Patent GB-493941-A (GB)
Title: Improvements connected with wear compensating mechanism for brakes
IPC: F16D65/52
Filed: 1937-03-16
Abstract: 493,941. Adjusting brake-shoes. JENKINS, A. H. S., REECE, W. C. J. D., and TUCK, A. W. March 16, 1937, Nos. 7621, 19885, and 33789. [Class 103 (i)) Wear compensating mechanism for brakes provided with a pair of pivoted shoes comprises slidable members carried by the shoes and adapted to contact the brake drum and which when depressed by wear of the shoe linings, permit rotation under spring action of members carried by the shoes whereby the normal position of the shoes is advanced. The arrangement may be such that the distance between the shoe pivots is extended. Tubular rods 13 slidable in tubular members 20 secured to brackets 4, 5 on the shoes 6, 7 carry plugs 14 which extend through the shoes and are flush with the surface of the shoe linings 15. The rods are held in position by springs 17 attached to pins 18 passing through slots 19 in the rods and engaging the brackets 4, 5 and to caps 16 abutting the ends of sleeves 22 screwed on the members 20. The sleeves 22 are slidable in sockets 8, 10 adapted to be adjusted by turning the head 12 to adjust the initial position of the shoes. Torsion springs 24 secured to the sleeves 22 and at 24<1> to the shoes tend to turn the sleeves but are normally prevented from doing so by the end pressure of the caps 16. The shoes pivot on rods 29, 30 screwed into a sleeve 26 capable of limited lateral movement against the action of a spring 28 engaging the part 27. A torsion spring 31 tends to turn the sleeve to move the rods outwardly, but is normally prevented by the end pressure on the rods by the brake release spring 34. When, with the shoes applied, wear of the linings 15 takes place, the rods 13 are pushed inwardly relatively to the shoes thus relieving the pressure of the caps 16 on the sleeves 22 which are then turned by the springs 24 and thus moved towards each other until the ends again abut on the caps. When the brake is released the shoes thus return only to the extent of the initial clearance. When the shoes return after wear they fulcrum in the sockets 8, 10 under the action of a release spring connected to the upper ends of the shoes relieving the pressure of the spring 34 on the rods 29, 30 which are thus moved outwardly by the torsion spring 31 to adjust the pivots to correspond with the wear. The shoes may instead pivot on the ends 40, 41, Fig. 2, of rods 38, 39 slidable in a bracket 36 fixed to the back plate and engaged by a cone 44 on a screwed rod 45 which is turned by a torsion spring 49 'to advance the cone and so adjust the pivots when relieved of the pressure of 'the spring 34. The member 13 instead of passing through the shoe may be disposed on the side thereof. According to the first Provisional Specification, the device comprises a pair of tubular members screwed at their inner ends into a collar white the outer ends carry slidable caps having a pin-and-slot connection with the shoes. A spring extending through the tubular members and attached to the caps normally prevents rotation of the collar under the action of a torsion spring. When wear of the shoe occurs, a plunger carried thereby is depressed and acts through a lever to displace one of the caps thus permitting rotation of the collar.