service repair manual

1. SERVICE REPAIR
E45XM E50XM E55XM E60XM E65XM [F108]

2. 8000 SRM 988 Electrical System
Tire Sizes
Model Steering Drive
S3.50 (S70XM) 18 × 6 × 12.1 22 × 9 × 16
S4.00 (S80XM) 18 × 7 × 12.1 22 × 9 × 16
S4.50-5.50XM (S100-120XM) 18 × 8 × 12.1 22 × 12 × 16
Hydraulic System
Item Specification
Hydraulic System Capacity 39.3 liter (10.4 gal)
Hydraulic Tank Capacity
(Total Tank Capacity)
35.5 liter (9.4 gal)
Relief Pressures*
Main Control Valve
Lift Circuit 22.0 MPa (3200 psi)
Tilt and Auxiliary Circuit 15.5 MPa (2250 psi)
Steering Circuit 10.7 MPa (1550 psi)
Hydraulic Pump**
Capacity 89 liter/min (23.5 gal/min)
Priority Flow None
*Oil temperature 50 to 100 C (120 to 210 F) and engine speed at 2500 rpm.
**Oil temperature 80 to 100 C (176 to 210 F) and engine speed at 2550 rpm.
Electrical System
Alternator Output
38 Amps @ 650 rpm (Hot)
GM V-6
62 Amps @ 2200 rpm (Hot)
42 Amps @ 650 rpm (Hot)
Perkins
62 Amps @ 2500 rpm (Hot)
All Models - 12 Volt, Negative Ground
1

3. Capacities 8000 SRM 988
Engine Specifications
Item GM V-6 4.3 Perkins 1004-4
Number of Cylinders 6 4
Firing Order 1-6-5-4-3-2 1-3-4-2
Bore 102.00 mm (4.00 in.) 103.00 mm (4.055 in.)
Stroke 88.40 mm (3.50 in.) 127.00 mm (5.00 in.)
Displacement 4.3 liter (262.4 in.3
) 4.0 liter (244.0 in.3
)
Compression Ratio 9.3:1 18.5:1
Idle Speed 675 to 725 rpm 725 to 775 rpm
Governor Speed 2400 to 2500 rpm 2450 to 2550 rpm
Stall Speed
Broken in Engine 1810 (Gas) 1735 (LPG)
+300/-50 rpm
2050 rpm ±50 rpm
New Engine 1710 (Gas) 1635 (LPG)
+300/-50 rpm
1950 rpm ±50 rpm
Timing 0 BTDC at 650 rpm 2 BTDC (Static)
Oil Pressure (Minimum) 207 to 380 kPa (30 to 55 psi) 280 kPa (41 psi)
Valve Clearance
Intake Not adjustable 0.20 mm (0.008 in.) Cold
Exhaust Not adjustable 0.45 mm (0.018 in.) Cold
Capacities
Item Quantity
Engine Oil
GM V-6 4.7 liter (5.0 qt)
Perkins 1004-4 8.0 liter (8.5 qt)
Cooling System 18.9 liter (20.0 qt)
Hydraulic Tank (Total Tank Capacity) 35.5 liter (9.4 gal)
Transmission 15.1 liter (16.0 qt)
Differential 5.7 liter (6.0 qt)
Fuel Tank 34.0 liter (9.1 gal)
Brake Fluid 0.2 liter (0.5 pt)
2

4. 8000 SRM 988 Lift Truck Weights
Lift Truck Weights
Unit kg lb
S3.50XM (S70XM) 5,515 11,937
S4.00XM (S80XM) 5,780 12,742
S4.00XM BCS (S80XM BCS) 5,995 13,217
S4.50XM (S100XM) 6,768 14,920
S4.50XM BCS (S100XM BCS) 7,245 15,973
S5.50XM (S120XM) 7,433 16,387
S5.50XMS (S120XMS) 7,527 16,589
S5.50XMSPRS (S120XMSPRS) 7,820 17,241
NOTE: Lift trucks equipped with overhead guard, mast, carriage, load backrest, forks, and LPG engine.
NOTE: S3.50-4.00XM (S70-80XM) and S4.00XM BCS (S80XM BCS) have 3099 mm (122 in.) two-stage LFL
mast.
S4.50-5.50XM (S100-120XM), S4.50XM BCS (S100XM BCS), S5.50XMS (S120XMS), and S5.50XMSPRS
(S120XMSPRS) have 2845 mm (112 in.) two-stage LFL mast.
3

5. Transmission Pressures (Single-Speed Powershift) 8000 SRM 988
Transmission Pressures (Single-Speed Powershift)
Port
No.
Transmission Pressures*
1 System
Pressure
1170 to 1380** kPa
(170 to 200 psi)
**Relief pressure
1379 kPa (200 psi)
2 Forward
Clutch
895 to 1035 kPa
(130 to 150 psi)
3 Reverse
Clutch
895 to 1035 kPa
(130 to 150 psi)
4 Torque
Converter
655 to 760 kPa
(95 to 110 psi)
5 Lubrication
Pressure
35 to 105 kPa
(5 to 15 psi)
6 Modulator
Pressure
Pressure Variation
*Oil temperature at least 50 to 65 C (120 to 150 F) and engine speed at 2000 rpm.
NOTE: The difference between Forward and Reverse clutch pressure must not be more than:
• Manufacturing limit 48 kPa (7 psi)
• Service limit 70 kPa (10 psi)
4

