Parking Brake System; Maintenance And Adjustments; Service Brake Bleeding - Manitowoc Grove 5540F Service Manual

5540F/YB5515 SERVICE MANUAL

Parking Brake System

Description Of Operation
The parking brake system consists of two-way switch in the
instrument panel, a solenoid valve and a parking brake. The
system connects into the service brake system and uses the
accumulator for system pressure.
Parking Brake
The parking brake is a disc-type brake Figure 9-5. The brake
disc is attached to the input shaft of the front axle. The brake
is attached to the frame behind the front axle. When the
parking brake switch is placed in the engage position,
hydraulic supply is shut off to the parking brake and the
springs in the parking brake apply the brake pads against the
brake disc, holding the crane from moving.
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Parking Brake Solenoid Valve
The parking brake solenoid valve Figure 9-6 is activated by
the parking brake switch in the operator's instrument panel. It
is a normally-closed solenoid valve. When the switch is
placed in the ENGAGE position, no current is sent to the
solenoid valve, thus the solenoid valve remains closed and
the parking brake is engaged.
When the parking brake switch is placed in the DISENGAGE
position, electrical current is sent to the solenoid valve. The
solenoid shifts the spool in the valve to open the circuit to the
parking brake. The hydraulic fluid, under pressure,
disengages the brake pads from the brake disc. Even though
the parking brake switch may be in the DISENGAGE
position, in the event of a loss of pressure in the accumulator
below what it takes to apply the service brakes, the parking
brake will engage.
GROVE
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MAINTENANCE AND ADJUSTMENTS

Park Brake
Solenoid Valve

Service Brake Bleeding

When ever a brake line is disconnected, the brake system
must be bled to remove any trapped air. Air in the brake lines
will cause the brakes to be spongy.
NOTE:
NOTE:
FIGURE 9-5
Rear Axle
1. Engage the parking brake and shut off the engine. Block
the rear wheels on both sides.
2. Attach a tube to the right hand bleed screw A Figure 9-7
ensuring that the free end of the tube is immersed in fluid
contained in a suitable container.
3. Open the brake bleeder screw and apply full pedal
strokes of the brake pedal until all air is expelled.
4. Close the brake bleed screw with the pedal fully
depressed.
5. Repeat steps 2 through 4 using the left hand bleed
screw.
Published 10-21-2010, Control# 198-04
Before working on the brake system, make sure
the crane is on level ground and that all four wheels
are chocked.
The accumulator must be charged before this
operation can be performed. If you are not sure the
accumulator is charged, engage the parking brake,
start the engine and let is run for several minutes.
Park Brake
Solenoid Valve
FIGURE 9-6
9
9-5