GB1155173A - Emergency brake actuator. - Google Patents

Abstract

1,155,173. Emergency brake actuator. BERG MFG. & SALES CO. 13 June, 1966, No. 26317/66. Heading F2F. In an emergency brake actuator, a piston 14 which operates a brake actuating member 11 is located in a housing 2 and may be held in one position in the housing by pressure of air admitted to the housing at one side B-1 of the piston against a biasing force applied by spring means 20 located at the opposite side of the piston B-2 whereby, when the air pressure falls below a value such that the biasing force moves the piston and thereby operates the brake actuating member, the air thereby discharged will be transferred to the opposite side B-2 of the piston via a valve member 50 but, when air pressure is applied to move the piston thereagainst the biasing force, the air then displaced by the piston movement is discharged from the housing via a filter 34. For normal brake operation, fluid pressure is supplied through an inlet 9 and against one side of a diaphragm 8 located in a housing portion 5 clamped to the housing 2 to move the diaphragm 8, the plate 10 and the rod 11 to apply the brakes of the vehicle. When the actuator is initially charged, pressure air from a compressor is delivered to the inlet 47 to move the valve 50 towards and into engagement with a seat 44 to close the passage portion 46 and fluid pressure is permitted to flow past the flexible peripheral portion 54 of the valve 50 through passage portion 45 and passage 40 into the chamber area B-1 between the piston 14 and the baffle 3 to move the piston 14 towards the "brakes-off " position and compress the power spring 20 as shown in Fig. 1. When the fluid pressure in the system, connected to the inlet 47, is reduced the fluid pressure within the chamber area B-1, passage 40 and passage portion 45 will cause the free floating valve element 50 to be moved off its seat and on to its seat 49. Fluid pressure will then flow from the area B-1 between the members 14 and 3 through passage 40, passage portion 45, seat 44, passage portion 46 and passage 41 and thus into area B-2 on the opposite side of the piston 14 and pressure flowing into the chamber portion B-2 will flow outwardly through the vent passage 33 and filter 34 to atmosphere. The pressure will also act against the rear face of the piston 14 to assist in its movement towards the brakes-on position under the influence of the spring 20. With the chamber portion B2- pressurized in this manner, the action of the piston 14 moving away from the rear closure plate 21 will not produce a suction effect which will draw in air or extraneous matter into the area B-2 behind the piston 14 so that the seals 29, 30, 31 are not subjected to a suction action or to damage. The rod 25 may be rotated by an external handle structure 28 for adjustment of the travel of the piston member 14. It is also stated that the time taken to apply the brakes is reduced by the above means. In an alternative embodiment disclosed in the Specification (Fig. 3, not shown) air is discharged from the housing through a filter located in a branch off the second passage instead of being provided in the closure plate 21. Reference has been directed by the Comptroller to Specifications 911,590 and 1,023,547.