6. 8000 SRM 988 Mast Speeds
Mast Speeds
Two-Stage Full Free-Lift Mast
Lifting Lowering
No Load Rated Load No Load Rated Load
Unit
m/sec ft/min m/sec ft/min m/sec ft/min m/sec ft/min
S3.50-4.00XM
(S70-80XM)
0.60 118 0.56 111 0.36 70 0.50 99
S4.50XM
(S100XM)
0.51 101 0.48 94 0.32 63 0.45 89
S5.50XM
(S120XM)
0.51 101 0.44 87 0.32 63 0.47 92
Two-Stage Limited Free-Lift Mast
Lifting Lowering
No Load Rated Load No Load Rated Load
Unit
m/sec ft/min m/sec ft/min m/sec ft/min m/sec ft/min
S3.50-4.00XM
(S70-80XM)
0.68 134 0.62 123 0.47 93 0.55 108
S4.50-5.50XM
(S100-120XM)
0.55 108 0.53 105 0.42 82 0.51 100
Three-Stage Full Free-Lift
Lifting Lowering
No Load Rated Load No Load Rated Load
Unit
m/sec ft/min m/sec ft/min m/sec ft/min m/sec ft/min
S3.50-4.00XM
(S70-80XM)
0.63 124 0.58 114 0.44 87 0.53 105
S4.50XM
(S100XM)
0.52 102 0.51 100 0.39 76 0.47 92
S5.50XM
(S120XM)
0.52 102 0.45 89 0.39 76 0.47 92
5

7. Torque Specifications 8000 SRM 988
Torque Specifications
FRAME
Counterweight Capscrew
1022 N•m (755 lbf ft)
ENGINE - GM V-6
Intake Manifold Capscrews
47 N•m (35 lbf ft)
Valve Cover Capscrews
10 N•m (7 lbf ft)
Exhaust Manifold Capscrews
35 N•m (25 lbf ft)
Center Port 25 N•m (20 lbf ft)
Outer Ports 50 N•m (35 lbf ft)
Camshaft Sprocket Capscrews
25 N•m (20 lbf ft)
Vibration Damper Capscrew
81 N•m (60 lbf ft)
Main Bearing Cap Capscrews
70 N•m (50 lbf ft)
Connecting Rods
45 N•m (35 lbf ft)
Flywheel Capscrews
80 N•m (60 lbf ft)
Flywheel Housing Capscrews
50 N•m (40 lbf ft)
Engine Mount to Engine Capscrews
30 N•m (25 lbf ft)
Engine Mount to Mount Plate Bolts
65 N•m (50 lbf ft)
Engine Mount to Flywheel Housing Capscrews
165 N•m (120 lbf ft)
Engine Mount Bolts
120 N•m (90 lbf ft)
ENGINE - PERKINS
Engine Mount to Engine Capscrews
65 N•m (50 lbf ft)
Engine Mount Bolts
120 N•m (90 lbf ft)
TRANSMISSION
Transmission Cover Capscrews
40 N•m (30 lbf ft)
Oil Pump Capscrews
40 N•m (30 lbf ft)
Torque Converter Housing Capscrews
40 N•m (30 lbf ft)
Control Valve Capscrews
20 N•m (15 lbf ft)
Differential Case Capscrews
140 N•m (105 lbf ft)
Ring Gear Capscrews
140 N•m (105 lbf ft)
Output Gear Nut
750 N•m (550 lbf ft)
Torque Converter Drive Plate Capscrews
45 N•m (35 lbf ft)
Differential Bearing Caps
225 N•m (166 lbf ft)
DRIVE AXLE
Brake Assembly to Axle Nuts
340 to 375 N•m (251 to 277 lbf ft)
Axle Mount to Frame
320 to 350 N•m (235 to 258 lbf ft)
Axle Shaft Flange Capscrews
225 to 250 N•m (166 to 184 lbf ft)
Axle Housing to Transmission Capscrews
65 N•m (48 lbf ft)
Hub Adjustment Nut
205 N•m (151 lbf ft) Initial
35 N•m (26 lbf ft) Final
Wheel Nuts
610 to 680 N•m (450 to 502 lbf ft)
STEERING SYSTEM
Axle Mount Capscrews
90 N•m (66 lbf ft)
6

8. 8000 SRM 988 Torque Specifications
Bearing Cap for Spindle
45 N•m (35 lbf ft)
Tie Rod Castle Nut
175 N•m (129 lbf ft)
Steering Cylinder Capscrews
225 N•m (166 lbf ft)
Wheel Bearing Adjustment Nut
200 N•m (148 lbf ft) Initial
35 N•m (26 lbf ft) Final
BRAKE SYSTEM
Back Plate Capscrews
340 N•m (251 lbf ft)
HYDRAULIC SYSTEM
Capscrews for Special Blocks for
Pump Drive Chain
20 N•m (15 lbf ft)
MAIN CONTROL VALVE
Through Bolt Nuts (5/16 in.)
20 N•m (15 lbf ft)
Through Bolts Nuts (3/8 in.)
45 N•m (35 lbf ft)
TILT CYLINDERS
Piston Nut
400 to 440 N•m (295 to 325 lbf ft)
Retainer
400 to 500 N•m (295 to 370 lbf ft)
Rod End Lock Capscrews
90 N•m (66 lbf ft)
Anchor Pin Retainer Capscrews
77 N•m (57 lbf ft)
LIFT CYLINDERS
Main Lift Cylinder Retainer Cap
340 to 410 N•m (251 to 302 lbf ft)
Free-Lift Cylinder Retainer Cap
400 to 475 N•m (295 to 350 lbf ft)
Free-Lift Cylinder Mount Capscrews
121 N•m (89 lbf ft)
MAST
Pivot Pin Capscrews
320 N•m (236 lbf ft)
Sideshift Carriage
Lower Hook Capscrews 78 N•m (58 lbf ft)
Side Roller Mount Capscrews 90 N•m (66 lbf ft)
7

