2. 1
LIFT TRUCK WEIGHTS*
S2.00XL (S40XL) 3390 7460
UNIT KILOGRAMS POUNDS
S2.50XL (S50XL) 3750 8250
S3.00XL (S60XL) 4325 9515
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
* Oil temperature at 55 to 65_ C (130 to 150_ F). Oil with different viscosity will change “Flow” values.
** Lift Truck Serial Number Codes
LIFT SYSTEM RELIEF PRESSURE*
Control Valves (3 plunger type)
with one Relief Value
Control Valves (4 plunger type)
with two Relief Valves
Primary
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
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
PUMP TYPE Gear Pump with Flow Control Valve
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)
LIFT AND STEERING SYSTEM
6.4 litres/min (1.7 gpm)
STEERING RELIEF PRESSURE, all units * 9.9 to 10.7 MPa (1435 to 1552 psi) @ 1000rpm
Secondary
S2.00–3.00XL (S40–60XL)
This section is for the following models:
5. 1
THE STEERING SYSTEM
GENERAL
This section describes the steering system. Description
and operation information is given for the system, hy-
draulic pump, flow control valve, steering control unit,
and the steering wheel and column assembly. Repair in-
formation 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. In-
formation for pump drive assembly on the GM engines
is in THE HYDRAULIC PUMP DRIVE ASSEM-
BLY, 1900 SRM 339.
DESCRIPTION
(See FIGURE 1. and FIGURE 2.)
The power steering system has no mechanical link be-
tween the steering column assembly and the steer
wheels. The control of the steering is through a hydrau-
lic 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,thisrotaryvalvehasaminimumrestrictiontooil
flow. During the steering operation, the steering control
unit sends and controls the oil flow to the steering cylin-
der. Hydraulic oil returns from the opposite end of the
steering cylinder to the steering control unit and then re-
turns to the hydraulic tank.
FIGURE 1. STEERING SYSTEM COMPONENTS
9602
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 CONTROL UNIT
2. MAIN CONTROL VALVE
3. FILTER
4. BREATHER
5. HYDRAULIC TANK
6. 2
FIGURE 2. STEERING SYSTEM, HYDRAULIC SCHEMATIC
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
12623
12. RETURN LINE*
13. LUBE LINE, DRIVE CHAIN*
14. JET PUMP*
15. HOUSING, CHAIN DRIVE*
*ON UNITS WITH GM ENGINE ONLY.
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 fol-
lowing 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 sys-
tems 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 di-
rected 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.)
Thehydraulicpump assemblyhasthehydraulicpump,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
outletforthesecondaryflow.Theprimaryflowisforthe
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
gearshavebushings.Thebushingshavepassagesforthe
oilflowtothepumpoutletandforlubrication.Sealspre-
vent leaks between sections and the outside of the pump.
7. 3
FIGURE 3. HYDRAULIC PUMP ASSEMBLY
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
DIESEL SHOWN
12642
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 posi-
tion. 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 hydrau-
lic 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 posi-
tionoftheadjusterandtheamountofcompressionofthe
spring determine the relief valve pressure. When the ad-
justment 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 sys-
tem and the lift and tilt system. The hydraulic pump re-
ceives 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 sup-
plies a constant flow of oil to the steering system. This
oil flow is controlled by the steering control unit to oper-
ate the steering cylinder. The relief valve on the hydrau-
lic 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.
8. 4
FIGURE 4. FLOW CONTROL VALVE AND
RELIEF VALVE PARTS
1. PLUG (2)
2. O–RING (2)
3. HOUSING,
VALVE END
4. O–RING (1)
5. O–RING (2)
6. HOUSING,
RELIEF VALVE
7. POPPET, RELIEF VALVE
8. RELIEF SPRING
9. ADJUSTER
10. LOCK NUT
11. REGULATOR SPRING
12. ORIFICE
13. REGULATOR PLUNGER
12642
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 cham-
bers 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
flowsthroughboresandpassagesinthebushingstoboth
sides of each bushing. Oil lubricates the bushings and
the gear surface of each bushing. Other bores and pas-
sages 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 di-
rects the oil flow to the pump inlet to decrease the pres-
sure. The decrease in pressure lets the spring return the
poppet back to the seat.
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10. 5
FIGURE 5. OPERATION OF THE FLOW CONTROL VALVE AND RELIEF VALVE
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
12651
13
14
15
16
17
9
18
19
20
21
2223
1
2
3
4
5
6
7
8
9
10
9
11
12
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. Re-
move the large hex nut. Use a puller to pull the steering
wheel from the shaft.
2. Remove the the two instrument panels from the col-
umn 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
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 assem-
bly 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 re-
moved (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 con-
nections on the steering control unit.
WARNING
If the hydraulic lines are incorrectly installed, re-
verse 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
11. 6
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
1336553
1
2
3
4
5
6
7
8
6
9
12
10 11
13
FIGURE 6. STEERING WHEEL AND STEERING COLUMN ASSEMBLY
(SERIAL CODE C177 AND C187) (1 of 2)
13. 8
FIGURE 7. STEERING WHEEL AND STEERING COLUMN ASSEMBLY
(SERIAL CODE B177 AND B187)
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
12658
Removal (Serial Code B177 And B187)
1. Remove the the two instrument panels from the col-
umn housing and disconnect the wires. Disconnect the
horn wire.
2. Remove the horn button and switch assembly. Re-
move the large hex nut. Use a puller to pull the steering
wheel from the shaft.
3.Removethecapscrewsthatfastenthecolumnhousing
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 assem-
bly 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
14. 9
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 in-
stalled in the top of the column. Guide the top end of the
shaft through the opening at the top of the column hous-
ing. The four studs on the steering control unit fit
through the top of the support bracket. Fasten the steer-
ing control unit in place with the four nuts and washers.
3. Install the four hydraulic lines to the correct port con-
nections on the steering control unit.
WARNING
If the hydraulic lines are incorrectly installed re-
verse 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 proce-
dures. 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 con-
trols the pressure and flow of the hydraulic oil to the
steering cylinder. The valve plate is held in its center po-
sition 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 au-
tomatically return to the straight line direction of travel
after turning a corner.
FIGURE 8. STEERING CONTROL UNIT
11124
1. PORT COVER
2. PORT MANIFOLD
3. ISOLATOR MANIFOLD
4. METERING RING
5. ROTOR ASSEMBLY
6. COVER PLATE, UPPER
7. DRIVE ASSEMBLY
8. VALVE SPRINGS
9. VALVE ASSEMBLY
10. DRIVE LINK
11. COMMUTATOR ASSEMBLY
12. DRIVE PLATE
13. THRUST BEARING
14. COVER AND TUBE ASSEMBLY
15. INPUT SHAFT FROM STEERING WHEEL
![SERVICE REPAIR
S40XL S50XL S60XL [B187]](https://image.slidesharecdn.com/hysterb187s40xlforkliftservicerepairmanual-201010151915/85/Hyster-b187-s40-xl-forklift-service-repair-manual-1-320.jpg)
