side.
Wron
Installation & Maintenance
g Des
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ign
Fig. 4.10: Increase the arc of contact
4.4 Couplings
Rigid couplings are used to connect shafts that are precisely aligned, whereas flexible couplings and U-joints accommodate varying degrees of misalignment between shafts. U-joints are used with applications where power must be transmitted from an input shaft that is situated at a certain angle to the output shaft.
Installation & Maintenance
Couplings are a very practical device designed to transmit mechanical power from one shaft to another shaft by connecting them together, but they are also designed to accomplish several other tasks. There are more than fifty types of mechanical shaft couplings used in different industrial applications, and they can be divided into three main categories: (1) flexible, (2) rigid and (3) universal joints.
In many applications couplings may be able to accommodate misalignment and dampen vibrations or shock load. For this reason, most industrial applications use flexible couplings, rather than the rigid types, because of these multiple practical functions.
4.4.1 Flexible Coupling Types Initially, flexible couplings were divided into two types : non-lubricated and lubricated. The non-lubricated model is fabricated for the most part from elastomeric or plastic and the metallic parts require lubrication. 1. Non-lubricated
-Disc -Elastomeric
2. Lubricated
-Grid (spring) -Gear
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The most commonly used couplings are those that allow for the greatest flexibility (minor shaft misalignment and axial capacity) while producing the lowest external loads on equipment. The type of coupling selected depends on each one’s capacities and characteristics with regards to each application’s needs. The most important characteristics taken into consideration are often the power and speed capabilities. Several parameters must be considered in order to make the best coupling(s) choice: 1. 2. 3. 4. 5. 6. 7.
Type of prime mover and load characteristics Shaft diameters and key sizes or spline configuration Horsepower rating of the equipment to be coupled Maximum operating speed Maximum operating misalignment Clearance limitations Ambient conditions
Installation & Maintenance
Metallic types are best suited to applications that require or permit: •
Torsional stiffness
• • •
Operation in relatively high ambient temperatures and/or presence of certain oils or chemicals; Electric motor drive only (metallic types are not generally recommended for gas/diesel engine drives); Relatively constant, low-inertia loads (generally not recommended for driving reciprocal pumps, compressors, and other pulsating machinery)
Elastomeric types are best suited to applications that require or permit: • • • •
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Torsional softness (absorbs shock and vibration, improved tolerance of engine drive and pulsating or relatively high-inertia loads) Greater radial softness (allows more angular misalignment between shafts, puts less reactionary or side load on bearings and bushings) Lighter weight/lower cost, in terms of torque capacity relative to maximum bore capacity Smoother and quieter
4.4.2 Shaft Misalignment There are four types of shaft misalignment: parallel, end float, angular and torsional deflection.
• Parallel Offset Misalignment Shaft center lines are parallel and do not meet.
• End Float Shaft floats or experiences longitudinal movement.
Installation & Maintenance
• Angular Misalignment
Shaft center lines meet at an angle.
• Torsional Deflection Twisting load around shaft; one shaft moves slightly ahead of the other one.
• Damping vibration Also, some types of flexible couplings dampen vibrations and reduce noise.
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4.4.3 Elastomeric Element Couplings Elastomeric couplings transmit torque between two shafts by means of an elastomeric material. (natural rubber, urethane, etc.). These flexible elements may be primarily stressed in tension, compression, shear or any combination of stresses. The Maskaflex coupling uses shear stress and generally produces lower shaft loads when subjected to parallel offset misalignment because it is tortionally softer.
