Komatsu WA150-5 Wheel Loader Repair Manual

Serial Number:
65001 and up
H50051 and up
Manuals: Shop Manual
General
Structure and Functions
Testing and Adjusting
Disassembly and Assembly
Maintenance Standard
Others
Manual Extract When parking brake lever is pulled (OFF to ON):
1) When parking brake is set in Free position • When the parking brake is released, both intermediate switch and bottom switch are closed.
The parking brake pilot lamp goes off regardless of the state of the parking
brake. Parking brake reminder caution lamp lights up and the alarm buzzer sounds only when the engine is stopped.

Then, the HST controller power hold relay operates and the current flows in the HST controller to hold the operation of the motor solenoid and clutch solenoid and prevent the machine from moving down on a slope, etc.

The parking brake is released.
2) When parking brake lever is moved from Free position to Mid position
If the parking brake lever is pulled a little, bottom switch is opened but the contacts of the parking brake relay are kept closed.
The parking brake pilot lamp and parking brake reminder caution lamp operate as in step 1).
The parking brake is kept released.
3) When parking brake lever is in Lock position • If the parking brake lever is pulled to the end, intermediate switch (1) is opened.
At this time, the current to the coil of the parking brake relay is cut out and the contacts are opened and the parking brake pilot lamp relay is turned OFF.

Since the current to the coil of the parking brake drag prevention relay is cut out, the forward-reverse solenoid circuit is opened. Accordingly, the machine does not move forward or in reverse even if the directional lever or the directional selector switch is operated.

The parking brake pilot lamp lights up only while the starting switch is in the ON position and goes off regardless of the state of the parking brake reminder caution lamp.
The parking brake is applied.