1. Install new O-rings on the pressure compensator
over-ride valve block and retain with petroleum jelly.
2. Install the PCOR valve block on the multi-function
block and install the screws.
3. Torque the screws to 11 Nm (8 ft•lbf).
4. Perform the PCOR pressure adjustments as de-
scribed below.
PROCEDURE:
The PCOR may be adjusted with the screw on the PCOR
valve block attached to the multifunction block. The setting
pressure is that system gauge pressure at which the PCOR
causes the motor displacement to start to increase. On a
test stand this point is when system flow begins to increase.
On a machine, with the motor shaft locked from turning, this
point is when maximum servo pressure becomes higher
than minimum servo pressure.
In order to measure the PCOR setting pressure on a test
stand, monitor system gauge pressure and system flow.
Provide a signal to the motor control to maintain the motor
at minimum displacement. Increase the system pressure
until system flow just starts to increase. The system pres-
sure at this point is the PCOR setting pressure. To adjust the
setting, loosen the lock nut with a 1
1
/
16
inch hex wrench.
Turn the adjusting screw, with a large screw driver or a
1
/
2
inch hex wrench until the desired setting is established.
Clockwise rotation of the adjustment screw will increase the
pressure setting approximately 1200 psi (83 bar) per turn.
While holding the adjusting screw from turning, torque the
locknut to 52 Nm (38 ft•lbf).
ADJUSTMENT:
In order to measure the PCOR setting pressure on a
machine, monitor the system gauge pressure (M1 or M2
gauge port), minimum servo pressure (M3 gauge port), and
maximum servo pressure (M4 gauge port). Apply the park-
ing brake, block the load, etc. to keep the motor shaft from
turning during this test. CAUTION: Take necessary precau-
tions to prevent personal injury if machine or load should
move during this test. While watching the gauges, very
slowly increase the pump displacement, thereby increasing
system pressure gradually (or use the pressure limiter
adjustment screw on the pump to increase the system
pressure gradually). Minimum servo pressure will increase
with the system pressure. At about 50 psi below the PCOR
set point the minimum servo pressure will stop increasing
with system pressure and the maximum servo pressure will
begin to increase. As system pressure is increased farther,
minimum servo pressure will begin to decrease and maxi-
mum servo pressure will begin to increase. When maximum
servo pressure becomes 50 to 100 psi higher than minimum
servo pressure the motor servo piston will begin to move
toward maximum displacement. The system pressure at
this point is the PCOR setting pressure. To adjust the
setting, loosen the lock nut with a 1
1
/
16
inch hex wrench and
turn adjusting screw until the desired setting is established.
Clockwise rotation of the adjustment screw will increase the
pressure setting approximately 1200 psi (83 bar) per turn.
While holding the adjusting screw from turning, torque the
lock nut to 52 Nm (38 ft•lbf).
WARNING
The following procedure will require the vehicle/
machine to be disabled (wheels raised off the ground,
work function disconnected, etc.) while performing
the adjustments to prevent injury to the technician
and/or bystanders.
© Danfoss, 2013
BLN-10118
•
Rev AA • September 2013
1
Service Kit Instructions
Series 51
Pressure compensator over-ride