Elastomeric Coupling Alternatives
Installation & Maintenance
Compression-type couplings generally offer two advantages over shear types. First, because elastomeric couplings have a higher load capacity in compression than shear, compression types can transmit higher torque and tolerate greater overload. Second, they offer a greater degree of torsional stiffness, with some designs approaching the positive-displacement stiffness of metallic couplings. Shear-type couplings in turn offer two general advantages over compression types. First, they accommodate more parallel and angular offset, while inducing less reactionary bearing load. This makes them especially appropriate where shafts may be relatively thin and susceptible to bending. Second, they offer a greater degree of torsional softness, which in some cases provides greater protection against the destructive effects of torsional vibration. The Maskflex coupling shown here is a shear-type coupling. The MASKAFLEX coupling is an elastomeric coupling composed of two flanges. This coupling has a flexible rubber tire with tension-member cords, such as nylon, that carry the load. These cords are vulcanized into the tire shape. This model is also called a tire coupling, named after it’s resemblance to a car tire.
Fig 4.12: Maskaflex coupling
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The two flange hubs are equipped with clamping plates, which grip the tire shaped element by its inner rims. The tire coupling is torsionally soft and can damp vibrations. High radial softness accommodates angular misalignment up to 4 degrees and parallel offset up to 1/8”. This unique elastomeric coupling has the capability to allow up to ¼” of axial shaft movement. These properties cover a wide variety of applications, such as those using internal combustion engines. Design variations are available, including an inverted tire coupling in which the tire element arcs inward toward the axis that has been designed for higher RPM service.
MASKAFLEX coupling tires are manufactured from; • Standard (Natural Rubber): This unit is designed for temperatures between 42C° and +82C°.
Power Transmission Fundamentals
Notes
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Power Transmission Fundamentals
Notes
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Power Transmission Fundamentals
Notes
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Power Transmission Fundamentals
Notes
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Contact your nearest Baldor Sales Office at these World Wide locations, or visit www.baldor.com United States Arizona Phoenix Power Reps, Inc. 4211 South 43rd Place Phoenix, AZ 85040 Tel.: 602-470-0407 Fax: 602-470-0464 Arkansas Clarksville Wade Black & Associates, Inc. 1001 College Avenue Clarksville, AR 72830 Tel.: 479-754-9108 Fax: 479-754-9205 California Hayward Golden Gate Baldor 21056 Forbes Street Hayward, CA 94545-1116 Tel.: 510-785-9900 Fax: 510-785-9910 Commerce Power Reps, Inc. 6480 Flotilla St. Commerce, CA 90040 Tel.: 323-724-6771 Fax: 323-721-5859 Colorado Denver Rocky Mountain Baldor, Inc. 3855 Forest Street Denver, CO 80207 Tel.: 303-623-0127 Fax: 303-595-3772 Connecticut Wallingford EMS, Inc. 65 S. Turnpike Road Wallingford, CT 06492 Tel.: 203-269-1354 Fax: 203-269-5485 Florida Tampa J.K. Kessler & Assoc. Inc. 3906 East 11th Avenue Tampa, FL 33605 Tel.: 813-248-5078 Fax: 813-247-2984 Georgia Alpharetta Sarka Sales Agency, Inc. 62 Technology Drive Alpharetta, GA 30005 Tel.: 770-772-7000 Fax: 770-772-7200
