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Threshold and Ramp Springs
Spring seat
Threshold spring
Threshold adjustment screw
locknut
J50
Spring seat
S10* S20
S10*
S10
J30
Ramp spring(s)
P106 438E
Multiblock
Some hydraulic proportional controls are used in conjunction with the multiblock. The multiblock is a
manifold with a shuttle-valve that routes high loop (system pressure) from port A or port B to the 4-way
valve to serve as servo supply and to the PCOR function. The shuttle valve also routes the low pressure
side of the loop to the PCOR function.
Multifunction Schematic
n
T6
T2
T1
T7 T8
T3
T4
U6
U7
T5
max.
disp.
A
L2
M4
M3
N
M1
L1
M2
M7
X1
M5
XA
XB
B
P106 417E
Control
Multiblock
PCOR Valve
BPD Spool
Shuttle
Loop Flush
4-Way Valve
Pressure Compensator OverRide (PCOR) Function
The Pressure Compensator OverRide (PCOR) function allows the motor to match its displacement to the
system load. The PCOR overrides the control command allowing the motor to increase displacement
when system pressure reaches a set level due to load. This permits the motor to regulate system pressure
by modulating the displacement of the rotating group. As displacement increases, available torque
increases. Output speed decreases and system pressure remains nearly constant at the PCOR setting.
The PCOR setting is adjustable from 110 to 370 bar [1595 to 5365 psi]. Optional orifices at locations T4, T5,
T6, U6, and U7 regulate the PCOR operation speed.
Service Manual
Series 51 Hydraulic Proportional Controls Service Manual
Introduction
8
11009446 • Rev BA • July 2014