GB728864A - Improvements in or relating to internal shoe-drum brakes - Google Patents

Abstract

728,864. Internal shoe-drum brakes. BRISSON, L. C. March 12, 1953 [March 19, 1952], No. 6859/53. Class 103 (1). In a braking device comprising two assemblies of shoes capable of co-operating with the brake drum, the first one being constituted by at least one starting shoe and the second by one or several braking shoes, the starting or driving shoes being acted upon by a controlling device and being connected to the device for the application of the braking shoes by means of a geared-down transmission mechanism which comprises a floating member 9 provided with shoulders against which bear pins 7, 8 carried along by the starting shoes 5, 6 and also provided with shoulders against which bear the ends of reducing levers 10, 11, the other ends 14, 15 of which bear against the braking shoes 16, 17, this transmission mechanism coming into action in one direction of running. In operation, in the forward direction indicated, the controlling device, constituted by a hydraulic cylinder 3 secured to a floating frame 2, operates to apply the starting shoe 6 against the rotating drum 20 and owing to the force exerted between the frame 2 and the shoe 6, the shoe 5, which is directly solid with the frame 2, is applied by the reaction against the drum 20 with equal pressure, thus both shoes 5 and 6 and consequently the frame 2 rotate with the drum. Through the intermediary of pins 7 and 8, solid with frame 2, the intermediate floating member 9 is carried in the same direction, the shoulders of which exert a thrust on the ends 23 and 24 of reducing levers 10 and 11, which are pivoted at 12 and 13 respectively to the stationary back plate 1 causing their ends 14 and 15 to press against one end of the braking shoes 16 and 17, resulting in their application against the brake drum. Eccentrically mounted stops 18 and 19 are provided for adjustment of the braking shoes 16 and 17 respectively. Centring of the frame and adjustment of the starting shoes 5 and 6 is achieved by an eccentric 21 together with a cam 31. The device may also be hand-controlled by means of the members 30, 29, 33, 35 disposed externally of the brake drum to operate the cam 31. In the reverse direction, the starting shoes 5 and 6 are applied, as before, against the brake drum but, as the rotation of the drum is in the reverse direction, the frame 2 tends to turn in the reverse direction to the preceding case and the two stops 4 and 4<SP>1</SP> secured to the floating frame 2, press directly on portions 27, 28 of the levers 10, 11 which turn about their pivots to apply the braking shoes 16 and 17 respectively.