GB1104557A - A quick release valve for railway vehicles equipped with automatic vacuum brake systems - Google Patents

Abstract

1,104,557. Vacuum brake systems. COMPAGNIE DES FREINS ET SIGNAUX WESTINGHOUSE. 26 April, 1966 [27 April, 1965], No. 18252/66. Heading F2F. A quick-release valve for manual operation, to enable release of a vacuum brake of an uncoupled rail vehicle, is adapted for application to a brake cylinder of the two-ohamber type and is also arranged so that the vacua in the auxiliary reservoir and in the brake pipe of a train to which the vehicle is coupled can be equalized without significant reduction of the vacuum in the brake pipe, the arrangement also allowing the vacuum in the auxiliary reservoir to be completely destroyed after uncoupling if repairs are to be carried out. As shown, the valve comprises a body 7 providing three chambers 16, 17, 18 which are connected respectively to the lower chamber 3 of the brake cylinder CF, which is in permanent communication with the brake pipe section CG within the vehicle, to the upper chamber 4 of the brake cylinder, and to the auxiliary reservoir RA. The valve assembly consists of a rod 28, to which are secured a compensating valve 27, a combined small-diameter valve element 35 and piston 50, and a piston 45. A large-diameter cap valve 32 is slidably mounted on the rod and urged by a spring 37 to engage the valve 35. Atmosphere acts in chambers 44, 47 on the pistons 50 and 45, respectively, to maintain the cap valve 32 normally out of contact with a seat 30 bounding a large-diameter passage 29. A check valve 22 is disposed in a passage leading from chamber 17 to upper chamber 4 of the brake cylinder, this passage being bypassed by a narrow passage 20. A rocking lever 42 acts through a domed head 41 on a rod 38 engageable with the lower end of rod 28, against the action of a spring 40. The valve operates as follows: when the vehicle is coupled to a train and equalization of the vacua in the brake pipe and in the auxiliary reservoir is desired, lever 42 is rocked; this opens the compensating valve 27 and at the same time causes cap valve 32 to close the large-diameter opening 29 and valve 35 to open the small diameter passage 33 by moving away from the cap valve 32, equalization thus taking place slowly. To release the brakes when the vehicle is uncoupled it is necessary only to flick the lever 42. Since pressures on opposite sides of piston 45 are both equal to atmosphere cap valve 32 is maintained in closed position by atmospheric air acting on its underside but valve 35 remains closed to retain vacuum in the auxiliary reservoir. If the vehicle is then recoupled to the train and a vacuum produced in the brake pipe the cap valve 32 will be opened automatically when the brake pipe vacuum approaches that of the auxiliary reservoir. Total destruction of the vacuum in the auxiliary reservoir of an uncoupled vehicle is effected by holding the lever 42 in a fully rocked position. The pistons 45, 50 may be replaced by pressure-sensitive piezo-electric crystals providing signals proportional to the respective pressure differences which, when amplified, are fed to an electromagnet acting on the rod 28.