STRUCTURE AND FUNCTION HYDRAULIC PUMP FUNCTION Port A is connected to the charge circuit. Port B is connected to the tank drain circuit. The pressurized oil fills port C through orifice a in valve ( 2A ). Poppet ( 2D ) is in tight contact with valve seat ( 2C ) 1 2A 2C 2D C 2E A a B RKS00010 If abnormal pressure is generated in the circuit or the shuttle valve of HST motor is at neutral and the oil pressure at ports A and C reaches the pressure set by spring ( 2E ), poppet ( 2D ) is pushed to direction, and oil at C is relieved to port B and pressure of the oil at C reduce.
2D 2E 2A C A B RKS00020 When the pressure of the oil at port C goes down, a differential pressure is occured between ports A and C because of orifice a in valve ( 2A ). Valve ( 2A ) is pushed to direction by oil pressure at port A , and oil at port A is relieved to port B . In this way, the pressure in the charge circuit is prevented from going any higher. 2A C A a RKS00030 B 10-26 SK818-5 SK820-5 turbo