Komatsu WA250-6, WA250PZ-6 Wheel Loader Service Manual

Table of Contents

• General
• Structure and Functions
• Testing and Adjusting
• Disassembly and Assembly
• Maintenance Standard
• Others

Manual Extract Gear shifting display function:

The HST controller displays the state of input signals related to gear shift on the monitor by sending them to the machine monitor via network.

1. Directional indicators
The directional lever position pilot lamps of the machine monitor indicate the state of the directional lever based on the input data to the HST controller.
When the directional lever is at the neutral position and no input signal is sent to the HST controller, all the directional lever position pilot lamps of the machine monitor go off.

If two independent signals were sent to the HST controller by accident, two directional lever position pilot lamps of the machine monitor may turn on at the same time.
As the directional lever is set to “R (reverse)” the HST controller activates the backup lamp relay to light the reverse lamp and sound the back-up alarm.

2. Speed range indicator
The travel speed range selector switch position pilot lamp of the machine monitor displays the state of the travel speed range selector switch being sent to the HST controller

Variable shift control system
-When the travel speed range selector switch is set to the 1st speed, the variable shift control signal allows adjusting the maximum speed in the range of 4 – 13 km.
Transfer clutch control function

-In order to reduce impacts resulting from connecting the transfer clutch or to prevent inadequate torque due to delayed connection of the transfer clutch, this function adjusts the clutch oil pressure to an optimum level for the machine state (travel speed, travel load, HST oil temperature, directional lever and accelerator opening ratio) by referencing the modulation table of the HST controller.

-In order to reduce lack of the torque, this function maintains the modulation control when the clutch is released.