GB1470767A - Brakes - Google Patents

Abstract

1470767 Wedge actuator; internal shoe drum brakes CENTRAX Ltd and RHH BARR 10 April 1974 [10 April 1973] 17150/73 Heading F2E A break-operating mechanism intended for internal shoe drum brakes comprises a pair of aligned transmission elements 11, 12, having a wedge 22 between them, complementarily inclined surfaces 15, 16 on the elements and 19, 20 on the wedge respectively, a roller 17 or 18 between each element 11 or 12 and the wedge 22, and a roller cage 35 in which the rollers are rotatably mounted, each of the transmission elements 11, 12 having a guide surface 42 or 43, Fig. 5, which faces generally axially of the transmission element, and the cage 35 having guide surfaces 44, 45, which engage the guide surfaces on the transmission elements. As shown, each transmission element has two guide surfaces, and the cage has correspondingly two pairs of guide surfaces. Also as shown, each element has a pair of further surfaces, e.g. 46, 47, (afforded by the cheeks of a groove the bottom surface of which forms the inclined surface 15 or 16) which face each other and between which the cage is held. The inclined surfaces 15, 16 are contacted by the rollers; the two guide surfaces, e.g. 46, 47, of each element form a track having an inclination relative to the axis of the element only half that of the inclined surface 15 or 16. The elements 11, 12, are guided by bores in a housing (not shown) secured indirectly to a fixed axle of a motor vehicle, and the wedge 22 is acted upon by a fluid-pressure actuator (not shown).