PDF Service Manual Caterpillar EP12 KRT Lift Truck - 1 MB
Perform expert-level repairs on your Caterpillar EP12 KRT lift truck with this official service manual.
The guide offers comprehensive instructions for diagnostics, disassembly, repair, and reassembly of all major components.
It's an indispensable tool for service technicians dedicated to maintaining the performance and reliability of Cat lift trucks.
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--- Page 1 ---
Service Manual
Chassis, Mast & Options
EP10KRT ETB10-00011-up
EP12KRT ETB10-20001-up
EP15KRT ETB10-50001-up
99759-65110
--- Page 3 ---
GENERAL INFORMATION
Serial Number Locations
Mast number Chassis number Nameplate
209010
1-2
--- Page 4 ---
VEHICLE ELECTRICAL COMPONENTS
Direction Lever
Structure
209144
1 Knob 4 Connector
2 Lever 5 Screw, Spring washer
3 Harness
2-5
--- Page 5 ---
MAIN CONTROLLER
Outline of Controller
The controller is the heart of the truck operating system.
The logic card contains decision making functions, and is
equipped with a battery discharge indicator and a
malfunction diagnostic function.
The controller is used to operate the drive motor and
hydraulic motor.
209026
1 Controller 5 Washer
2 Logics assembly 6 Spring washer
3 Cover 7 Connector
4 Screw
3-3
--- Page 6 ---
MAIN CONTROLLER
Malfunction Detection
Display
LED
Reset
Malfunction Detection method/condition Error Fail-safe process method
code
Thermal
Battery
Brush
Brake
Error
Drive motor overheat Signal input * AL065 Output power control Cooling
Pump motor overheat Signal input * AL017 Output power control Cooling
Controller overheat Signal input * AL062 Output power control Cooling
Drive motor brush wear *
Pump motor brush wear *
Brake fluid low *
Drive motor transistor wire Check the main circuit voltage level * AL060 Line contactor OFF Power reset
breakage
Drive motor transistor shorting Check the main circuit voltage level * AL032 Line contactor OFF Power reset
Drive motor stall timer Time duration elapsed * AL072 Line contactor OFF Power reset
Drive motor transistor drive error Error detection signal from drive card * AL060 Line contactor OFF Power reset
Drive motor current sensor error Check the current sensor output value * AL053 Line contactor OFF Power reset
Drive motor armature over current 500 A * AL069 Line contactor OFF Power reset
Drive motor field over current 50 A * AL057 Line contactor OFF Power reset
Drive motor field error Compare the current instruction value * AL058 Line contactor OFF Power reset
and actual current valve
Drive motor field drive error Error detection signal from H bridge * AL015 Line contactor OFF Power reset
card
Pump motor transistor wire breakage Check the main circuit voltage level * AL028 Line contactor OFF Power reset
Pump motor transistor shorting Check the main circuit voltage level * AL028 Line contactor OFF Power reset
Pump motor transistor drive error Error detection signal from drive card * AL028 Line contactor OFF Power reset
Pump motor current sensor error Check the current sensor output value * AL056 Line contactor OFF Power reset
Pump motor over current 500 A * AL035 Line contactor OFF Power reset
Line contactor error Check the main circuit voltage level * AL037 Line contactor OFF Power reset
Regeneration diode error Check the main circuit voltage level * AL032 Line contactor OFF Power reset
Drive motor armature diode error Check the main circuit voltage level * AL032 Line contactor OFF Power reset
Pump motor armature diode error Check the main circuit voltage level * AL028 Line contactor OFF Power reset
Drive motor armature breakage Check the main circuit voltage level * AL032 Line contactor OFF Power reset
Pump motor armature breakage Check the main circuit voltage level * AL028 Line contactor OFF Power reset
Accelerator error Input range exceeded * AL078 Line contactor OFF Power reset
3-13
--- Page 7 ---
MAIN CONTROLLER
System Construction
209038
3-23
--- Page 8 ---
MAIN CONTROLLER
Flow Chart showing how to make Program changes using
Digital Console fitted with Eprom CK ULTRA.
1) Opening Display.
Display
2) Press ENTER to go into the General Menu.
3) The Display will show: PARAMETER CHANGE.
Keyboard
4) Press ENTER to go into the Parameter Change facility.
5) The Display will show the first Parameter.
6) Press either ROLL UP and ROLL DOWN to display
the next parameter.
7) The names of the Parameters appear on the Display.
8) When the desired Parameter appears, the Display will
show a Level Number that will be between 0 and 9.
press either PARAM (Top Right) or SET (Bottom
Right) buttons to change the Level value.
9) The Display will show the New Level.
10) When you are satisfied with the results of the changes
you have made, Press OUT.
11) The Display asks “ARE YOU SURE ?”
