THEORY OF OPERATION - CONTINUED
STEERING SYSTEM - CONTINUED
Pressure may suddenly increase due to steering resistance. Steering pump load control may not regulate
pump output at a fast enough rate. If this occurs, steering system backup relief valve connects steering con-
trol valve inlet passage to hydraulic oil tank.
Spring holds steering relief valve poppet against valve seat.
Steering pump pressure is sensed in backup relief valve through steering pump inlet hole. This pressure
acts on annular face.
If pressure acting on annular face exceeds pressure setting on backup relief valve, poppet moves left
against spring. Pressure is then relieved to hydraulic oil tank through two outlet holes.
Drain holes connect spring chamber to hydraulic oil tank.
Pressure setting of steering system backup relief valve is adjustable.