Patent GB-261092-A (GB)
Title: Improvements relating to track braking apparatus for railways and the like
IPC: B61K7/08
Filed: 1925-08-12
Abstract: 261,092. Westinghouse Brake & Saxby Signal Co., Ltd., (Union Switch & Signal Co.). Aug. 12, 1925. Arresting-grips or frictional apparatus on permanent way; fluid-pressure; indicators, applications of.-Brake apparatus of the kind comprising power-operated devices arranged on the track for engagement with the wheels or other part of a vehicle and adapted to be controlled from a distant point comprises either of the following features : (a) electropneumatic operating means subject to the control of the braking pressure whereby the pressure established is dependent upon the position of the operator's switch or (b) means for indicating at the point of control the braking pressure actually obtained. Pars 3<a>, 4<a> arranged alongside the running rails 1. 1<a> are adapted to be applied to the wheats of the vehicle through springs 5 interposed between these bars and bars 3. 4 which are respectively secured to operating bars 6, 7 provided with racks 6<a>, 7a engaged by pinions 8. Arms 8<a> on the pinions are connected by a link 11 and are operated by a piston 14. The valve mechanism comprises valves 27, 30 respectively controlling the supply and exhaust to one side of the piston for applying and regulating the application of the brake and a valves 33 for supplying and exhausting the pressure fluid on to the other side of the piston tor effecting the return of the mechanism after an application. Each of these valves is controlled by an electromagnetically actuated pilot valve 19 which according as it is energized or de-energized supplies or exhausts, through pipes 38, 22 and port 21, pressure fluid to or from the upper side of the actuating pistons 24, 29, 32 of the valves 27, 30, 33. To apply the brake the switch 45 is closed to energize the valve magnet P, thereby admitting pressure fluid to the upper side of piston 29 to close, the exhaust valve 30. The switch 47 is then closed on contact 48 to energize the valve magnet R, thus causing the piston 24 to be moved to unseat valve 27 and admit .pressure fluid by passages 37, 15 to the application side of the piston 14. The pressure in the cylinder can be reduced or entirely released by opening the switch 45, thus permitting the pressure fluid in the cylinder to lift the valve 30 and escape by way of the port 31. When the pressure has thus been exhausted from the application side of the piston 14, the switch 47 may be closed on contact 49 to energize the valve magnet. N, thereby causing the exhaust valve 33 to be seated and valve 35 to be opened to admit pressure fluid from passage 37 to the release side of piston 14 to return the mechanism to the .normal position. In order that the operator may be informed of the braking pressure in the cylinder A, a pressure gauge is provided comprising an element 41 in communication with and responsive to the pressure in the cylinder A and adapted electrically to control an indicator 43. Fig. 3 shows an alternative arrangement in which the pressure established in the cylinder A is determined bv the position of the operator's switch 47. A diaphragm 52 subject to the pressure in the cylinder actuates a switch 51 included in the circuit of the pressure supply valve Rand engaging a series of contacts 55<a>, 59<a> one or other of which is included in the circuit according as the switch arm 47 is in engagement with one or other of a series of contacts 55-59. The arrangement is such that the contacts 55<a>-59<a> are successively broken with increasing pressure in the cylinder A.