Komatsu PC88MR-10 Shop Manual page 201

Regulator valve (2) is pressed to the left by the reaction force of spring (3).
The main pressurized oil from the control valve passes through check valve (4) and blocks the circuit to
regulator piston (5) by using regulator valve (2).
The oil in control chamber (C) is drained through oil passage (e) of regulator valve (2) and port (D).
Swash plate (6) is set to the maximum angle, and consequently the motor capacity becomes maximum
and the machine travels at low speed.
At high travel speed (motor swash plate angle is minimum)
1. 2nd travel speed selector solenoid valve
2. Regulator valve
3. Spring
4. Check valve
5. Regulator piston
6. Swash plate
7. Parking brake piston
8. Main pump
9. Travel control valve
10. Merge-divider valve
11. Self-pressure reducing valve
12. Brake valve
When 2nd travel speed selector solenoid valve (1) is energized, the pressurized oil from main pump (8)
flows into port (P).
Regulator valve (2) is pushed to the right by the pressurized oil flowing into port (P).
The pressurized oil from the control valve passes through check valve (4), then flows through oil passage
(f) of regulator valve (2) into control chamber (C) and pushes regulator piston (5) to the left.
Swash plate (6) is set to the minimum angle, and consequently the motor capacity becomes minimum and
the machine travels at high speed.
PC88MR-10
10 Structure and function
Travel motor
10-123