Pump Control Neutral - Adjust
SMCS Code: 5653-025
(1) Part of 4C-4892 Fittings Group
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
Perform the Pump Servo Neutral - Adjust before
doing the test. The position of the servo piston
will affect the pressure readings that are obtained
from the adjustment of the eccentric screw.
Make sure that the parking brake is applied. Make sure
that the propel control lever is in neutral.
(1) Servo ports. (2) Adjustment screw. (3) Pump control.
Remove the plugs from servo pods (1).
Assemble the two 8T-0855 Pressure Gauges with the
proper fittings from 4C-4892 Fittings Group. Install the
two pressure gauges at servo ports (1).
Start the engine and run the engine at 1200 rpm.
Read the pressure on the two pressure gauges. If the
pressures are not identical, the pump control must be
Adjustment screw (2) is an eccentric adjuster.
One half of a revolution of the adjustment screw
gives all the adjustment that is possible. A small
amount of movement of the adjustment screw (2)
makes a large pressure change.
To adjust the pump control, loosen the locknut and turn
adjustment screw (2) in either direction in order to attain
equal pressures on the two pressure gauges. When the
pressures are equal, hold the adjustment screw and
tighten the locknut.
Stop the engine. Remove the two pressure gauges
from servo ports (1), and install the two plugs.