Patent GB-152391-A (GB)
Title: Improvements in or relating to vacuum brake systems and apparatus for railway vehicles and the like
IPC: B60T13/46
Filed: 1919-07-02
Abstract: 152,391. Luard, E. S. July 2, 1919. Fluid - pressure.- Vacuum brake apparatus is provided with one or m o r e supplementary pumps on one or more vehicles of the train in addition to the usual ejector on the locomotive. These pumps may be driven by an electric or other motor, from the axle of the vehicle, or by the oscillations of the vehicle, and means are described f o r cutting them out when the brakes are applied and when the normal vacuum is attained. As shown in Fig. 1, the pump 9 is driven by an electric motor 8, the current for which may be supplied by accumulators charged by a dynamo driven by the vehicle wheel axles. The pump 9 is connected by the pipe 11 to the train-pipe 1 to which is attached a cut-out device 13, operative when the brakes are applied, and a governor 27 to limit the degree of vacuum normally maintained in the train-pipe. The device 13 comprises a chamber 15, Fig. 5, constantly open to the train-pipe and separated by a diaphragm 18 from a chamber 14 normally communicating by a passage 23 in the stem 20 with the chamber 15. When air is admitted to the train-pipe in applying the brakes, the diaphragm is raised and the passage 23 is closed by the part 14<a> of the casing. The upward movement of the stem 20 opens a switch in the pump motor circuit. The pump governor 27 comprises a diaphragm 29, Fig. 6, exposed on its under side to the trainpipe pressure and to the pressure of a spring 38 and on its upper side to the atmosphere. When the vacuum in the train-pipe reaches an amount determined by the spring 38 the diaphragm 29 is depressed and the stem 23 attached thereto opens a second switch in the pump-motor circuit. Fig. 2 shows means for actuating a supplementary pump 50 by the oscillations of the vehicle body on the springs 52. A crank 54 pivoted to the vehicle underframe and engaging the spring 52 is connected by a rod 56, including a stroke adjusting device 60, Fig. 4, to a transverse horizontal lever 57 pivoted to the underframe and connected at its inner end to the piston rod of the pump. The return stroke of the piston rod is effected by a spring connected to the lever 57. The rod 56 is in two parts the end of one part 56 being socketed in a sleeve 63, Fig. 4, secured to the other part 56<a>. Springs 65, 68 are disposed between a collar 66 fixed to the part 56 and abutments on the sleeve 63. If the oscillation of the vehicle should be such as would impart a stroke of excessive length to the pump the sleeve 63 contacts with one of the fixed brackets 61 and further movement of the rod 56 is taken up by the spring 65. The spring 68 absorbs shock on the return movement. Fig. 10 shows a suitable double-acting pump comprising intake and discharge passages and valves 72, 73, 76, 77 and 74, 75, 78, 79 respectively. To render the pump ineffective when the brakes are applied, valves 82 are adapted to be opened to connect the chambers of the pump cylinder to atmosphere by rods 83, 84 connected to the stem 20 of the cut-out device, Fig. 5. A similar arrangement of valves may be connected to the device shown in Fig. 6 for cutting-out the pump when the vacuum in the train-pipe tends to become excessive. The devices shown in Figs. 5 and 6 may instead be arranged to open a by-pass connecting the ends of the pump cylinders. The pumps may be actuated by the lateral oscillations of the vehicle.