PDF Service Manual Caterpillar GC25K HP Lift Truck - 2 MB
This service manual provides in-depth maintenance and repair information for Caterpillar GC25K HP lift trucks.
It is designed for technicians and contains detailed procedures for troubleshooting, disassembly, and assembly of all major systems.
Proper servicing is essential for the safety and performance of your lift truck.
This manual is the key to performing professional-level repairs and keeping your equipment in top condition.
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--- Page 1 ---
Service Manual
Chassis & Mast
GC15K AT81C-00011-up GC25K AT82C-00011-up
AT81D-00011-up AT82D-00011-up
AT81E-00011-up AT82E-00011-up
GC18K AT81C-00011-up GC25K HP AT82C-90011-up
AT81D-00011-up AT82D-90011-up
AT81E-00011-up AT82E-90011-up
GC20K AT82C-00011-up GC30K AT83C-00011-up
AT82D-00011-up AT83D-00011-up
AT82E-00011-up AT83E-00011-up
GC20K HP AT82C-90011-up
AT82D-90011-up
AT82E-90011-up
For use with 4G63/4G64 Engine Service Manual and
Liquefied Petroleum Gas Supplements. 99719-80150
--- Page 3 ---
GENERAL INFORMATION
Serial Number Locations
Nameplate
Mast serial number Transmission serial number Engine serial number
207070
1-2
--- Page 4 ---
COOLING SYSTEM
Structure and Function
209479
The cooling fan is installed inside the engine compartment.
This helps minimize radiator core clogging and retain high
cooling efficiency even in continuous operation for hours.
The radiator’s lower tank has a built-in transmission oil
cooler.
2-1
--- Page 5 ---
ELECTRICAL SYSTEM
Major Electrical Components
Starter Switch (with Anti-Restart Lock)
This switch has a built-in anti-restart lock, so the key
cannot be turned from (ON) to (START) position
while the engine is running.
(OFF)
(ON)
B M
(START)
S
203561A
Connection Chart
Terminal B M S
Component Fuse box, battery, Fuse box, fuel-cut Starter, neutral switch
Key alternator solenoid (powershift
position transmission models)
(OFF)
(ON)
(START)
3-5
--- Page 6 ---
POWER TRAIN
Removal and Installation
Removal of Engine, Transmission (Torque Converter), Reduction Gear and
Differential
NOTE
Separate the engine-power line combination from the
front axle housing at the differential carrier.
2
1
8
3
9
4
10
6
5
12
7
13
11
205946
Sequence
1 Overhead guard 7 Master cylinder
2 Engine cover, Front cover, Floor plate, 8 Radiator hoses, Radiator
Radiator cover 9 Air cleaner rubber hose, Exhaust pipe
3 Steering wheel 10 Universal joint
4 Battery, Power line harness 11 Front axle shaft
5 Fuel hose, Accelerator pedal linkage 12 Engine mounting bolt
6 Choke cable 13 Power line
4-1
--- Page 7 ---
POWERSHIFT TRANSMISSION
Control System
Cable
1 8
3
4
7
6 2
5
207136B
Main components
1 Directional control lever (F-N-R shift lever) 6 Forward-reverse selector valve
2 Clutch (inching) lever (solenoid valve assembly)
3 Bracket (inching) 7 Inching lever
4 Control valve assembly 8 Brake pedal
5 Clutch valve plunger
The operator can perform two types of control on the Inching
transmission : forward-reverse switching and inching. When the operator depresses inching pedal 2, the cable
connected to the pedal pulls inching lever 7, causing it
to turn in the direction of the arrow. Clutch valve
Forward-reverse switching
plunger 5 having been held retracted in the valve body
When the operator moves directional control lever 1 by the lever until then is moved out by the force of the
into the F or R position, electric current flows to the F spring in the direction of the arrow. When the plunger
or R solenoid to cause the plunger in the solenoid to moves out, the pressure oil passage to the clutch is
move. The spool connected to the plunger then moves throttled and, at the same time, the pressure oil being
and allows pressure oil to flow to the forward or supplied to the clutch is drained, causing the pressure to
reverse clutch to engage the clutch. This completes the drop. As the pressure reduces, the clutch becomes
engine power path from the output shaft to the engaged only partially. The amount of oil drained
differential. depends on how much the inching pedal is depressed.