9. 1300 SRM 399 Mechanical Description
General
This section contains description and operating principles of the single speed powershift transmission. There
are two parts in this section. The first part describes mechanical components of the transmission. The second
part describes hydraulic operation of the transmission.
Mechanical Description
GENERAL
The transmission has a housing, torque converter,
oil pump, control valve, three shaft assemblies, ring
gear, pinion, and differential assembly.
TORQUE CONVERTER
The torque converter is installed between engine and
transmission. See Figure 1. The torque converter
has three main parts: impeller, turbine, and stator.
1. TURBINE
2. IMPELLER
3. STATOR
4. ONE DIRECTION
CLUTCH
5. STATOR TUBE
6. TRANSMISSION
INPUT SHAFT
7. PUMP DRIVE
SHAFT
Figure 1. Torque Converter
The impeller is connected to the flywheel of the en-
gine by a flexible disc. A flange on the impeller en-
gages with the oil pump for the transmission and op-
erates the pump when the engine is running.
The turbine fits inside the impeller and engages with
the input shaft of the transmission. The stator also
fits inside the impeller and engages with the stator
tube on the transmission.
OIL PUMP
The transmission has its own hydraulic system. An
oil pump is installed on the cover of the transmission
inside the torque converter housing. The oil pump is
driven by the impeller of the torque converter. The
transmission cover has passages for oil to flow to and
from the oil pump.
SHAFT ASSEMBLIES
The three shaft assemblies are: input shaft (with for-
ward clutch assembly), reverse clutch shaft (with re-
verse clutch assembly), and countershaft. See Fig-
ure 2.
Input Shaft
The input shaft is driven by the engine through
the torque converter and rotates in the direction of
engine rotation. The input shaft has the forward
clutch assembly. The clutch is installed in the for-
ward clutch housing and has a piston, friction discs,
separator plates, pressure plate, and return spring.
The teeth on the forward clutch housing are engaged
with the teeth on the reverse clutch housing. The
hub for the forward clutch is engaged with the coun-
tershaft gear.
Reverse Clutch Shaft
The reverse clutch shaft is installed next to the input
shaft. The teeth on the reverse clutch housing are en-
gaged with the teeth on the forward clutch housing.
During operation, the reverse clutch shaft rotates in
the opposite direction of engine rotation. The reverse
1

10. Mechanical Description 1300 SRM 399
clutch assembly has a piston, friction discs, separa-
tor plates, pressure plate, and return spring. The
hub for the reverse clutch is engaged with the coun-
tershaft gear.
Countershaft
The countershaft connects the direction clutches to
the pinion shaft. The small gear on the countershaft
is engaged with the drive gear for the pinion. The
pinion, in turn, drives the ring gear and differential
assembly.
Ring Gear, Pinion, and Differential
The ring gear and pinion provide a gear reduction
and change the direction of the power flow. The dif-
ferential permits the drive wheels to turn at different
speeds when the lift truck is turning a corner.
1. INPUT SHAFT
2. FORWARD CLUTCH
3. REVERSE CLUTCH
4. COUNTERSHAFT
5. OUTPUT GEAR
6. PINION
7. RING GEAR
Figure 2. Shafts Arrangement
2

11. 1300 SRM 399 Mechanical Description
Clutch Assemblies
The two clutch assemblies use similar parts and op-
erate in the same manner. See Figure 3 and Figure 4.
Friction discs and separator plates are installed in
the housing in a sequence. Each friction disc is next
to a separator plate. Separator plates have a smooth
surface while the friction discs have a friction mate-
rial on the surface. The hub in each clutch assembly
engages with the inner splines of the friction discs.
Outer splines of the separator plates engage with the
grooves in the clutch housing.
A pressure plate holds the friction discs and separa-
tor plates in the housing. A return spring keeps the
piston retracted against the housing. There is an ori-
fice in each piston. The orifice releases any oil pres-
sure in the piston housing caused by centrifugal force
after the clutch is disengaged. There is enough clear-
ance in the clutch assemblies to let the friction discs
rotate freely when a clutch assembly is not engaged.
Figure 3. Clutch Assemblies
Legend for Figure 3
1. INPUT SHAFT ASSEMBLY
2. FORWARD CLUTCH HOUSING
3. FORWARD CLUTCH ASSEMBLY
4. FORWARD CLUTCH HUB
5. REVERSE CLUTCH SHAFT ASSEMBLY
6. REVERSE CLUTCH HOUSING
7. REVERSE CLUTCH ASSEMBLY
8. REVERSE CLUTCH HUB
A. REVERSE B. FORWARD
1. FORWARD
CLUTCH HUB
2. COUNTERSHAFT
3. REVERSE CLUTCH
HUB
4. FORWARD
CLUTCH HOUSING
5. REVERSE CLUTCH
HOUSING
6. OUTPUT GEAR
Figure 4. Clutch Assemblies Operation
3

