| 摘要 |
972,307. Fluid-pressure brakes; brake indicators. WESTINGHOUSE BREMSENG.m.b.H. July 3, 1961 [July 5, 1960], No. 23880/61. Headings F2E and F2F. A driver's brake valve device is basically the same as that described in Specification 914,840 but, in addition, is provided with a charging- flow valve device for limiting main reservoir charging impulses and overcharging of the brake system in dependence upon the degree of the previous brake application, the length of the train and the type of railway stock (e.g. freight or passenger) to which the brakes are fitted. The latter two variables corresponding to an axle total are set by a manually variable choke 51 which controls the flow of compressed air from the brake pipe 65 to a limiting reservoir 75, the pressure in which controls two valves 28, 43 limiting the charging flow. The valve 43 is adapted to close a vent connection to the control chambers 32, 34, respectively, of a pilot valve 1 and relay valve 2 and the other valve 28 is adapted to close a connection to an overcharge limiting member 26 coupled to the pilot valve 1. These connections are also controlled by valves 10, 11 operated by the handle 9 of the driver's brake valve device. The choke device 61 allows the flow of compressed air to be reduced or increased by means of a needle valve 76 or to be cut off completely by a valve member 77. An indicator 78 mounted on a control rod of the choke device 51 is adapted to operate in conjunction with a scale 79 calibrated to indicate the length and type of a train by the number of its axles, to give the magnitude of the compressed air flow in a pipe 80 leading to the main brake pipe 65. The charging flowlimiting reservoir 75 is filled as a function of a pre-set axle total and the force of the preceding application of the brakes. When the pressure in the reservoir. 75 reaches a certain value, it overcomes the force of a limiter spring 50 and moves a diaphragm 48 downwards, causing the valves 28, 43 to close. The supply of air through a choke 24 and pipe 30 to a timing reservoir 25 is thus interrupted and the supply of main reservoir air is cut off in the manner described in Specification 914,840. |
