Patent GB-198665-A (GB)
Title: Improvements in or relating to brake apparatus for vehicles provided with supporting springs
IPC: B61H13/32
Filed: 1923-05-22
Abstract: 198,665. Leer, A. I. van. May 22, 1923. Force-transmitting mechanism; compensating for wear.- Brake mechanism of the kind in which the point of connection of a pull rod of the mechanism to a lever arm is adjusted automatically in accordance with the load to vary the braking pressure is provided with means for positively preventing this point of connection from creeping along the lever during the application of the brakes or with automatic slack adjusting means whereby the tendency to creep is prevented from exceeding a certain amount. The pull rod 1 is pivoted at 3 to the pull rod 6 and has a block 2 slidably engaged in the slotted lever 5. The rod 1 is connected by the strap 18 and bar 20 to the spring buckle 19 and thus if the body is displaced on the springs by a variation of load a corresponding displacement of the block 2 is effected. In the release position the slot in the lever 5 is concentric with the pivot 3. When the brakes are applied the rod 1 is no longer radial to the slot and there is consequently a tendency for the block 2 to creep along the slot. To prevent the movement of the lever 5 from exceeding a certain amount and thus to keep this tendency to creep as small as possible, a slack adjusting device is interposed in the pull rod. This device may comprise a rack 7 on the rod 6 engaged and supported by a tooth 8 on the rod 9 which carries a pawl 13 by a pin and slot connection 15. The pawl 13 engages by gravity a rack 16 fixed to the vehicle body. If in applying the brakes the slack exceeds the amount allowed by the slot 15, the pawl 13 slips a tooth of the rack 16 and when the lever 5 is returned to its original position in the release movement the tooth 8 on the rod 9 slips a tooth of the rack 7. To indicate when the lever 5 has been returned to the original position, the nut on the screw device by which the lever is actuated is caused to abut against a collar on the screw. Springs 17 are interposed between the bar 20 and the strap 18 to take up vertical movements of the body when the brakes are applied. As shown in Fig. 2, the link 1 is adjusted by a link 25 connected to a strap 26 on the axle box and to an arm 24 on a shaft 23 which carries a second arm 22 connected by the link 21 to the link 1. The link 25 is connected to the strap 26 by a pin and slot 28 to allow for the play of the bearing springs and a spring is interposed in the link 25 to serve the purpose of the springs 17, Fig. 1. A counterweight 27 is provided on an extension of the arm 22. The block 2 and the face of the slot 4 with which it engages when the brakes are applied, are provided with teeth to prevent the block from creeping. The means for taking up excessive slack comprises a pawl 31 pivoted to the end of the pull rod 30 which is connected at 3 to the pull rod 1, and a pawl 34 pivoted at 35 in a slot in a bracket fixed to the vehicle body; both of these pawls engage a rack on the pull rod 33. If in the application of the brakes, the movement of the rod 30 exceeds that which corresponds to the play allowed by the pin and slot at 35, the pawl 34 slips a tooth of the rack of the rod 33 and in the return movement, the pawl 31 also takes up a tooth of the rack. The Specification as open to inspection under Sect. 91 (3) (a) states that the rack 7 may be provided on the bar 9 and the tooth 8 on the rod 6. The arrangement may be such that the end of the rod 6 supports the adjustment end of the rod 9. This subject-matter does not appear in the Specification as accepted.