38 - 1
Service Procedures
Testing the Pilot Pressure
1 Position the backhoe to enable access to the pilot
supply valve.
Before proceeding further the pilot circuit accumulator
pressure must be vented.
2 Stop the engine. With the operator seat set in the rear
facing position (for backhoe operation), switch the
starter to ON without starting the engine. Operate the
joystick controls several times to vent the servo
pressure from the accumulator. Switch the starter
switch to the OFF position.
3 Connect a 0 - 50 bar pressure gauge to the test point
A.
4 With the engine running at 1500 revs/min, operate a
backhoe service fully. At the same time check the
reading on the gauge. It should be 35 bar (36 kgf/cm
2
507 lbf/in
2
).
If necessary adjust the pressure as follows:
1 Stop the engine. Loosen lock nut B and adjust screw C.
Turn screw C clockwise to increase pressure and anti-
clockwise to decrease the pressure. When the pressure
is correct, tighten the locknut and check the pressure
again. Adjust as required.
Renewing the Pilot Supply Valve Oil Filter
1 Position the backhoe to enable access to the pilot
supply valve.
2 Stop the engine. Clean off all dirt on and around the
filter cap D. Undo the cap. Remove and discard the
filter element. The servo system is easily damaged by
contaminated hydraulic oil. When installing a new filter
element make sure that no dirt is allowed to enter the
pilot supply valve.
Section D Controls
9803/3280
Section D
38 - 1
Issue 1
Precision Control (Servo)
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