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COMPONENT OPERATION / HST Pump
FORWARD / REVERSE SELECTION SOLENOID VALVE
The forward/reverse selection solenoid valve controls the pump displacement angle direction and changes the delivery direction (port A or port B) of pressure oil. Pressure oil from the DE pump solenoid valve to control the displacement angle control cylinder acts on the forward/reverse selection solenoid valve. The forward or the reverse selection solenoid valve is excited and the spool is operated according to the signal from the FNR lever. Then, the hydraulic circuit to the corresponding displacement angle control cylinder is connected.
Therefore, the pump displacement angle is controlled and the delivery direction of pressure oil is changed. T4FC-03-08-005 T4FG-03-04-001
T3-4-7
COMPONENT OPERATION / HST Pump
De Pump Solenoid Valve
The DE pump solenoid valve is a proportional solenoid valve and controlled by the command signal from the HST control unit.
The command signal is a current value. The pump displacement angle is the maximum at the maximum current value and is the minimum at the minimum current value.
The spool position is changed by changing a current value so that the servo piston operation is controlled.
