Servo Pressure Check
Front Propulsion Pump
(1) Front propel pump. (2) Servo pos.
After stopping the machine, apply the parking brake.
Remove and plug the two hoses from servo ports (2)
that connect to the brake interlock valve. Install two
4000 kPa (580 psi) gauges in the servo ports.
Start the machine and operate at high idle. Release the
Observe the pressure on both gauges with the control
lever in neutral. The differential pressure between the
two gauges should be within 69 kPa (10 psi) of each
If the differential pressured is greater than 69 kPa
(10 psi), proceed to the procedure "Manual
Displacement Control Neutral Adjustment".
Gradually move the control lever forward. The
differential pressure between gauges installed in servo
port (2) should increase in proportion to output system
pressure. As an example, you have an output system
pressure of 6890 kPa (1000 psi) requiring a differential
pressure of 482 kPa (70 psi) or an output system
pressure of 60 000 kPa (5000 psi) will require a
differential pressure of 1240 kPa (180 psi). The position
of the control lever determines the swashplate angle.
If the differential pressure does not increase,
check the following:
Charge pressure inadequate to fully stroke the pump.
Servo pressure leakage (past the servo piston).
Remove the pressure gauges from servo ports (2) and
install the hoses back to the brake interlock valve.