4 - 7
Auxiliary Relief Valves
General
The auxiliary relief valves (ARV’s) are set to a higher pressure
than the main relief valve (MRV). To permit pressure testing
of the ARV’s it is necessary to temporarily adjust the MRV to
a higher setting (refer to view B on page 4 - 1). Proceed as
follows:
1 Prepare the machine
a Put the operator levers into neutral and lower the
gate lock lever. Start the engine and park the
machine on level ground. Operate the dipper out
and lower the boom to set the bucket on the
ground.
b Run the engine at maximum no-load speed in
the S mode.
2 Increase MRV Pressure
Loosen MRV lock nut Y and turn pressure adjusting
screw Y 180° clockwise. Tighten lock nut X.
3 Restore Original MRV Pressure
After completion of all ARV pressure testing, loosen
lock nut X and turn adjusting screw Y, 180° anti-
clockwise and restore the original MRV setting
pressure.
4 Stop the engine
Section E Hydraulics
9803/6410
Section E
4 - 7
Issue 1
Pressure Testing
296590a
312450
YY
XX
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