12. Hydraulic Operation 1300 SRM 399
Hydraulic Operation
TORQUE CONVERTER
The torque converter has two main functions. It
works as a fluid clutch to transfer power from the
engine to the transmission. Also, the torque con-
verter multiplies torque. The torque of the engine is
increased by the torque converter when additional
torque is needed to move the lift truck. If the need
for additional torque is low, the torque converter
works as a fluid coupling.
The impeller has a set of curved blades that send oil
out from the center of the impeller when the impeller
turns. Oil is moving at high speed when it leaves the
impeller. Because the impeller is curved, oil flows
into the outer edge of the turbine. Oil pushes the tur-
bine in the direction of the engine rotation. Oil then
flows from the outside to the center of the turbine.
Turbine blades change direction of oil flow so that oil
leaving the center of the turbine is going in the di-
rection opposite of engine rotation. See Figure 5. The
stator is between the turbine and impeller in the cen-
ter of the torque converter. When oil hits the stator
blades, the one-direction clutch prevents the stator
from turning against engine rotation. See Figure 6.
Blades of the stator change direction of oil so that
oil enters the impeller in the direction of engine ro-
tation. The stator permits the torque converter to
increase the torque of the engine. Force of the oil en-
tering the impeller from the stator helps the impeller
and engine turn.
As the speed of the lift truck increases, the oil from
the turbine flows toward the impeller. The centrifu-
gal force of the rotating turbine sends the oil that is
in the turbine against the oil flow from the impeller.
The oil moving in this direction decreases the amount
of oil flow to the impeller from the stator. Because
the oil flow to the impeller decreases, the additional
force on the impeller decreases. Less torque is avail-
able as the speed of the lift truck increases.
When the lift truck is traveling at a constant speed
on a level surface, the turbine and impeller turn at
approximately the same speed. The centrifugal force
of the oil is the same for both the impeller and tur-
bine. The oil does not flow through the stator and
no additional torque is transferred. The rotating oil
hits the back of the stator blades and turns the stator
in the direction of engine rotation. The one-direction
clutch permits the stator to turn with engine rota-
tion. The impeller, turbine, stator, and oil rotate as
a unit when there is no load on the turbine.
When the lift truck starts up a ramp, the turbine
has a resistance to turning. The centrifugal force of
the oil in the turbine decreases. The oil again flows
from the impeller through the turbine and stator and
enters the impeller with force. The torque converter
again increases torque when the turbine speed is less
than the impeller speed.
1. TURBINE 2. STATOR 3. IMPELLER 4. OIL FLOW
Figure 5. Oil Flow through Torque Converter
4

13. 1300 SRM 399 Hydraulic Operation
1. OUTER RACE
2. ROLLERS
3. SPLINES ON
INNER RACE
Figure 6. One Direction Clutch
SHAFT ASSEMBLIES
The input shaft and the reverse clutch shaft have oil
passages that connect the clutch assemblies to the
control valve and the lubrication circuit. Seal rings
are installed on the shafts to make sure the oil flows
to the correct passages. The oil flow to engage a
clutch enters at the groove in the shaft. The oil flow
for lubrication enters the ports at the end of the shaft.
See Figure 4.
CONTROL VALVE
NOTE: The information below applies to early model
S3.50-5.50XL (S70-120XL) (D004) lift trucks.
General
The control valve is installed on the top of the trans-
mission housing. See Figure 7. Holes in the control
valve gasket permit oil to flow from the valve body
to passages in the transmission housing. The con-
trol valve has several regulators and spools to control
the oil pressure and oil flow in the transmission. The
control valve has the pressure regulators for: system
pressure, clutch pressure, and torque converter pres-
sure. The pressure regulators for the lubrication cir-
cuit are in the output end of the housing. The control
valve uses three spools for modulation of oil pressure
to the clutch assemblies. See Figure 8. These spools
are: a drain spool, a modulation valve, and an ac-
cumulator. On units with a direction control lever,
there are two manually operated spools in the con-
trol valve: an inching spool and plunger, and a direc-
tion spool. On units with a MONOTROL® pedal, the
direction spool is actuated by oil from two solenoid
valves installed on the control valve. On all units
the inching plunger is actuated by the inching/brake
pedal.
System Regulator
The system regulator is a spool and spring assembly
that keeps the oil pressure for the operation of the
transmission at 1032 to 1312 kPa (150 to 190 psi).
See Figure 8. The regulator receives oil from the oil
pump before the oil goes through the oil filter. Oil
that is diverted by the regulator goes to the lubrica-
tion circuits.
Clutch Pressure Regulator
Oil flows to the clutch pressure regulator after it goes
through the oil filter. The regulator is a spool and
spring assembly that keeps the oil pressure for the
clutch assemblies at 827 to 965 kPa (120 to 140 psi).
See Figure 8.
The oil supply from the regulator flows to the inching
spool. Oil that flows past the regulator goes to the
torque converter circuit.
Torque Converter Regulator
The torque converter regulator is a spool and spring
assembly that controls the pressure in the circuit for
the torque converter. See Figure 8. The regulator
keeps the pressure at 765 to 903 kPa (111 to 131 psi).
Oil for the regulator comes from the oil that goes past
the clutch pressure regulator. The torque converter
regulator sends excess oil flow to the lubrication cir-
cuit.
Inching Spool
The inching spool controls the oil supply for the
clutch assemblies. See Figure 8. The inching spool
receives oil from the oil filter. The inching spool
can control the oil pressure from 476 to 588 kPa
(69 to 81 psi) to 0 kPa (0 psi). The inching plunger
is connected to the inching pedal. The movement
of the inching plunger lets the inching spool move
in its bore. When the inching plunger and inching
spool are fully retracted, oil flows around the spool
without restriction. As the inching plunger extends
from the bore, the inching spool makes a restriction
5

