GB297448A - Improvements relating to track brake devices - Google Patents

Abstract

297,448. Westinghouse Brake & Saxby Signal Co., Ltd., (Assignees of Down, S. G.). Sept. 22, 1927, [Convention date]. Electric and magnetic; fluid-pressure ; skid.- Electromagnetic track brake shoes for railway vehicles are arranged to be moved into contact with the rail by means, such as fluid-pressure, other than the magnetic attraction between the shoe and the rail and to be subsequently and automatically energized, to avoid the necessity of supplying a high initial current for this purpose. The shoe 1 is carried by a piston 5 in a cylinder 6 to which pressure fluid is supplied by pipes 12, 17 past a spring pressed piston valve 10 which in its normally seated position connects the cylinder 6 to an exhaust port 15 by way of a passage 19. The circuit of the magnetizing coils of the shoe 1 includes contacts 26, 27 adapted to be connected by a contact 25 carried by a piston 21 the cylinder 20 of which is connected to the cylinder 6. The pipe 12 is connected to the straight air pipe of the fluid pressure braking system or to the usual brake cylinder. When pressure fluid is thus supplied to the pipe 12 the piston 10 is moved upwardly when the pressure reaches a predetermined value to close the exhaust passage 19 and permit the passage of the fluid to the cylinder 6 and the switch cylinder 20. The piston 5 is first moved to bring the shoe 1 into contact with the rail and consequent upon the further rise of pressure the piston 21 is moved to close the contacts 25, 26, 27 and energize the shoe. When the pressure fluid is released from the pipe 12 the piston 21 is first moved to break the circuit and the piston 5 then withdraws the shoe. When the fluid pressure falls to a predetermined valve the piston 10 re-seats and the pressure fluid remaining in the pipe 17 is vented through the passage 19. The pistons 10, 21 seat upon circular ribs 11, 22 so that only a restricted area is exposed to the fluid pressure until the pistons are unseated, a rapid movement of the pistons being thus ensured.