GB1420149A - Dual hydraulic brake valves - Google Patents

Abstract

1420149 Dual brake valves CLAYTON DEWANDRE CO Ltd 16 April 1974 [19 April 1973] 19057/73 Heading F2F A dual brake valve which controls two independent circuits actuating separate sets of brakes has two valve assemblies operable simultaneously through a balance beam 1 displaced by pedal-actuated input plunger 3 and at least part of a reaction force is created by a reaction mechanism other than through the beam. As shown, each valve assembly comprises a plunger 7 one end of which forms an exhaust valve seat 8 which when engaged by a poppet type valve element 9 cuts off communication between a brake connected port 12 and an exhaust connection 15. Further movement of the element 9 lifts the head thereof from an annular valve seat 11 to establish communication between an accumulator connection 13 and port 12. The beam 1 is pivoted to a carrier 5 forming part of the plunger 3 and spring biased reaction pistons 17, 18 accommodated in a bore 16 act on the carrier 5 through a pad 5a to provide the reaction force independent of beam 1. A passage 19 leads from one end of bore 16 to the port 12 of one valve assembly and the space between pistons 17, 18 is connected by a passage 20 to the port 12 of the other assembly. If the fluid pressure into passage 19 fails, piston 18 provides the reaction, and if fluid pressure to passage 20 fails, piston 17 transmits reaction through piston 18. A passage 23 provides a visual indication of failure of either of seals 22.