Drum Drive Motor
(1) Brake line
Remove brake line (1) from the drum propel motor.
Plug the brake line and cap the fittings.
Location of Propel Pumps
(2) Pressure test port. (3) Pressure test port.
Connect two 60000 kPa (8700 psi) pressure gauges to
pressure test ports (2) and (3).
Start the engine and run the engine at full throttle.
Release the parking brake.
Move the speed selection switch to the HIGH SPEED
Move the propel control lever to the full FORWARD
direction and the full REVERSE direction. Read the
pressure gauges. The pressure at both gauges should
peak at 48000 ± 1700 kPa (6960 ± 250 psi).
At this pressure, the drum and the wheels should not
If the drum and the wheels move, refer to Propel
System Troubleshooting in order to diagnose the
Servo Valve (Piston Pump) -Test and Adjust
SMCS Code: 3205-25; 3205-081
4000 kPa (600 psi)
Personal injury or death can result from sudden machine
Sudden movement of the machine can cause injury to
persons on or near the machine.
To prevent injury or death, make sure that the area around
the machine is clear of personnel and obstructions before
operating the machine.
Care must be taken to ensure that fluids are contained
during performance of inspection, maintenance, testing,
adjusting and repair of the machine. Be prepared to
collect the fluid with suitable containers before opening
any compartment or disassembling any component
Refer to Special Publication, NENG2500, "Caterpillar Tools
and Shop Products Guide", for tools and supplies suitable
to collect and contain fluids in Caterpillar machines.
Dispose of all fluids according to local regulations and
Before conducting the testing and adjusting on the servo valve,
the following steps must be followed:
Apply the parking brake.
Place the propel control lever in neutral.
Place the machine in a position against a solid,
stationary object such as a loading dock.
Perform this test on both of the propel pumps.