14. Hydraulic Operation 1300 SRM 399
in the oil flow to the direction spool. When the inch-
ing plunger is fully extended, the inching spool stops
the flow of oil to the direction spool. At the same
time, the inching spool opens a passage to the sump
for the oil from the direction spool. On units with
a MONOTROL pedal, the inching plunger actuates
the neutral start switch when the plunger is fully
extended.
1. VALVE BODY
2. CLAMP
3. FORWARD/REVERSE
SOLENOIDS
4. ADAPTER
5. O-RING
6. ACCUMULATOR SPOOL
7. SPRING
8. PLUG AND O-RING
9. BRACKET
10. MANUAL CONTROL NEUTRAL
START SWITCH
11. STEEL BALL
12. MONOTROL NEUTRAL START
SWITCH
13. FITTING
14. TUBE
15. MODULATOR REGULATOR
SPOOL
16. TRIMMER SPOOL
17. QUICK DUMP VALVE
18. OIL SEAL
19. INCHING SPOOL PLUNGER
20. WASHER
21. INCHING SPOOL
22. MONOTROL DIRECTION
SPOOL
23. INCHING SPOOL STOP
24. DIRECTION SPOOL PLUG
25. SNAP RING
26. SPRING CAP
27. MANUAL CONTROL
DIRECTION SPOOL
28. SLOTTED PIN
29. PACK REGULATOR SPOOL
30. MODULATOR REGULATOR
SPOOL
31. GASKET
32. FILTER
33. NUT
Figure 7. Control Valve - Early Model S3.50-5.50XL (S70-120XL) Lift Trucks
6

15. 1300 SRM 399 Hydraulic Operation
Direction Spool, Manual Control
This direction spool is actuated by the direction con-
trol lever. See Figure 8. The spool has three po-
sitions: FORWARD, NEUTRAL, and REVERSE.
The spool is held in each position by a detent ball.
The spool actuates the neutral start switch. The oil
flow to the direction spool comes from the inching
spool. There is no oil flow past the direction spool
when the spool is in the NEUTRAL position. When
the spool is moved to FORWARD or REVERSE, oil
flows to the accumulator through the drain spool, the
modulation spool and the forward or reverse clutch.
Direction Spool, MONOTROL Pedal
NOTE: Applying the parking brake actuates a
switch that de-energizes the Forward and Reverse
solenoids.
This direction spool is actuated by the oil flow from
two solenoids installed on the top of the control
valve. See Figure 8. The spool has three positions:
FORWARD, NEUTRAL, and REVERSE. The
spool is held in the NEUTRAL position by a spring
arrangement. The oil flow to the Forward and Re-
verse solenoids comes from the inching spool. There
is no oil flow past the direction spool when the spool
is in the NEUTRAL position. When the spool is
actuated by one of the solenoids, oil flows to the ac-
cumulator through the drain spool, the modulation
spool, and the forward or reverse clutch.
Modulation Spool
The modulation spool works with the drain spool ori-
fice to control the movement of the accumulator. See
Figure 8. The oil flow that goes through the drain
spool also pressurizes the modulation spool. The oil
pressure can push against the modulation spool to
open the drain passage. Oil that is not needed for
modulation of the clutch assemblies flows through
the drain passage.
Figure 9 shows the pressure change in the modula-
tion circuit when a clutch is being applied.
Accumulator
The accumulator is used to slow the ratio of clutch
engagement. See Figure 8. This delay reduces the
shock and stress to the drive train when engaging
the transmission or changing the direction of travel.
When a clutch is engaged, the oil flow for the clutch
must go to the accumulator and fill the chamber. The
time it takes for the accumulator to fill controls the
time it takes for the clutch to engage.
Drain Spool
The drain spool is a spool and spring assembly that
controls the flow of oil to and from the accumulator.
See Figure 8. When a direction change is occurring,
oil flows through an orifice in the drain spool and
then flows to the accumulator. As the chamber for
the accumulator fills, the oil pressure is adjusted by
the modulation spool. When a direction change first
starts, pressure to the drain spool decreases. The
spring pressure of the accumulator causes the accu-
mulator spool to push the oil from the cavity. The oil
from the accumulator pushes the drain spool against
its spring, letting the oil flow to the drain circuit.
MONOTROL PEDAL
NOTE: The information below for the MONOTROL
pedal applies to early model S3.50-5.50XL (S70-
120XL) (D004) lift trucks.
The MONOTROL pedal controls the speed of the en-
gine and the operation of the direction spool. See
Figure 10 and Figure 11. The pedal pad is held to
the pedal frame by a pivot shaft. The pedal pad ro-
tates on the shaft and is held in the FORWARD or
REVERSE position by magnets in the pedal frame.
There are two switches in the MONOTROL pedal as-
sembly. A switch on the cowl is actuated by the park-
ing brake lever. The operation of this switch controls
the flow of battery power to the MONOTROL pedal
switches and the starter circuit. When the parking
brake is applied, the starter circuit is energized and
the MONOTROL circuit is de-energized. When the
parking brake is released, the MONOTROL circuit is
energized and the starter circuit is de-energized. The
engine can only be started after applying the parking
brake or depressing the inching/brake pedal. When
the MONOTROL pedal is in the FORWARD posi-
tion, both pedal switch buttons are actuated. Battery
power flows through both pedal switches to energize
the Forward solenoid. When the MONOTROL pedal
is in the REVERSE position, both pedal switch but-
tons are released. Battery power flows through both
pedal switches to energize the Reverse solenoid.
7

