Patent GB-1175706-A (GB)
Title: An Automatic Two-Line Compressed-Air Brake
IPC: B60T15/14
Filed: 1967-03-13
Abstract: 1,175,706. Compressed-air brakes. OERLIKON-BUHRLE HOLDING A.G. 13 March, 1967 [26 April, 1966], No. 11723/67. Heading F2F. In an automatic compressed-air brake, particularly for railway vehicles, the brake can be actuated both electro-pneumatically and purely pneumatically and includes an electropneumatic brake-release valve 103 which, during its electro-pneumatic release, connects a supply pipe 101 to a brake pipe 20 and to a triple-valve 93 connected to the brake pipe, a driver's brake valve 1 comprising an automatic device 47 for producing charging pulses, and means which render the device for producing charging pulses inoperative during the electro-pneumatic operation of the brake. The circuit illustrated consists of a driver's valve 1, a charging valve 26 having one chamber 40 communicating with a control reservoir 43, another chamber 41 communicating with a pipeline 58 leading to a chamber of a valve member 17 actuated by a cam surface 16 on a body 2 of the driver's valve. A main reservoir 45 supplies fluid under pressure from a supply pipe 101 to the chamber 44 of the charging valve 26 and thence to chamber 46 of the driver's valve via pipeline 44a. An auxiliary valve, forming the automatic device 47 for producing charging pulses, has two chambers 54, 54a connected to an auxiliary reservoir and a pipeline 59 respectively. The brake equipment of the coaches of the train includes an electro-pneumatic brake valve 102 and an electro-pneumatic release valve 103. One chamber of each of the electro-pneumatic valves is connected through a choke 112 to the supply pipe 101 and to the auxiliary reservoir 98 associated with a triple valve 93 which controls supply of pressure fluid to the brake cylinder 96. A pneumatic double switch 66 is connected to the solenoids 113 of the valves 102 and 103 and the solenoid 78 of an electropneumatic by-pass valve 76. Operation.-When the driver's valve 4 is in the release position illustrated in the Fig. in which the body 2 assumes its highest position, wherein the spring 8 is at its weakest tension, the lower compartment of the driver's brake valve is connected to the control reservoir 43 which balances the spring force adjustable by means of a cover 5. The valve disc 12 is urged upwards by the spring 11 to shut off the admission of compressed air originating from the main reservoir 45 below the diaphragm 10. In this position the valve member 17 is lifted and the pressure of the brake pipe 20 prevails in the pipe compartment 41 of the charging valve 26 so that compressed air can emerge into the atmosphere through the bore 37 from the brake pipe 20. When the pressures in the two chambers 40, 41 of the charging valve are equal, this outlet is interrupted by the valve member 30 bearing against the valve disc 34 and there is equality of pressure at both sides of the diaphragm 52 in the auxiliary valve 47 so that the valve member 51 is urged against its seating by the spring 55 and compressed air is prevented from emerging from the control reservoir 43 through the choke bore 39. The pressure drop occurring in the brake pipe 20 takes place with delay in comparison with the drop in the control pressure and the pressure in the chamber 65 of the pneumatic double switch 66 drops with even greater delay because this chamber 65 together with a time reservoir 64 is connected to the brake pipe 20 through the choke 63. The pressure in the chamber 65 predominates over the pressure in the chamber 71 so that the pair of contacts 74 is bridged by the contact disc 70. As a result of the closing of the working contact 74 of the double switch 66 the voltage of the battery 86 is applied to the brake conductor 87 and the electro-pneumatic brake valve 102 opens. As a result, the brake pipe 20 in each coach is connected to atmosphere through the choke 111 of this valve 102 and is therefore vented in the individual coaches in addition to the venting occurring in the charging valve 26. The pressure in the brake pipe 20 drops rapidly to the value of the set control pressure and as a result the triple pressure valve 93 allows compressed air to pass from the supply reservoir 98 into the brake cylinder 96. When the pressure in the brake pipe 20 has dropped to such an extent that the piston 69 descends under the action of the spring 75 and the brake circuit is interrupted so that the brake valve 102 closes again. Pneumatic release.-During a partial purely pneumatic release of the brake of the train the locomotive driver opens a switch 92 and turns the driver's handle 4 into the position corresponding to a specific release stage to enable the body 2 to be displaced downwardly and the spring 8 to be compressed to a greater extent while the valve member 17 remains in the position illustrated. The valve disc 12 is lifted from its seating 13 and compressed air flows out of the main reservoir 45 under the diaphragm 10 and from here to the control reservoir 43, into the control compartment 40 and below the diaphragm 52 of the auxiliary valve 47. Under the influence of the control pressure, which is predominant, the auxiliary valve 47 opens as also does the charging valve 26. Compressed air now flows out of the main reservoir 45 into the pipe chamber 41 and into the brake pipe 20 through the choke 57 into the chamber 54 and the auxiliary reservoir 56. At the same time compressed air flows out of the control reservoir 43 through the branch pipe 59 under the diaphragm 52 and through the lifted valve member 51 of the auxiliary valve 47 into the chamber 38 of the charging valve 26 when the pressure in the latter and below the diaphragm 52 rises immediately to the value set by the driver's handle 4. The brake pipe 20 is gradually filled until the pressure in the pipe chamber 41 is able to hold the pressures supporting one another in the two chambers 38 and 40 in equilibrium. The chamber 38 of the charging valve 26 no longer receives any supply of compressed air and gradually empties through the choke bores 39. The greater of the release step set at the driver's handle 4 the longer time is taken for filling the auxiliary reservoir 56 to the same pressure. The rise in the pressure reaches the compartments 71 and 72 of the double switch 66 and causes the displacement of the contact disc 70, belonging to the pair of contacts 74a, against the action of the spring 75 whereas the contact disc 70 associated with the pair of contacts 74 remains unaffected. With electropneumatic braking when the switch 90 is closed the release valve 103 in the coaches of the train is energized through the connection of the pair of contacts 74a by the contact disc 70. The electro-pneumatic release valve 103 opens the connection between the supply pipe 101 and the brake pipe 20 leading through the choke 112 so that the brake pipe is filled not only through the charging valve 26 but also from the individual coaches. The magnet coil 78 of the electro-pneumatic valve 76 is energized through the connection between the pair of contacts 74a so that this valve 76 opens as a result of which the response of the auxiliary valve 47 is prevented because the filling of the pressure of chamber 54 of the auxiliary valve 47 of the delay choke 57 is by-passed by the open electromagnetic valve 76. In a second embodiment (not shown) differs from that previously described in that the auxiliary valve 47 which produces the pressure pulses does not cooperate exclusively with the charging valve 26 but also directly with the brake pipe 20. The pressure difference produced in the auxiliary valve 47 during purely pneumatic release of the brake causes the supply pipe to be connected directly to the brake pipe 20. During the electro-pneumatic release of the brake, the electro-pneumatic valve 78 is opened in the manner described above and again by-passes the choke 57 delaying the filling of the pressure chamber 54 as a result of which the formation of the pressure difference in the auxiliary valve 47 is prevented and so the production of charging pulses is prevented.