22 - 1
Pressure Testing
Main Relief Valve (M.R.V.) - In situ
The MRV is housed in the loader valve block. Make sure that
the hydraulic oil is at working temperature, i.e. 50°C (122°F).
Lower the excavator bucket and loader shovel to rest on the
ground; stop the engine; operate the control levers to vent
residual hydraulic pressure.
1 Connect a 0 - 400 bar (0 - 6000 lbf/in
2
) pressure gauge
to test connector A, adjacent to the loader valve.
2 With the engine running at 1500 revs/min, check M.R.V.
pressure by raising or lowering the loader arms until the
rams are fully open or closed and noting the maximum
gauge reading. CAUTION: Do not select 'float'. The
maximum pressure should be as stated in Technical
Data.
Note: The rams must be 'held' open or closed when reading
gauge.
3 If the pressure is incorrect, remove dome nut B,
slacken locknut C and adjust screw D. Turn it
clockwise to increase pressure and anti-clockwise to
decrease the pressure. When the pressure is correct,
tighten the locknut.
Section E Hydraulics
9803/7130
Section E
22 - 1
Issue 1
Service Procedures
DD
CC
BB
DD
CC
AA
S206300
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