GB593595A - Improvements in the slack adjusting mechanism of brake gear - Google Patents

Abstract

593,595. Compensating for wear in brakes. GRESHAM & CRAVEN, Ltd., and GRESHAM, J. N. June 7, 1945, No. 14410. [Class 103 (i)] Relates to slack-adjusters for brake mechanism, in which a housing carrying a pawl is turned by engagement of an arm in a slot in a projection on the housing so that the pawl slips a ratchet tooth during the application stroke if this is excessive and during the return stroke turns the ratchet wheel and thus one part of a screw- and-nut member to take up the slack. In order that the adjustment may not be excessive, the slot is so formed that the arm is only effectively coupled to the housing during a predetermined part of the stroke of the arm. As shown, a pull-rod of a brake-operating mechanism comprises a screw-threaded rod a, a tubular part b and a rotatable sleeve c to which is secured a nut d engaging the rod a. A ratchet wheel i secured to the sleeve c is engaged by a pawl carried by a housing g rotatable on the sleeve. One arm m of a lever pivoted at p on the member b is connected by a link to a fixed point o and the other arm l of the lever extends through a slot k in an arm j carried by the housing g. The slot is of approximately T-form. During movement of the pull-rod to the right hand to apply the brake, the lever 1, m has an initial idle movement about its pivot p in which the arm l moves across the top of the slot. As the brake blocks wear, the arm l engages the other side of the slot and so turns the arm j to the position j<1> and then to position j<11>, causing the pawl to slip over the ratchet teeth, and further movement of the lever if it takes place does not affect the position of the arm j since the arm l then moves along the stem of the T. During the return movement of the pull-rod and the lever, the arm is returned from position j" to the original position shown during which the ratchet i is turned to shorten the rod.