Mechanotechnics N5

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Mechanotechnics N5

This document includes important informa on about the revised curriculum for Mechanotechnics N5, scheduled for implementa on in 2021. Contact jayshil.bhula@macmillaneduca on.co.za to request a sample copy of the TVET First approved textbook or visit our website at www.macmillaneduca on.co.za. For best results, use TVET First Mechanotechnics N5!

Summary of changes in the 2021 curriculum:

• The 8 modules remain the same with some content changes. Weigh ngs for modules are now prescribed. The 2021 curriculum gives more detail on curriculum requirements for each module. • In Module 1, students now need to draw and label diagrams of gear systems. They also work with more types of fi nal drives. • New content in Module 3 includes explaining and describing belts and belt drives, principle types of belt feeders, and the opera on of conveyor belts and pipe conveyors. Horizontal and inclined belts are no longer covered. • Module 4 now covers bucket conveyors in addi on to bucket elevators.

This is the weigh ng for each module in the Mechanotechnics N5 curriculum which is being implemented from 2021.

Curriculum 1990 Modules Curriculum 2020 Modules

Module 1 Epicyclic gears and gear trains Module 1 Epicyclic gears and gear trains [weigh ng 10%] Module 2 Reduc on gearboxes Module 2 Reduc on gearboxes [weigh ng 10%] Module 3 Belt drives Module 3 Conveyor belts and belt drives [weigh ng 15%] Module 4 Bucket elevators Module 4 Bucket elevators and bucket conveyors [weigh ng 15%] Module 5 Rope haulages Module 5 Rope haulages and aerial ropeways [weigh ng 20%] Module 6 Elevators Module 6 Elevators [weigh ng 10%] Module 7 Rail and road trac on calcula ons Module 7 Rail and road trac on [weigh ng 10%] Module 8 Flywheels Module 8 Flywheels [weigh ng 10% ]

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In the table below, the fi rst column summarises the old curriculum and the second column explains what has changed in the 2021 curriculum.

Previous curriculum 2021 curriculum

Module 1: Epicyclic gears and gear trains Module 1: Epicyclic gears and gear trains

Objec ve Make calcula ons with regard to epicyclic gears and reduc on gearboxes. General aim Apply calcula ons with regard to epicyclic gears and gear trains.

1.1 Epicyclic gears made up of spur gears or bevel gears 1. Epicyclics made up of spur gears • Label the epicyclic spur gears from a given diagram. • Describe the epicyclic gear train. 2. Epicyclics made up of bevel gears • List the applica on of epicyclic bevel gears. 3. Applica on of epicyclic bevel gears [NEW] • Describe situa ons where epicyclic gears can be used. • List examples of instances where epicyclic gears are used. • Draw and label a typical epicyclic gear system.

1.2 Applica on of epicyclic gears on the cyclometer mechanism, Humpage’s gear mechanism and diff eren al mechanism 4. The cyclometer mechanism • Describe the cyclometer mechanism. • Draw and label the cyclometer mechanism. 5. Humpage’s gear • Describe the Humpage gear system. • Draw and label a Humpage gear system. 6. Diff eren al mechanism • Describe the diff eren al mechanism. • Label the bevel wheel diff eren al from a given diagram. 7. Other types of fi nal drive [NEW] • Describe the rear wheel drive system. • Explain the front wheel drive system. • Describe the func ons of the clutch in the fi nal drive gear system.

1.3 Calcula ons of simple epicyclic gear trains by tabular method (torque included) 8. Epicyclic gear drive calcula ons • Calculate the speed of selected epicyclic gear trains. • Determine the number of teeth and the PCD of selected gear trains.

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Previous curriculum 2021 curriculum

• Determine the speed of sha s of epicyclic gear trains. • Calculate the brake consump on on epicyclic gears. • Calculate the torque required to keep gears sta onary.