12) Press ENTER to accept the changes, or Press OUT if
you do not wish to accept the changes and wish to
make further modifications to the parameters.
13) The Display will show: PARAMETER CHANGE
14) Press either ROLL UP and ROLL DOWN to display
other parameters or press OUT.
3-33
--- Page 9 ---
MAIN CONTROLLER
(6) Description of alarms menu
The microprocessor in the chopper remembers the last five
alarms that have occurred. Display
Items remembered relative to each alarm are: the code of
the alarm, the number of times the particular alarm Keyboard
occurred, the hour meter count, and the chopper
temperature.
This function permits deeper diagnosis of problems as the
recent history can now be accessed.
Flow chart showing how to use the ALARMS function via
the digital console.
1) Opening Display.
2) Press ENTER to go into the General menu.
3) The Display will show:
4) Press ROLL UP or ROLL DOWN button until
PARAMETER CHANGE appears on the display.
5) The display will show:
6) Press ENTER to go into the ALARMS function.
7) The display will show the most recent alarm.
8) Each press of the ROLL UP button brings up following
alarms. Pressing ROLL DOWN returns to the most
recent.
9) If an alarm has not occurred, the display will show:
ALARM NULL.
10) When you have finished looking at the alarms, press
OUT to exit the ALARMS menu.
11) The display will ask CLEAR LOGBOOK?
12) Press ENTER for Yes, or OUT for NO.
13) Press OUT to return to the opening display.
3-43
--- Page 10 ---
TROUBLESHOOTING FOR CONTROL CIRCUITS
Problem: Brake Oil, Low Level
Symptom:
(1) Low brake oil indicator ON.
Normal vehicle operation.
Possible Cause:
(2) Insufficient brake oil, open wiring, display unit defect.
Checks:
(3) Check oil level in bare oil reservoir tank
• Oil level lower than LOW mark
Add brake oil.
• Oil level higher than LOW mark
(4) Disconnect battery plug. Disconnect level sensor connector CN10, and check continuity.
• Continuity
Replace level sensor.
• No continuity
(5) With connector CN10 and CN19 disconnected, check continuity between harness connector CN10 socket wire
140-L (blue) and CN19 and between 139-O (orange) and controller.
• No continuity
Correct or replace wiring.
• Continuity
Replace traction logic card.
Brake oil level sensor: Normally OFF
(Low oil level: ON)
209050
4-6
--- Page 11 ---
TROUBLESHOOTING FOR CONTROL CIRCUITS
Problem: Drive Motor, Field Over-current
Symptom:
(1) Display = “AL057”.
Inhibit drive and hydraulic operation. Normal power steering operation.
Possible Cause:
(2) Traction current sensor failure, faulty wiring, fault in logic card.
Checks:
(3) Disconnect battery plug.
Inspect field wiring for wire breakage and short.
• Broken or shorting
Correct or replace faulty components.
• No broken and no shorted wire
(4) Replace logic card.
• Unacceptable
Replace controller.
4-16
--- Page 12 ---
TROUBLESHOOTING FOR CONTROL CIRCUITS
Problem: Forward / Reverse Lever, Tilt Lever, Attachment 1 Lever, Attachment 2
lever, Faulty Setting
Symptom:
(1) Display = “AL079”.
Inhibit vehicle operation. Line contactor OFF.
Possible Cause:
(2) Key switch turned on while forward / reverse lever was left either in forward or reverse position. Key switch
turned on while tilt lever, Attachment 1 lever or Attachment 2 lever was in ON position or accelerator pedal was
depressed. Faulty forward / reverse lever switch, tilt lever switch, Attachment 1 lever switch and Attachment 2
lever switch; logic card defect.
Checks:
(3) Move forward / reverse, tilt, Attachment 1 and / or Attachment 2 levers to neutral. Select direction of movement
again and depress accelerator pedal.
• Normal vehicle operation
Correct starting procedure requires all of forward / reverse, tilt, Attachment 1 and Attachment 2 levers be in
neutral position and accelerator pedal be released when key switch is turned on.
• No change
(4) Use self-diagnostic function to locate faulty circuit or component.
• Faulty component located
Correct or replace faulty component.
• Faulty component not located
Replace logic card.
209055
209056
4-26
--- Page 13 ---
TROUBLESHOOTING FOR CONTROL CIRCUITS
Problem: Battery Consumption
Symptom:
(1) Battery low indicator “AL066”.
Poor traction power and acceleration. Lifting speed slower than normal.
Possible Cause:
(2) Much consumption with small capacity or poor battery.
Checks:
(3) Check battery voltage in case of both operating and non operating.
• Battery voltage lower than 23.6 V
Check the following:
Battery capacity
Power supply to pump motor
Large cargo load
• Battery voltage higher than 23.6 V
Replace logic card.