Speed control is achieved only by way of the When inching pedal 2 is depressed, the brake pedal
accelerator pedal. With lever 1 in the neutral position, follows the inching pedal movement. As soon as the
solenoid in the selector valve is not energized, so the clutch pressure drops to zero, the brakes starts working.
valve spool remains in the neutral position. Neither of Using inching pedal 2 alone, the operator can make
the clutches is then engaged and no power is partial clutch engagement and braking controls.
transmitted to the output shaft.
5-4
--- Page 8 ---
POWERSHIFT TRANSMISSION
Suggestions for Disassembly
1. Removing idler gear shaft ball bearing
Use a gear puller.
200112
2. Removing output shaft
(1) Use bevel pinion puller (special tool) to remove the
output shaft. The shaft will come out, leaving the
output gear behind in the transmission case.
Special tool needed
91868 - 02100
Bevel pinion puller or
91268 - 00300
203530
(2) Use a press to remove the bearing from the output
shaft.
200091
3. Removing input shaft ball bearing
Use a special tool to remove the ball bearing from the input
shaft.
Special tool needed
Ref. Part name Part No. Q’ty
No.
1 Puller 91268 - 13810 2
2 Plate 91268 - 13820 1
3 Bolt F1035 - 10020 2 207120
4 Gear puller T-24
– 1
(Banzai make)
5-14
--- Page 9 ---
POWERSHIFT TRANSMISSION
Inspection and Adjustment
Testing Hydraulic Pressure WARNING
1. Run the engine at low idle for a while. Stop the engine To reduce the risk of personal injury, when
and , one minute later, check the oil level in the the hydraulic pressure is tested, move the
transmission with the oil level gauge. truck to a clear area, that is level. Keep
2. Warm up until the transmission oil temperature rises. all other personnel away from the truck.
3. Check the no-load minimum and maximum speeds of Use lifting equipment or a safe method to
the engine. If the speeds are not correct, make an lift the front of the truck until the front
adjustment by referring to SERVICE MANUAL for the wheels are off the floor. Put wood blocks
engine. or jack stands of the correct capacity
Unit: rpm under it to hold it in this position while
Truck Model GC20K/20K HP pressure tests are performed.
GC15K GC25K/25K HP
Item GC18K GC30K
No-load minimum
700 ± 50 700 ± 50
speed
No-load maximum
2600 2600 to 2650
speed
4. After checking the engine speeds, stop the engine.
Raise the front wheels. To do this, jack the front axle
housing, or place wood blocks under the outer mast and
tilt the mast forward.
CAUTION
The front wheels will rotate when the clutch
pressure is tested.
5. Connect a pressure gauge to the tap for a pressure to be
tested. The pressure taps are located as shown.
5-24
--- Page 10 ---
POWERSHIFT TRANSMISSION
Service Data
A: Standard value B: Repair or service limit
Unit: mm (in.)
Truck Model GC20K HP
GC15K GC20K
GC25K HP
GC18K GC25K
Item GC30K
Stall speed (tolerance ± 100 rpm) rpm A 2130 1780 1960
At 1600 ± 100 engine rpm
A 930 to 1180 (9.5 to 12.0) [135 to 171]
kPa (kgf/cm2) [psi]
Main At 800 ± 50 engine rpm
pressure B 785 (8) [144], min
kPa (kgf/cm2) [psi]
At 2500 ± 100 engine rpm
B 785 to 1177 (8 to 12) [114 to 171]
kPa (kgf/cm2) [psi]
At 1600 ± 100 engine rpm
A 930 to 1180 (9.5 to 12.0) [135 to 171]
kPa (kgf/cm2) [psi]
Clutch At 800 ± 50 engine rpm
pressure B 785 (8) [144], min
kPa (kgf/cm2) [psi]
At 2500 ± 100 engine rpm
B 785 to 1177 (8 to 12) [114 to 171]
kPa (kgf/cm2) [psi]
At 1600 ± 100 engine rpm
A 100 to 490 (1 to 5) [14.3 to 71]
Torque kPa (kgf/cm2) [psi]
converter At 800 ± 50 engine rpm
inlet B 98 (1) [14]
kPa (kgf/cm2) [psi]
pressure At 2500 ± 100 engine rpm
B 98 to 588 (1 to 6) [14 to 85]
kPa (kgf/cm2) [psi]
At 1600 ± 100 engine rpm
A 100 to 490 (1 to 5) [14.3 to 71]
Torque kPa (kgf/cm2) [psi]
converter At 800 ± 50 engine rpm
outlet B 49 (0.5) [7]
kPa (kgf/cm2) [psi]
pressure At 2500 ± 100 engine rpm
B 49 to 343 (0.5 to 3.5) [7 to 50]
kPa (kgf/cm2) [psi]
Lubricating At 1600 ± 100 engine rpm
oil pressure A 98 to 147 (1 to 1.5) [14 to 21]
kPa (kgf/cm2) [psi]
10-m (33 ft) starting acceleration (no load) sec A Within 5
0 0
Outside diameter of surface of boss A 55 −0.030 (2.17 −0.000118 )
for oil seal 1 B 54.90 (2.1614)
55.155 to 55.225
A
Inside diameter of bushing 2 (2.17145 to 2.17421)
B 55.4 (2.181)
Pump boss
200409
5-34
--- Page 11 ---
FRONT AXLE AND REDUCTION DIFFERENTIAL
5. Raise the front end of the truck. Use any of the
following three methods.
