Steering Accumulator Charging Procedure - Komatsu 930E-2 Shop Manual

STEERING ACCUMULATOR CHARGING
PROCEDURE
Do not loosen or disconnect any hydraulic line or
component until engine is stopped and key switch
has been "Off" for at least 90 seconds.
Pure dry nitrogen is the only gas approved for use
in the steering accumulators. The accidental
charging of oxygen or any other gas in this com-
partment may cause an explosion. Be sure pure
dry nitrogen gas is being used to charge the accu-
mulators.
When charging or discharging the nitrogen gas in
the accumulators, be sure the warning labels are
observed and the instructions regarding the
charging valve are carefully read and understood.
1. With engine shut down and key switch in the "Off"
position, allow at least 90 seconds for accumula-
tors to bleed down. Turn steering wheel to be
certain no oil remains in accumulators.
2. Remove charging valve guards.
If nitrogen pressure is present in the accumula-
tors, make certain only the small swivel hex nut is
turned during the next step. Turning the complete
valve assembly may result in the valve assembly
being forced out of the accumulator by the nitro-
gen pressure inside.
3. Remove charging valve cap (1, Figure 6-6). Turn
small swivel hex nut (4) three complete turns
counterclockwise.
4. Depress the valve stem and hold down until all
nitrogen has been released.
5. If a loss in nitrogen pressure is the reason for
recharging, inspect the charging valve and accu-
mulator for damage. Replace or repair items, as
necessary, before charging procedure.
6. Connect the nitrogen charging kit to the charging
valves. Open the regulator and charge the accu-
mulators simultaneously to 1400 psi (9.65 MPa).
NOTE: If a loss in nitrogen pressure occurred during
operation, oil may still be present in the accumulator
below the piston. This oil can be bled off during the
L06021
1. Valve Cap
2. Seal
3. Valve Core
4. Swivel Nut
5. Rubber Washer
nitrogen charging procedure by turning the steering
wheel back and forth or by actuating the bleed down
solenoid by turning the key switch "On" and then "Off".
NOTE: When charging the accumulators, allow ade-
quate time for the system to fully charge. Insure all oil
has returned from the accumulators to the hydraulic
tank.
7. Shut off charging kit and check pressure gauge
reading. If gauge does not maintain 1400 psi (9.65
MPa) continue charging procedure until pressure
is stabilized.
8. Remove the charging kit and tighten small hex nut
on charging valve to 4 ft.lbs. (5.4 N.m) torque.
NOTE: If a new charging valve was installed, the valve
stem must be seated as follows:
9. Install charging valve cap (1) and tighten finger
tight. Install charging valve guard and tighten
capscrews to 25 ft.lbs. (33.9 N.m) torque.
10. Operate truck and check steering.
Steering Circuit Component Repair
FIGURE 6-6. CHARGING VALVE
a. Tighten small hex swivel nut to 10.5 ft.lbs.
(14.2 N.m) torque.
b. Loosen swivel nut.
c. Retighten swivel nut to 10.5 ft.lbs. (14.2 N.m)
torque.
d. Again, loosen swivel nut.
e. Finally, tighten swivel nut to 4 ft.lbs. (5.4 N.m)
torque.
6. Valve Body
7. O-ring
8. Valve Stem
9. O-ring
L6-5