Patent GB-190930088-A (GB)
Title: Improvements in Automatic Brakes for Railways.
Inventor: BOIRAULT LOUIS
IPC: B61H11/02
Filed: 1909-12-23
Granted: 1910-04-28
Abstract: 30,088. Boirault, L. Dec 24, 1908, [Convention date]. Actuated by relaxation of pull.- In railway-vehicle brakes of the type in which application is effected by the engagement of a cam on the running axle with a lever connected to the brakes, this lever is arranged to be automatically moved into engagement with the cam by a spring-actuated device, so as to apply the brakes, when the tension on the couplings is relaxed. The spring device is arranged to rotate a brake shaft 11, which is fitted with gear for moving the lever. The brake shaft 11 carries a loose clutch sleeve 30, Figs. 2 and 3, provided with a spring- pressed bolt 35 engaging a curved guide 36, which is fixed to the vehicle frame and formed with one or more recesses 38 serving to release the shaft 11 from the bolt 35 for hand-actuation. The sleeve 30 is connected at 39, 40 to rods 41,42 respectively. The rod 41 is connected to a lever 43 which is controlled by a projection 52 formed on a tail-piece 51 extending from a hook 50, which is arranged beside the main draw-hook 47 so as to slide longitudinally thereon, a slot 48 being provided in the hook 47 for this purpose. The rod 41 is further connected to a spring 45, which is compressed as shown in Fig. 2 when the coupling is subjected to tension, but rotates the shaft 11, as shown in Fig. 3, to apply the brake when the tension is relaxed. The rod 42 is connected to a lever similar to the lever 43 arranged in connexion with the draw-hook at the opposite end of the vehicle. Hand actuation.-In a brake of the type which is actuated by the engagement of a cam on the vehicle axle with a lever connected to the brake blocks, the lever is brought into the line of action of the axle cam by the rotation of other cams mounted on a transverse operating-shaft, fitted with counterweighted handles. The shaft may also be operated automatically by the vehicle drawgear by means of a clutch. which surrounds the shaft and under certain conditions, becomes released therefrom to allow of hand-actuation. A lever 2, Fig. 4, connected with the brake pull-rods by a rod 5, is brought against a cam 3 on the axle 4 by rotation of a shaft 11 having handles 12 moving between stops 13, 14, Figs. 4 and 6. The shaft 11 carries a fixed cam 15 fitted with a bent lever 18, which engages and rotates a loose cam 16, thereby moving a lever 9, connected to the lever 2 by a rod 8, into the position shown in Fig. 6. The shaft 11 may be operated by the draw-gear through a clutch comprising a loose sleeve 30, Figs. 2 and 3, having a spring-pressed bolt 35 engaging a groove 32 in the shaft 11 and a curved guide 36 fixed to the vehicle frame. The guide 36 is formed with a recess 38 situated so that the bolt 35 becomes released from the shaft 11 when the clutch is moved to the position shown in Fig. 3 to apply the brakes, by the relaxation of the pull on the drawgear, thus allowing the shaft 11 to be actuated by hand to release the brakes. Another recess, similar to the recess 38, may be formed in the guide 36 so that the shaft 11 is released when the clutch is in the position shown in Fig. 2 ; or the guide 36, instead of being fixed to the vehicle frame, may be mounted on the shaft 11 so that it may be rotated at will to bring the recess 38 opposite the bolt 35. The shaft 11 may be rotated from the brake van by chain or other transmission. Actuated by running axle; force-transmitting mechanism.-Brakes are applied by the engagement of a cam upon the vehicle axle with a lever which is brought into the line of action of the axle cam by rotation of a transverse brake shaft effected either by hand, by fluid pressure, or automatically by the vehicle draw-gear, means being provided for locking the parts when the brakes are applied. An axle cam 3, Fig. 4, engages a lever 2 which is connected to rods 5, 8, the former of which is pivoted to a transverse lever connected to the brake pull-rods, while the rod 8 is connected to a lever 9 adapted to be displaced by the rotation of a shaft 11. This shaft carries a fixed cam 15 fitted with a bent lever 18, one end of which is pressed by a spring 20 into engagement with another cam 16 loose on the shaft 11, so that rotation of the shaft brings the parts into the position shown in Fig. 6. The cam 3 then engages the lever 2 and effects a pull upon the rod 5 to apply the brakes. The rod 5 also pulls back a pawl 22 pivoted thereto, whereupon the pawl is moved downwards by the engagement of a pin 28 thereon with the curved face of a fixed bracket 25. In the downward movement of the pawl, its face 29 bears against the pivot 10 of the lever 9, and a projection 23 on the pawl engages with the end 24 of the lever 18, as shown in Fig. 7, thereby locking the brakes in the applied position. As the projection 23 of the pawl slips over the end 24 of the lever 18, the other end 19 of this lever is moved out of engagement with the cam 16, so that when the cam 3 has rotated sufficiently to release the lever 2, the cam 16 and the levers 9, 2 fall to their original position, thus preventing the lever 2 from being worn by the cam 3. When the shaft 11 is turned back to release the brakes, the cam 15 releases the pawl 22 and moves it and the lever 18 back to the position shown in Fig. 4.