Steering Circuit Component Repair - Komatsu 930E-2 Shop Manual

STEERING CIRCUIT COMPONENT REPAIR

BLEEDDOWN MANIFOLD VALVE
Do not loosen or disconnect any hydraulic line or
component connection until engine is stopped and
keyswitch has been "off" for at least 90 seconds.
Hydraulic fluid escaping under pressure can have
sufficient force to enter a person's body by pene-
trating the skin and cause serious injury and pos-
sibly death if proper medical treatment by a
physician familiar with this injury is not received
immediately.
Removal
NOTE: It may not be necessary to remove the bleed-
down manifold from the truck for component replace-
ment. If the problem area has been isolated, remove
inoperative component and replace with a new one.
1. Perform normal truck shutdown procedures. Turn
keyswitch "Off" and allow 90 seconds for the
accumulators to bleed down. Manually bleed
brake system accumulators located in hydraulic
components cabinet.
2. Disconnect wires at the solenoids (7 & 15, Figure
6-1) and presssure switch (6).
3. Disconnect, identify and plug each hydraulic line
to prevent contamination.
4. Remove mounting capscrews and remove the
bleed down manifold. Clean exterior of manifold
before starting disassembly.
Installation
1. Install bleeddown manifold. Tighten mounting cap-
screws to standard torque.
2. Unplug lines and attach. Tighten connections
securely. Install new O-rings at flange fittings.
3. Attach electrical leads to solenoids and pressure
switch. If check valves or relief valves were re-
moved, replace using new O-ring seals.
4. Start the engine and check for proper operation
and leaks. Check steering and brake application.
NOTE: Adjustment of the relief valves is not necessary
or recommended. Relief valves are factory preset. Do
not attempt to rebuild or repair if relief valves are
defective. Replace as a unit. The check valves are also
replaced only as units.
L06021 Steering Circuit Component Repair
FIGURE 4-1. BLEEDDOWN MANIFOLD
1. To Hoist Valve, Power Up
2. To Hoist Valve, Power Down
3. Spare Pressure Port
4. Test Port
5. To Brake System
6. Steering System Pressure Switch
7. Steering Accumulator Bleed Solenoid
8. Supply To Flow Amp
9. Return From Flow Amp
10. To Front Steering Accumulator
11. To Rear Steering Accumulator
12. Relief Valve, 600 psi (4.1 MPa)
13. Relief Valve, 4000 psi (28.0 MPa)
14. Autolube Pump Supply Port
15. Hoist Up Solenoid Valve
16. Return From Hoist Pilot Valve
17. Hoist Pilot Valve, Power Down
18. Hoist Pilot Valve, Power Up
19. Return to Tank
20. Feedback Pressure to Unloader valve
21. Supply From Pump
L6-1