PROPORTIONING BRAKE VALVE WITH DUAL AREA SECONDARY PISTON

摘要

A dual circuit brake valve includes a relay piston (50) having primary (82) and secondary (84) areas which are normally communicated to the pressure level at the primary outlet or delivery port (18). The relay piston (50) responds to a pressure differential across the relay piston to control communication to the secondary outlet or delivery port (22). A control mechanism (92) is responsive to a control signal to vent the 48 secondary area (84) to thereby establish a differential area across the relay piston (50), so that the relay piston (50) will establish a pressure level at the secondary outlet or delivery port (22) which is a predetermined fraction of the pressure level at the primary outlet or delivery port (18).