Main Valve Spool Moves Without Oil Passing To Cylinder/Motor; Cylinder/Motor Operates Without Remote Controller Being Operated - Danfoss PVG 100 Service Manual

Service Manual
System Troubleshooting

Main Valve Spool Moves without Oil Passing to Cylinder/Motor

Cause
Insufficient oil supply to valve
Optional pressure compensator in valve section
not functioning
Insufficient load pressure at compensator spring
chamber
Cylinder/motor load too high for pressure setting
of the system
Blocked LS galleries
Shuttle valve faulty
Blocked LS lines to pump controller
Oil bypassing at shock valve/anticavitation check
valve
Internal leakage in cylinder/motor
Too much leakage in LS spool in pump control
Load too high for system
Internal leakage in cylinder/motor
Shock valve or anti-cavitation check valve faulty
System relief valve pressure set too low for load
Cylinder/motor load too high for pressure
settings of system

Cylinder/Motor Operates without Remote Controller being Operated

Cause
Spool control tension rod loose
Electrical feedback transducer not in neutral
position
Remote electrical controller neutral position
switch faulty
Sticking pressure control valve in remote
hydraulic controller
Sticking main spool in valve section
Internal fault in the PVE/PVEH/PVEO
PVG 100 Proportional Valves
Check
Check the pump per manufacturers procedure
Check compensator spool
LS drilling holes plugged
Check pressure at the valve
Inspect for blockage in LS galleries
Inspect shuttle valve
Inspect LS lines from PCG to pump controller
Check if stuck open or damaged
Inspect for by-passing of oil per cylinder/motor
manufacture per manufactures procedure
Check bleed orifice in LS control
Check for proper system pressure
Inspect for bypassing of oil per cylinder/motor
manufacturer specification
Inspect for damage and contamination
Install pressure gauge and check pressure
Check load pressure at PVB-LS port
Maximum system pressure should be approx. 25
Bar [365 PSI] above highest load pressure
Check pump pressure compensator setting
Check
Confirm torque on spool control tension rod
Check the feedback pin in the PVE. It should be
loose
Disconnect the connection at the PVE. It should
come back to neutral
Disconnect the hydraulic signal line from valve
Remove manual, electrical, and hydraulic
actuators from the valve section. Remove main
spool from valve section and inspected for
damage. If no damage reinstall the main valve
spool. Spool should move freely in the valve
section bore.
PVEO check continuity. All other PVE, check LED
(Red means internal error)
11048807 • Rev BA • October 2014
Corrective action
Repair or replace pump per manufacturers
procedure
Replace spool
Clean or replace
If pressure is set to spec. per valve lower load on
cylinder/motor
Remove blockage in LS galleries
Repair or replace
Remove blockage in LS lines from the PVG valve
to pump controller
Replace valve
Repair or replace cylinder/motor per
manufactures procedure
Use a LS pump control with no bleed orifice
Adjust pressure to valve specification
Repair or replace cylinder/motor
Repair or replace cylinder/motor
Adjust pressure to system specification Lower
load
Reduce load pressure if exceeds maximum
pressure limit of the system
Adjust maximum system pressure if necessary
Adjust pump pressure compensator setting if
necessary
Corrective action
Torque to 8 Nm [70 lbf•in]
Replace module
Repair or replace faulty switch or wiring at
remote controller
Repair or replace faulty remote hydraulic
controller
Replace the valve module and main spool if any
damage is found on the main spool
Replace faulty PVE/PVEH/PVEO
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