Patent GB-144316-A (GB)
Title: Improvements in or relating to brake operating devices for railway vehicles
IPC: B61H13/02
Filed: 1920-06-04
Abstract: 144,316. Boirault, L. June 4, 1919, [Convention date]. Actuated or applied by relaxation of pull; hand actuation; force-transmitting mechanism. - Relates to vehicle brakes of the type in which application is effected by the engagement of an eccentric mounted on an axle with a lever which is moved into the path of the eccentric by means of a cam. The invention consists in means for operating the cam either by hand, or automatically by relaxation of the pull on the coupling, and in means for regulating the brake pressure. The lever 19, which carries a shoe 23 adapted to engage with the eccentric 35 on the axle, is pivoted to an arm 24 loosely mounted on a shaft 5, and is connected by means of a link 20 to the arm 16 of a bell-crank lever, the other arm 15 of which is pivoted to the brake-rod 17. Bearing against the lower arm 15 and ' lever 19 respectively are two similar cams 9, 8 loosely mounted on a shaft 3 and carrying pairs of pawls 13, 14 which engage a fixed toothed ring 2, and on the shaft 3 between the cams 9, 8 is fixed a cam-like member 10 which is slotted at 11 to engage a pin 12 on the cam 8. The cam 9 is connected to the lug 26 on the end of the rod 17 by means of a chain 29 secured at 31 to the cam and connected to a spring-controlled rod 27 passing through the lug 26. The member 10, when the brakes are cut off, holds the pawls 13, 14 out of contact with the ring 2, but when the shaft 3 is rotated in a counter-clockwise direction, the first action of the member 10 is to release the pawls 13, 14. Continued rotation of the member 10 rotates the cam 8 by means of the pin 12, thereby turning the lever 19 so that the shoe 23 engages with the eccentric 35, the rotation of which causes the lever 19 to turn about the connexion 25 and to actuate the brake-rod 17 through the link 20 and lever 15, 16. The chain 29 causes the cam 9 to rotate in contact with the arm 15. To set the apparatus for application of the brakes, the shaft 3 is rotated by means of a pivoted toothed sector 38 which gears with a pinion 39 on the shaft 3. For hand control, the sector 38 is actuated by a weighted lever 40 which is released by means of hand-levers 37 on a transverse shaft 41 which carries arms 42 by a pin 44 on which the lever 40 rests. The shaft 3 may also be rotated by mechanism controlled from the brake-van. For automatic control from the coupling, a rod 50 pivoted to the sector 38 is notched to engage a pin 52 on the end of a lever 53, which is operated by the coupling-rod through a spring 54, the weighted arm being released by chains which connect the arms 42 to the safety coupling-chains. When the weighted lever is held in the raised position by the arms 42, the rod 50 is disengaged from the pin 52 by means of a lever 48, 49 connected by a link 47 to an arm 46 on the shaft 41. Rotation of the shaft 3 when the vehicle is stationary applies the brakes, the arm 19 being in this case turned about its pivot 32 by the cam 8. The brake-rod 17 carries a spring 33 which bears against the brake lever 34, and the sector 38 is connected by an adjustable link 57 to a lever 58 which is adapted to engage a pin 60<a> on the lever 34. The pressure applied to the brake-blocks is thus rendered independent of the wear of the blocks as the extent of movement permitted to the lever 58, and thus to the cam 8 after the lever 34 has ceased to move by reason of the blocks being in contact with the wheels, is substantially constant. Indicators, applications of.-According to the Specification as open to inspection under Sect. 91 (3) (a), to indicate when the brake shoes require renewal, a pivoted plate 61 is supported in the raised position by the engagement of a projection 66 with a lever 63, which carries a coverplate 60 and is provided with an adjustable eccentric member 70, that is engaged by a suitable part of the brake mechanism when the shoes become worn so that the lever 63 is moved away from the projection 66, thereby allowing the plate 61 to drop into the position shown in Fig. 7 (Cancelled). This subject-matter does not appear in the Specification as accepted.