GB1364540A - Overrunning brakes - Google Patents

Abstract

1364540 Over-running brakes for trailers KOBER-MANPAR AG 23 Nov 1971 [27 Nov 1970] 45342/73 Divided out of 1364539 Heading F2E An over-running brake for trailer wheels comprises an internal shoe drum brake with two shoes including an expanding device so mounted between two adjacent shoe ends that in one direction of hub rotation the primary and secondary shoes act respectively as leading and trailing shoes and in the reverse direction their functions are reversed, an adjusting device mounted between the other ends of the shoes, and resiliently compressible bracing means supporting a bolt which is mounted in a guide slot formed in the secondary shoe and extending at an acute angle to the tangent at the radiallyadjacent friction surface of the secondary shoe, the bracing means bearing against the secondary shoe at a position closer to the expanding device than the guide slot. As shown, the upper shoe 2, Figs. 1 and 3, is anchored at 10, while the lower shoe 3 is adjustably anchored at 32, 34 (see below) to a slackadjusting device. The shoes are actuated by two levers 16, 16<SP>1</SP> and 17, Fig. 2, pivoted together at 18 and operated by a Bowden cable 56. A stop 57, Fig. 1, limits the movement of lever 16, 16<SP>1</SP>. When the trailer is moving forward (arrow 4, Fig. 1), 2 is the leading shoe and 3 is the trailing shoe. For forward and over-running braking, anchoring of shoe 3 is effectively by contact of a bolt 21, located in a slot 20 in the web of shoe 3, with the bottom end of part 32 of the slackadjusting device. Trailer reversing.-When the trailer is reversed by the tractor vehicle, the Bowden cable 56 is automatically pulled, tending to apply the brakes. But the wheel is now rotating in direction 5, Fig. 1, so shoe 3 is the leading shoe. Initial friction contact between the drum and shoe 3 moves shoe 3 counter-clockwise, whereupon the shoe, by means of part 24 of a stay structure 22 forming part of the bracing means, compresses two springs 25 and is thereby enabled to move transversely of bolt 21 by slot 20, the end of the shoe web meanwhile riding up into a gap 34, Fig. 3, provided in the end of part 32. Slot 20 is so orientated in relation to the tangent to the drum at that point that the abovedescribed movement of the shoe carries it away from the drum. Since also, in these circumstances, shoe 2 is the trailing shoe, and since the shoes are floating, the brake is hardly applied at all. Part 23 of stay 22 is in two parallel sections joined by the bolt 21. Slack-adjusting.-The device consists of the parts 10, 32, Fig. 3, with adjacent wedge-shaped ends, mounted in a tube 29 through which extends transversely a threaded member 31 whose wedge end 30 engages the parts 10, 32. The end of member 31 is located outside the back plate and provided with an adjusting nut.