HYDRAULIC SYSTEM RT770E
2-58
Published 11/26/2014, Control # 447-05
HYDRAULIC ACCUMULATOR
Description
The hydraulic accumulators are located inside the
superstructure on the left side under the main hoist. The
purpose of each accumulator is to provide stored energy, an
oil volume of 1.99 L (122 in
3
) at a maximum pressure of
138 bar (2000 psi), to actuate the service brake circuits. The
dual accumulator charge valve regulates flow to the
hydraulic accumulators to provide fully powered
independently separate, primary (front) and secondary
(rear), service brake circuits.
Each accumulator has two chambers divided by a piston.
One side is pre-charged to 62 bar (900 psi) with high purity
nitrogen. This maintains a constant pressure in the other
chamber which is connected to the modulating brake valve.
After the accumulators are fully charged, they will provide the
necessary brake system flow and pressure to actuate the
brakes.
The accumulator consists of a piston, seals, gas valve, and a
gas valve guard.
Maintenance
Removal
1. With the engine shutdown, deplete the hydraulic
pressure in the accumulators by depressing the service
brake pedal several times.
2. Tag and disconnect the hydraulic hose from the
accumulator. Cap or plug the line and port.
3. Remove the two nuts securing each clamp half. Remove
each clamp half and accumulator from the turntable.
Installation
1. Position the accumulator in the clamps and secure with
the removable clamp halves and nuts.
2. Connect the hydraulic hose to the port on the
accumulator as tagged during removal.
3. Pre-charge the accumulator. Refer to Procedure H -
PreCharging The Accumulator, page 2-27.
4. Start the engine and check accumulator and hoses for
leaks. Make repairs as needed.
5. Depress the brake pedal several times, make several
turns with the steering wheel, and swing the
superstructure left and right. Verify the brakes, swing,
and front steering work properly.
Servicing
The pre-charge nitrogen pressure should be checked every
200 hours or once a month, whichever comes first. Refer to
Procedure G - Accumulator Pre-Charge Pressure, page 2-
26.
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