Komatsu WA65-6, WA70-6, WA80-6, WA90-6, WA100M-6 Loader Service Manual

Table of Contents

• Safety
• General
• Structure and Functions
• Testing and Adjusting
• Disassembly and Assembly
• Others

Manual Extract Regulating valve (DA valve):

The DA valve regulates the control pressure (Pst) from which engine speed on the machine starts to travel.
HST charge pump oil (P) flows against orifice (7). The pump flow increases as soon as the engine speed is raised and increases the force against orifice (7).

At a certain engine speed piston (6) lifts up from the seat and control pressure (Pst) is generated.
The (Pst) pressure moves the servo piston, which moves the swash plate to the selected travel direction (forward or reverse).
The higher the engine speed, the greater the HST charge pump oil flow and the bigger the force to orifice (7). As a result the control pressure increases in accordance with the engine speed and so the travel speed increases.
The remaining oil flows to charge pressure port (Psp) to charge the HST circuit and to PPC.