Hyster B187 (S50XL) Forklift Service Repair Manual

LIFT TRUCK WEIGHTS*

UNITKILOGRAMSPOUNDS

S2.00XL (S40XL)33907460

S2.50XL (S50XL)

S3.00XL (S60XL)

37508250

43259515

Lift trucks equipped with overhead guard, mast, carriage, load backrest extension, forks, gasoline engine and operator.

S2,00–2.50XL (S40–50XL) has 3760 mm (148 in) two–stage mast.

S3.00XL (S60XL) has 3600 mm (142 in) two–stage mast.

HYDRAULIC SYSTEM

LIFT AND STEERING SYSTEM

MAIN FLOW (Lift, Tilt & Attachment)*

A187** @ 2000 rpm with no load

Mazdz/Isuzu

GM 4–153

B187** @ 2000 rpm with no load

Mazda/Isuzu

GM 4–181 engine

CONTROLLED FLOW (Steering), all units

LIFT SYSTEM RELIEF PRESSURE*

Control Valves (3 plunger type) with one Relief Value

Control Valves (4 plunger type) with two Relief Valves

Primary

Secondary

46.5 litres/min (12.3 gpm)

54.1 litres/min (14.3 gpm)

44.7 litres/min (11.8 gpm)

54.1 litres/min (14.3 gpm)

6.4 litres/min (1.7 gpm)

19.30 to 20.00 MPa (2800 to 2900 psi) at full flow. Check at inlet line to control valve port.

19.30 to 20.00 MPa (2800 to 2900 psi) at full flow. Check at inlet line to control valve with Lift spool in the “full lift” position

15.15 to 15.85 MPa (2200 to 2300 psi) at full flow. Check at inlet line to control valve with Tilt spool in the “full tilt” position

STEERING RELIEF PRESSURE, all units * 9.9 to 10.7 MPa (1435 to 1552 psi) @ 1000rpm

*Oil temperature at 55 to 65 C (130 to 150 F). Oil with different viscosity will change “Flow” values.

**Lift Truck Serial Number Codes

This section is for the following models:

S2.00–3.00XL (S40–60XL)

GENERAL

THE STEERING SYSTEM

This section describes the steering system. Description and operation information is given for the system, hydraulic pump, flow control valve, steering control unit, and the steering wheel and column assembly. Repair information for the steering cylinder, the hydraulic pump, and the steering control unit is given in the sections THE STEERING AXLE, 1600 SRM 10 and 1600 SRM 258 and THE HYDRAULIC SYSTEM AND GEAR PUMP ASSEMBLY, 1900 SRM 130 and THE STEERING CONTROL UNIT, 1600 SRM 257. Information for pump drive assembly on the GM engines is in THE HYDRAULIC PUMP DRIVE ASSEMBLY, 1900 SRM 339.

DESCRIPTION

(See FIGURE 1. and FIGURE 2.)

The power steering system has no mechanical link between the steering column assembly and the steer wheels. The control of the steering is through a hydraulic circuit. The hydraulic oil flows from the hydraulic pump through the steering control unit and returns to the hydraulic tank.

The steering control unit is a rotary valve operated by the steering wheel. When the steering wheel is not moved, this rotary valve has a minimum restriction to oil flow. During the steering operation, the steering control unit sends and controls the oil flow to the steering cylinder. Hydraulic oil returns from the opposite end of the steering cylinder to the steering control unit and then returns to the hydraulic tank.

6.SCREEN

7.DRAIN PLUG

8.TEST PORT

9.STEERING CYLINDER

10.HYDRAULIC PUMP

11.FLOW CONTROL VALVE AND RELIEF VALVE

12.TO UPRIGHT

13.TO/FROM TILT CYLINDERS

14.THIS RETURN LINE ON ALL UNITS EXCEPT THOSE UNITS WITH GM ENGINE

15.THIS RETURN LINE GOES TO CHAIN DRIVE FOR HYDRAULIC PUMP ON UNITS WITH GM ENGINE

1. STEERING SYSTEM COMPONENTS

1.HYDRAULIC TANK

2.FILTER

3.HYDRAULIC PUMP

4.FLOW CONTROL VALVE

5.RELIEF VALVE

6.STEERING CONTROL UNIT

7.STEERING WHEEL

8.STEERING CYLINDER

9.TEST PORT

10.TO MAIN CONTROL VALVE

11.RETURN LINE ON ALL UNITS EXCEPT THOSE WITH GM ENGINE

12.RETURN LINE*

13.LUBE LINE, DRIVE CHAIN*

14.JET PUMP*

15.HOUSING, CHAIN DRIVE*

*ON UNITS WITH GM ENGINE ONLY.