Module 2: Reduc on gearboxes Module 2: Reduc on gearbox

Objec ve Make calcula ons with regard to epicyclic gears and reduc on gearboxes. General aim Apply calcula ons with regard to gearbox reduc on and epicyclic gear system. 2.1 Construc on and uses 1. Func ons • List func ons of reduc on gears. 2. Types of gears used in a reduc on gearbox • Describe how spur gears, helical toothed gears and double helical toothed gears work. • List the advantages and disadvantages of using helical toothed gears and double helical toothed gears. 3. Construc on of gear trains • List the factors that should be taken into account when arranging a gear train. 4. Uses of speed reducers • List the uses of speed reducers. (see point 2.4 below) 5. Worm and worm wheel gear reduc on unit • Describe the func ons of worm and worm wheel reduc on unit.

2.2 Three-speed and reverse gearbox 6. Three-speed gearbox • Describe the func on of the three-speed gearbox. 2.3 Calcula ons on reduc on gearboxes 7. Reduc on gearbox calcula ons • Calculate the number of teeth on selected gears. • Calculate the speed of sha . • Select suitable gears and calculate actual reduc on and the distance between sha s from the diagram. • Calculate the drive ra os from sketches given. • Calculate the delivery speed of gearbox. • Calculate the velocity ra o of the gearbox. 2.4 Calcula ons on worm reduc ons (see point 5 above.)

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Previous curriculum 2021 curriculum

Module 3: Belt drives Module 3: Conveyor belts and belt drives

Objec ve Make calcula ons with regard to fl at belt, v-belt and conveyor belt drives. General aim Apply calcula ons with regard to fl at belt, v-belt and conveyor belt drives. 1. Flat and v-belt drives [NEW approach to theory] • Explain the func ons of the fl at and v-belt drives. • Draw and label fl at and v-belts. • List the materials that are used to make fl at and v-belts. • Explain the causes of slippage on fl at belts and v-belts. • List ways by which slippage may be prevented on fl at belts and v-belts.

3.1 Calcula ons only, on fl at- and v-belt drives (centrifugal force included) 3.1.1 Flat belts (open and cross drives) a) Speed ra os between pulleys b) Maximum force in belt c) Ra o between forces, ght side to slack side d) Eff ec ve belt force e) Power transmi ed by fl at belts f) Length of open belts g) Length of crossed belts 3.1.2 V-belts as for fl at belts a) Speed ra os between pulleys b) Maximum force in belt c) Ra o between forces, ght side to slack side d) Eff ec ve belt force 2. Belt speeds • List acceptable speeds at which v-belts and fl at belts may run.

3. Types of belts: open belts, crossed belts, right angular fl at belts and angular fl at belts [NEW] • Draw and label the following types of belts: a) open belts b) crossed belts c) angular fl at belts. 4. Belt drive calcula ons • Calculate the belt velocity, ini al tension, centrifugal tension, belt mass, belt length and angle of contact. • Calculate diameter of pulleys. • Calculate power transmi ed to driven sha s. • Calculate sha speed.

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Previous curriculum 2021 curriculum

e) Power transmi ed by fl at belts f) Length of open belts 3.1.3 Determining the number of belts (v-belts) 3.1.4 Force on bearings 3.1.5 Moments of iner a

3.2 Belt conveyors 5. Belt conveyors • Describe what belt conveyors are. • Draw and label a conveyor and a belt. • Draw and label a typical arrangement of belt conveyors. • Explain what tracking the belt refers to. • List the eff ect of off -centre loading.

3.2.1 Horizontal and inclined belts

3.2.2 Construc on of belts; driving mechanisms; methods employed to prevent belt slippage; belt tensioning devices

3.2.3 Care of belts; methods used in joining belts; safety devices; belt conveyor rollers 6. Factors aff ec ng the training of the belt • State the factors that aff ect the training of a belt. 7. Training opera ons • Fully explain training opera ons. • List the methods that are used to prevent belt slippage. 8. Types of lagging • Draw well labelled diagrams to show diff erent types of lagging. 10. Principal types of belt feeders [NEW] • With the aid of diagrams, explain the principal types of belt feeders. • List the advantages and disadvantages of belt feeders. • Name various ways of carrying belts. 11. Methods of joining belts • List two main methods of joining conveyor belts and give examples of each. 12. Stopping and holdback devices • List the common types of holdback devices. 13. Opera on of conveyor belts [NEW] • With the aid of diagrams, explain the opera on of conveyor belts. • Describe a tandem belt drive.

