Patent GB-1310972-A (GB)
Title: Disc-brakes
IPC: F16D65/097
Filed: 1970-07-10
Abstract: 1310972 Hydraulic spot-type disc brakes; dismantling FRANCAISE DU FERODO SA 10 July 1970 [11 July 1969 7 Aug 1969 27 March 1970] 33683/70 Heading F2E A spot-type disc brake comprises an operating unit, including a cylinder and one piston acting on one brake shoe at one side of the disc and a second oppositely-moving piston acting through a ring-like transfer member on the other brake shoe at the other side of the disc, and a generally-bracket-shaped fixed support comprising a plate member 20 parallel to the disc 12 and a positioning member 21 perpendicular thereto and facing the edge of the disc, the plate member 20 facing the operating unit 13 and including a frame portion (around a window 23) for limiting movement of the first brake shoe 11 in both circumferential directions and at least one radial direction, and the positioning member 21 including at least one longitudinal support abutment 37A or 37B for radially retaining the second brake shoe 11<SP>1</SP> and at least two transverse support abutments 36A, 36B, for limiting movement of the second brake shoe 11<SP>1</SP> in both circumferential directions, the transverse supporting abutments being formed at two of the transverse extremities of the positioning member, and there being two lateral extensions 42A, 42B, provided on the second brake shoe 11<SP>1</SP> for co-operation with the transverse support abutments. First embodiment, Figs. 1 to 4, construction.- A fixed support 10 in the form of a bracket consists of a plate member 20 with fixing lugs 22A, 22B, parallel to the disc 12, and a positioning member 21 extending over the top of the disc. Plate 20 has a window 23 with bearing surfaces 25 in which a first brake shoe 11 is retained by a spring blade 28 engaged under a pin 27. An operating unit 13 consisting of a cylinder containing two pistons 15, 16, has lugs 14A, 14B, by which it is secured (by screws 65A, 65B) to the plate member 20. The lugs are recessed for hanging on centring sleeves to assist screw location. The operating unit has two longitudinal beads 68A, 68B, beneath which is located, for guiding, a transfer ring 17. The transfer ring is pressed against the beads 68A, 68B, by spring blades 34A, 34B, screwed to the plate member 20 at 33A, 33B, and is moved perpendicularly to the disc 12 by piston 16. At the other side of the disc 12 the second brake shoe 11<SP>1</SP> includes a metal plate 40<SP>1</SP> which at its radially outer region engages, for sliding, transverse supporting abutments 36A, 36B, and longitudinal supporting abutments 37A, 37B, of the narrower end portion of the positioning member 21. Midway of the plate 40<SP>1</SP> a tongue 52 is cut and bent out so that its free edge 53 bears against the radially outer surface of the transfer ring 17. The friction lining of the second shoe 11<SP>1</SP> is divided into two parts 41A, 41B, leaving a ventilation space 51. In operation, hydraulic fluid is applied to the region between pistons 15, 16, whereupon piston 15 applies shoe 11 directly, while piston 16 moves shoe 11<SP>1</SP> via transfer ring 17, which is guided under beads 68A, 68B, and by the operating unit bearing-surfaces 67A, 67B, Fig. 3, adjacent to the beads. For dismantling, screws 65A, 65B are firs t removed, after which the operating unit 13 may be withdrawn radially without disconnecting its hydraulic circuit. Next, the first brake shoe 11 may be removed axially from its window 23. Thirdly, transfer ring 17 may be moved axially to free it from shoe 11<SP>1</SP>, which may then be withdrawn from the positioning member 21. Optionally, a further tongue 72, Fig. 4, may be provided in plate 40<SP>1</SP> for locating purposes. Second embodiment, Figs. 7 to 9 (not shown), construction.-This is basically the same as the first embodiment with a number of detail modifications. Thus, the lugs and beads are omitted from the operating unit 13. Instead, the unit is formed as a simple section of tube (but having internal seal-holding grooves as before), and around its end adjacent plate 20 is welded a semi-circular fixing flange (82). The inner end of the transfer ring is located by an overhanging projection (91) at the outer end of piston 16, this serving also as a radially outer supporting surface for ring 17. Radially-outward pressure on ring 17 is now provided by torsion springs (95A, 95B) instead of spring blades 34A, 34B. Each such torsion spring has a helical portion secured by a screw to plate member 20 and an elongated end which underlies ring 17. Axial guiding of ring 17 is provided by generator lines of operating unit 13, and by the extreme circumferential edges of a positioning member 21. Instead of one tongue 52 bent out from plate 40<SP>1</SP>, two spaced tongues (90A, 90B), are provided. Operation and dismantling are as before. Third embodiment, Figs. 11, 12, 14, construction.-The fixed support 110 consists of a plate member 120 and a positioning member 121 together made from a single piece of sheet metal, Fig. 14, and two reinforcing plates 110A, 110B, located by punched portions 119A, 119B, 217A, 217B, and welded at 111 to plate member 120. The positioning member 121 is partially arcuate, but is provided with flat supporting abutments-longitudinal, 137A, 137B, and transverse, 136A, 136B,-for guiding the second shoe 11<SP>1</SP>, Fig. 11. A window 123 for accommodating the first shoe 11 is provided. Springs 140A, 140B, Fig. 12, are located around supporting studs 112A, 112B, respectively, and serve to hold the first shoe 11 against the radially outer boundary of window 123 besides pressing transfer ring 117 against longitudinal beads 68A, 68B, provided on the operating unit 13. Plate 40<SP>1</SP> of the second shoe 11 is provided with a tongue 52, as before, Fig. 11, and is engaged by two supporting zones 150A, 150B, provided on transfer ring 117. The friction lining is again in two parts 41A, 41B. Operation and dismantling are substantially as previously described. In all embodiments, the springs which load the transfer ring radially outwards serve also to retain the second shoe 11<SP>1</SP> against the inside of the positioning member of the fixed support. In all embodiments, the springs associated with the first brake shoe serve also to absorb vibrations.