Check system pressure using the boom function to ensure that the Main Relief valve (MRV) is functioning correctly.
Check that the anti cavitation valves (ACV) are working correctly.
Check pilot pressure to either end of the spool to verify that the travel proportional pilot control valve (PPC valve) is working and to ensure two things:
1. That without any application to the control pedals there is a 0 bar reading on both sides of the spool, if this is the case then the spool should be in the neutral position from a hydraulic perspective.
2. That full hydraulic application pressure is being obtained as each application is made in either direction.
Remove the spool end cap and check for damage along with the main control valve body, control valve casting lands and spool lands to check for damage that can result from the spool spinning from excessive flow.
Check the travel brake for correct release and apply actuation.
Connect four gauges to the rotary joint. Apply left and right hand sides, both forward and reverse individually and record the pressures and their corresponding function to ensure the rotary joint is in working order, for example:
What you want to see:
LHF
A 310 bar
B 0 bar
C 0 bar
D 0 bar
LHR
A 0 bar
B 310 bar
C 0 bar
D 0 bar
And so on...
And an example of what you don’t want:
LHF
A 310 bar
B 310 bar
C 0 bar
D 100 bar
LHR
A 310 bar
B 310 bar
C 260 bar
D 0 bar
