Leakproof Hydraulic Disc Brakes
Page 64

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PATENT No. 885,973 shows a disci brake assembly in which the friction pads are hydraulically pressed on to the disc. The chief point of the scheme is the means used to eliminate any possibility of leakage of fluid. (Dunlop Rubber ' Co., Ltd., 1 Albany Street, London, N.W.1.)
Several schemes are shown in which the hydraulic pressure is applied to a flexible diaphragm. A simple flat diaphragm will suffice for short-stroke applications, or a "rolling stocking" type may be used for a somewhat longer stroke.
For circumstances in which considerable heat may be generated, it may be preferable to use the all-metal construction shown in the drawing.
The view shown is one half of the mechanism, the cylinder being duplicated on the other side of the disc. The sliding plunger (1) that compresses the friction pads is moved into action by a group of metal bellows (2) when hydraulic pressure is applied to their interior. Though three bellows are shown, two only or even one may be used if the magnitude of the load permits.