WARNING
(1) Do not replace the tire when the truck is
loaded to prevent possible personal injury.
(2) Be sure to get off the truck when raising the
front tire.
(3) Stop raising the truck when the tire just
clears the ground. Do not raise the truck
more than is necessary to prevent possible
personal injury.
(4) Do not put any portion of your body under
the truck. Securely support the truck by
blocks after raising it.
Method 1 — Position the jack under the frame and raise
the truck until the tire clears the floor.
100828
Method 2 — Tilt the mast all the way back, place wood
blocks under the mast, and tilt the mast
forward.
CAUTION
After raising the front end, securely support it
by blocks.
200227
Method 3 — Fasten a hoist to the mast and lift the front
end of the truck as shown.
207085
6-3
--- Page 12 ---
FRONT AXLE AND REDUCTION DIFFERENTIAL
Reassembly
200243
Sequence
1 Taper roller bearings 3 Spring pin
2 Differential gear assembly 4 Reduction gear
This assembly consists of (must be factory-assembled 5 Carrier, Side bearing caps, Side bearing nuts,
unit): Lock washers, Bolts, Lock plate, Lock washer,
Differential case, Thrust washers, Bevel gears, Bolts
Pinions, Pinion shaft
Suggestions for Reassembly
1. Reassembling differential pinions
The thrust washers of the differential gears are to be used
for adjusting the backlash between the differential gears
and pinions. Measure the backlash and, if it exceeds the
limit, replace the thrust washers.
A: Standard value B: Repair or service limit
Unit: mm (in.)
0.18 to 0.23
Backlash between A
(0.0071 to 0.0091) 200244
differential gears
and pinions
B 0.5 (0.020)
6-13
--- Page 13 ---
REAR AXLE
Structure and Function
Rear Axle
207022
1 Rear axle 5 Tie rods
2 Steering cylinder 6 Wheel assembly
3 Steer knuckles 7 Shims
4 King pins
The truck is steered by the rear wheels. The rear axle is
connected to the frame by its center pivot shaft. Because of
the center pivoting feature, the rear axle can oscillate up to
3° in each direction.
7-1
--- Page 14 ---
REAR AXLE
Suggestions for Disassembly
1. Removing retainer and bearing
Use a puller to remove the retainer and bearing cone from
the knuckle.
207031
Inspection after Disassembly
1. Tie rods and pins
(1) Make sure that the pins are free of any surface flaws
such as grooving or stepped wear. Examine the tie rod
pin weld for cracking.
(2) Examine the bearings for wear or damage.
(3) Examine the tie rods for damage and alignment.
Inspect the welds for signs of cracks.
NOTE
If a pin must be replaced, replace its bearing as well.
2. Kingpins
Check the kingpins for any surface flaws such as grooving
or stepped wear. Inspect the pins for cracks at the bearing
shoulder.
3. Kingpin bearings
Examine the rollers and bearing races for grooving,
abrasive wear, pitting, bruising, or corrosion. Replace both
the cup and cone of damaged bearings.
4. Knuckles
Inspect the inside of each knuckle for wear or damage. Be
sure to examine for casting cracks. Check the tie rod pin
hole. Examine the wheel nut threads for damage.
5. Seals and O-rings
Examine all seals and O-rings for damage such as cuts and
tears. Replace seals which show signs of aging.
