GB277118A - Improvements relating to vacuum braking apparatus for railway trains - Google Patents

Abstract

277,118. Le Clair, L. J., Brackenbury, A. G., and Westinghouse Brake & Saxby Signal Co., Ltd. June 11, 1926. Fluid - pressure.- A vacuum braking apparatus for railway trains comprises a brake application device provided with a valve 4 for automatically establishing communication between the train pipe and the atmosphere in which the flow of air to the train pipe through the automatic valve 4 is arranged to be independently controlled by a valve 15, so as to permit of graduation independently of the extent of opening of the automatic valve. The opening movement of the valve, in an emergency application, is effected automatically by the pressure obtaining within a vacuum chamber 2 relative to that obtaining in the train pipe 44. The stem of the valve 4 is perforated to receive a cam 10 on a spindle 11 and is extended and attached to a diaphragm 7 separating a vacuum chamber 2 from an atmospheric air chamber 5. The supply of air to the chamber 5 is regulated by a cylindrical valve element 14 provided with a valve 15 which co-operates with a valve seat 16 on the body portion 1. The valve 15 and valve seat 16 are provided with ports which register in the " off " position of the valve 4. When the handle 19 attached to the valve element if is moved from the " off " to the " on " position the valve 4 is raised by the cam 10 and the ports in the valve 15 and seat 16 at first close and then admit air into the chamber 5 by means of a narrow circular port in the valve overlapping one of the ports in the seat 16. This part of the movement corresponds to a service application of the brakes. Further movement of the handle 19 causes large ports in the valve 15 and seat 16 to register so that the chamber 5 is in free communication with the atmosphere, this position corresponding to an emergency application of the brakes. The valve 4 is opened automatically when air enters the pipe 44 during an application of the driver's valve. The air enters the vacuum chamber 2 through a small port 8 in the valve 4 so that the pressure of the atmosphere on the diaphragm 7 opens the valve. In modifications the air can be admitted to the train pipe through restricted orifices covered by a valve mounted on the valve 4, which former valve is raised in the initial movement of a lever, the valve 4 being raised after the orifices have been uncovered. The handle 9 and valve element 14 may be looselv mounted on the spindle 11 and a catch handle provided so that the valve 4 is only opened when the catch is properly gripped by the operator.