Procedure H - Precharging The Accumulator; Procedure I - Swing Valve Work Port Reliefs Pressure - Manitowoc Grove RT770E Service Maintenance Manual

RT770E
4. Turn the gas chuck "T" handle all the way down
(clockwise) which will depress the core in the gas valve.
5. Check the pre-charge pressure. It should be 62 bar +4/-
0 (900 psi +50/-0).
6. If the pressure is 62 bar +4/-0 (900 psi +50/-0), remove
the charging valve assembly by turning the "T" handle all
the way out on the gas chuck and then opening the
bleed valve Figure 2-11.
7. Hold gas valve from turning. Loosen swivel nut and
remove charging assembly. Reinstall gas valve cap and
guard.
8. Repeat for other accumulator.
1
2
3
5
Item
1 Gas Valve Guard
2 Gas Valve
3 Accumulator
4 Gauge
5 Gas Chuck
6 Bleed Valve

Procedure H - PreCharging The Accumulator

1. With the engine off, discharge all of the pressurized oil
stored in the accumulators by depressing the service
GROVE
4
6
6659-6
FIGURE 2-11
Description
Published 11/26/2014, Control # 447-05
brake pedal on the cab floor several times. Remove the
gas valve guard and gas valve cap on the accumulator
Figure 2-11.
2. Ensure that the nitrogen supply bottle is shut off, then
attach the charging valve assembly to it.
3. Before attaching the charging assembly Figure 2-11 to
the accumulator gas valve, back the gas chuck "T"
handle all the way out (counterclockwise).
4. Close the charging assembly bleed valve. Without
looping or twisting the hose, attach the swivel nut to the
accumulator gas valve and tighten to 1.1 to 1.7 Nm (10
to 15 lb-in).
5. Turn the gas chuck "T" handle all the way in (clockwise),
which will depress the core in the gas valve.
6. Crack open the nitrogen bottle valve and slowly fill the
accumulator. Shut off the valve when the pre-charge
pressure is 62 bar +4/-0 (900 psi +50/-0).
7. If the pre-charge pressure is higher than 62 bar +4/-0
(900 psi +50/-0), close the nitrogen bottle valve and
slowly open the bleed valve on the charging assembly
Figure 2-11 until the pre-charge pressure is correct.
8. Remove the charging assembly by turning the "T"
handle all the way out (counterclockwise) on the gas
chuck and then open the bleed valve.
9. Hold gas valve from turning. Loosen the swivel nut and
remove the charging assembly. Reinstall the gas valve
cap and guard.
10. Repeat for the other accumulator, as required.
Procedure I - Swing Valve Work Port Reliefs
Pressure
1. Install pressure check diagnostic quick disconnect with
gauge onto test nipple at swing valve inlet test port (5,
Figure 2-12).
2. With the swing brake ON and the engine running at full
RPM, swing left and adjust "A" port swing relief to
152 bar ±4 (2200 psi ±50).
3. With the swing brake ON and the engine running at full
RPM, swing right and adjust "B" port swing relief to
152 bar ±4 (2200 psi ±50).
HYDRAULIC SYSTEM
2-27
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