Copyright Goodheart-Willcox Co., Inc.
Chapter 18 Load-Sensing Pressure-Compensating (LSPC) Hydraulic Systems 439
to the downside of a callback repair, the technician’s lack of ability to follow
the manufacturer’s service instructions may have voided the manufacturer’s
warranty, reduced the machine’s normal life cycle, and placed personnel in
danger due to the overly responsive hydraulic system.
Note
If a technician could substantially increase the low-pressure
standby value to a high value such as 2000 psi (138 bar), the
LSPC system would operate more as a traditional PC system than
the traditional LSPC system. The system would be noisy, operate
at a high pressure constantly, and its actuators would respond very
quickly to DCV spool movements.
Figure 18-17. In the working mode, the axial piston pump output pressure will equal the working pressure plus the
flow control spring value (also known as margin pressure). Bias spring pressure overcomes the resistance of the
control piston, pushing the swash plate at a greater angle to increase the displacement of the rotating axial pistons.
Bias spring
Swash
plate
DCV
Control piston
Axial piston
Flow control
spool (300 psi)
1000 psi to extend
Pressure
compensator
spool (2500 psi)
Axial piston
Shuttle valve