FIGURE 2. STEERING SYSTEM, HYDRAULIC SCHEMATIC

If the hydraulic pump does not operate, a check valve closes and permits the steering control unit to continue control of the steering system. The lift truck is difficult to steer when the steering pump does not operate,. The steering control unit can make the hydraulic pressure necessary to steer the lift truck.

The hydraulic circuit for the steering system has the following parts: hydraulic tank, hydraulic pump assembly, steering control unit, steering cylinder, filter and breather. The steering system, and the lift and tilt system are separate systems of the hydraulic system. Both systems use the common hydraulic tank and hydraulic pump. A breather lets air into the hydraulic tank and a plug can be removed to drain the tank.

Oil from the tank is supplied to the hydraulic pump. When the steering wheel is stationary, the oil flow is directed to the main control valve. When the steering wheel is turned, oil flows to the steering control unit. Four lines connect the steering control unit to the supply (IN) port, return (OUT) port, left (LT) and right (RT) steering cylinder ports.

Hydraulic Pump Assembly (See FIGURE 3.)

The hydraulic pump assembly has the hydraulic pump, a flow control valve and a relief valve. The valves are in the end housing of the assembly. The inlet is in the side of the pump body. The pump outlet connects directly to the end housing and the flow control valve. The flow control valve has the outlet for the primary flow and the outlet for the secondary flow. The primary flow is for the steering control unit. The end housing has an internal passage that directs oil flow from the relief valve to the inlet side of the pump gears through a passage in the pump body.

The hydraulic pump assembly fastens to the engine at the timing gear cover. The splines of the pump shaft fit into a gear on the engine which turns the pump shaft when the engine operates. The shafts on each side of the gears have bushings. The bushings have passages for the oil flow to the pump outlet and for lubrication. Seals prevent leaks between sections and the outside of the pump.

1.SNAP RING

2.OIL SEAL

3.HOUSING, FLANGE END

4.BACK–UP RING, LEFT (2)

5.BUSHING

6.BACK–UP RING, RIGHT (2)

7.BUSHING (2)

8.DRIVEN GEAR

9.DRIVE GEAR AND PUMP SHAFT

10.HOUSING, VALVE END

11.O–RING

12.SEAL, BUSHING

13.SEAL, BODY

14.PUMP BODY

Flow Control Valve (See FIGURE 4.)

The flow control valve makes sure the steering system has a constant supply of oil. The flow control valve has a spring, a plunger with an orifice, and two plugs with O–rings. The spring keeps the plunger in the correct position. Oil pressure can move the plunger and compress the spring. The plugs keep the plunger and spring in the bore and they also keep the oil in the correct chamber. O–rings are used to seal the plugs.

Relief Valve (See FIGURE 5.)

A relief valve in a bore in the end housing of the hydraulic pump prevents the oil pressure in the steering system from increasing above specifications. The relief valve has the following parts: a relief valve housing, a poppet, a spring, an adjuster, a lock nut and O–rings. The position of the adjuster and the amount of compression of the spring determine the relief valve pressure. When the adjustment is correct, the lock nut will hold the adjuster in

the correct location and O–ring will seal the adjuster against the relief valve housing.

OPERATION

Steering System

(See FIGURE 1. and FIGURE 2.)

The hydraulic pump sends oil flow to the steering system and the lift and tilt system. The hydraulic pump receives oil from the hydraulic tank through a screen at the outlet of the tank. The oil from the pump flows directly to the flow control valve. The flow control valve supplies a constant flow of oil to the steering system. This oil flow is controlled by the steering control unit to operate the steering cylinder. The relief valve on the hydraulic pump assembly limits the pressure in the steering system. On units not using a GM engine, oil from the steering system is returned to the hydraulic tank. On units with a GM engine, the oil flows to the chain drive assembly for the hydraulic pump.

FIGURE 3. HYDRAULIC PUMP ASSEMBLY

The secondary flow from the pump goes to the main control valve. A relief valve on the main control valve

limits the pressure in the system. The test port is at the right turn (RT) connection of the steering control valve. The oil returning from the main control valve flows through a filter in the oil line and then to the tank. The filter removes small particles from the oil.

