GB1374634A - Dual brake valves - Google Patents

Abstract

1374634 Dual brake valves CLAYTON DEWANDRE CO Ltd 12 Dec 1972 [31 Dec 1971] 60972/71 Heading F2F In an hydraulic dual brake valve, two valve assemblies, each assembly having a valve member 11 displaced with respect to a fixed seating 10, to control fluid flow between a pressure source connected chamber 3 and a brake line chamber 5, are actuated by a plunger 8 actuated by a balance beam 24, each member 11 being urged to its seating by a spring loaded tubular valve guide 12; a blow-off type safety valve 19 is disposed coaxially with each assembly in a further chamber 18 connected to the chamber 3 and when open discharges fluid through an exhaust passage formed axially of the valve assembly. Upon actuation by a thrust member 23 through the beam 24, each plunger 8 has a stem which engages one element 11b of the valve member 11, in the form of a dumbbell, to block communication between the brake line chamber 5 and passages 15, 16 to a reservoir. Further plunger movement lifts the other element 11a of the member 11 from its seating 10 to communicate pressure fluid to the brake line chamber 5 via a port 4, a filter 22, and the chamber 3. If the pressure exceeds a predetermined value, the safety valve is opened by pressure in the chamber 18, connected to the chamber 3 via a passage 21, to communicate the chambers with the reservoir. Braking reaction is produced by pressure fluid in the chamber 5 acting on a piston part 9 of the plunger 8. Upon pressure failure in one of the circuits, the associated plunger 8 moves leftwardly to engage a circlip 25 against a housing shoulder, allowing continued actuation of the other plunger.