STRUCTURE AND FUNCTION HYDRAULIC PUMP PPA, PPB. If the relation of pressure dimension of PPA, PPB is reversed (i.e. PPA rection. On SK714-5, AS valve is not installed, so pressurized oil from PPC valve is directly inducted to control piston. On SK815-5, AS valve is installed and lower pressure between AS valve output pressure and PPC pressure is se- lected by shuttle valve and inducted to control piston (see topic “shuttle valve”). 10-24 SK714-5 SK815-5 Function of the control piston (on non-induction of pilot signal) • There are no pressure, so control piston (5) doesn’t move and main pump is on neutral condition.
P =0 5 P =0 P =0 5 P =0 PA PB PA PB RKS00230 Function of the control piston (on induction of pilot signal) Function of the control piston (on induction of pilot signal) SK714-5 SK815-5 5 5 P > P P > P PA PB PA PB RKS00240 • When pressurized oil which has the pressure PPA, PPB (PPA>PPB) is led from pilot line (PPC or AS valve), contro piston (5) moves the ( ) direction. Control piston (5) moves the balanced position by spring force and pressure