SPECIFICATIONS

Vehicle Systems Testing And Adjusting
13. Restriction caused by system components.
Operate the hydraulic and steering systems with
an ammeter and a pressure gauge installed. If
amperage draw and oil pressure are too high,
see Testing And Adjusting and Specifications for
the acceptable amperage draws and oil pressure,
the system must be inspected for both mechanical
and hydraulic restrictions.
Problem 4: Low resistance to ground [battery
potential either positive (+) or negative (-) or a
medium voltage is in direct contact with truck
frame (body) or drive motor body.]
Probable Cause:
1. Dirty battery, electrolyte on top of cells and is in
contact with the frame. Current flows through
battery box which places a voltage on the truck
frame.
Clean off the battery with baking soda and water
solution.
2. Battery or control panel wire connections in contact to
truck frame.
Make a continuity test to move the wire from
contact. Remove wires in sequence until the fault
is cleared. The fault will be in the wire last
disconnected.
3. Dirty motor.
Remove the metallic or carbon dust with air
pressure.
4. Wet pump motor.
Dry the motor with heat to 90°C (190°F).
Problem 5: Commutator surface has groove or
extra wear.
Probable Cause:
1. Brushes are worn too low, brush wires caused
arcing on commutator.
Inspect the commutator for damage. If the arcing
caused light pitting on commutator, install new
brushes and seat the brushes with the Brush
Seater Stone which will also clean the commutator
surface.
Make another inspection, if there is still pitting,
commutator surface must be machined only to
the minimum diameter as shown in
Specifications.
2. Dirty motor, and possibly salt water got inside.
Disassemble motor, remove the debris with air
pressure. If necessary, dry the motor with heat to
90°C (190°F).
3. Grade of brushes mixed.
Make sure all of the brushes are of Caterpillar
standards. Do not use other brands of brushes.
4. Overload on brushes.
Check the brush springs for the correct installation
and make sure the lift truck is operating at a
rated capacity.
Problem: Lift truck has slow hydraulic speeds.
Probable Cause:
1. Hydraulic pump motor overheated and pump
motor thermal switch opens (if equipped).
Allow the motor to cool so the thermal switch will
close. See Specifications for thermal switch will
opening and closing temperatures.
2. Pump motor control circuit overheated and thermal
switch opens.
Allow the control panel to cool so the Controller
thermal switch will close. The thermal switch
opens at 85 L 4 °C (185 L 7 °F) and close at
73 L 4 °C (163 L 7 °F).
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