PDF Service Manual Caterpillar EP20K Lift Truck - 2 MB
This collection of service manuals provides comprehensive repair and maintenance information for the Caterpillar EP20K electric lift truck.
It covers all major systems, including the electrical, hydraulic, and mechanical components.
Technicians will find detailed troubleshooting charts, wiring diagrams, and step-by-step repair procedures.
This is the definitive guide for servicing your Cat EP20K forklift.
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--- Page 1 ---
Service Manual
Chassis, Mast & Options
EP20K ETB8B-00011-up
EP25K ETB8B-50001-up
EP30K ETB9B-00011-up
EP35K ETB9B-50001-up
For use with EP20K-EP35K
Controller Service Manual. 99759-6D100
--- Page 4 ---
VEHICLE ELECTRICAL COMPONENTS
10
12
11
13
211640
10 Joystick box (FC only) 12 Hydraulic controller
11 Traction controller 13 Contactor
2-2
--- Page 5 ---
VEHICLE ELECTRICAL COMPONENTS
Fuses
Capacity (A) Location Main connecting device
325 Traction motor
325 Contactor assembly Pump motor
50 Steering pump motor
15 Horn switch, Lighting switch
Fuse holder
10 Key switch, Contactor
NOTE
Refer to Parts Manual for proper replacement fuses.
Lamp Specification Chart
Item Bulb
Quantity Bulb color Remarks
Lamp 80 V External diagram
Head lamps 2 Clear 55 W
Working lamp 1 Clear 55 W
205833
2-12
--- Page 6 ---
VEHICLE ELECTRICAL COMPONENTS
(2) How to cope with a failed (open-circuit) seat switch.
Your troubleshooting investigation might reveal that the
seat switch is an open-circuit or otherwise faulted and
will not function.
In such a case, you can create a temporary circuit
through the seat switch wiring. The method is
explained in this illustration. The seat switch is a
safety part. Be sure to replace it with a new one as
soon as possible.
Two connectors are in the seat
switch line at the indicated
location; Open these connectors,
and couple up the male and
female connector halves to form
a circuit bypassing the seat
switch.
205012B
! CAUTION
Illustrated above is a band-aid method
permissible only in an emergency situation. Be
sure to restore the seat switch line to the normal
hookup after replacing the failed switch.
2-22
--- Page 7 ---
POWER TRAIN
6. Put matching marks on the terminals (4 places) of
the drive motor and disconnect the drive motor
cables from the terminals.
7. Disconnect the thermal sensor and brush wear
sensor wire harness from the main harness B at the
connector.
8. Disconnect the pulse generator from the harness at
their connectors (2 places). Provide matching
marks on the connectors before disconnection.
9. Ready an oil pan with a capacity of 10 liters (3
U.S.gal) or so to receive oil that flows out when
hoses and pipes are removed from the hydraulic 208368
system.
208401
10. Remove the return line from the hydraulic control
valve.
(1) Loosen the hose clamp on the hydraulic tank
side end of the return line to let air in the air
line. (This is to prevent oil in the tank from
being siphoned when the return line is
disconnected.)
(2) Remove the bolt A.
(3) Loosen the arrow-marked hose clamps and
remove the return line hose and pipe.
11. Disconnect the pump delivery hose at the hydraulic
205836
control valve.
12. Disconnect the service brake hydraulic pipe at the
brake side joint.
13. Unclamp the parking brake cable and disconnect it 14. Remove the axle drain plug and let oil out where
at the parking brake lever. necessary. [8.5 liters (2.3 U.S.gal)]
3-6
--- Page 8 ---
TRANSFER AND DIFFERENTIAL
6. Remove the spacer 21, then remove the third gear 22.
The third shaft 19 is fitted with the bearing inner race
20. The inner race 20 may be left fitted to the third
shaft 19 if it is in a satisfactory condition for reuse. If
it needs to be replaced, remove it using an appropriate
puller.
7. Remove three bolts 23, then remove the lock plate 24.
Apply an aluminum bar to the second shaft 25 from the
drive motor fitted side, and hammer the bar lightly to
force the second shaft 25 out of place with O-rings 26
and 27 fitted to it.