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Previous curriculum 2021 curriculum

• Explain how an interlocking and mul -sec on conveyor works. • Explain the purpose of guards on belt conveyors.

3.2.4 Calcula ons in respect of: belt speeds, belt tensions ( ght and slack side), contact angle on pulley, power transmi ed, belt capacity, drive effi ciency and tandem drives (combined horizontal and inclined belts to be considered)

17. Belt conveyor calcula ons • Calculate the power required for belt conveyors, the minimum mass of tension carriage assembly necessary to prevent belt spillage. • Calculate belt tension and the number of plies in a belt. • Calculate belt tension on slack side, angle of contact between the belt and pulley, the length of the belt between loading and discharging points, the capacity of load the belt can convey in kg/s, the speed at which the belt can travel in km/h, the length in m, eff ec ve belt tension and maximum working tension in the belt. 3.2.5 Loading of conveyor belts 9. Loading Explain diff erent types of loading with the aid of a labelled diagram.

3.2.7 Removal of steel from non-magne c materials 14. Magne c separators • Explain the purpose of magne c separators on belt conveyors. • List the diff erent types of magne c separators. • State the advantages and disadvantages of magne c separators. 15. Pipe conveyors [NEW] • Describe how pipe conveyors work. • Name the problems that have been solved by introducing pipe conveyors. • Draw a well-labelled diagram to show a pipe conveyor. • List the uses of pipe conveyors. • List the advantages and disadvantages of pipe conveyors.

3.2.8 Correct belts speeds; interlocking sequence; government regula ons applicable to elevators 2. Belt speeds • List acceptable speeds at which v-belts and fl at belts may run. 16. Safety precau ons and safety devices. • List the government regula ons C28 and standards that are applicable to belt conveyors, i.e. SANS and NOSA.

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Previous curriculum 2021 curriculum

Module 4: Bucket elevators Module 4: Bucket elevators and bucket conveyors

Objec ve To understand and be able to make calcula ons concerning the working and construc on of the diff erent types of bucket elevators Aim To understand and be able to make calcula ons concerning the working and construc on of the diff erent types of elevators 4.1 Purpose of bucket elevators; diff erent types of bucket elevators 1. Bucket elevators • State two categories of bucket elevators. • List the three main types of bucket elevators. • Determine the func ons of hold back devices. • Explain the purpose of tensioning devices. • List the func ons of tail pulleys. • Iden fy the advantages and disadvantages of bucket elevators. • List the purpose of the bucket elevator. • Explain with the aid of a labelled sketch the working opera on of a con nuous bucket elevator and centrifugal bucket elevators.

(See point 4.2 below.) 2. Bucket conveyors • Explain the purpose of bucket conveyors. • Name the diff erent types of conveyor buckets. • List advantages and disadvantages of diff erent type of bucket conveyors.

4.1.1 Centrifugal discharge of bucket elevators; posi ve of gravity discharge elevators; types of material that can be conveyed; methods of loading and discharge 4.1.2 Moun ng of buckets to belt or chain 4.1.3 Safety devices: Stopping and hold back devices; tensioning devices 4.1.4 Service pla orms; driving mechanisms; main problems experienced with bucket elevators; construc on of tail pulley

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Previous curriculum 2021 curriculum

4.1.5 Calcula ons of: pulley diameters; belt lengths; volume and mass per bucket; power and effi ciency

3. Bucket elevators and bucket conveyors • Calculate volume load delivered, number of buckets, volume per bucket, chain or belt speed, power of motor, effi ciency, power to li load against gravity, the diameter of head pulley, and the total length of chain. • Calculate the chain speed of bucket elevators. 4.2 Bucket conveyors See point 2 above. 4.2.1 Methods of loading and discharge; various arrangements of bucket conveyors 4.2.2 Driving mechanisms

Module 5: Rope haulages Module 5: Rope haulages and aerial ropeways

Objec ve To understand the working and be able to make the concomitant calcula ons of rope haulages and aerial cable ways Aim To understand the working of rope haulages and aerial ropeways and be able to apply the concomitant calcula ons 5.1 General arrangement: a) endless ropes and b) main and tail rope types 1. Rope haulages a) Endless rope haulages b) Main and tail rope haulages c) General factors • Describe the two major rope haulage systems. • Make a neat diagram to indicate the opera on of endless rope haulage. • Describe the main tail rope haulage. • List the general factors that aff ect rope haulages.

