SYSTEM / Hydraulic System Inching Circuit • The signal from the HST control unit excites the DE pump solenoid valve and moves the spool. The circuit between the DE pump solenoid valve and the forward/reverse selection solenoid valve is connected to the hydraulic oil tank. (Refer to Control System / HST Brake (Inching) Control.) • Therefore, as the control pressure in the HST pump displacement angle decreases, the displacement angle control cylinder is operated in order to return to the neutral position. • Consequently, the HST pump displacement angle is changed to neutral and the HST pump delivery flow rate is reduced. • As the HST pump delivery flow rate is reduced, the rotation speed of the HST motor decreases and the machine is slowed down. • The control pressure in the HST pump displacement angle is changed according to the depressing amount of the brake pedal. When depressing the brake pedal fully, the HST pump displacement angle becomes neutral.
T2-2-18
