Emerson Damcos, Service Manual

Page: 61 / 144

Damcos LPU: Troubleshooting Guide LPU Service Manual
February 2017 SM 8000-100-01 Ed 04
61
Pump not rendering sufficient oil at high pressure (“valve
running too slowly”)
Reason: LPU is built up, so that oil quantity from pump, independent of adjusted speed, is reduced to approx-
imate 240 cm
3
/min from pressure exceeding 75 bar. If flow is considerably below this quantity, see
“Pump rendering too low (or no) pressure in one or both directions” on page 51.
The pressure should only exceed 65 bar for a few seconds, when breaking valve away or closing
valve.
Pump not rendering sufficient oil at low pressure (“valve
running too slowly”)
Action: • Check adjustment of opening and closing speed (see “Speed adjustment for Actuator on LPU
(v.2)” on page 83).
• While pump is running at high pressure in end position, valve housing for speed adjustment is
loosened by a 19 mm wrench (must be turned maximum 3 turns, as there is full pump pressure
below housing), until airless oil is running from it. Then valve housing is tightened, and pump
flow is checked again. If pump flow is still not OK, dismount adjusting screw for speed control,
check with a screw driver that the ball bearing behind this can be moved back and forth by press-
ing it. Check mobility of the piston in valve housing for speed adjustment.
• Dismount tank and check if filter in suction pipe is blocked.
• Dismount tank and valve block, check the mobility of the bearing, and observe if any pistons in
rotor are sticking. Stator is dismounted (pressed out from the tan side), and blown through, to
remove plugging, if any, in the longitudinal holes.
• Remounting of stator: stator must be pressed in until direction pin is below surface of block.
When seated correctly, the free stator length is approximate 19 mm. Do not use metal hammer
directly on the stator. (See “Replace Pump in LPU” on page 93).