Patent GB-190928373-A (GB)
Title: Improvements in Apparatus for Braking Vehicles.
Inventor: RAULT LOUIS BO
IPC: B60T1/04
Filed: 1909-07-16
Granted: 1910-02-10
Abstract: 28,373. Boirault, L. July 16. Actuated by running axle; force-transmitting mechanism.-In vehicle brakes of the type applied by the engagement of a cam on the axle with a lever or other operating-member which is moved into action by hand or automatically under the influence of a release of the vehicle-couplings, means are provided (1) for locking the apparatus in the brakes-applied position comprising a cam-shaped pawl which is itself locked by another cam, and (2) for automatically regulating the degree of braking in accordance with the load on the vehicle. (1) The operating- member comprises a shoe 2<a> adapted to engage with a cam 3 on the axle, and formed on a rod 8<a>, which is supported by a link 8<b> pivoted to the vehicle frame, and by a lever 9<a> suspended from an horizontal lever 6<a>, which is pivoted at 6<b> and connected to the brake rod 1. The shoe 2<a> is moved into the path of the cam 3 by the engagement of a cam 16<a>, Fig. 4, on an operating-shaft 11<a> with a block 9b pivoted to the lever 9<a> The face 16<e> of the cam 16<a> then abuts against the face of the block 9<b>, as shown in Fig. 5, so that the rotation of the cam 3 causes the lever 9<a> to rock about the pivot 9<d>, thus oscillating the lever 6<a> and applying the brakes. The parts are locked in this position by a pawl 22<a>, Fig. 4, the cam-face 29<a> of which falls behind and engages the lever 6<a>, the face 29<a> being shaped so as to present, relatively to the radii of the pawl, an inclination which is preferably equal to or slightly greater than the angle of friction. To prevent the pawl from being lifted under the reaction of the lever 6<a>, a locking-cam 86, Fig. 4, is provided, being loosely mounted on the shaft 11<a> and formed with a heavy extension 86<a>, which rests upon a stud 16<f> on the cam 16<a>. When the cam 16<a> is moved for application of the brakes, the cam 86 turns to the position shown in Fig. 5, and locks a projection 22<c>, Fig. 4, on the pawl 22<a> by a wedging action. The cam 16<a> is further prevented from turning back from the position shown in Fig. 5 by the engagement of a spring pawl 87, pivoted at 22<b>, with notches 16<g> formed on the cam 16<a>. When the shaft 11<a> is moved to release the brakes, this pawl 87 is moved out of engagement with the notches by means of inclined planes 88<a>, Fig. 4, formed on a toothed sector 88 fixed to the shaft 11<a> ; the inclines 88<a> are arranged so as to cover up the notches 16<g> when the parts are in the released position, Fig. 1, while leaving them uncovered when in the position shown in Fig. 5. For further safety, the notches 16<g>, Fig. 4, are arranged in steps, so that if the pawl 87 is jerked out of one of the notches, it is retained by the next one. (2) In order to regulate the degree of braking automatically in accordance with the load, the shoe 2<a> is formed with its operating- surface inclined to the vertical, so that the braking effect is increased as the frame of the vehicle, and consequently the shoe 2<a> becomes lowered under the increased load. Specifications 28,620/07 and 1174/09 are referred to. Hand actuation.-The shaft 11<a> which controls the cam 16<a> for bringing the shoe 2<a> into contact with the axle cam 3, may be operated by handles 12 fixed at its ends, or by a lever 89, Fig. 6, arranged in the cab and connected with the shaft 11<a> by transmission members, such as an arm 89<a> rigid with the lever 89, a connecting-rod 90, bent lever 91, Fig. 1, rod 92, and arm 93 fixed on the shaft 11<a>. Compensating for wear is effected by means of an arm 94, Fig. 1, which is rigid with the lever 91 and is arranged to strike against a stop 95 adjustably secured to the brake rod 1. When the cam 16<a> is moved to the applied position, Fig. 5. it tends to rotate farther under the influence of a counterweight 12<a> so long as the axle cam 3 does not press the lever 9<a> against the cam 16<a>, such farther rotation being limited by engagement of the arm 94 and stop 95. As the brake shoes wear, the rod 1 advances further, thus allowing the arm 94 and cam 16<a> to turn to a further extent in accordance with the amount of wear. Indicators, applications of.-The operating handlever 89, Fig. 6, moves over a sector 96 which is graduated to show the degree of application of the brakes, and is moved automatically on the pivot 97 in accordance with the amount of wear occurring in the brake gear, so that the indications given are always correct. The sector 96 is held in position by the engagement of a spring bolt 98<a> with a fixed toothed sector 99. When sufficient wear occurs in the brake gear, an incline 87<d> on the lever 89 lifts the bolt 98<a> at the end of the movement, and advances the sector 96 through one tooth along the fixed sector 99.