US 4,571,007 AGranted

Proportioning relay valve

AssigneeAllied Corporation

InventorsRichard W. Carmichael, John G. Nosse

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Abstract

A proportioning relay valve (10) includes a housing (12) receiving a relay piston (28) which controls communication between supply (14), exhaust (18) and delivery or outlet (16) ports. Control pressure is communicated to the relay piston (28) through a proportioning piston (58). The proportioning piston (58) is controlled by the pressure level at the actuating pressure port (22) to proportion communication to the relay piston (28) when the pressure level at actuating pressure port (22) is low and to permit unproportioned communication to the relay piston (28) when the pressure at actuating pressure port (22) is high. A bypass passage (80) and relief valve (86) also control the proportioning piston (58) so that unproportioned communication to relay piston (28) is permitted regardless of the pressure level at the actuating pressure port (22) when pressure at the control port (20) exceeds a predetermined value.

Claims9

Dependent claims

Proportioning control valve for a fluid pressure braking system comprising a housing, an inlet port, an outlet port, a control port, and an actuating pressure port carried by said housing, valve means in said housing for controlling communication between the inlet and outlet ports, means for operating said valve means for establishing a pressure level at said outlet port as a function of the pressure level at the control port, said operating means including proportioning means shiftable from a first condition wherein the operating means carries said valve means to establish a pressure level at the outlet port as a first function of the pressure level at the control port to a second conditon wherein said valve means establishes a pressure level at said outlet port as a second function of the pressure level at said control port, said proportioning means being responsive to the pressure level at said actuating pressure port to shift said proportioning means between the first and second conditions, and means responsive to a predetermined pressure level at said inlet port for overriding the pressure level at the actuating pressure port to cause said proportioning means to shift to said first condition regardless of the pressure level at the actuating pressure port.

Proportioning control valve for a fluid pressure braking system comprising a housing, said housing having an inlet port and an outlet port, valve means carried by said housing for controlling communication between the inlet and outlet ports, a relay piston slidably mounted in said housing for operating said valve members, a control port on said housing for communicating control air to said relay piston to thereby cause said relay piston to establish a pressure level at said outlet port as a function of the pressure level communicated to said relay piston, proportioning means controlling communication between said control port and said relay piston, said proportioning means being shiftable from a first condition permitting substantially uninhibited communication from the control port to the relay piston to a second condition proportioning communication to said relay piston to thereby establish a pressure level at the latter proportionally less than the pressure level at said control port, and an actuating pressure port carried by said housing, said proportioning means including proportioning control means responsive to the pressure level at the actuating port to shift between said first and second conditions.

Dependencies are inferred from the claim text.