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Indiana Indianapolis The Scott Group, Inc. 5525 W. Minnesota St. Indianapolis, IN 46241 Tel.: 317-246-5100 Fax: 317-246-5110
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Pennsylvania New Kensington Baldor Pittsburgh 159 Prominence Drive New Kensington, PA 15068 Tel.: 724-889-0092 Fax: 724-889-0094
Iowa Des Moines Baldor Industrial Solutions 1800 Dixon St., Suite C Des Moines, IA 50316 Tel.: 515-263-6929 Fax: 515-263-6515 Maryland Elkridge Baldor of Baltimore, LLC 6660 Santa Barbara Road, Suite 22-24 Elkridge, MD 21075 Tel.: 410-579-2135 Fax: 410-579-2677 Massachusetts Worcester Redman & Associates 6 Pullman Street Worcester, MA 01606 Tel.: 508-854-0708 Fax: 508-854-0291 Michigan Sterling Heights Industrial Rotating Products 5993 Progress Drive Sterling Heights, MI 48312 Tel.: 586-978-9800 Fax: 586-978-9969 Minnesota Rogers Perkins Power-Motion Products 21080 134th Ave. North Rogers, MN 55374 Tel.: 763-428-3633 Fax: 763-428-4551
New Jersey Pennsauken Childs & Assoc., Inc. 1035 Thomas Busch Hwy Pennsauken, NJ 08110 Tel.: 856-661-1442 Fax: 856-663-6363 New York Auburn Baldor NY - Penn Inc. One Ellis Drive Auburn, NY 13021 Tel.: 315-255-3403 Fax: 315-253-9923 North Carolina Greensboro Motion Resources, Inc. 1220 Rotherwood Road Greensboro, NC 27406 Tel.: 336-272-6104 Fax: 336-273-6628 Ohio West Chester Baldor Cincinnati, Inc. 2929 Crescentville Road West Chester, OH 45069 Tel.: 513-771-2600 Fax: 513-772-2219 Macedonia Engineered Sales, Inc. 8929 Freeway Drive Macedonia, OH 44056 Tel.: 330-468-4777 Fax: 330-468-4778 Oklahoma Tulsa Baldor Oklahoma 7170 S. Braden, Suite 140 Tulsa, OK 74136 Tel.: 918-366-9320 Fax: 918-366-9338
Tennessee Memphis Baldor Power Solutions, LLC 3126 Norbrook Dr. Memphis, TN 38116 Tel.: 901-346-4722 Fax: 901-346-4725 Texas Dallas Kilpatrick Sales 2920 114th St – Suite 100 Grand Prairie, TX 75050 Tel.: 214-634-7271 Fax: 214-634-8874
Houston Baldor Electric of Southern Texas 10355 W. Little York Road, Suite 300 Houston, TX 77041 Tel.: 281-977-6500 Fax: 281-977-6510 Utah Salt Lake City Rocky Mountain Baldor, Inc. 2230 South Main St. Salt Lake City, UT 84115 Tel.: 801-832-0127 Fax: 801-832-8911 Wisconsin New Berlin Baldor Power Solutions, LLC 1960 South Calhoun Road New Berlin, WI 53151 Tel.: 262-784-5940 Fax: 262-784-1215
Canada Alberta Edmonton Baldor Motors & Drives (Alberta), Ltd. 4053 92 Street Edmonton, Alberta T6E 6R8 Tel.: 780-434-4900 Fax: 780-438-2600
British Columbia Port Coquitlam Canadian Electro Drive (1982), Ltd. 1538 Kebet Way Port Coquitlam, BC V3C 5M5 Tel.: 604-421-2822 Fax: 604-421-3113 Manitoba Winnipeg Industrial Agencies 54 Princess Street Winnipeg, MB R3B 1K2 Tel.: 204-942-5205 Fax: 204-956-4251 Ontario Toronto Baldor Electric Ontario, Inc. 2750 Coventry Road Oakville, ON L6H 6R1 Tel.: 905-829-3301 Fax: 905-829-3302 Quebec Montreal Baldor Quebec Atlantique inc. 5155, rue J.A. Bombardier Saint-Hubert, QC J3Z 1G4 Tel.: 514-933-2711 Fax: 514-933-8639 MEXICO Baldor Sales Office Oficina Corporativa de Ventas y Centro de Distribución Blvd. al Aeropuerto Km. 2 Col. San José El Alto León , Gto. CP 37545 Tel. (47) 7761 2030 Fax (47) 7761 2010
Baldor Electric Company
© Baldor Electric Company BEC-16
P.O. Box 2400 Fort Smith, AR 72902-2400 U.S.A. Ph (479) 646-4711 • Fax (479) 648-5792 International Fax (479) 648-5895 www.baldor.com • www.maskapulleys.com
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