OPERATOR'S MANUAL MAINTENANCE

Section E - Hydraulics
Service Procedures
Main Relief Valve (MRV) Pressure
E-221 E-221
9803/9880-3
Main Relief Valve (MRV) Pressure
TE-012
1 Prepare the Machine
a Operate the dipper out and lower the boom to set
the bucket on the ground.
C030150-1
Fig 3.
b Make the machine safe, refer to Section E,
Service Procedures.
c Install a 0 - 400 bar (0 - 6000 lb/in
2
) pressure
gauge in TP1 or TP2.
d Start the engine, and confirm that the engine is at
its maximum no-load speed and it is in the E mode
to test standard pressure and L mode to test
power boost pressure.
e Raise the boom and then operate the dipper out
control. Read the pressure gauge with the dipper
ram stalled at the end of its stroke.
f If it is outside the limits, stop the engine and adjust
the MRV as below.
Note: For accurate setting, the pressure should be
adjusted up to the required level.
2 High Pressure Setting (Power Boost)
A406580-C1
Fig 4.
a Make the machine safe, refer to Section E,
Service Procedures.
b Remove servo hose E and plug hose.
c Start the engine, and confirm that the engine is at
its maximum no-load speed and it is in the E
mode.
d Stall the dipper.
e Hold nut C and release lock nut B and screw the
low pressure setting nut A clockwise all the way
in.
f Hold nut C and slacken nut D. Screw nut C in, to
increase pressure or out to decrease pressure.
g Once required pressure is achieved on the
pressure gauge, hold nut C and lock nut D back
up.
3 Low Pressure Setting (Standard)
C
A
E
D
B