8. Remove the second gear 28 with the ball bearing 29
attached. The ball bearing 29 may be left fitted to the
second gear 28 if it is in a satisfactory condition for
reuse. If it needs to be replaced, remove it using an
appropriate puller.
9. Remove the snap ring 30. Remove the input gear 31
fitted with the ball bearings 32 from the transfer case
33 using a slide hammer puller. The ball bearing 32
may be left fitted to the input gear 31 if it is in a
satisfactory condition for reuse.
Press fit
Transition fit
208397
4-6
--- Page 10 ---
FRONT AXLE
2. Installation of oil seal retainer and bearing inner
race
(1) Pack the taper roller bearing inner race 6 with
AUTOLEX A or equivalent grease; force grease inside
the bearing cage using your palm.
(2) Install the seal retainer 5 in the illustrated direction
using the special tool.
(3) Install the bearing inner race 6 using the special tool.
Special tool needed
Installer 64309-12300
204852
3. Reassembly of wheel hub and drum sub-assembly
(1) Once the wheel hub 7 and the brake drum 8 have been
separated, always replace the bolts 9 and the nut 10
with new ones. Stake the bolt end crisscross using a
flat tip chisel.
59 ± 5.9 N·m
Nut tightening torque (6.0 ± 0.6 kgf·m)
[43.4 ± 4.3 lbf·ft]
(2) Press-fit the bearing outer race 11 in the hub 7 using
the special tool.
Special tool needed
Installer 91268-05700
(3) Install the oil seal 12 in the illustrated direction into the
hub 7 using the bearing and seal driver.
(4) Install the oil seal 13 in the illustrated direction into the
hub 7 using the bearing and seal driver.
(5) Press-fit the bearing outer race 14 in the hub 7 using
the bearing and seal driver.
(6) Fill AUTOLEX A or equivalent grease into the portion
shown with in the illustration. Apply the grease
also to the oil seal lip. Take care that grease does not
enter inside the brake drum 8. 208258A
(7) Install the deflector 15 and tighten the bolts 16 to the
torque given below.
9.8 ± 1.0 N·m
Bolt tightening torque (1.0 ± 0.1 kgf·m)
[7.2 ± 0.7 lbf·ft]
4. Installation of wheel hub and drum sub-assembly
(1) Carefully install the wheel hub and drum sub-assembly
in the front housing while keeping it level.
(2) Adjust the hub bearing preload.
Refer to “Adjusting Hub Bearing Preload” on the next
page.
5-10
--- Page 11 ---
REAR AXLE
Steering Cylinder
12 8 4 9
10
3
6 7 5 8 11
Detail A Detail B Detail C
13 1 2
4 3
208146
1 Cylinder tube 8 Snap ring
2 Piston rod 9 O-ring
3 Piston 10 Guide ring
4 Cylinder head 11 Piston seal
5 Bushing 12 Spherical bearing
6 Wiper 13 Tie rod
7 U-seal
6-2
--- Page 12 ---
REAR AXLE
3. Assembling Rear Axle Hub
1 2 3
9
10
11
12
8
7
6 4 5
211071
Sequence
1 Oil seal retainer 6 Oil seal
2 Bearing cone 7 Wheel bolt
Assembly parts 3 to 7 prior to final assembly. 8 Bearing cone
9 Inner nut
3 Hub
10 Lock washer
4 Bearing cup
11 Outer nut
5 Bearing cup
12 Cap
Suggestions for Reassembly
1. Install the seal retainer 1 in the illustrated direction
with the special tool (64309 - 40400).
2. Install the bearing cone 2 with the special tool (64309-
40400).
