Accumulator Charging Procedure - Komatsu 930E-2 Shop Manual

ACCUMULATOR CHARGING
PROCEDURE
(Frame Mounted Brake Accumulators)
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 and the
brake accumulators have been manually bled
down.
Pure dry nitrogen is the only gas approved for use
in the brake accumulators. The accidental charg-
ing of oxygen or any other gas in this compartment
may cause an explosion. Be sure pure dry nitrogen
gas is being used to charge the accumulators.
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, the Rest switch ON and
key switch in the OFF position, allow at least 90
seconds for steering accumulators to bleed down.
Turn steering wheel to be certain no oil remains
in accumulators.
2. Open the bleed valves (6 & 7, Figure 3-1) located
on the brake manifold in the hydraulic compo-
nents cabinet to completely bleed the pressure
from all brake system accumulators.
3. 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.
4. Remove charging valve cap (1, Figure 3-28). Turn
small swivel hex nut (4) three complete turns
counterclockwise.
5. Depress the valve stem and hold down until all
nitrogen has been released.
6. 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.
J03019 1/99
1. Valve Cap
2. Seal
3. Valve Core
4. Swivel Nut
5. Rubber Washer
6. Valve Body
7. O-ring
8. Valve Stem
9. O-ring
7. Connect the nitrogen charging kit to the charging
valves. Open the regulator and charge the accu-
mulators simultaneously to 1400 psi (9.8 MPa).
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.
8. Shut off charging kit and check pressure gauge
reading. If gauge does not maintain 1400 psi (9.7
MPa) continue charging procedure until pressure
is stabilized.
9. 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:
a. Tighten small hex swivel nut to 10.5 ft.lbs.
b. Loosen swivel nut.
c. Retighten swivel nut to 10.5 ft.lbs. (14.2 N.m)
d. Again, loosen swivel nut.
e. Finally, tighten swivel nut to 4 ft.lbs. (5.4 N.m)
10. 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.
11. Close brake accumulator bleed valves.
12. If necessary, recharge the smaller brake accumu-
lators. Refer to "Accumulators, Hydraulic Compo-
nents Cabinet, Charging Procedure".
13. Operate truck and check brake system operation.
Brake Circuit Component Service
FIGURE 3-29. CHARGING VALVE
(14.2 N.m) torque.
torque.
torque.
J3-29