GB1260421A - Improvements in or relating to hydraulic dual brake systems - Google Patents

Abstract

1,260,421. Dual master cylinders; drivers' brake valves. STROMBERG HYDRAULIC BRAKE & COUPLING CO. 16 Jan., 1969, No. 2716/69. Heading F2F. An hydraulic dual brake system intended especially for road vehicles comprises at least one master cylinder and two separate ducts leading from that cylinder or cylinders to an auxiliary fluid control device having the spaced-apart outlets for connection to separate braking means. The auxiliary fluid control device is described below. One result of its use is that the start of pressure application to one of the brake circuits occurs before the start of pressure application to the other brake circuit, so that the pressure in the latter circuit during build-up is lower than that in the former. Furthermore, during its use, communication between the master cylinder and the brakes is interrupted. The road vehicle hydraulic dual brake system partly shown in Fig. 1 comprises tandem master cylinders 1, 2, and ducts 4, 5, leading to inlets 6, 7, respectively of the fluid control device 8 (see also Fig. 3). When the control device 8 is idle and the master cylinders 1, 2 are operated, hydraulic fluid supplied to inlet 6 flows past an open valve 25, 27, Fig. 4, through the open end of a power piston 13, and through an outlet 11 to the front wheel brakes. Similarly, hydraulic fluid supplied to inlet 7 flows past a similar open valve 26, 28, through the open end of a floating piston 15, and through an outlet 12 to the rear wheel brakes. When the control device is operated by its pedal 19, push-rod 18 forces piston 13 to the right and with it the floating spring 14 and floating piston 15, a return spring 16 being. compressed thereby. The first result of this movement is that balls 27 and 28 lose contact with stop-pins 31, 32, Fig. 4, and move on to their respective seats 25, 26; communication between inlet 6 and outlet 11, and between inlet 7 and outlet 12, is thereby interrupted. The movement of the floating piston 15 forces hydraulic fluid out of the device 8 through outlet 12 to the rear wheel brakes. As soon as the pressure applied by the power piston 13 exceeds the resistance of the return spring 16 and the pressure generated by piston 15, floating spring 14 yields, permitting piston 13 to approach piston 15 and force hydraulic fluid out of outlet 11 to the front wheel brakes. Failure in either of the brake systems may be compensated for by excessive travel of piston 13; the necessarily-longer slot 23 in piston 13 allows for this. Floating spring 14 may be adjustably preloaded by abutting its left-hand end against the flange of a stove-pipe-shaped sleeve fitted over the adjacent end of piston 13; the sleeve is keyed to a bolt threaded into the adjacent end of piston 15, the bolt being rotatable by the sleeve to vary the pre-loading. When piston 13 approaches piston 15, the sleeve slides along the bolt (Fig. 5, not shown).