STRUCTURE AND FUNCTION HYDRAULIC PUMP 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 PA =0 P PB =0 5 RKS02180 Function of the control piston (on induction of pilot signal) P PA P PB > 5 RKS02190 When pressurized oil which has the pressure PPA, PPB (PPA>PPB) is led from pilot line (PPC or AS valve), control piston (5) moves the ( ) direction. Control piston (5) moves the balanced position by spring force and pressure PPA, PPB. If the relation of pressure dimension of PPA, PPB is reversed (i.e. PPA rection.
AS valve is installed and lower pressure between AS valve output pressure and PPC pressure is selected by shuttle valve and inducted to control piston (see topic “shuttle valve”). 10-20 SK818-5 SK820-5 turbo