Standby supply system for delivering pressure fluid to a user component

Claim 1

A standby supply system for delivering pressure fluid to a user component comprising: a primary fluid source; a first check valve coupling the pressure fluid of said primary source to said user component; an accumulator; a second check valve coupling the pressure fluid of said primary source to said accumulator for charging thereof; and e a valve arrangement coupled to said primary source, said accumulator and said user component, said valve arrangement being responsive to pressure from said primary source to control a connection from said accumulator to said user component; said valve arrangement including a housing having a longitudinal stepped bore accommodating a stepped piston slideable therein in an axial direction, an inlet chamber coupled to said primary source and an outlet chamber coupled to said user component, said piston having a front surface on its larger diameter portion exposed to pressure from said primary source in said inlet chamber and its smaller diameter portion projecting into said outlet chamber to control a passageway connecting said outlet chamber to said accumulator, the end of said passageway adjacent said outlet chamber being a valve seat and the end of said smaller diameter portion being a closing member for said valve seat, said inlet chamber being coupled to said outlet chamber by said first check valve, and said outlet chamber being coupled to said accumulator by said second check valve, said piston being biased in a direction to open said passageway.