16. Hydraulic Operation 1300 SRM 399
Figure 8. Hydraulic Arrangement of Transmission
8

17. 1300 SRM 399 Hydraulic Operation
Legend for Figure 8
1. OIL PUMP
2. FILTER
3. SYSTEM PRESSURE
REGULATOR
4. CLUTCH REGULATOR
5. TORQUE CONVERTER
REGULATOR
6. TORQUE CONVERTER
7. OIL COOLER
8. COLD OIL RELIEF VALVE
9. INCHING SPOOL
10. FORWARD SOLENOID
11. REVERSE SOLENOID
12. DIRECTION SPOOL
13. DRAIN SPOOL
14. ACCUMULATION AND
MODULATION SPOOL
15. INPUT SHAFT (FORWARD)
16. REVERSE CLUTCH SHAFT
17. LUBRICATION CIRCUIT
1. CLUTCH DISENGAGES
2. OTHER CLUTCH FILLS WITH OIL
3. MODULATOR CONTROLS INCREASE IN OIL
PRESSURE
4. OTHER CLUTCH ENGAGED
Figure 9. Modulation Circuit Operation
1. PEDAL PAD
2. SWITCH
3. SWITCH BUTTON
4. MAGNET
5. PLATE FOR
MAGNET
6. PEDAL FRAME
Figure 10. MONOTROL Pedal
CONTROL VALVE
NOTE: The information below applies to later
model S3.50-5.50XL (S70-120XL) lift trucks and
S3.50-5.50XM (S70-120XM) model lift trucks. See
Figure 12.
General
The control valve is installed on the top of the
transmission. The inching spool, direction spool,
modulator circuit, regulator for clutch pressure, and
the regulator for the torque converter are part of the
control valve. The position of the inching spool is
controlled by the inching/brake pedal. The oil filter
for the transmission is also mounted on the control
valve.
A manifold with two solenoid valves is installed
on top of the control valve. The solenoid valves
are actuated by the direction control lever or the
MONOTROL pedal. The solenoids control the posi-
tion of the direction spool. See Figure 12.
Regulator for Clutch Pressure
The regulator for clutch pressure controls oil pres-
sure for applying clutches to engage the transmis-
sion. The control pressure of the regulator is 862 to
1048 kPa (125 to 152 psi). Oil that flows to the regu-
lator for clutch pressure flows to the torque converter
circuit and oil lubrication circuit. An orifice in the
valve body and transmission case makes sure that
there is always some oil flow to the torque converter.
Inching Spool Assembly
Inching is the slow movement of a lift truck while
a high engine speed is used for faster operation of
the hydraulic system. Inching function is normally
used for fine movements of the lift truck when han-
dling a load. Operation of inching pedal decreases
the oil pressure to a clutch so that the clutch is not
completely applied.
9

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19. Hydraulic Operation 1300 SRM 399
Wire Color Gauge
B
E
J
K
T
W
X
CC
FF
LL
HM
PM
XM
Red
Yellow
White
Red
Black
Black
Red
Yellow
Brown
White
Yellow
Black
Red
14
16
14
14
16
14
16
14
10
14
18
18
18
1. BATTERY
2. STARTER
3. IGNITION SWITCH
4. PARKING BRAKE SWITCH
5. FUSE
6. BRAKE PRESSURE SWITCH
7. NEUTRAL START SWITCH
8. MONOTROL PEDAL SWITCH
9. REVERSE SOLENOID
10. FORWARD SOLENOID
11. TO ALTERNATOR
12. TO IGNITION SWITCH
Figure 11. MONOTROL Pedal Electrical Circuit (All Lift Truck Models)
10

20. 1300 SRM 399 Hydraulic Operation
The inching spool assembly has an inching spool,
inching spool plunger, and three springs. Oil flows to
the inching spool from the transmission pump. The
inching spool controls the oil flow and pressure to the
direction spool. When inching function is not used,
oil flows through the inching spool to the direction
spool. Operation of the inching function causes a
restriction of oil flow to the direction spool and the
clutch. This operation decreases the oil pressure
to the direction spool (and clutch) as the inching
spool plunger is extended. When the inching spool
plunger is completely extended, oil pressure to the
direction spool (and clutch) is approximately zero.
The clutch is then released and the transmission is
in NEUTRAL. See Figure 12.
1. VALVE BODY
2. PRESSURE REGULATOR -
TORQUE CONVERTER
3. PRESSURE REGULATOR -
CLUTCH
4. SPRING
5. PLUG AND O-RING
6. INCHING SPOOL PLUNGER
7. OIL SEAL
8. FITTING
9. COPPER GASKET
10. SNAP RING
11. SPRING CAP
12. DIRECTION SPOOL
13. INCHING SPOOL
14. MODULATOR REGULATOR
15. QUICK DUMP VALVE
16. MODULATOR PISTON
17. FORWARD SOLENOID
18. REVERSE SOLENOID
19. MANIFOLD
20. TUBE
21. GASKET
Figure 12. Control Valve - Later Model S3.50-5.50XL (S70-120XL) Trucks and S3.50-5.50XM
(S70-120XM) Trucks
11