6. Hydraulic pipes
Inspect the hydraulic pipes for cracks, especially at the
joints with the end fittings. Check for leaks.
7. Cylinder rod
Examine the rod for surface or plating damage. Inspect the
rod for straightness. Examine the piston for damage check
the tie rod pin hole for damage or wear.
7-11
--- Page 15 ---
REAR AXLE
Service Data
A: Standard value B: Repair or service limit
Unit: mm (in.)
Truck Model GC20K/20K HP
GC15K
GC25K/25K HP
GC18K
Item GC30K
Oscillating angle A 3°
Toe-in A 0°
Caster A 0°
Camber A 1°
A 0.8 (0.031)
Total fore-aft play of axle at center pin 1
B 1.2 (0.047)
Inside 2 A 82° 80°
Turning angle
Outside 3 A 59° 55°
Tightening torque for support bolts 4
A 145 (14.8) [107]
N·m (kgf·m) [lbf·ft]
Tightening torque for knuckle stopper bolt
A 67 (6.8) [49]
lock nuts 5 N·m (kgf·m) [lbf·ft]
Rear Axle Cylinder minimum test pressure
A 10500 (107) [1522] 16000 (163) [2320]
kPa (kgf/cm) [psi]
2
4 5
3
1
207043
7-21
--- Page 16 ---
BRAKE SYSTEM
Disassembly and Reassembly
Master Cylinder
Disassembly
8
❋ 7
6
5
4
3
2
1
204924
Sequence
1 Clevis, Locknut, and Push rod 5 Spring seat, Primary cup, and Cup spacer
2 Boot 6 Return spring
3 Snap ring 7 Cylinder body
4 Secondary cup and Piston 8 Reservoir and Wire band
NOTE
The parts (❋) to be changed periodically are included
in the Repair Kit.
8-6
--- Page 17 ---
BRAKE SYSTEM
Inspections and Adjustment
1. Operational test of automatic adjusting device
(1) Set the wheel brake properly, and adjust the drum-to-
lining clearance to the specification. Pull the adjusting
lever while pushing the cable, as shown, to see if the
lever turns the adjusting screw by one tooth and, as the
push is removed, returns to the original position. If it
does, the device is in satisfactory condition.
200281
(2) If the lever fails or is sluggish to turn the adjusting
screw in the above test, the possible cause is that the
lever is not properly positioned relative to the toothed
wheel. Be sure that the lever is so positioned that its
actuating tip touches the toothed wheel at a level about
9 mm (0.35 in.) under the center line of the screw, as
shown.
9 mm (0.35 in.)
(3) Where the automatic adjusting device is suspected of
malfunctioning during normal use of the machine, the
following possible causes must be considered: 200282
(a) Adjusting spring is not correctly hooked to primary
shoe.
(b) Any of these parts is in bad condition to require
replacement:
i) fitting cable, ii) adjusting lever, and iii) adjusting
screw.
2. Manual adjustment
The drum-to-lining clearance can be adjusted by rotating
the adjusting screw with a screwdriver put to the toothed
wheel. The hole through which the screwdriver tip can be
inserted is provided in the backing plate.
Unit: mm (in.)
Truck Model GC20K/20K HP
GC15K
GC25K/25K HP
GC18K
Item GC30K
200283
Clearance
between drum 0.25 to 0.5 0.1 to 0.35
and lining (0.009 to 0.019) (0.004 to 0.013)
8-16
--- Page 18 ---
STEERING SYSTEM
Structure and Functions
General
Oil flow
Valve 3 Right turn: R SL SR L
Tank 1 Pump 2 Inlet sec PF P T T2 T1 Tank 1
Left turn: L SR SL R
209462
Main steering system components
1 Tank (hydraulic) 4 Steering gear
2 Hydraulic pump 5 Steering wheel
3 Inlet section of hydraulic valve 6 Steering cylinder
(with built-in flow divider valve)
The steering system of this machine is operated and pump, rotates together with the steering wheel. When
controlled completely hydraulically. the steering wheel is turned, the pump rotor turns and
The oil drawn by hydraulic pump 2 from hydraulic tank forces the oil into steering cylinder 6 through port R or
1 is forced to steering gear 4 via the flow divider valve L of steering gear 4. This pushes the piston in steering
and then through port PF in inlet section 3. When cylinder 6 and forces the oil on the other side toward
steering wheel 5 is not turned, the oil flows through port L or R of the steering gear. The oil then goes out of
port T of the steering gear to port T2 in the inlet section the steering gear through port T and enters port T2 of
and then returns to hydraulic tank 1. the inlet section 3. From port T1 of the hydraulic
control valve, the oil flows into hydraulic tank 1.
