Komatsu 830E Shop Manual page 486

HOLD OPERATION (Figure 7-8)
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 return the incoming pump oil to
the tank through Port 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 allowing the springs to center the
spools and close all ports to trap the oil in the cylin-
ders and hold the body in its current position.
L7-10
FIGURE 7-8. HOIST CIRCUIT: HOLD POSITION
1. Hoist Relief Valve 2500 psi (17.2 MPa)
2. Flow Control Valve
3. Low Pressure Relief Valve 75 psi (517 kPa)
4. Counterbalance Valve
5. Rod End Work Port
6. Hoist Cylinders
7. Rod End Spool
8. Head End Spool
9. Head End Work Port
10. Return Port
11. Supply Port
12. Pilot Supply Port
13. Power Up Pilot Line Solenoid Valve
14. Raise Pilot Port
15. Down Pilot Port
16. Power Down Relief Valve, 1500 psi (10.5 MPa)
17. Anti-void Check Valve
18. Load Check Valve
19. High Pressure Passage
20. Low Pressure Passage
21. Pilot Operated Check Valve
22. Manifold Power Up Port
23. Manifold Power Down Port
24. Solenoid Valve Return Port
25. Overcenter Manifold Check Valve (CV)
Hoist Circuit L07027