Patent GB-1061601-A (GB)
Title: Improvements in or relating to vehicle brakes
IPC: F16D65/22
Filed: 1965-01-20
Abstract: 1,061,601. Hydraulic brakes. SOC. ANON. FRANCAISE DU FERODO. Jan. 20, 1965 [Jan. 23, 1964; June 22, 1964], No. 2527/65. Headings F2E and F2F.  In a braking device for at least two wheels (e.g. the front wheels 10, 11) of an automobile vehicle, each wheel brake has a primary chamber 33 (Fig. 2) defining the expansion chamber of the operating means of the brake and a secondary chamber 35 absorbing the drag forces of each brake, the device being actuated by means of a master cylinder 14 for supplying equal or proportional volumes of fluid to the two primary chambers, balancing means 44 being provided to act between the two secondary chambers, two modulating chambers 52, 54, which vary in volume at the same time as the reaction chambers and fluid pressure connection means is provided between each modulating chamber and each primary chamber whereby during braking, the drag forces on each wheel are modified with respect to the drag forces on the other wheel by a correcting factor depending upon the pressure in the primary chamber of the other wheel so as to obtain a balancer braking. As shown in Fig. 1, the secondary chambers of the front wheel brakes are connected by lines 37 and 38 to the rear wheel cylinders 65 and through lines 55 and 57 respectively with the reaction chambers 51, 53 of the balancing means 44. Fluid under pressure is supplied through lines 27 and 28 to the front wheel brake primary chambers 33 from the respective operating chambers 21 and 22 of the tandem master cylinder 14 and at the same time the pressures in the lines 27 and 28 are transmitted via lines 58 and 56 respectively to the modulation chambers 54, 52 respectively of the balancing means 44. In operation, when the brake pedal 20 is depressed the master cylinder piston 19 is displaced towards the left and the chambers 21 and 22 respectively deliver fluid under pressure through conduits 27 and 28 into the primary chambers 33 of the front brakes 10 and 11 to cause the brake shoes 31 and 32 to be applied against the brake drums of the front wheel brakes. The contact of the brake shoes against the brake drums tends to produce a self-energizing action which has the effect of putting the secondary chambers 35 under high pressures and through the conduits 37, 55 and 38, 57 these high pressures are transferred into the reaction chambers 51 and 53 separated by the double piston 48, 49 of the balancing means 44. At the same time these high pressures are also conveyed by means of conduits 59 and 60 into the chambers 65 of the rear wheel brakes 12 and 13. By the above means a balancing of the braking between the front wheels 10 and 11 is achieved irrespective of the operating conditions. In an alternative embodiment (Fig. 5, not shown) the balancing means 44 is dispensed with and the. secondary chambers 35 are connected directly together. In Fig. 7 (not shown) the balancing means 44a is mounted integrally with the tandem master cylinder arrangement 14. In Fig. 6 (not shown) the front wheels of the vehicle are provided with brakes of the disc type comprising a moving stirrup member having the primary chamber 33 and co-operating with a double cylinder having a secondary chamber 35 and a modulation chamber 72, the secondary chamber 35 of the two front wheels being connected together and connected via line 76 with the rear wheel brake actuators. A line 77 connects a chamber 78 behind the operating piston of the tandem master cylinder to introduce a slight servo assistance effect. In Fig. 9 (not shown) an alternative design of disc brake is applied to the front wheels of the vehicle and takes the form of a rotating disc 110 adapted to be gripped by a pair of brake pads 111 when the latter are energized by means of two braking cylinders 113 and 114 carried by a plate 112 rotatably mounted coaxially with the brake disc 110. A balancing device is interposed between the plate 112 and a fixed frame of the brake 115 and comprises a cylinder 116 and piston means 117 which define a chamber 118. In a further embodiment (Fig. 8, not shown) pressure limiting devices are arranged respectively in two supplied conduits provided for supplying pressure to the rear wheel brake unit.