GB576503A - Improvement in brake mechanism - Google Patents

Abstract

576,503. Brakes. TIMKEN-DETROIT AXLE CO. Oct. 27, 1943, No. 17743. Convention date, Nov. 13, 1942. [Class 103 (i)] In an internal-expanding brake in which an actuating-lever is pivoted adjacent one end of a shoe and a fulcrum member transmits motion from the lever to the shoe, resilient means are provided between, and acting directly upon, the shoe and lever for constantly maintaining contact of the shoe and lever with the fulcrum member. As shown two such brake shoes A are positioned between abutments 41, 42 which engage faces 38, 39 on the webs 37 of the shoes. The abutment 41 of each shoe is pivoted on an eccentric portion 19 of an anchor pin 15 revoluble by a squared end for adjustment of the abutment 41 to take up wear of the lining and lockable by a nut 21. Serrations may be provided on collar 20 to engage serrations on the opposed face of the backing-plate 10, to give a positive lock. The flange 18 acts as a journal for one side member 52 of a pressure-lever, the other side member 51 of which is journalled on a smaller concentric part 17 of the pin 15. The lever 51, 52 is actuated by a cylinder D and the side members 51, 52 are slotted to clear the pin 16 carrying the abutment 42, and the two levers are connected by a retracting-spring 72. The members 51, 52 are spaced by a welded strip 54 on which bears slidably, the flat face of a presser block 74 having a curved face engaging a similarly curved recess in the web of the brake shoe which is positioned between the members 51, 52. The shoe and the presser 74 are kept in mutual contact by a compression spring 76 housed in openings in the members 51, 52 and in the shoe web. One end of the spring bears on a shallow boss 79 on the wall of the opening in the shoe web, and is thereby centred, whilst the other end of the spring bears on a plate 83 having positioning-tongues engaging in the spring and the openings in the members 51, 52, the arrangement being such that movement of the shoe circumferentially of the drum is accommodated by sliding of the plate 83. In a modification, the portions 17, 18 of the pin 15 are formed as cams so that revoluble adjustment of the pin 15 effects compensating adjustment of the lever at the same time as the abutment is adjusted. This modification is particularly advantageous when it is desired to use thick brake linings. In a further modification, the back plate is formed to ensure a free circulation of air to cool the brake cylinder.