5.1.1 Gearbox construc on; chimes wheel; methods of impar ng mo on to the rope on the endless rope type haulage; types of brakes used; return and sheave wheels; rollers (pineapple and conical types) 2. Gearbox construc on a) Driving winch b) Driving sheave (chimes wheel) c) Defl ec on and return sheave • Explain the ropes haulage construc on with the aid of a labelled diagram. • Describe the func on of driving winch, driving sheave (chimes wheel), defl ec on and return sheaves with the aid of a labelled diagram.

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Previous curriculum 2021 curriculum

5.1.2 Methods of a aching cars to rope 3. Methods used to a ach trucks to rope a) Jockey or clip b) Elswick clip c) Smallman’s clip • Name and describe three methods that are used to prevent rope haulage from reversing a er stopping. • Make a neat labelled sketch of Jockey, Elswick clip and Smallman’s clip used to a ach a car to the moving rope haulage. 5.1.3 Safety devices; derailment devices 4. Brake on driving gear a) Opera ng features of brakes b) Electromagne c brake rollers • Explain the purpose of brakes on haulage drives. • With the aid of labelled diagrams, explain the opera ng features of brakes. • Describe what a pineapple roller is and how it func ons. 5. Safety devices a) Hold back devices b) Pivoted prop stopping devices c) Deacon derailment devices d) Self-locking worm devices e) Cut-out rails f) Signalling system g) Drop rail h) Safety aspects i) Trip wire j) Slack in haulage ropes k) Tension carriage • Discuss a good signalling system that can be used with rope haulage. • Make neat, labelled sketches of the safety devices, describe the purpose of each and explain its opera on. • List common faults associated with tension devices.

5.1.4 Tensioning devices; common faults

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Previous curriculum 2021 curriculum

6. Automa c detachment of truck a) Spacing of truck b) Haulage of rope • Describe why spacing of trucks is important in haulage system. • Defi ne how automa c detachment of trucks is done using disengaging frame. • List diff erent types of materials used to make haulage ropes.

5.1.5 Calcula ons of: number of trucks; capacity; moment of iner a; rope diameter; ul mate rope strength; factor of safety; power and effi ciency

7. Calcula ons of haulage rope system • Calculate the number of trucks, capacity, rope diameter, ul mate rope strength, factor of safety, power and effi ciency, breaking force of rope, rolling resistance, rope fric onal resistance, me taken by tub to complete journey. 5.1.6 Capstan winches See point 8 below. 5.2 Aerial ropeways 5.2.1 Construc on; diff erent types; advantages and disadvantages 5.2.2 Calcula ons of: span; defl ec on; number of containers; capacity and power (ver cal component excluded) 8. Aerial ropeways a) Types of aerial ropeways b) Advantages and disadvantages of bi-cable ropeways over mono-cable c) Safety factors d) Calcula ons on aerial ropeways e) Capstan winches f) Capstan winches calcula ons • Describe the func ons of aerial ropeways. • Explain what mono-cable and bi-cable ropeway systems are and list their advantages and disadvantages. • Explain what we mean by transporta on of cableways, hois ng and conveying cableways. • Calculate tension due to self-weight, tension due to loads, and total tension in rope. Defi ne the func ons of capstan winches. • Calculate the total mass, rail resistance, slope resistance, total tension in rope, number of turns around drum, calculate power and torque on drum.

