Sauer Danfoss 51 Series Service Manual page 32

Bent Axis Variable Displacement Motors
Component Adjustment (Continued)
Fig. 30-19 - Two Line Hydraulic
Proportional Control, Type HP
Fig. 30-20 - Adjusting Control Threshold
(Type HP)
32
Two Line Hydraulic Proportional Control
(Type HP)
The differential control start pressure for this control
may be adjusted with the adjusting screw on the end
cap (opposite the control block). Control start is that
differential pilot pressure at which the motor displace-
ment starts to decrease.
To check the control start setting, install gauges to
51000023 monitor the pilot pressures (tee into the pilot lines
connected to ports X1 and X2), and the minimum
angle servo pressure (port M3).
NOTE: The pilot signals may be determined by prime
mover speed, other shaft speeds, or other
control pressures, depending upon the de-
sign of the vehicle / machine control circuit.
Increase the pilot signal differential to the required
control start pressure. An increase in minimum angle
servo pressure will be noted as the motor displace-
ment starts to decrease.
The differential control start pressure should be the
51000047
same no matter which pilot pressure is higher. Differ-
ences in control operation when the pilot pressure
differential is reversed indicate a problem with the
shuttle spool in the control block.
To adjust the control start differential pressure, loosen
the lock nut using a 10 mm hex wrench and turn the
adjusting screw with a 4 mm internal hex wrench.
Turning the screw clockwise increases the control
start pressure. Torque the lock nut to 9 Nm (6.6 ft•lbsf)
after adjusting.
Shut down the prime mover. Remove the gauges and
install the gauge port plugs. Return the pump and
motor controls to their normal operation.
Servo pressure supply oil is usually provided inter-
nally from the main system ports of the motor. If
external servo pressure supply is utilized, a minimum
of 25 bar (360 psi) is required to change the motor
displacement with the motor shaft turning, and a
minimum of 70 bar (1015 psi) is required with the
motor shaft locked.
Series 51
30 - 10