GB243053A - Improvements in and relating to brakes - Google Patents

Abstract

243,053. Rubury, J. M. Aug. 18, 1924. Blocks and shoes acting on drums; actuated or applied by running axle or wheel.-Brakes of the kind in which shoes are pivotally connected together and are capable of limited movement about the axis of the drum with which they engage comprise a leading shoe adapted to be operated at one end by a cam and pivotally connected at or near the other end to a fixed support and a following shoe pivotally connected at one end to the leading shoe at a point other than the fixed pivot and adapted to coact at the other end with an abutment whereby the leading shoe, when applied to the drum, transmits force to the following shoe. The abutment may be fixed or may form part of a double cam which actuates both shoes, or it may be so arranged that the reaction of the following shoe thereon tends to turn the cam in such a manner as to increase the pressure on the leading shoe. Fig. 1 shows a leading shoe b mounted on a fixed pivot e and a following shoe c pivoted to the shoe b at h and adapted to engage a fixed abutment z. When the cam i is operated both shoes are applied and the pressure on the shoe c is augmented by the frictional force acting on the shoe b. Fig. 8 shows a form in which the shoes b, c are both connected to fixed pivots e by links e<1>, e<2> and are connected together by a link h<3> which is adjustable in length to compensats for wear. The cam i acts upon both sides and serves as an abutment for one or the other according to the direction of rotation of the drum. The links e<2>, h<3> may be dispensed with, the shoe c being in this case directly pivoted to the shoe b. The face i<1> of the cam which engages the shoe c is disposed further from the axis of the cam than is the other face, so as to compensate for the extra movement imparted to the shoe c by the shoe b. Fig. 6 shows another modification in which the cam i is in the form of an eccentric having a flat surface i<2> for engagement with the shoe b, the cylindrical surface of the cam being embraced by a jaw c<2> on the end of the shoe c. The centre of the eccentric may be shown as arranged to fall below the centre of the shaft d, whereby the frictional force on the shoe c tends to increase the turning movement given to the cam by the lever f in applying the brakes. A similar effect may be produced by connecting the end of the shoe c to an arm on the spindle of the cam. One or more intermediate shoes may be introduced between the two end shoes. Fig. 10 shows one such arrangement in which the shoes b, k are mounted on fixed pivots e and are connected to each other and the shoe c by links h', h<5>. The cam i has a flat surface i<2> for engaging the shoe b and the cylindrical surface i coaxial with the cam spindle engaged by a jaw part c' on the end of the shoe c.