Hydraulic Pump (See FIGURE 3.)

The engine turns the shaft of the hydraulic pump. The drive gear of this shaft turns the driven gear of the pump. The gear teeth of the pump have a close tolerance. The gears also have a close tolerance to the pump body and the bushings. The tolerances and seals make tight chambers between the gear teeth. When the teeth of each gear move apart at the inlet port, they make a vacuum. Oil from the tank enters the inlet port and is moved by the gear chambers around the circumference. Passages on the opposite side of the inlet connect the gear chambers for the outlet oil to the flow control valve. Oil at the inlet flows through bores and passages in the bushings to both sides of each bushing. Oil lubricates the bushings and the gear surface of each bushing. Other bores and passages in the bushings let the outlet oil go to the sides of the bushings away from the gears.

Flow Control Valve (See FIGURE 5.)

The oil at the outlet of the hydraulic pump enters the valve chamber near the center of the plunger (20). The oil flows through the orifice (16) in the plunger to the steering system port. This oil also flows to the relief valve (23). If the oil flow at the pump outlet is more than the primary flow (13) for the steering system, the plunger will move. This plunger movement allows the secondary flow to go to the lift and tilt circuit (12). The plunger will also move and decrease or stop the flow of oil to the lift and tilt system if the pump flow decreases. The plunger continues to move to make sure the steering system always has a constant supply of oil.

Relief Valve (See FIGURE 5.)

The pressure in the steering system is sensed at the relief valve (23). If the pressure increases to the relief valve setting, the poppet (8) in the relief valve will move against the spring (2). When the poppet moves off the seat, oil flows through an internal passage (17) that directs the oil flow to the pump inlet to decrease the pressure. The decrease in pressure lets the spring return the poppet back to the seat.

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STEERING WHEEL AND COLUMN ASSEMBLY

The steering wheel attaches to the steering shaft with splines. See FIGURE 6. and FIGURE 7. A large nut holds the steering wheel onto the steering shaft. The horn button is the cover for the center of the steering wheel. The lower end of the steering shaft is machined and engages the drive plate inside the steering control unit. The shaft and steering control are fastened inside the column assembly.

Removal (Serial Code C177 And C187)

1. Remove the horn button and switch assembly. Remove the large hex nut. Use a puller to pull the steering wheel from the shaft.

2. Remove the the two instrument panels from the column housing and disconnect the wires.

3. Remove the two capscrews that fasten the column housing to the support bracket. Remove the column housing.

4. Make an identification of the hydraulic hoses at the steering control unit so that the hydraulic hoses can be correctly connected during assembly. Disconnect the

1.ADJUSTER

2.RELIEF SPRING

3.LOCK NUT

4.BACK–UP RING

5.O–RING

6.HOUSING, RELIEF VALVE

7.O–RING

8.POPPET

9.FLOW, RELIEF PRESSURE

10.O–RING

11.CHECK BALL

12.PORT TO LIFT SYSTEM

13.PRIMARY FLOW

14.PORT TO STEERING SYSTEM

15.REGULATOR SPRING

16.ORIFICE

17.INTERNAL PASSAGE FOR RELIEF PRESSURE TO THE PUMP INLET

18.PORT, PUMP OUTLET/VALVE INLET

19.SECONDARY FLOW

20.REGULATOR PLUNGER

21.PUMP HOUSING

22.FLOW CONTROL VALVE (REGULATOR) SECTION

23.RELIEF VALVE SECTION

hydraulic hoses at the bottom of the steering control unit.

5. Remove the lock nuts and flat washers that fasten the steering control unit to the bracket on the cowl of the lift truck. Remove the steering control unit and shaft assembly from the lift truck.

6. Remove other parts as needed for repair.

Installation (Serial Code C177 And C187)

1. Install any parts of the support bracket that were removed (see FIGURE 6.)

2. Install the steering control unit and shaft assembly into the support bracket.

3. Install the four hydraulic lines to the correct port connections on the steering control unit.

WARNING

If the hydraulic lines are incorrectly installed, reverse steering can occur, the steering operation can be unpredictable, or the steering wheel can turn without the operator’s motions.

4. Make sure the rubber seal is installed in the top of the column housing. Guide the top end of the shaft through

FIGURE 5. OPERATION OF THE FLOW CONTROL VALVE AND RELIEF VALVE

the opening at the top of the column housing. Install the two capscrews that fasten the column housing to the support bracket.

