UNDERCARRIAGE RT880E SERVICE MANUAL
8-26 Published 11-10-2014, Control # 524-00
PARK BRAKE SOLENOID VALVE
Description
The park brake solenoid valve (Figure 8-29) is located on the
front side of the carrier aft center frame cross member. The
valve is a three-way two position solenoid valve. The park
brake valve is used to control the application of the crane’s
spring-applied, hydraulically-released parking brake.
Positioning the Park Brake switch to OFF shifts the three-
way, two-position solenoid valve so hydraulic oil can flow to
the parking brake actuator, extending it. When the actuator
extends, it releases the park brake.
Positioning the Park Brake switch to ON shifts the three-way,
two-position solenoid valve so hydraulic oil can drain from
the actuator. The parking brake actuator’s rod retracts,
forcing hydraulic oil through the valve and the case drain
manifold back to the transmission reservoir. As the actuator
retracts, it applies the parking brake.
A pressure switch is installed in the line to the actuator.
When the park brake is applied, a lack of hydraulic oil
pressure keeps the pressure switch closed, which turns on
the red LED indicator on the switch.When the park brake is
released, pressure buildup opens the switch, which turns off
the indicator.
Maintenance
Removal
1. Tag and disconnect the hydraulic lines attached to the
valve. Cap or plug lines and ports. Remove the valve.
Installation
1. Position the valve and connect the hydraulic lines to the
valve as tagged during removal.
2. Connect the electrical connector to the valve as tagged
during removal.
3. Apply and release the park brake several times. Verify
the park brake holds the crane when applied. Verify the
park brake doesn’t drag when released.
4. Check for leaks. Make repairs as needed.
Port (3)
Port (2)
Port (1)
2
3
1
FIGURE 8-29
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