21. Hydraulic Operation 1300 SRM 399
Direction Spool
The direction spool controls oil flow to the direc-
tion clutches. See Figure 13. The direction spool
has three positions: FORWARD, NEUTRAL, and
REVERSE. When the direction spool is in its FOR-
WARD position, oil flow and pressure is sent to apply
the forward-low clutch. When the direction spool is
in its REVERSE position, oil flow and pressure is
sent to apply the reverse clutch. When the direction
spool is in its NEUTRAL position, oil pressure to
both clutches is reduced to approximately zero. Both
clutches are released and the transmission is in
NEUTRAL. When the direction spool is moved to
control a direction of travel, oil flows to and from the
clutch assemblies and also to the modulator circuit.
Two electric solenoids control the position of the di-
rection spool in the transmission control valve. Elec-
tric switches in the MONOTROL pedal or direction
control lever energize and de-energize the solenoids.
The solenoids open and close small valves that send
oil flow to the ends of the direction spool. Only one
solenoid is energized for each direction. When a di-
rection solenoid is energized, the oil pressure to one
end of the direction spool moves the direction spool
so that a clutch is applied. Oil flow and pressure on
the ends of the direction spool move the spool to ei-
ther its FORWARD or REVERSE position.
Figure 13. Control Valve - Later Model S3.50-5.50XL (S70-120XL) Trucks and S3.50-5.50XM
(S70-120XM) Trucks
12

22. 1300 SRM 399 Hydraulic Operation
Legend for Figure 13
1. TORQUE CONVERTER
REGULATOR
2. CLUTCH PRESSURE
REGULATOR
3. INCHING SPOOL WITH
MONOTROL CONTROL
4. DIRECTION SPOOL,
MONOTROL CONTROL
5. TRIMMER SPOOL
6. CONTROL VALVE BODY
7. TRIMMER REGULATOR
SPRING
8. ACCUMULATOR SPRING
9. ACCUMULATOR SPOOL
10. SPRING
11. QUICK DUMP SPOOL
12. DIRECTION SPOOL, MANUAL
CONTROL
13. INCHING SPRING
14. INCHING PLUNGER SPRING
15. PACK REGULATOR SPOOL
16. SNAP RING
17. CONVERTER REGULATOR
SPOOL
18. CONVERTER REGULATOR
SPRING
19. PACK REGULATOR SPRING
20. INCHING STOP
Direction Spool, Manual Control
This direction spool is actuated by the direction con-
trol lever. See Figure 13. The spool has three po-
sitions: FORWARD, NEUTRAL, and REVERSE.
The spool is held in each position by a detent ball.
The spool actuates the neutral start switch. The oil
flow to the direction spool comes from the inching
spool. There is no oil flow past the direction spool
when the spool is in the NEUTRAL position. When
the spool is moved to FORWARD or REVERSE, oil
flows to the accumulator through the drain spool, the
modulation spool and the forward or reverse clutch.
Modulator Circuit
A modulator circuit is used to control the rate of ap-
plication of the clutches. When the direction spool
is moved to select a direction of travel, the modula-
tor circuit controls the application of the clutch dur-
ing a 1.5 to 2.0 second period. The modulator cir-
cuit controls the pressure increase to apply the clutch
smoothly. This delay and smooth application of pres-
sure reduces the shock and stress to the drive train
when engaging the transmission or changing direc-
tions. See Figure 12.
Regulator for Torque Convertor
When the engine speed is low, oil flows to the torque
converter through an orifice in the bore in the clutch
pressure regulator. The pressure regulator for the
torque converter stays closed until the pressure to
the torque converter increases to 765 to 903 kPa
(111 to 131 psi). When the pressure regulator for
the torque converter opens, oil that does not go to
the torque converter flows directly to the passage
to cool and lubricate the parts of the transmission.
Oil that flows to the torque converter goes through
the oil cooler before entering the passage to cool and
lubricate the clutches. See Figure 13.
LUBRICATION CIRCUIT
Oil supply for the lubrication circuit comes from
oil that flows past the system regulator, torque con-
verter regulator, and oil cooler. There is a lubrication
circuit for each clutch assembly. The lubrication cir-
cuit supplies oil at 96 to 138 kPa (14 to 20 psi).
DIRECTION CONTROL LEVER
NOTE: The information in the following paragraph
applies to S3.50-5.50XM (S70-120XM) (E004, F004)
model trucks only.
The direction control lever is used to control opera-
tion of direction solenoids. See Figure 14. When the
lift truck has a direction control lever, an accelera-
tor pedal is used to control the speed of the engine.
The control lever actuates two switches. In the NEU-
TRAL position, both of the switches are closed. The
lever must be in this position to start the lift truck.
When the lever is moved to the FORWARD position,
the forward switch is open and the reverse switch is
closed. In this position the forward solenoid is ener-
gized. In the REVERSE position, the reverse switch
is open and the forward switch is closed, energizing
the circuit for the reverse solenoid.
13

