Patent GB-722861-A (GB)
Title: Improvements in or relating to hydraulic braking systems
IPC: F16D57/06
Filed: 1952-10-16
Abstract: 722,861. Hydraulic brakes. HARVEY, J. F. W. Oct. 16, 1952. No. 25971/52. Addition to 716,799. Class 103 (1). A hydraulic brake comprises a rotatable member which contains a braking hub member which is adjustable from a concentric position to eccentric positions and vice versa, and a coupling between the braking hub and the rotatable member, including an outer floating hub rotatable on the inner hub and a plurality of angularly spaced hydraulic ram devices connecting the outer hub to the rotatable member and included in a hydraulic circuit having individual liquid flow channels from respective ram devices to a single control valve which operates to create a strangling effect in the circuit and means connecting the valve to the braking member so that when the valve is operated it causes the braking member to be adjusted to an eccentric position in which the hydraulic rams are displaced and thereby establish a hydraulic pressure through said circuit which progressively tightens the coupling and in the fully closed position of the valve locks the rotating member to the braking member. The brake assembly ABC rotates with control valve 38 open, the entire assembly rotating freely around the rotational axis of axle I. The plate C is adapted for mounting upon the wheel or member to be braked. When the brake lever 18 is moved, the inner braking hub 9 is then displaced off centre progressively as the lever is moved towards the maximum "on" position. As the braking hub 9 moves off-centre the outer floating hub 7 instead of rotating concentrically with axle 1, begins to oscillate eccentrically so that some of the rams 2 (A-D) of the hydraulic ram devices HR (1-4) are forced radially outwards while others expand. Hydraulic pressure is thus established which causes flow of fluid in ducts 13 (AD) and via the valve port 27 in the control valve 38, the respective rams reciprocating while the assembly rotates. This sets up a circulatory action of the fluid and a progressive action is applied to the assembly ABC due to the pressure needed to force the oil through the system. As the brake lever is moved towards the maximum brake "on" position the valve opening becomes progressively smaller due to the strangling effect of the control valve 38 and the effect is to make the circulation of the oil more difficult. When the maximum brake "on" position is reached (as illustrated in the Figs. 1 and 2; Fig. 2 being a section through II-II of Fig. 1), the valve 38 seals off all fluid ducts 13 (A-D), thus blocking the fluid flow from and to the hydraulic chambers of the hydraulic ram devices HR (1-4). As the rams are unable to reciprocate, the assembly becomes locked to the braking hub 9 and rotation ceases. On release of the brake, the control valve 38 is opened and the braking hub is moved back to its position concentric with the axis of axle I, thus allowing the assembly to rotate freely without any reciprocating motion of the rams and consequently no fluid flow. When the control valve 38 is fully open, the reserve fluid chamber spring loaded rams 34 (A-D), operating in chambers 14 (AD), are free to replenish the main circuit with fluid via the non-return valves (31 (A-D) and supply ducts 36 (A-D).