When the operator turns the steering wheel, the oil
flows to a small hydraulic pump in the steering gear. For more detail of the oil flow, refer to the “Hydraulic
The pump rotor, the core element of the small hydraulic Schematic of Hydraulic System” section (page 11-2).
9-1
--- Page 19 ---
STEERING SYSTEM
Inspection and Repair
(1) Inspecting sliding surfaces between the spool and the
housing and between the spool and the sleeve
(a) Check for defective sliding movement in sub-
assembly condition.
(b) If any defective movement is found, check sliding
surfaces.
If any defect such as abnormal wear, rust or a
scratch is found, replace the steering control valve
assembly.
Reassembly
200787
Sequence
1 Long housing 7 Thrust needle, Race bearings
2 Check valve, Retainer, Ball, O-ring, 8 Seal gland bushing, Oil seal, Dust seal,
Check seat, Set screw O-ring
3 Control sleeve 9 Retaining ring
4 Control spool 10 Drive shaft, Spacer plate, O-ring
5 Centering spring 11 “Gerotor” set, O-ring
6 Pin 12 End cap, O-ring, Spacer, Bolts
9-11
--- Page 20 ---
HYDRAULIC SYSTEM
Hydraulic Tank
207069
1 Air breather, Cap 4 Suction strainer
2 Oil level gauge 5 Return filter
3 Drain plug
The tank is internally provided with two filtering means,
suction strainer with a 150-mesh screen for catching gritty
particles in the oil and return filter built in the relief valve
and capable of catching 15-micron and larger particles in
the oil returning from the control valve.
The oil level in the hydraulic tank changes as the mast is
raised and lowered, causing air to flow out of and into the
tank through the breather. The breather is fitted with a
filter to prevent dust from entering the tank.
11-3
--- Page 21 ---
HYDRAULIC SYSTEM
Removal and Installation
WARNING
Hydraulic oil, under pressure can remain in the hydraulic system after the engine and pump have
been stopped. Personal injury can be caused if this pressure is not released before any work is
done on the hydraulic system. To prevent possible injury, lower the lift bracket to the ground, turn
the engine off and move the control levers to make sure all hydraulic pressure is released before
any fitting, plug, hose or component is loosened, tightened, removed of adjusted. Always move
the truck to a clean and level location away from the travel of other machines. Be sure that other
personnel are not near the machine when the engine is running and tests or adjustments are
made.
Hydraulic Pump
Removal
205965
Sequence
1 Universal joint 4 Clamp, Suction hose, Elbow, O-ring
2 Drive pulley, Lock nut, Boss 5 Hydraulic pump
3 Main delivery hose, Joint, O-ring
11-13
--- Page 22 ---
HYDRAULIC SYSTEM
Suggestions for Disassembly
(1) Do not disassemble main relief valve 1 and steering
system relief valve 2 unless it is impossible to adjust
the setting of the valve.
(2) Do not change the combination of valve housing and
spool.
Inspection and Repair
(1) Check the valve housings for cracks and sliding
surfaces for wear. Also, inspect the check valve seat
for wear.
(2) Check the spools for damage, seizure or distortion.
Also, check for operating effort.
157 to 216 N
Operating effort of spool
(16 to 22 kgf)
(full stroke)
[35.2 to 48.5 lbf]
(3) Check the poppet (tilt lock valve) for damage or
seizure.
Reassembly
To reassemble, follow the reverse of disassembly sequence,
and do the following steps:
(1) Clean the disassembled parts with high flash-point
solvent. Blow them dry with compressed air; however,
this does not apply to rubber parts.
(2) Apply hydraulic oil to the spools when inserting them
into the valve blocks.
(3) Position the poppet (tilt lock valve) correctly.
(4) Apply grease to the O-rings when fitting them between
the valve housings to prevent them from twisting.
(5) Do not use any type of sealant.
(6) Tighten the tie bolts (securing the valve housings) as
evenly as possible to prevent distorsion of the
housings. Remember, a failure to follow this
precaution will result in sluggish movement of the
spools.