| 摘要 |
993,333. Fluid-pressure brakes. CLAYTON DEWANDRE CO. Ltd. March 5, 1964 [March 22, 1963], No. 11433/63. Headings F2E and F2F. In fluid-pressure braking apparatus of the kind having a dual control valve 19 for controlling the admission of compressed air or vacuum from a pair of independent reservoirs 18 to a dual compressed air or vacuum servomotor connected hydraulically with two independent sets of brakes 12, 13, the servomotor consists of a pair of cylinders 1, 2 arranged end-to-end, pistons 5, 6 in the respective cylinders and an operating rod 9 extending coaxially within the cylinders for operating the primary piston 10 of a tandem master cylinder 11 the separate outputs of which are connected to the brakes 12, 13, the rod 9 having abutment surfaces, formed by the rearward end and a shoulder 14 respectively, for contact with the pistons 5, 6 such that the combined thrust of the pistons 5, 6 is normally transmitted to the rod 9 but on failure of either section of the compressed air or vacuum system one piston only moves the rod 9 to actuate the master cylinder with reduced thrust. As shown, the servomotor is designed for operation by compressed air which is admitted to chambers behind the pistons 5, 6 on operation of the dual control valve 19 via pipes 20, 21. The chambers are formed respectively by end wall 1a of cylinder 1 and a dividing wall 3. Spring 16 returns the rod 9 when the brakes are released. A travel indicator is provided comprising a rod 24 contacted by piston 6 and having a coloured mark 26 which when visible indicates the need for brake adjustment. Alternatively an enlargement on the outer end of the rod 24 may operate a switch controlling a buzzer or indicator light (Fig. 3, not shown). Each of the pistons 5, 6 has both a ring seal 7 and a lubricant-impregnated felt or like ring 8. |
