Patent GB-1008717-A (GB)
Title: Improvements in and relating to automatic adjusting devices for brake actuating mechanisms
Inventor: CHOUINGS LESLIE CYRIL
IPC: F16D65/18
Filed: 1961-12-28
Abstract: 1,008,717. Fluid pressure brakes. AUTOMOTIVE PRODUCTS CO. Ltd. Dec. 18, 1962 [Dec. 28, 1961], No. 46509/61. Headings F2E and F2F. An automatic adjusting device for the piston and cylinder of a fluid pressureoperated brake comprises a friction member for maintaining the piston and cylinder in relatively adjusted positions and which is arranged for axial movement in response to increase of fluid pressure to compress a resilient means, the arrangement being such that the friction member and piston (or cylinder) move together until the resilient means is fully compressed, after which relative movement between the friction member and the piston (or cylinder) takes place, this movement being reversed during the initial stages of release of the brake when the high pressure is distorting the calliper, the resilient means being permitted to expand when pressure falls below a predetermined value so that the relative movement then ceases and the parts retract to provide a clearance determined solely by the permitted expansion of the resilient means. In one embodiment, Fig. 1, the friction member is a ring 5 frictionally engaging piston 12 and which is arranged in an enlargement 3 of the cylinder 1, being initially held in position by a spring 6 fitted in an enlargement 4 in the cylinder communicating with the enlargement 3. A seal 9 prevents ingress of dirt. When fluid is supplied to the cylinder it acts on both the piston and the ring 5 so that they move together until spring 6 is fully compressed, the frictional grip of ring 5 on the piston slightly exceeding the maximum force of the spring. Further increase of pressure causes piston 2 to slide through ring 5. Upon release of the brake this sliding movement is reversed until pressure falls low enough to allow spring 6 to expand. In the modification of Fig. 3, a Belleville washer 13 replaces the spring 6, the enlargement 4 being open-ended but closed by a spring clip 11. In the modification of Fig. 5, a spiral spring 14 is compressed axially by movement of the sealing ring 5, a different type of seal 15 replacing the seal 9. Combinations of the above arrangements can also be used. In another embodiment. Fig. 6, piston 16 is arranged to provide a bore in which slides a friction member in the form of a disc 22 grooved at 21 to receive a friction ring 20. Disc 22 is secured to a shaft 23 on which is also secured a piston 24 operating in a chamber 25 connected by a passage 26 to the main chamber of the cylinder 17. Seals 18, 19 are also provided. The operation is analogous to that of the previous embodiment, the piston 16 sliding over the ring 20 only when spring 27 is fully compressed, while the area of piston 24 determines the point during release at which spring 27 is allowed to expand. Fig. 9 shows a different type of friction disc 31 not requiring a separate friction ring. In the modification of Fig. 10, a Belleville washer 47 replaces the spring 27 and a friction disc 38 which may take various forms (Figs. 11-13, not shown) is backed up by a piston 40.