4-36
--- Page 14 ---
MOTORS
Pump Motor
D2 −SH
M A1 +SH
Thermo Fan Brush
switch wear
Indicator
D2
A1
3
1 6
2
5
4
13
12
10
8 11
9
7
209188
Main components
1 Drive end bracket 8 Set of brushes with springs
2 Bearing 9 Thermal protector
3 Armature 10 Bearing
4 Gasket 11 Commutator end bracket
5 Connection plate 12 Fan
6 Stator 13 Cover
7 Brush holder
5-4
--- Page 15 ---
MOTORS
Troubleshooting
Problems with rotation of the motor are attributable not only to a fault in the motor itself but also to a fault in the
controller that supply the motor with electric power. Therefore, you should perform motor troubleshooting also
referring to the Troubleshooting section in the “Group 3 Main Controller” in addition to this page.
Low supply voltage Charge battery and improve power
supply condition.
Blown fuse Replace.
Excess load Reduce load.
Motor does not Faulty wire connection Repair, or re-tighten wire connections.
start.
Broken wire in control device Repair or replace.
Faulty brush connection Clean and repair.
Broken wire in field coil Repair or replace.
Broken wire in armature coil Repair or replace.
Motor starts but Low supply voltage Charge battery and improve power
does not run at supply condition.
rated speed. Faulty connection of armature circuit Repair connections.
Motor produces Defective bearings Replace bearings.
abnormal Loose mounting bolts Retighten bolts and nuts.
vibrations Contact between armature and field coil Repair or replace.
and noise. Abnormal whistling sound Clean and repair brush.
Incorrect installation Correct installation condition.
Severe external vibration Remove the cause of vibration, or take
appropriate vibration-insulating
Bearing overheat measures.
Defective bearings Replace.
Oil degradation or shortage in bearings Replace.
Faulty brush contact surfaces Correct brush surfaces to ensure full
contact on commutator.
Faulty brush contact Clean commutator surface.
Brush Replace brush and spring.
malfunction
Faulty brush sliding Clean brush holder and ensure free
movement of brushes.
Incorrect brush dimension or material Replace.
Sparks generated at brushes (faulty commutation)
Dirtiness or damage Grind with sand paper or stone, and
Commutator wipe with clean cloth.
malfunction High mica Undercut mica.
High bar (commutator surface Grind with grinding stone or correct
irregularity) with lathe.
Short-circuit of commutator Remove conductive foreign materials
Armature from commutator and commutator
malfunction segments.
Broken wire or short-circuit in Repair or replace.
armature coil
Field coil Broken wire or short-circuit in field coil Repair or replace.
malfunction Broken wire or short-circuit in external Correct by referring to wiring diagram.
circuit on field side
Excessive Excessive load Reduce load.
armature current Short-circuit in external circuit on Correct short-circuit.
armature side
Insufficient ventilation due to dust Clean
Excessive load Reduce load.
Coil overheat
Short-circuit or broken wire Correct by referring to wiring diagram.
Insulation degradation due to moisture Dry.
5-14
--- Page 17 ---
REAR AXLE
(2) Rear axle assembly schematic
1 Rear axle housing
2 Wheel shaft
not illustrated gear set, consisting of input pinion, helical gear, bevel pinion shaft and crown gear
3 Housing top section (with integrated input pinion)
4 Housing cover
5 Centering ring
6 Lock plate
7 Final stop (2x)
8 Oil filler-and oil inspection plug
9 Oil drain plug
3 5
7
6
7 6
8
2
1 4
9
209224
7-10
--- Page 18 ---
REAR AXLE
Tap with a plastic hammer or a copper mandrel from the
bottom against the top section 1, so that it loosens from the
axle housing.
Cautiously lift off and remove the housing top section.
1
NOTE
Housing top section can only be replaced completely.
Centering ring can be reused.
NOTE
209235
Remove cylinder pins, breather valve and grease
nipples only in case of damage. Check housing top
section according to chapter “Reassembly”, step 15.1
and keep it properly.
2.1 Remove input from the housing top section and 2
disassemble it
With two assembly levers press cover assembly 2
cautiously against the bearing outer ring (with radial shaft
seal, grooved ball bearing, O-ring and input pinion) out of
the bearing bore.
209236
! CAUTION
Do not damage the input pinion toothing!
Damages might cause louder running noises!
Helical gear
NOTE
Prior to removing the grooved ball bearing 3 , the 3
helical gear has to be taken off first, as indicated in
page 7-31 step 7.1.
209237
Pull grooved ball bearing 3 with a bearing extractor out of
the bore hole in the housing top section and remove it.
3
209238
7-20
--- Page 19 ---
REAR AXLE
5. Preassemble bevel pinion shaft
With bush “C” cautiously install bearing inner ring 1 until
contact.