Special tool needed
Bearing installer 64309 - 40400
3. Tapping with hammer, fit the wheel bolt 7 into the hub
bolt hole. 207032
6-12
--- Page 13 ---
BRAKE SYSTEM
Specifications .......................................................................................... 7 – 1
Structure and Functions ....................................................................... 7 – 2
General ..................................................................................................... 7 – 2
Wheel Brake Assembly ............................................................................. 7 – 3
1. Service Brake Mechanism ................................................................ 7 – 4
2. Parking Brake Mechanism ................................................................ 7 – 4
3. Automatic Adjusting Mechanism ....................................................... 7 – 5
Brake Pedal Assembly .............................................................................. 7 – 6
Reservoir Tank .......................................................................................... 7 – 7
Wheel Cylinder ......................................................................................... 7 – 7
Brake Master Cylinder .............................................................................. 7 – 8
Procedures and Suggestions for Disassembly, Inspection and
7
Reassembly .......................................................................................... 7 – 9
Wheel Brake ............................................................................................. 7 – 9
Master Cylinder and Fluid Reservoir ......................................................... 7 – 17
Wheel Cylinder ......................................................................................... 7 – 19
Inspection and Adjustment ................................................................. 7 – 21
Automatic Adjustment ............................................................................... 7 – 21
Manual Adjustment ................................................................................... 7 – 21
1. Brake Pedal Adjustment ................................................................... 7 – 22
2. Brake Switch Installation ................................................................... 7 – 22
3. Brake Fluid Line Bleeding ................................................................. 7 – 22
Installation of Parking Brake Cable and Adjustment of
Parking Brake Lever Operating Effort .................................................... 7 – 23
Brake Test ................................................................................................. 7 – 23
Troubleshooting ...................................................................................... 7 – 24
Service Data ............................................................................................ 7 – 26
--- Page 14 ---
BRAKE SYSTEM
Procedures and Suggestions for Disassembly, Inspection and Reassembly
Wheel Brake
Disassembly
2 ton class and 2.5 ton class
3 5
10
6
7 9
2
6 3
8
1
8 2
1
6
8
4
211764
Sequence
1 Return springs 7 Strut, Spring
2 Fitting cable, Cable guide 8 Shoe and lining (primary), Parking brake lever,
3 Shoe hold pin, Shoe hold spring, Cup, Pin Retainer, Spring washer
4 Adjusting lever, Adjusting spring and Return 9 Wheel cylinder
spring 10 Backing plate
5 Brake cable
6 Shoe guide plate, Shoe and lining (secondary),
Adjusting screw
7-9
--- Page 15 ---
BRAKE SYSTEM
Wheel Cylinder
Disassembly
200278 200279
Sequence
1 Connecting link 5 Return spring
2 Boot 6 Bleeder screw, Cap
3 Piston 7 Cylinder body
4 Piston cup
NOTE
Parts marked with (❋) are included in the repair kit.
7-19
--- Page 16 ---
BRAKE SYSTEM
A: Standard value B: Repair or service limit
Unit: mm (in.)
Truck Models 3 ton class 3.5 ton class
Item
Inside diameter of brake drum 1 A 310 + 00.15 (12.20 + 00.006 )
B 312.0 (12.28)
Thickness of lining 2 A 5.67 (0.22)
B 3 (0.12)
Clearance between drum and shoe 3 A 0.1 to 0.35 (0.004 to 0.014)
(one side)
Wheel brakes
Return spring 4 Free length A Primary: 120 (4.72)
Secondary: 139.2 (5.48)
Length under test force A Primary: 134 (5.28) Secondary: 145.4 (5.72)
Test force A 226 ± 23 (23 ± 2.3) [51 ± 5.1]
N (kgf) [lbf]
Spring 5 Free length A 126 (4.96)
Length under test force A 145.4 (5.72)
Test force A 78.5 ± 7.8 (8 ± 0.8) [17.6 ± 1.76]
N (kgf) [lbf]
Tightening torque for backing plate bolt 6
A 215 ± 21.5 (21.9 ± 2.2) [158.6 ± 15.9]
N·m (kgf·m) [lbf·ft]
208391
7-29
--- Page 17 ---
STEERING SYSTEM
Procedures and Suggestions for Removal and Installation
Steering Column Assembly
Removal
4 5
9
8
10
211769
Sequence
1 Steering wheel, Cap, Nut, Washer 7 Hose, Pipe, Hose clamp, Connector, O-ring
2 Console box (front panel) 8 Tilt steering lock lever, Spacer, Lock bolt,
3 Central vehicle monitor panel Lock plate, Pin, Lock nut
4 Direction lever 9 Steering column assembly
5 Console box (rear panel) 10 Steering control valve
6 Floor plate
WARNING NOTE
Hydraulic pressure can cause personal For servicing the steering cylinder, see “Group 6
injury. Before any steering system hydraulic REAR AXLE ”.
lines or components are disconnected, For servicing the pump and valve, see “Group 9
make sure all hydraulic pressure is released HYDRAULIC SYSTEM”.
in the steering system. Move the steering
wheels to the left and right, then straight.
