Patent GB-479811-A (GB)
Title: Improvements relating to the automatic regulation of compressed air brakes
IPC: B60T8/32
Filed: 1937-04-06
Abstract: 479,811. Fluid-pressure brakes. GALLUSSER, H. April 6, 1937, No. 9715. [Class 103(i)] Devices for reducing the pressure in the brake cylinders of a fluid-pressure brake system for railway vehicles in dependence upon fall of speed of travel comprise electrically actuated shut-off and exhaust valves arranged between the source of pressure and the cylinders the valves being controlled by a speedometer and by pressure gauges of which one is connected between the source of pressure and the shut-off valve while another or others is or are connected between the cylinders and. the shut-off valve. Fig. 2 shows an arrangement in which a two-stage automatic reduction of brake cylinder pressure with fall of speed is obtained. Cut-off and relief valves 12, 13 are disposed in the pipe 11 connecting the main control valve to the cylinder 10. Pressure gauges 17, 22 connected between the valves 12, 13 and the cylinder are adapted to open contacts E, B when the pressure falls for instance to 3À5 atm. and 2À5 atm. respectively and a third pressure gauge 15 connected to the pipe 11 on the other side of the valves opens a contact A when the pressure falls to a value slightly below that at which the contact B is opened. A speedometer 18 is adapted to close contacts D, C when the speed falls respectively to, for instance, 37 and 20 miles per hour. At high speeds with the brakes released the condition of the parts is as shown except that the contacts C, D are open. The valves 12, 13 are thus de-energized and are respectively open and closed as shown. When the brake is applied at full pressure (5 atm.), contacts A B E are closed and when the speed falls to 37 m.p.h. the contact D completes the circuit of the valves 12, 13 thus closing valve 12 and opening valve 13. When the cylinder pressure has fallen to 3À5 atm. the contact E opens the circuit of valve 13 which then closes. When the speed falls further to 20 m.p.h. contact C closes the circuit of valve 13 again and when the cylinder pressure has fallen to 2À5 atm. this circuit is again re-opened. Complete release is effected by reducing the pressure in pipe 11 by the main valve, the contact A being thus opened to de-energize and open the valve 12. In a simpler arrangement providing only one stage of automatic pressure reduction, the pressure gauge 22 and the speedometer contacts D are dispensed with, the valve 12 being connected to the contact C. Fig. 3 shows an arrangement in which with falling speed the pressure in an auxiliary cylinder 25 is reduced to zero in two stages, the pressure in the main cylinder 10 being unaffected. The speedometer contact D is arranged to close when the speed falls to 37 m.p.h. and the contact C to open when the speed falls to 20 m.p.h. An additional valve 26 is in one position adapted to close the supply connection to the cylinder 25 and open the cylinder to atmosphere and in the other position to reverse these connections. At high speeds with the brakes released the apparatus is in the condition shown except that contacts C, D are respectively closed and open. If then full pressure is supplied to pipe 11, cylinder 10 is charged and closing of the gauge contact A at 2 atm. completes the circuit of valve 26 to permit charging of cylinder 25 and closing of the gauge contact B. Upon fall of speed to 37 m.p.h. contact D completes the circuit of valves 12, 13 so that the supply connection is cut off and the cylinder exhausts until the pressure having fallen to 2À5 atm. contact B reopens the circuit of the valve 13. Upon further fall of speed to 20 m.p.h. the contact C opens the circuit of valve 26 so that the cylinder 25 completely exhausts.