Service Manual Damcos LPU: Troubleshooting Guide LPU
SM 8000-100-01 Ed 04 February 2017
48
– Pressure switch is adjusted, so that pressure switch breaks by falling pressure at
100 ±5 bar. Pressure switch must close below 125 bar by rising pressure.
• Short breaks of pressure switch
– Replace pressure switch! See “Replace pressure switch” on page 109.
• Pressure switch breaks below 105 bar, no short breaks
– Check electrical connections from pressure switch. If no other faults are detected, replace
printed circuit board. See “Replace Printed Circuit Board” on page 105.
3. Large leakage in the hydraulic system, or misadjusted safety valve
Action: Mount hand pump, actuator is fully opened by hand pump, pressure gauge is mounted.
Then if: • Pressure remains constant
Leakage in solenoid valve, quick connection B or external leakage, e.g. at pressure switch. Possi-
bly too low adjusted pressure at pump relief valve (pump safety valve).
– Check for external leakage, if no leakage, adjust pump pressure (see “Pump pressure adjust-
ment for LPU” on page 85). If this cannot be adjusted any higher, check internal sealings and
flow reducing valve (opening speed adjustment).
– Replace solenoid valve (see “Replace Solenoid Valve in LPU-D” on page 107), flow reducing
valve or sealings. Then safety valve is readjusted to 150 bar (see “Pump pressure adjustment
for LPU” on page 85).
Note! If oil has too low viscosity or is very hot this might be the reason for a too low pressure.
• Pressure drops
Leakage in actuator, or possibly bypass valve, release valve, emergency valve or shuttle valve.
– Check o-rings on shuttle valve and emergency valve, possibly replace release valve, see
“Replace release valve in LPU” on page 99.
– Check for external leakage.
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