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Previous curriculum 2021 curriculum

Module 6: Elevators Module 6: Elevators

Objec ve To understand the working and construc on of elevators, and be able to make the concomitant calcula ons

6.1 Goods and passenger elevators; construc on of elevators; construc on of hois ng drum; electromagne c brake

6.2 Balancing of elevator; safety catches on elevator

6.3 Layout of elevator sha of passenger and goods elevators; guide rails for elevator and counter-weight; construc on of counterweight

6.4 Springs and hydraulic buff ers at the bo om of the hatchway; automa c door locks on entrances to hatchways

6.5 Over-winding of elevators 6.6 Composi on and construc on of ropes 6.7 Government regula ons applicable to elevators Aim To understand the working and construc on of elevators, and be able to make the concomitant calcula ons

1. Types of elevators a) Goods elevators b) Passenger elevators c) Electromagne c brake • Describe two types of elevators. • List the major diff erences between goods and passenger elevators. • Draw a labelled diagram to show the arrangement of goods and passenger elevators. 3. Guides for elevator car and balance mass a) Safety catches b) Wedge clamp • Explain how modern li s are supported. • Explain why elevator cars are counter-weighted. • Explain the opera on principle of a wedge clamp type of safety device with the aid of a labelled diagram. 2. Construc on of passenger cars • Describe the details of a li well. • Explain the func ons of the driving confi gura on, driving sheave.

4. Springs and hydraulic buff ers • Explain the reasons why springs and oil buff ers are required.

5. Government regula ons • List various pieces of legisla on related to safety aspects when using elevators.

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Previous curriculum 2021 curriculum

6.8 Calcula ons of: tension in the ropes; accelera on and decelera on; moment of iner a of drum; total torque; power and effi ciency 6. Elevator calcula ons • Apply calcula ons of the following: a) Tension in the ropes b) Accelera on and decelera on c) Moment of iner a of drum d) Total torque e) Power f) Effi ciency

Module 7: Rail and road trac on calcula ons (Including inclines) Module 7: Rail and road trac on

Objec ve To make calcula ons concerning rail and road resistance Aim Apply calcula ons concerning rail and road resistance

7.1 Locomo ve trac ve eff ort 1. Basic principles and defi ni ons of rail trac on, trac ve eff ort of locomo ve and drawbar pull • Defi ne the following basic principles and defi ni ons: a) Rolling resistance b) Incline resistance c) Accelera on and decelera on force d) Drawbar pull.

7.2 Drawbar pull 7.3 Accelera on and decelera on

7.4 The eff ect of centrifugal force around curves and condi ons for no sided thrust (super eleva on included) 2. Symbols; road trac on formulae; mo on on level roads, mo on up and down inclines • Discuss the eff ect of centrifugal force around curves and condi ons for no side thrust (super eleva on included). • Calculate the mo on on level roads, mo on up and down inclines.

3. Skidding and overturning on curved track a) Symbols b) Unbanked and banked tracks (super eleva on) • Calculate super eleva on. • Explain the maximum safe speed to prevent skidding and overturning on unbanked curves.

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Previous curriculum 2021 curriculum

7.5 Maximum safe speed to prevent skidding and overturning

7.6 Power • Calculate maximum speeds without skidding and without overturning on banked curves. • Calculate coeffi cient of fric on between wheels and rails. • Calculate the rolling resistance, incline resistance, accelera on force, accelera on, decelera on, trac ve eff ort of locomo ve, drawbar pull.

Module 8: Flywheels Module 8: Flywheels

Objec ve To make calcula ons concerning fl ywheels Aim Apply calcula ons concerning a fl ywheel 8.1 Purpose of a fl ywheel 1. Purpose of a fl ywheel a) Comparison between circular and linear mo on • List the func ons of a fl ywheel. • Explain the diff erence between circular and linear mo on. 8.2 Elementary calcula ons concerning moment of iner a; torque and power required for angular accelera on 2. Elementary calcula ons concerning moment of iner a, torque and power required for angular accelera on • Convert linear velocity to angular velocity and vice versa. • Convert linear accelera on to angular accelera on. • Calculate velocity, accelera on, angular accelera on and angular decelera on, moment of iner a, kine c energy, uniform torque, me required for accelera on, average force, mass, distance the load can be raised, work done, fric onal torque, power and energy.

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