8-6
--- Page 18 ---
T1
B4 L R
STEERING SYSTEM
Steering cylinder
A4
B3
A3
Displacement: 100 cm3 /rev.
B2 (6.10 cu. in./rev.)
A2 Relief: 6.5 MPa
(66.3kgf/cm2)
P T [942.9 psi]
A1 Pump motor 80V Steering motor 80V
8-16
Gear pump Gear pump (Steering)
Displacement: Displacement: 5.7 cm 3 (0.35 cu. in.)/rev.
(1.74 cu. in./rev.)
Return Suction
filter strainer
15 m 100 mesh
Hydraulic Circuit Diagram (2 Ton Class and 2.5 Ton Class)
P T2
211771
--- Page 19 ---
HYDRAULIC SYSTEM
Hydraulic Pump
1 2
1
Hydraulic pump for 2 ton class and 2.5 ton class
Displacement: 28.8 cc/rev.
(1.76 cu. in./rev.)
4 LS P EF
3
1
5
Hydraulic pump for 3 ton class and 3.5 ton class
Displacement: 29.0 cc/rev.
(1.77 cu. in./rev.)
211625
1 Inlet port 4 Secondary port (EF)
2 Outlet port 5 Load sensing port (LS)
3 Priority port (P)
9-5
--- Page 20 ---
HYDRAULIC SYSTEM
Lift section
4 3
A1
2
yy
;;
;;
yy
“b1”SOL
Blocking oil
207441
Emergency Lift Lock Mechanism
With the proportional electromagnetic pressure control Consequently, pressure equalizes before and after
valve on the “b1” SOL side in activation (lift in orifices 3, 4, and the load check valve returns to its seat
lowering operation), if spool sticking should occur, by spring force to lock the cylinder.
deactivation of the proportional electromagnetic
pressure control valve cancels pilot pressure in cap 2.
As a result, the lift lock valve moves to the position
indicated in the diagram, and the pilot oil passage
closes.
9-15
--- Page 21 ---
HYDRAULIC SYSTEM
Main Relief Valve
Main Relief Valve Operations
The main relief valves are installed between high-pressure
oil passage HP and low-pressure oil passage LP, and
perform the following operations.
(1) Chamber D is filled with oil entering through orifices
in main poppet C, thus main poppet C and sleeve E are
firmly seated because of the difference in area sizes.
208613
(2) When pressure in HP reaches the preset pilot spring
force, pilot poppet F opens. Oil flows around the pilot
poppet and passes through the holes and enters low-
pressure passage LP.
208614
(3) Because pilot poppet F opens, oil flows from HP to
chamber D through orifices in main poppet C. This oil
flow results in pressure differences between HP and
chamber D, thus causing main poppet C to open and
allow oil to flow directly from HP to LP.
208615
9-25
--- Page 22 ---
HYDRAULIC SYSTEM
(3) Place wood blocks under the inner mast (dual-stage full
free panoramic mast) or middle mast (triple-stage full
free panoramic mast).
Make sure the right and left wood blocks are the same
in height.
202983
(4) Hitch a sling to the second lift cylinder 5 behind the
mast, remove cylinder clamp retaining bolts, and gently
remove the second lift cylinder 5.
Hitch the sling securely to the cylinder. The cylinder
cannot be lifted straight up since the mast cross-
member is located above the cylinder. Tilt the cylinder
and move it away from the cross-member to remove.
Be careful not place the hands between the cylinder
and mast.
207618
Installation
To reinstall, follow the removal sequence in reverse, and
follow the instructions below:
(1) Install chain wheel support assembly 4 parallel to a
line connecting the centers of chain anchor bolt holes
on the first lift cylinder 3 to prevent chains from
twisting.
