GB968958A - Master cylinder for hydraulic brake mechanisms with separate circuits, more particularly for vehicles - Google Patents

Abstract

968,958. Hydraulic brakes. FIAT S.p.A. Nov. 13, 1962 [March 29, 1962], No. 42899/62. Heading F2F. A tandem master cylinder for an hydraulic braking system for vehicles comprises a first (5) and second (23) pistons, a first spring 43 interposed between the pistons and a second spring 33 interposed between the second piston 23 and an end plug 2 closing the cylinder 11, a first chamber 18 between the pistons communicating with one brake circuit on the vehicle through an outlet 22 and a second chamber 26 between the second piston 23 and the end plug 2 communicating with the other brake circuit of the vehicle through outlet 35 and characterized in that the first spring 43 is mounted under a higher preload than the second spring. The pre-loading of the first spring 43 is achieved by providing a unit such as that shown in Fig. 2 positioned between the first and second pistons as shown in Fig. 1. Upon actuation of the master cylinder the first piston 5 is moved to the left and the pre-load of the spring 43 exceeds the pre-load on spring 33 the latter is compressed first and the pistons 5 and 13 perform simultaneously the movement in the direction of the plug 2 until the communication of the compression chambers 18, 34 and their respective reservoirs is simultaneously cut out. The braking action then starts in the circuit connected with the compression chamber 34 and, subsequently, in the brake circuit connected with the chamber 18. Sealing rings 27 and 15 act as valves simultaneously to cut out the communication between their respective reservoirs and the adjacent compression chambers.