Patent GB-190728620-A (GB)
Title: Improvements in Railway Car Brakes.
Inventor: BOIRAULT LOUIS
Filed: 1907-12-30
Granted: 1908-12-30
Abstract: 28,620. Boirault, L. Dec. 30. Brakes.-In a brake which is operated by a cam on the axle of the vehicle, a lever connected with the brake shaft is adapted to be brought into engagement with the cam by a second cam, the further rotation of which, after the brake has become automatically locked on, removes the lever from the path of the axle cam. In the form shown in Fig. 1, the brake shaft 1, which operates the suspended block 9 by means of an arm 2, rod 3, and spring 6, is connected also by a link 12, with a lever 13. This lever is pivoted to a link 17, a pin 29 on which engages a fixed vertical slot 19, while a link 21 pivoted to the link 17, is also provided with a pin 22 engaging the slot 19. The pins 29, 22 also engage the slots 26, 30 of a cam 25, mounted on a shaft 23 adapted to be rotated by a hand-lever 31 or a pneumatic cylinder. Normally the pins 29, 22 are situated at the ends 26 of the slots, and the lever 13 is retracted from the axle cam 14 ; but on rotating the cam 25, the pins are brought together until the position shown in Fig. 1 is reached, when the lever 13 is brought into the path of the axle cam 14, and farther rotation of the cam 25 is prevented by a snug 36 on the shaft 23, which engages a tappet 37 on a slide 33 resting on the end of an arm 11 on the shaft 1. The cam 14 then acts on the lever 13 and applies the brakes, and the consequent rotation of the arm 11 allows the slide 33 to drop and lock the brakes on. The fall of the slide permits the farther rotation of the cam 25, so that the pins 29, 22 come to the ends 30 of the slots and the lever 13 is moved out of the path of the axle cam. The shaft 23 may be operated from the brake van by means of a lever 38, Fig. 6, toothed wheels 39, 40, 41, 42, and transmission members comprising chains 43 and belts or cables 44. The hand-lever 31 may be mounted on the shaft of the intermediate wheels. In the modification shown in Figs. 8 and 9, the pin 18<a> on the link 17<a> slides in slotted brackets 19<a> under the influence of the cam 25<a>, mounted freely on the shaft 23<a> but adapted to be rotated by a projection 25b on the hub of the cam, which engages with a small amount of play in a recess in a second cam 22<a> fixed on the shaft 23<a>. When the cam 25<a> has been rotated sufficiently to bring the lever 13<a> into engagement with the axle cam 14<a>, its farther rotation is prevented by the engagement of the cam 22<a> with a stop 37<a> on the slide 33<a> until the brakes have been applied, whereupon the consequent movement of the arm 11<a> on the brake shaft 1<a> moves the rod 11<b> and enables the projection 33b on the slide 33<a> to descend behind the projections 11<c> of the rod 11<b> so as to lock the brakes on. The farther rotation of the cam 25<a> then slightly retracts the lever 13<a>, which in this case is provided with rollers 13<b>. In a further modification, the cam 25<a>, instead of being mounted directly upon the shaft 23<a>, is mounted upon an eccentric on the shaft, the eccentric having a stud engaging with a certain amount of play in a recess in the cam, so that, should it be required to take the brakes off with the vehicle at rest and with the axle cam turned towards the lever 13<a>, the displacement of the cam 25<a> without rotation, which first takes place owing to the rotation of the eccentric within the cam, prevents the necessity of forcing the lever 13<a> through the position of maximum braking.