GB1263050A - Improvements in automatic axially-acting slack-adjusters for vehicle brake riggings - Google Patents

Abstract

1,263,050. Slack adjusters; transmitting mechanism; disc brakes. SVENSKA A.B. BROMSREGULATOR. 27 Nov., 1970, No. 56556/70. Heading F2E. An automatic axially-acting slack-adjuster for a vehicle brake rigging is constructed and operates as described below. Operation with normal slack.-Live brake lever 11, Fig. 2b, is turned counterclockwise about its mid-point by a piston-rod (not shown) pivoted at the lowest point of the lever and moving to the right. Dead brake lever 13 is pivoted at its lowest point to a fixed point (not shown) and is linked at its mid-point by a drawbar (not shown) to lever 11, so that lever 13 turns clockwise. Housing barrel 30, Fig. 2a, having end cover 33, Fig. 2b, is attached to spindle 28, Fig. 2a, which is attached to a pullrod (15, Fig. 1, not shown). The initial effect of the piston-rod movement is that lever 11 pulls a pull-rod 12 and pushes a sensing-rod 26 leftwards through plug 52, thereby compressing spring 51, while lever 13, via plug 52 and tubular rod part 27, pulls the whole slack-adjuster to the right, without compression of two prestressed springs 31, 32, at this stage. As soon as the transmitted braking force exceeds the force of springs 31, 32, these are compressed between a sleeve 34 mounted on the tubular rod part 27 and the end cover 33 of housing barrel 30; a conical shoulder 35 on sleeve 34 thereby loses contact with a nut 29 mounted on non-selflocking threads on spindle 29. Sensing rod 26 through its shoulder 53, Fig. 2b, spring support 45 (now in contact therewith), spring 46, locking- ring 47 and a tubular thrust member 43, pushes nut 29 into contact with another conical shoulder 36 provided on a further sleeve 37 carried by the sleeve 34. The braking forces are now transmitted from plug 52 through tubular rod part 27, sleeves 34 and 37, nut 29 and spindle 28. Operation with excessive slack.-The axial distance between shoulder 53 and spring support 45 will be traversed before the transmitted braking forces become great enough to cause compression of the springs 31, 32. Nut 29 will now be displaced towards the left away from shoulder 35 by tubular thrust member 43, and will start spinning freely between shoulders 35, 36. Springs 31, 32 (pro-stressed-see above) will expand, causing spindle 28 to be drawn further into the tubular rod part 27, thus effectively shortening the slack-adjuster. This continues until the braking surfaces have engaged and the braking forces have increased sufficiently to cause compression of springs 31, 32, and engagement of shoulder 36 with nut 29. Operation with insufficient slack, e.g. after fitting of new pads.-A braking force exceeding the force of springs 31, 32, will be transmitted prior to engagement between shoulder 53 and spring support 45. Nut 29 will then leave conical shoulder 35 and rotate in the sense opposite to the previous one, while springs 31, 32, are further compressed, the overall effective length of the slack adjuster being thereby increased. The axial distance between shoulder 53 and spring support 45 (i.e., the distance determining the desired slack in the rigging) may be adjusted by means of adjusting screw 54, Fig. 2b. Fig. 1 (not shown), is an outline drawing of two colinear axles each carrying one brake disc. A brake pad carried by a pivoted dead lever is engageable with the further side of one disc, and a brake pad carried by a live lever linked by a draw-bar to the dead lever is engageable with the nearer side of the same disc; the free end of the live lever has attached to it the pull-rod (15) connected to spindle 28, Fig. 2a. An exactly analogous arrangement for the other disc includes the corresponding pull-rod 12, Fig. 2b, connected to the further live brake lever 11.