Patent GB-278358-A (GB)
IPC: B60T13/66
Filed: 1927-09-27
Abstract: 278,358. British Thomson-Houston Co., Ltd., (Assignees of Ives, C. A., Macloskie, G., and Davis, H. A.). Sept. 28, 1926, [Convention date]. Sand, distributing on wheel tracks. - Relates to brake systems for vehicles comprising electromagnetically-applied track brakes and fluid-pressure. applied brakes, particularly wheel brakes. The track brake is automatically energized for a predetermined length of time upon an emergency or a predetermined straight application of the fluid-pressure brakes or the track brake may be energized for a predetermined length of time at the will of the operator when a straight application has been made. The escape of the pressure-fluid from the timing reservoir that determines the duration of the application of the track brake may be used to operate a track-sanding appliance. The system shown in Fig. 2 includes a combined automatic and straight fiuid-pressure wheel brake system controlling also a magnetic track-brake 10. The wheel brake cylinder 3 is normally connected to the pipe 6 through the emergency valve 4 and a straight air application is made by operation of the driver's valve 2 to connect the pipe 6 to the main reservoir pipe 5. An emergency application is effected by a reduction of pressure in the pipe 7 whereupon the valve 4 connects the pipe 5 to the brake, cylinder 3. The track brake 10 is normally held clear of the track by a spring 14 and is brought into contact therewith by fluid-pressure acting on a piston 13 simultaneously with the energization of the brake by a fluid-pressure operated switch 15. The switch 15 and piston 13 are controlled by a relay device 17 comprising a diaphragm 20 connected to a double-beat valve 19 whereby normally with the diaphragm chamber open to atmosphere the switch 15 and piston 13 are also open to atmosphere by the passage 23. Compressed air is supplied to the chamber of the diaphragm 20 to apply the track brake, upon an emergency application of the fluid-pressure brake by a reservoir 25 normally connected to the main reservoir 1 by the emergency valve 4 which in its emergency position connects the reservoir 25 to a pipe 34 leading to the relay valve 17. The pipe 34 is provided with a restricted outlet 35 so that alter an interval the pressure acting on the diaphragm of the relay valve reduces sufficiently to permit the spring 22 to return the valves 19 and effect the de-energizing and withdrawal of the track brake. The pressure-fluid that escapes from the outlet 35 may be used to operate a track-sanding appliance. To effect the application of the track brake upon a predetermined straight air application of the fluid-pressure brake, a valve device 38 is provided comprising a diaphragm 40 operating a double-beat valve 39 which normally with the diaphragm chamber at atmospheric pressure connects a reservoir 43 to the main reservoir 1 by pipe 24. The pipe 41 leading to the valve device 38 is normally connected to atmosphere by way of the passages 49, 53. The, passage 53 is controlled by a plunger 55 subject to the opposing pressures of a spring and that in the straight air pipe 6 wherebv when the pressure in this pipe reaches the value determined by the spring the plunger opens the connection, of this pipe to the relav device 38, the valve 39 of which then connects the reservoir 43 to a restricted outlet 45 and to the relay device 17 past a double-check valve. The track brake 10 is thus applied for a predetermined time dependent upon the outlet 45. When the fluid-pressure, brakes are released the track brake is de-energized if this has not already been effected by the outlet 45. The release of the track brake is also effected upon opening the car doors. For this purpose the pressure pipe 61 leading from the control valve 62 to the door engine may be connected also to the chamber of a piston 60 which upon the supply of pressure-fluid to the pipe 61 operates a valve 50 to connect the pipe 41 to atmosphere. The operation of the track brake may be prevented when a straight air application of the fluid-pressure brake is made or an immediate release of the track brake may be effected by a valve 57 which is adapted in one position to connect the two sections of the pipe 41 and in another to close such connection and to connect the section leading to the relay device 38 to atmosphere.