GB472273A - Improvements in or connected with internal-expanding brakes for motor and other road vehicles - Google Patents

Abstract

472,273. Compensating for wear in brakes. PAGE, A. (Page, W.) March 20, 1936, Nos. 8322/36 and 8071/37. [Class 103 (i)] An adjusting device for a shoe 4 of an internalexpanding brake comprises a spring-pulled ratchet bar 11 or the like loosely pivoted to the shoe and cooperating with the toothed lower edge of a slot 16 in an angle - bracket 14 or other member fixed to the back-plate so that during application of the brake, should the wear of the shoe-lining 7 be sufficiently great, the bar 11 slips over the tooth 17 and on release of the brake the shoe is retained in a position nearer the drum 3. To provide for retraction of the shoe from an over-adjusted position into which it is moved when the drum is heated and which may cause, in the case of a vehicle brake, locking &c. of the road wheel on cooling of the drum, means are provided for automatically moving back the bar 11 to the necessary extent over the tooth 17. For this purpose, the friction head 21 of a plunger having a shank 22 occupies a recess 23 on the periphery of the shoe and projects slightly beyond the outer surface of the shoe lining, the shank extending through the shoe and having its bifurcated end passing over a projection 20 on the bar 11. Should the bar be over-adjusted to the extent of one tooth by the adjusting device when the drum is heated, it is retracted by the same amount when the drum cools by the shank 22 engaging the projection 20, the bar 11 being tipped about its pivot 13 and raised from the tooth 17, and the shoe thus pulled into correct position by the return spring. In modifications (a) the plunger is movable laterally and has a side projection normally spaced from the bar 11, and (b) a pin on the shank engages an elongated hole in a depending extension of the bar. As shown, the brake is operated by a fluid-pressure device but any other actuating means may be employed.