If no press is available, the bearing can be installed in
accordance with the following NOTE.
NOTE
Heat bearing ring up to 90ºC maximum and install it
until it makes contact.
Install subsequently until contact after cooling down!
206260
6. Install bevel pinion shaft into the housing
Wet the cage space between rollers of the bearing inner ring
with gear oil.
Insert preassembled bevel pinion shaft from the bottom into
the housing. With clamping fixture "F", apply a slight
preload to the bearing outer ring.
209261
7-30
--- Page 21 ---
REAR AXLE
16.1 Install housing top section
4
Provide sealing surface of the housing with a thin layer of
LOCTITE 574.
NOTE
The plane face of the housing and the housing top
section have to be cleaned with LOCTITE Fast
Cleaner and must be free of grease before assembling.
209288
Place housing top section onto the rear axle housing, so that
the cylindrical pins in the rear axle housing are positioned
in the fitting bores of the top section.
Screw in the socket head bolts 1 at the bottom side of the
rear axle housing as well as inside the housing top section
and tighten them uniformly.
In addition, install the two socket head bolts 2, hexagon
nuts 3 and washers 4
209232A
16.2 Check axial play of the input in housing top
section
209233A
Have wheel shaft rotated several times.
For measurement of the axial ply of the input, a dial gauge
with a magnetic stand is to be positioned right-angled onto
Dial gauge
the plane face of the inout pinion and the dial indicator
must be set to "Zero".
Mark the position of the dial gauge on the pivoting bearing
with a color pencil. 4
With both hands, press the input pinion upwards and
downwards.
Read the axial bearing play on the dial gauge.
Axial play of grooved ball bearing: 0.1 to 0.4 mm.
When checking a bearing play has to be
209289
measurable.
7-40
--- Page 22 ---
BRAKE SYSTEM
3. Automatic Adjusting Mechanism
Shoe end moves
away from Primary shoe
anchor pin. Secondary
Anchor pin shoe
Drum rotation
(during reverse movement)
Brake released Brake applied Brake released
Fitting cable
ll
Pu Pivot
Adjusting nut Adjusting screw Sprocket (24 teeth) Adjusting lever
spring
Adjusting lever
sion
ten
Ex Adjusting sprocket
Sprocket rotation in direction of arrow causes
extension by this dimension
209158
The automatic adjusting mechanism maintains the The adjusting mechanism does not operate while the
correct lining-to-drum clearance of approximately 0.1 lining-to-drum clearance is within the proper range.
to 0.25 mm. It can operate only when the brakes are The adjusting screw in the brake on an RH wheel has a
applied during reverse movement of the truck. When right-handed thread, and the adjusting screw in the
the lining has worn approximately 0.03 mm, the brake on an LH wheel has a left-handed thread.
adjusting sprocket turns by one tooth to recover a
proper lining-to-drum clearance.
When the operator depresses the brake pedal with the
lining-to-drum clearance excessively large, the top end
of the secondary shoe moves away from the anchor pin.
At this time, the fitting cable that runs from the anchor
pin to the adjusting lever via the sheave on the
secondary shoe is pulled upward, causing the adjusting
lever to swing about its pivot. The edge of the adjusting
lever thus turns the sprocket. The resulting increase in
the adjuster’s dimension causes the lining-to-drum
clearance to decrease.
8-4
--- Page 23 ---
BRAKE SYSTEM
Master Cylinder and Fluid Reservoir
Disassembly
209161
Sequence
1 Clevis, Lock nut, Push rod 6 Return spring
2 Boot 7 Cylinder body
3 Stopper ring 8 Clamp
4 Secondary cup, Piston 9 Fluid reservoir
5 Spring seat, Primary cup, Cup spacer 10 Harness
NOTE
Replacement parts marked with an asterisk (❋) are
included in the repair kit.
8-14
--- Page 24 ---
BRAKE SYSTEM
Service Data
A: Standard value B: Repair or service limit
Unit: mm
Truck Model EP10KRT EP12KRT EP15KRT
Item
Height of pedal 1 A 288 ± 3
Free play of pedal 2 A 3 to 10
Play of push rod 3 A 1 ± 0.5
2
Brake
pedal
1
3
209162A
Inside diameter of cylinder body 1 A 19.05 + 00.052 (3/4 inch)
− 0.020
Diameter of piston 2 A 19.05 − 0.053
A 0.020 to 0.105
Clearance between cylinder and piston
B 0.2
0
Diameter of primary cup (lip side) 3 A 20 − 0.3
Diameter of secondary cup (lip side) 4 A 20.2 ± 0.2
Master Free length of return spring 5 A 46.8
cylinder
4 2 5
1 3 207077
8-24
--- Page 25 ---
STEERING SYSTEM
Steering Column Assembly
6
7
1
Boss 2
(internally threaded)
9 11