GB1010625A - Improvements in vehicle brakes of the internal shoe drum type - Google Patents

Abstract

1,010,625. Internal shoe drum brakes. H. TEVES, E. A. TEVES, and M. TAUSEND, [trading as ALFRED TEVES MASCHINEN-UND ARMATURENFABRIK K.G.]. Nov. 7, 1963 [Nov. 19, 1962], No. 43969/63. Heading F2E. In an internal shoe drum brake having a turnbuckle type slack adjuster operated by a cable attached to one of the brake shoes, the cable operates a lever pivoted to a stationary member and having at its operated end a slide block which is slidable axially in the slackadjuster casing and is connected internally of the casing to a bush having sprung helical teeth engageable with corresponding helical teeth on a sleeve, the sleeve being rotated by ratchet operation of the sprung teeth when axial movement of the bush corresponding to excessive wear takes place, rotation of the bush causing opposite axial movement of two tappets engaging threads of opposite hand in the sleeve to compensate for the wear. As shown, Fig. 3, the adjuster casing 39 has a slot 45 for guiding axial movement of slide block 29 which is screwed into the bush 43. Leaf springs 44 secured within an annular recess within the bush extend circumferentially and have inwardly bent ends providing spring helical teeth which co-operate with helical teeth 42 on sleeve 41 of the turnbuckle. Tappets 12, 13 whose shanks 46, 47 engage threads of opposite hand within the sleeve 41 engage the webs of brake shoes 5, 6. In one brake embodying the adjuster, Fig. 1, the shoes are slidably and pivotally mounted on the tappets and are operated as leading and trailing shoes in the direction of rotation of drum 3 shown by the arrow, by an hydraulic cylinder 2, rotation in the opposite direction causing operation as a servo-shoe brake owing to sleeve 41 being permitted slide in one direction in casing 39 but being prevented from sliding in the opposite direction by a shoulder engaged by an enlarged end 48 of the sleeve. Lever 26 which carries the slide block 29 is pivoted at 27 to back plate 1 and is connected by cable 17 to shoe 6, the cable passing through a sheath 18 anchored on lugs 21 of the cylinder 2 and casing 39, respectively. In the embodiment of Fig. 2, the cable connects the lever 26 to shoe 5, shoe 6 being mounted for circumferential movement through a link 31 on a carrier 34 which engages the respective piston of cylinder 2 and the respective tappet of the adjuster. The cable sheath is anchored on lugs 35, 22 on the carrier and casing 39, respectively.