GB975192A - Improvements relating to brake slack adjusters - Google Patents

Abstract

975,192. Brake slack adjusters; ratchet gearing. WESTINGHOUSE BRAKE & SIGNAL CO. Ltd. Aug. 28, 1962 [Aug. 29, 1961], No. 31109/61. Headings F2E and F2Q. A brake slack adjuster has one part 7, Fig. 1, the rotation of which in one direction relative to a brake operating mechanism 1 reduces slack, the part 7 having associated with it a driving part 9 which is rotated when the motion of the operating mechanism 1 exceeds a predetermined amount. Motion of the driving part 9 is imparted to the part 7 as motion in one direction as a result of the tightening effect of a spring 16 or band of material against the part 7 (or part 9), rotation of the part 7 in the opposite direction being prevented by the tightening effect of a further spring 8 or band of material. When a brake application is made the operating lever 1 is forced in the direction of the arrow Y whereby a worm 2 on a shaft 7 can drive a gear 3 mounted on a shaft which carries a cam, the rotation of which applies the brakes. If slack adjustment is required the lost motion between a pin 14 on the sleeve 9 and the side of a slot 21 in a pivoted lever 15 connected by a swinging link to the axle assembly is taken up and continued movement of the lever 1 causes the sleeve 9 to rotate, the spring 16 tending to unwind as it rotates about the shaft 7. At the same time the spring 8 is tending to tighten into gripping engagement with the shaft 7 thereby acting to prevent the worm 2 from rotating. On release of the brakes the lost motion between the pin 14 and slot 21 is taken up in the reverse direction, subsequent to which the spring 16 tightens into gripping engagement with the shaft 7 and spring 8 releases it from its locking engagement with the shaft 7. The relative movement between the lever 1 and arm 15 is then translated as angular movement to the shaft 7 via sleeve 9 and spring 16, the rotation of shaft 7 causing the worm 2 to rotate the gear 3 thereby taking up slack by automatically resetting the cam. In another embodiment, Figs. 4 and 5, brake application is by way of lever 4 which turns in an anticlockwise direction to move the push rod 6 to the right through trunnion 10 and nut 9 in screw-threaded engagement with the rod 6. If slack adjustment is required the right-hand fork 23 of a lever 22 contacts a fixed pin 24 after the brake clearance X has been taken up. Further movement of the lever 4 causes the pin 24 to rotate the lever 22 clockwise and thereby rotate plates 15, 16 through the connection 20, 21 in a counterclockwise direction looking in the direction of arrow A. A spring 13 held at one end in a slot 12 tightens on the nut 9 to prevent rotation thereof in a counter-clockwise direction if friction between the plates 15, 16 tends to rotate the nut 9. A spring 19 tends to loosen on the nut 9. On release of the brakes the spring 26 forces the rod 6 and adjuster to the right. The clearance X is first taken up and then continued movement causes the lever 22 to turn in a counter-clockwise direction, thereby turning the plates 15, 16 in a clockwise direction so that the spring 13 loosens on the nut 9 and the spring 19 tightens on the nut to turn it in a clockwise direction relating to the rod 6 to thereby increase the effective length of the rod 6. In a modification a pin-and-slot connection is provided between the lever 22 and a sleeve on the nut 9.