Danfoss Series 42 Service Manual

Item Description Action
SCR (system check / relief) valves The SCR valves are malfunctioning or
improperly set.
Verify that the SCR valves are operating
and properly set. Repair or replace
them as necessary.
Displacement limiters Displacement limiters may be
improperly adjusted such that the
servo piston is locked in place.
Verify that the displacement limiters
are adjusted to the proper setting.
System will not operate in one direction
Item Description Action
Input control signal (linkage,
current, or pressure)
The pump is receiving a faulty control
signal: (MDC - binding or broken
linkage; EDC - faulty or inadequate
electrical signal; HDC - blocked or
incorrectly orificed control lines).
Verify that the input signal is correct
and identical in both directions. Adjust,
clean, repair, or replace the control
module as necessary.
SCR (System Check/Relief) valves The SCR valves are malfunctioning or
improperly set.
Verify that the SCR valves are operating
properly. Repair or replace them as
necessary.
Pump control A damaged or biased pump control
may be sending a signal commanding
the pump to stroke only in one
direction.
Verify that the pump’s control is
functioning properly. Repair or replace
it as necessary.
Servo pressure The drain or supply path to one side of
the servo piston may be blocked.
Verify that the servo supply and drain
paths are unobstructed and that any
orifices are of the correct size and free
of debris. Clean or repair them as
necessary.
Displacement limiters (if
equipped)
The displacement limiters may be
improperly adjusted such that the
servo piston is prevented from moving
in one direction.
Verify that the displacement limiters
are adjusted properly.
Neutral difficult or impossible to find
Item Description Action
Input control signal (linkage,
current, or pressure)
The pump is receiving a faulty control
signal: (MDC - binding or broken
linkage; EDC - faulty or inadequate
electrical signal; HDC - blocked or
incorrectly orificed control lines).
Verify that the input signal is correct
and identical in both directions. Adjust,
clean, repair, or replace control module
as necessary.
System pressure With no input signal to the control, a
pressure delta may exist between the
two sides of the working loop.
Readjust pump neutral setting. Refer to
adjustment procedure.
Servo pressure With no input signal to the control, a
pressure delta may exist across the
servo piston.
Readjust the control neutral setting.
Refer to adjustment procedure.
PCP pressure (EDCs only) With no input signal to the control, a
pressure difference may exist across
the control spool.
Replace the EDC.
Service Manual Series 42 Axial Piston Closed Circuit Pumps
Troubleshooting
520L0638 • Rev 0300 • July 2015 29

Danfoss Series 42 Specifications

General

Brand	Danfoss
Model	Series 42
Category	Water Pump
Language	English