GB325059A - Servo shoe brakes - Google Patents

Abstract

325,059. Riley (Coventry), Ltd., and Riley, S. Dec. 24, 1928. Blocks and shoes acting on drums.- In a servo-brake, two actuating cams 10, 11 rotatable about fixed axes engage the opposite ends of brake shoes 2, 3 and are interconnected by loadbalancing mechanism 17 such that servoaction can be obtained in either direction of rotation. The cams 10, 11 are connected by their arms 13, 14 and links 16 with the ends of a balance beam 17 connected with the brake rigging 18. The opposite ends of the shoes 2, 3 may be connected by links 19 with a floating radius arm 7 so that as the shoes are applied there is an outward thrust on their ends 4, 5. On application of the brakes, with the drum 9 rotating in the direction of the arrow, the cams 10, 11 turn and force the shoes into contact with the drum, and the shoe 2 leaves the cam 10 when a rotational effect is imparted to it by the drum. The frictional drag on the shoe 2 is imparted through the links 19 to the shoe 3 which abuts the cam 11 and turns this cam back into its original position. Further movement of the brake rigging turns the cam 10 to follow up the movement of the end of the shoe 2 and applies additional brake pressure. The abutting faces of the cams 10, 11 with the ends of their respective shoes may be parallel so that there would be an outward component of pressure from the cams against the adjacent ends of the shoes. The Provisional Specification states that the ends 4, 5 may engage guides so that as they move from their " off " position they move outwards slightly.