Patent GB-263828-A (GB)
Title: An improved servo brake
IPC: B60T13/58
Filed: 1926-12-24
Abstract: 263,828. Compagnie Internationale des Freins Automatiques, Soc. Anon., (Assignees of Pieper, H.). Dec. 24, 1925, [Convention date]. Addition to 226,830. Fluid-pressure. - In brake mechanism for a train of vehicles, such as described in the parent Specification, wherein the brakes are applied by liquid under the pressure of a gas and are released by vacuum which restores the gas to its original state, the application of the brakes is controlled by a distributor valve on each vehicle subject to vacuum in a pipe extending throughout the length of the vehicle. A vessel 6, Fig. 1, containing liquid under pressure is provided on each vehicle for applying the brakes, release being effected by causing a partial vacuum produced on one of the vehicles, as by a steam ejector 56, to be transmitted by a duct 57 throughout the length of the train and to act upon the brake piston 4' of each vehicle, the application of the brakes on each vehicle being controlled by a, distributor mounted on the vehicle and itself controlled by the partial vacuum in a second duct 77 also extending throughout the length of the train. The duct 57 communicates through a duct 90 in which is a non-return valve 72 with a vacuum reservoir 88 which communicates through a duct 89 containing a cock 78 with the control duct 77. Steam is supplied to the ejector 56 through a cook 58 which may be connected with the cock 78 by linkage 79 for simultaneous operation. The control duct 77 is connected to each distributor which comprises a chamber containing a diaphragm 32 acted upon by a spring 29 and connected to a sliding member 73 on which is a piston 81, subjected to the fluid pressure in the duct 6', and a valve 8 for controlling communication between the vessel 6 and the brake cylinder. Air may be admitted at 82 through the cock 78 to the duct 77, and the decrease in vacuum allows the spring 29 to force down the member 73 and open the valve 8 against spring pressure to apply the brakes. The release of the brakes is effected by restoring the vacuum in the duct 77 by connecting it through the cock 78 with the reservoir 88, thus causing the diaphragm 32 and the member 73 to rise and close the valve 8, while the vacuum in the duct 57 acts on the piston 4<1>. The ends of the ducts 57, 77 are closed by plugs 80, and by inserting a cock in the duct 77 between the vehicle with the ejector and the coupled trailer vehicle, the former vehicle may be uncoupled with the brakes of the trailer vehicle in the release position. For the rapid application of the brakes of vehicles remote from the cock 78, the dictributors of these vehicles may be provided with a spring-closed valve 84, Fig. 2, which is opened to allow air to enter, when the member 73 is depressed, by a bridge piece 83 on the member 73 acting on a collar on the valve stem. The valve 8 of the distributor may be replaced by a non-return valve 8a, Fig. 3, and a valve 8<b> on the member 73, the spring 29 being dispensed with and equivalent action obtained by a diaphargm 32<a> attached to the member 73 and acted upon by the pressure of the vessel 6 on one face and the vacuum of the control duct 77 on the other face. An arrangement for maintaining the brakes of the trailer vehicles released when the locomotive with the vacuum-producing devices is uncoupled is shown in Fig. 4 and comprises vessels 86 in which a partial vacuum is produced by connection past non-return valves 93 to the duct 57 and which are connected to an additional duct 87 communicating at intervals with the duct 77 through cocks 88. Before the duct 77 is uncoupled from the locomotive, it is opened through the cock 88 to the duct 87, so that both ducts are cut off from the atmosphere and the brakes are held released although the duct 57 may be at atmospheric pressure. The brakes may be applied on an uncoupled vehicle by opening the duct 77 to atmosphere and may be released by connecting the vacuum vessel 86 to the duct 57 by unseating the valve 93. According to the Specification as open to inspection under Sect. 91 (3) (a) the control duct 77 may contain compressd air, the distributors being modified; the release of the brakes may be effected by electromagnetic means. The Specification includes also the subject-matter of Specification 279,905. This subject-matter does not appear in the Specification as accepted.