5. Install the steering wheel onto the splines at the top of the shaft. Install the large nut on the shaft. Tighten the nut to 40 to 50 N.m (30 to 40 lbf ft).

6. Attach the the electrical wire for the horn to the horn switch. Install the horn switch and button assembly to the hub of the steering wheel.

7. Connect the wires to the correct connectors for the electrical gauges. Install the electrical gauges.

1.STEERING WHEEL

2.HORN BUTTON

3.NUT

4.SHAFT

5.COLUMN ASSEMBLY

6.STEERING CONTROL UNIT

7.SUPPORT BRACKET

8.COWL

9.SUPPLY LINE, “IN”

10.RETURN LINE, “OUT”

11 LEFT TURN LINE, “LT”

12.RIGHT TURN LINE, “RT”

13.COLUMN HOUSING

FIGURE 6. STEERING WHEEL AND STEERING COLUMN ASSEMBLY (SERIAL CODE C177 AND C187) (1 of 2)

FIGURE 6. STEERING WHEEL AND STEERING COLUMN ASSEMBLY (SERIAL CODE C177 AND C187) (2 of 2)

Removal (Serial Code B177 And B187)

1. Remove the the two instrument panels from the column housing and disconnect the wires. Disconnect the horn wire.

2. Remove the horn button and switch assembly. Remove the large hex nut. Use a puller to pull the steering wheel from the shaft.

3. Remove the capscrews that fasten the column housing to the support bracket. Remove the column housing.

4. Make an identification of the hydraulic hoses at the steering control unit so that the hydraulic hoses can be correctly connected during assembly. Disconnect the hydraulic hoses at the bottom of the steering control unit.

5. Remove the lock nuts and flat washers that fasten the steering control unit to the bracket on the cowl of the lift truck. Remove the steering control unit and shaft assembly from the lift truck.

6. Disconnect the wiring harness and pull it through the support bracket.

7. Remove the four capscrews and washers that fasten the support bracket to the cowl and remove the support bracket.

Installation (Serial Code B177 And B187)

1. Attach the support bracket to the cowl and fasten with the four capscrews and washers. Install the column housing on the support bracket and fasten with the

FIGURE 7. STEERING WHEEL AND STEERING COLUMN ASSEMBLY (SERIAL CODE B177 AND B187)

capscrews. Put the wiring harness through the bracket and connect the harness plug.

2. Install the steering control unit and shaft assembly into the column housing. Make sure the rubber seal is installed in the top of the column. Guide the top end of the shaft through the opening at the top of the column housing. The four studs on the steering control unit fit through the top of the support bracket. Fasten the steering control unit in place with the four nuts and washers.

3. Install the four hydraulic lines to the correct port connections on the steering control unit.

WARNING

If the hydraulic lines are incorrectly installed reverse steering can occur, the steering operation can be unpredictable, or the steering wheel can turn without the operator’s motions.

4. Install the steering wheel onto the splines at the top of the shaft. Install the large nut on the shaft. Tighten the nut to 40 to 54 N.m (30 to 40 lbf ft).

5. Connect the wires to the correct connectors for the electrical gauges and horn wire terminal. Install the electrical gauges. Install the access cover on the steering column with four capscrews and washers.

6. Attach the the electrical wire for the horn to the horn switch. Install the horn switch and button assembly to the hub of the steering wheel.

STEERING CONTROL UNIT

This section has a description and operation for the steering control unit. See the section STEERING CONTROL UNIT, 1600 SRM 257 for repair procedures. See the paragraph Steering Wheel and Column Assembly for removal and installation procedures.

Description (See FIGURE 8.)

The steering control unit is a hydrostatic unit controlled by the steering wheel, and is mounted inside the housing for the steering column. The steering control unit has a shaft assembly, control valve section and a metering section. The hydraulic hoses for the steering system are connected to the bottom of the assembly.

Operation, Control Valve Section

The steering control valve has an open center and is a valve plate that rotates. The steering control valve controls the pressure and flow of the hydraulic oil to the steering cylinder. The valve plate is held in its center position by two sets of three coil springs. When the valve plate is in the center position, the hydraulic oil flows from the hydraulic pump, through the steering control unit, and returns to the hydraulic tank. When the valve plate is moved from its center position by the steering wheel, a port is opened in the isolator manifold and the hydraulic pressure is sent to the metering section. The open center operation permits the steering system to automatically return to the straight line direction of travel after turning a corner.