Hold Operation - Komatsu 930E-2 Shop Manual

HOLD OPERATION (Figure 7-7)
The pilot valve spool is positioned to allow the pilot
supply oil entering port (12) to return to the tank
through Port (10). Pilot supply pressure in ports (12)
then decreases to no pressure allowing flow control
valve (2) to open and route the incoming pump oil to
the brake cooling circuit through port (23) and back to
the tank.
L7-10
Both pilot ports (14 & 15) in the pilot valve are closed
by the pilot valve spool. In this condition pressure is
equalized on each end of each main spool (7 & 8)
allowing the springs to center the spools and close all
ports to trap the oil in the cylinders and hold the body
in its current position.
Hoist Circuit L07023