(2) Adjust the chain tensions. 207638
(Refer to “Inspection and Adjustment” in “GROUP 10
MAST AND FORK”.)
(3) Extend and retract the lift cylinders several times under
no load condition to bleed air out of the cylinder
circuits and to make sure that the cylinders move
smoothly.
(4) After proper operation is confirmed, check the oil level.
9-35
--- Page 23 ---
HYDRAULIC SYSTEM
Disassembly of Attachment Section Assembly
207564A
Sequence
1 Cap, Socket-head bolt 5 Cap, Socket-head bolt
2 Spring 6 Spring, Spring seat
3 Spring seat 7 Proportional electromagnetic pressure control
4 Spool valve
Suggestions for Disassembly
For disassembly procedures, refer to the tilt section.
9-45
--- Page 24 ---
HYDRAULIC SYSTEM
Main Relief Valve
203490
1 Cap 7 Lock nut The seal kit consists of parts 13
2 Plug 8 Pilot spring and 14.
3 Sleeve 9 Spring 13 O-ring
4 Main poppet 10 O-ring 14 O-ring
5 Pilot seat 11 Back up ring
6 Poppet 12 O-ring
Disassembly (2) Insert the parts into cap 1 in appropriate sequence
Do not disassemble the main relief valve unless it fails through opening in the top of the cap.
to limit the pressure properly. If the main relief valve is (3) Screw plug 2 (with the adjuster kit attached) into
disassembled, the relief pressure setting must be the cap by hand. It must be possible to screw the
readjusted. The disassembly procedure is as follows: plug into the cap smoothly.
(1) Loosen lock nut 7 of the adjuster kit, then turn the (4) Tighten plug 2 into cap 1 using a wrench.
adjuster screw twice counterclockwise to reduce Unit: N·m (kgf·m) [lbf·ft]
force of spring 8.
(2) Hold cap 1 in a vise, then unscrew and remove plug Tightening torque 69 to 78 (7 to 8) [51 to 58]
2 to allow easy removal of the internal parts.
Pressure adjustment
Inspection after disassembly
(1) Turning adjuster screw clockwise increases the
If an abnormality is evident and does not take the form
relief pressure setting. Turning it counterclockwise
of damage that can be rectified by lapping, replace the
decreases the relief pressure setting.
main relief valve assembly with a new one.
(2) Adjust relief pressure setting to 18.1 +− 0.5
0 MPa (185
(1) Check whether main poppet 4 slides smoothly +5 + 71
− 0 kgf/cm ) [2631 − 0 psi].
2
inside the sleeve. It must slide smoothly.
(3) Tighten lock nut to the torque shown below while
(2) Visually inspect the spring. It must not be bent or
holding the adjuster screw to prevent it from
otherwise damaged.
turning.
(3) Visually inspect the contact surfaces of pilot poppet
Unit: N·m (kgf·m) [lbf·ft]
6 and pilot seat 5. They must be free of damage
and uneven wear. Tightening torque 27 to 31 (2.8 to 3.2) [20.2 to 23.1]
(4) Visually inspect the orifice. Remove any blockage.
For instructions on pressure inspection and adjustment
Reassembly
on the vehicle, see page 9-71.
Only O-rings 13 and 14 are available as service parts.
(1) Hold cap 1 vertically in a vise with the plug end at
the top.
9-55
--- Page 25 ---
HYDRAULIC SYSTEM
Reassembly
13 15 12 11 10 1 8 7 5 6 9 4 2 3
❋ ❋ ❋ ❋ ❋ ❋
14
208616
Sequence
1 Piston rod assembly 10 Sleeve
2 Piston seal 11 Shim
3 Bushing NOTE: Parts 10 and 11 are used only in the 3° and 6°
4 Cylinder tube backward tilt cylinders.
5 Guide bushing
12 Tilt socket
6 Buffer ring
13 Spherical bearing
7 Rod packing
14 Bolt, Nut
8 Dust seal
15 Grease nipple
9 O-ring
NOTE
Parts marked with ❋ are included in the seal kit.
9-65
--- Page 26 ---
Hydraulic control valve (FC)
T1
B4 L R
Steering cylinder