GB1366306A - Brake adjuster mechanisms - Google Patents

Abstract

1366306 Slack adjusters GIRLING Ltd 13 Sept 1971 [11 Sept 1970] 43531/70 Heading F2E An adjuster for an internal shoe drum brake has a coupling member 17 sensing movement of the shoes 10, 11 to one 10, of which it is pivoted at 15, member 17 having arcuate slots 18 receiving a pin 16 fastened to shoe 11 so that member 17 moves with shoe 10 while shoe 11 moves in the opposite direction, a follower member 19 being provided pivotally connected to member 17 by a pin 20. A tension spring 25 is provided connected to a pin 26 in one corner of member 19 and to coupling member 17 adjacent pin 15. A sheated cable has one end of its sheath 22 attached to member 17 at 24 and one cable end is pivotally connected to one corner of member 19 the other end of the cable 23 being connected to a bell crank 28 of an adjustable abutment assembly 12. Crank 28 is pivotally mounted on a pin 29 and carries a rack 31 provided with teeth 32. When the brakes are actuated follower member 19 is pivoted clockwise to move cable 23 relative to sheath 22 and to relieve the tension therein whereupon crank 28 is pivoted anti-clockwise under the action of a spring 33. Teeth 30 of rack 31 engage the teeth of a toothed adjuster drive wheel 34. If sufficient lining wear has occured teeth 30 co-operate with new teeth on wheel 34 and adjustment is effected by rotation of wheel 34 on return of the brake shoes 10, 11, under the action of spring 25. A manual adjustment is effected by a member 36, Fig. 5, (not shown), the ends of which are shaped to engage teeth (37) of a contrate wheel (38) attached to wheel 34. Member (36) is biased out of engagement with wheel (38) by means of a spring (39) and is fitted with a sleeve (40) connected by a pivot pin (42) to a lever (43) pivotally connected to a cam (44) coaxial with, and adjacent, wheel 34. When member (36) is depressed for manual adjustment sleeve (40) is also moved causing cam (44) to be rotated by lever 43, cam (44) deflecting bell crank 28 so that teeth 31 move out of engagement with adjuster wheel 34, member (36) engaging contrate wheel (38) to allow wheel 34 to be rotated. In a further embodiment a manual adjuster member 56, Fig. 9 (not shown), is provided in two parts, a smaller diameter part protruding through adjuster assembly cover 35 and the other part having a blind bore receiving spring (39). A release member (58) has one end portion (57) non-rotatably attached between the two parts of member (56) and the main portion is bent at right angles to end portion (57) and has bifurcated arms (59), (60) extending between wheels (38) and 34. When member (56) is depressed release member (58) is moved to engage teeth 30 which thereby disengage from wheel 34 allowing the latter to be rotated, via contrate wheel (38), by member (58). An alternative means of sensing brake shoe movements comprises members 46, Fig. 7 (not shown), located on pin 15 and the free ends of which are bent inwardly to protrude through a slot (47) in a tube (48) to support a retaining collar (49). As shoes 10, 11 are moved apart a spring (50) provided in tube (48) is compressed to move cable 23, held by the closed end of tube (48), relative to sheath 22, held by collar (49), to act on bell crank 28.