GB725996A - Improvements in or relating to hand brake operating mechanisms - Google Patents

Abstract

725,996. Hand brake operating mechanism. LEYLAND MOTORS, Ltd. March 18, 1954 [April 8, 1953], No. 9497/53. Class 103 (1). In a hand brake operating mechanism to enable the rapid take-up of clearance caused by wear or loss of travel in the components of the mechanism, a first lever element 1 pivoted at 4 to a fixed support 5 is pivoted at one end 8 to a brake rod 7 and has formed at its other end an arcuate rack 6. Pivoted at 3 to the first lever element 1 in a second. lever element 2 on which is pivoted a pawl 9 which is urged by a spring 10 into engagement with the teeth of the rack 6. Pivoted to the pawl 9 is a radius rod 11 which is pivoted to a sear 12 which pivoted to a second pawl 16 through a link 19. The second pawl 16 is engageable with the teeth of a rack 18 presented by the fixed support S. The sear 12 is connected to a push rod 20 pivoted to a handle 21 mounted on the second lever element 2. A spring 22 urges the push rod 20 to the position in which the sear 12 is out of line with an abutment 14 on the fixed support 5 and in which the pawl 16 is urged into engagement with the teeth of the rack 18.. In operation, when it is desired to apply the brake, the second lever 2 is moved to the left of the " brake-off " position illustrated in Fig. 1 and pivots about a fulcrum 15 formed on the fixed support 5 thus causing the first lever element 1 to move about its pivot 4 in a direction away from the second lever 2, the pawl 9 slipping over the teeth of the rack 6 on the first lever element 1. This has the effect of taking up the clearance in the brake mechanism (this position being shown in Fig. 2). The second lever element 2 is then moved to the right, the pawl 9 engaging with the teeth of the rack 6 to cause the second and first lever elements 2 and 1 to move as a unit about pivot 4 to apply the brakes, the pawl 16 sliding over the teeth of the rack 18 thus preventing return movement of the lever elements 1 and 2 to retain the brakes in the applied position. To release the brakes, the handle 21 is moved to lift the pawl 16 from engagement with the rack 18 and to bring the sear 12 into line with the abutment 14 on the fixed support 5. The second lever element is then moved to the left to release the brakes; the first and second lever elements 1 and 2 remaining in the same angular relation to one another. Continued movement of the second lever element 2 brings the sear 12 against the abutment 14 and the pawl 9 is moved out of engagement with the rack 6 and the mechanism is returned to the "brake-off" position illustrated in Fig. 1. A modification is described in which the handle 21 is replaced by a thumb-operated button mounted in the handle of the second lever element 2.