Patent GB-205621-A (GB)
Title: Improvements relating to fluid pressure braking apparatus
IPC: B61H13/32
Filed: 1922-08-18
Abstract: 205,621. Cloud, J. W. Aug. 18. 1922. Force-transmitting mechanism. - Relates to means for varying in accordance with the load on the vehicle the leverage through which the pull or thrust exerted by the brake cylinder is transmitted to the brake rigging. Automatic devices for taking up slack therein are described. In brake rigging of the type comprising a pair of brake levers connected respectively to the brake cylinder piston and a fixed point, an additional lever is interrosed between the brake cylinder piston and one of the levers, the fulcrum of this additional lever being variable in position. In the arrangement shown in Fig. 1 the brake piston rod 11 is connected to the brake rods 5, 6 by a lever 9, rod 8, levers 2, 3, and adjustable rod 4. The pivot pin 15 for the lever 9 engages a slot 14 therein, and is mounted on a lever 16 pivoted at 17. This lever is rocked to shift the pin 15 and thus to alter the leverage of the primary lever 9, when air under pressure is admitted by pipe 21 to cylinder 20 containing an opposing spring. The pin 15 is guided during this movement by the part 22 of the fixed abutment 13. The pipe 21 may be supplied from the brake pipe or auxiliary reservoir, or other part of the braking system, and may be connected to an endcock of the type described in Specification 202,735. It may be connected to apparatus adapted to set the device 20 in accordance with the load on the vehicle. When the pipe 21 is connected to the brake pipe, the passage in the interior of the device 20 may be restricted so that in the event of the brake pipe parting, the release of fluid under pressure from the cylinder 20 will be delayed until the automatic brake application is effected. The pressure exerted by the brake cylinder piston will then prevent the device 20 from moving the fulcrum pin 15 to light-load position. The pipe 21 may be controlled by a plug cock actuated by handles on either side of the vehicle. The lower end of the lever 9 is supported by a pin 23 which is guided in a slot 24. The slot 14 in the lever 9 may be straight or curved, and may be so formed that a portion of the slack in the brake rigging is taken up when the device 20 is actuated. Fig. 3 shows a modification in which the lever 9 passes through an aperture in a slide 34 connected to the brake cylinder piston rod 11 and at the other end through an aperture in a slide 32 connected by a rod 31 to the brake lever system 2, 3. The lever 9 is pivoted at 36 upon one end of a lever 16 which is pivoted upon a bracket 37 and is adapted to be actuated by the setting device 20. Fig. 9 shows a further modification in which the lever 16 carrying the fulcrum pin for the lever 9 is shifted mechanically instead of by the fluid-pressure device 20 The lever 16 has a tcothed segment 62 engaging a worm 63 on a shaft which may be rotated from either side of the vehicle bv hand wheels 66. The adjustment of the lever 16 by the worm 63 may be effected automatically in accordance with the load on the vehicle. Compensating for wear.-In the arrangement shown in Fig. 1 automatic slack adjustment is provided by a nut 25 having the usual right and left handed screw threads, the nut being arranged to be rotated by a pawl and ratchet 26 operated by a bell crank lever 27. A rod 30 connected to the brake cylinder piston rod 11 has stops 28, 29 adapted to engage a fork on one arm of the lever 27 so that upon excessive movement of the brake cylinder piston, the nut 25 is actuated to take up slack. A modified slack adjuster is shown in Fig. 3. The rod 51 connected with the brake cylinder piston actuates, through a pin- and-slot connection 50, a bell crank lever 49 which is connected by link 47 and shackle 46 with a pawl carrier 45, Fig. 5. The spring- pressed pawl 44 is adapted to rotate a ratchet 42 on a shaft 41 which has a screw engaging a nut 39. One end of the brake lever 3 is pivoted to this nut 39. If the stroke of the piston rod 11 exceeds a predetermined amount, the screwed shaft 41 is rotated, and the lower end of the lever 3 is adjusted to take up the slack. A spring- pressed locking pawl 43 is provided for the ratchet 42.