23. Hydraulic Operation 1300 SRM 399
1. CONTROL LEVER
2. FORWARD
SWITCH
3. SWITCH
ACTUATOR
4. REVERSE SWITCH
Figure 14. Direction Control Lever
MONOTROL PEDAL
NOTE: The information below for the MONOTROL
pedal applies to later model S3.50-5.50XL (S70-
120XL) (D004) lift trucks and to S3.50-5.50XM
(S70-120XM) (E004, F004) model lift trucks.
The MONOTROL pedal controls speed of the engine
and operation of direction solenoids. See Figure 11,
Figure 15, and Figure 16. The pedal pad is held
to the pedal frame by a pivot shaft. The pedal pad
rotates on the shaft and is held in the FORWARD or
REVERSE position by magnets in the pedal frame.
There are two switches in the MONOTROL pedal
assembly. When the MONOTROL pedal is in the
FORWARD position, both pedal switch buttons are
actuated. Battery power flows through both pedal
switches to energize the forward solenoid. When the
MONOTROL pedal is in the REVERSE position,
both pedal switch buttons are released. Battery
power flows through both pedal switches to energize
the reverse solenoid.
Start Circuit, MONOTROL Pedal
For units with a MONOTROL pedal there are two
switches on the bracket for the parking brake lever.
The switch on the right-hand side of the bracket
supplies power to the direction solenoids. When the
parking brake is applied the switch de-energizes the
direction solenoids. When both of the solenoid valves
close (de-energized), the centering spring moves the
direction spool to the NEUTRAL position.
1. PEDAL PAD
2. PEDAL FRAME
3. MAGNET
4. PIVOT SHAFT
5. SPRING
6. MAGNET PLATE
7. SWITCH
Figure 15. MONOTROL Pedal S3.50-5.50XL
(S70-120XL) (Later Model) Lift Trucks
The switch on the left-hand side of the bracket pre-
vents the engine from starting unless the parking
brake is applied.
When inching/brake pedal is fully depressed, service
brakes are applied and a disc on the end of the inch-
ing spool actuates the neutral start switch. Neu-
tral start switch is in series electrically with pres-
sure switch in the brake system. The disc actuates
the neutral start switch and pressure in the brake
system closes the brake switch. The pressure switch
in the brake system makes sure that brakes are ap-
plied. When neutral start switch and brake switch
are both closed, start circuit, controlled by ignition
switch, can be energized. When inching/brake pedal
is fully pushed down, oil pressure to the clutch pack
is reduced to zero. This operation makes sure that
14

24. 1300 SRM 399 Hydraulic Operation
the transmission clutch is disengaged and brakes are
applied when the engine is started.
1. PEDAL PAD
2. PEDAL FRAME
3. MAGNET
4. PIVOT SHAFT
5. SPRING
6. MAGNET PLATE
7. SWITCH
Figure 16. MONOTROL Pedal S3.50-5.50XM
(S70-120XM) Lift Trucks
Creep Speed Switch
NOTE: The creep speed switch is an optional feature
on S3.50-5.50XM (S70-120XM) model lift trucks.
A switch is installed on the accelerator or
MONOTROL pedal to slow movement of the lift
truck at idle speed. When the accelerator or
MONOTROL pedal is not applied, the switch opens
the electric circuit to the transmission controller. As
the pedal is depressed, the switch closes, energizing
direction solenoids.
OIL FLOW DIAGRAMS
NOTE: The following information applies to all
lift truck models. The diagrams shown in Figure 17
through Figure 20 apply to early model S3.50-5.50XL
(S70-120XL) (D004) lift trucks.
The diagrams shown in Figure 21 through Figure 24
apply to later model S3.50-5.50XL (S70-120XL)
(D004) lift trucks and to S3.50-5.50XM (S70-120XM)
(E004, F004) lift trucks.
Neutral
When engine is running and transmission is in NEU-
TRAL, the oil pump supplies oil to the following reg-
ulators: system regulator, clutch regulator, inching
spool, and forward and reverse solenoids or direction
spool. See Figure 17 or Figure 21, depending on your
model of lift truck.
Forward
When the direction spool is moved to the FORWARD
position, oil from the inching spool flows past the
direction spool. See Figure 18 or Figure 22. Oil
then flows to the drain spool, modulation spool, for-
ward clutch, and lubrication regulator for the for-
ward clutch. Oil flow at the clutch assembly pushes
on the piston to engage the clutch.
Forward-Inching
Pushing on the inching/brake pedal while lift truck is
moving decreases oil pressure to the direction spool.
See Figure 19 or Figure 23, depending on your model
of lift truck. Pressure in the accumulator shifts the
drain spool so that some oil from the accumulator
flows to the drain passage. Decrease in oil pressure
that engages the forward clutch lets the clutch par-
tially disengage. Clutch completely disengages when
inching plunger is fully extended. Inching operation
lets operator move the lift truck slowly while keeping
a high engine speed for hydraulic functions.
Reverse
As the direction spool moves for a direction change,
it opens the drain circuit for the forward clutch and
the accumulator. Oil in the accumulator chamber
pushes against the drain valve and flows to the drain
passage. When the direction spool is in REVERSE
position, the drain passages for the accumulator are
closed. See Figure 20 or Figure 24. Oil from the inch-
ing spool fills the accumulator chamber and engages
the reverse clutch.
15