Komatsu WA450-3, WA450-3LL Wheel Loader Service Manual

Table of Contents

01 GENERAL
10 STRUCTURE AND FUNCTION
20 TESTING AND ADJUSTING
30 DISASSEMBLY AND ASSEMBLY
40 MAINTENANCE STANDARD

Manual Outline Transmission Control Valve

The oil from the pump passes through the flow valve and torque converter oil filter, enters the transmission valve, and is divided into the pilot circuit and clutch actuation circuit.
The priority valve adjusts the delivery pressure of the pump and ensures the pilot pressure and oil pressure used to release the parking brake.

The pressure of the oil flowing to the clutch actuation circuit is regulated and automatically shifted to the most suitable range by the electronic control modulation valve, and actuates the clutch.
The oil relieved by the main relief valve is supplied to the torque converter.

The electronic control modulation valve senses the travel speed of the machine and revolving speed of the engine, and operates the proportional solenoid valve according to the command current from the transmission controller to control the flow and pressure of the oil and reduce the shocks at changes of the gear speed and engage the clutch smoothly.

In addition, when the machine is traveling, the clutch pressure is kept constant. The pressure of the oil flowing to the pilot valve is regulated by the pilot reducing valve, and actuates the directional and range spools as the solenoid valves are switched ON or OFF.
When the directional and range spools are switched, the oil, whose pressure is regulated by the electronic control modulation valve, is supplied to the selected clutch to provide the necessary speed range.