Ls Signal - Danfoss PVG 100 Service Manual

Service Manual
PVG 100 Component Troubleshooting
Failure mode
In closed center systems the valve sections are
unstable
Valve operation is slow to respond or does not
respond

LS Signal

PVG 100 Proportional Valves
Location: PVP (inlet) module.
Function: Provide a signal to the variable pump controller to create a pressure differential to have the
pump come on stroke for a closed center system.
Cause
Insufficient LS flow to satisfy pump controller
Excessive air entrained in the hydraulic oil
Air trapped in LS line
Insufficient LS flow to satisfy pump controller
Excessive air entrained in the hydraulic oil
Air trapped in LS line
PVG valve is mounted above hydraulic oil reservoir when shut down and sits idle for some time, the valve
could be voided of oil and this would cause the valve to operate erratically and be slow to respond.
Serviceability: Port is serviceable. Connect hose to LS port on pump.
LS connection plug
6 mm
35 Nm
[310 lbf•in]
Description: The PVG100 uses an internal LS signal network for both Open Center and Closed Center
systems. In Open Center systems the internal LS signal network provides a resolved load sense signal to
the pressure adjustment spool controlling the proper amount of flow and pressure to the operating valve
sections. In Closed Center systems the internal LS signal network provides a resolved load sense signal
directly to the LS pump control which in turn provides the proper amount of flow and pressure to the
operating valve sections.
11048807 • Rev BA • October 2014
Corrective action
Ensure that the LS controller on the pump does
not have excessive internal leakage - 0.4 l/min
[0.106 gal/min]. Repair or replace the variable
pump controller per pump manufactures
specifications
If there is more than one valve in the system
ensure that the LS shuttles are all working
properly
Ensure that the oil has enough dwell time in tank,
has good anti-foaming agent, and pump inlet
vacuum is within manufacturers specifications
Bleed air for LS line at highest point
If more than one section, ensure that the LS
controller on the pump does not have excessive
internal leakage. Repair or replace the variable
pump controller per pump manufactures
specifications
Ensure that the oil has enough dwell time in tank,
has good anti-foaming agent, and pump inlet
vacuum is within specifications
Bleed air for LS line at highest point
P107 923E
25