Patent GB-1437687-A (GB)
Title: Brake operating device
IPC: F16D65/42
Filed: 1974-01-25
Abstract: 1437687 Transmitting mechanisms; brake cylinders; wear adjustment; indicating WABCO WESTINGHOUSE 25 Jan 1974 [29 Jan 1973] 03705/74 Headings F2E and F2F A manually operable mechanism 20 for adjusting the spacing between a friction lining and a braking surface comprises two pieces 21, 22 slidable rotationally and translationally relative to one another, one of the pieces (e.g. 22) having at least one pin 34 attached thereto for engagement with play in a respective guide slot 23 in the other piece (e.g. 21) whereby the pieces 21, 22 are relatively movable to one of a number of adjustment positions. In the embodiment illustrated by Fig. 1, the mechanism 20 is incorporated in a brake cylinder 1, 2 the piece 21 being fixed to cylinder part 1 and the piece 22 being movable and carrying two pins 34 for two slots 23 in piece 21. The piece 22 has a four-sided head 36 for engagement by a spanner for rotation, and a spring 35 biases the pieces 21, 22 apart; both pieces 21, 22 are formed as cylindrical sleeves. The cylinder 1, 2 has a spring applied, compressed-air released piston 5 and a cable 15 crosses the cylinder and has its two ends connected to a respective driving lever of brake parts carrying friction linings, thus allowing bilateral brake application for the two wheels of the same axle of a lorry or trailer. A tube 5c of the piston receives an end adaptor 13 of a Bowden cable 14 of the tension cable 15 while an adaptor 31 of a tube 32 for cable 15 is attached to piece 21. A slider 10 co-operable with tube 5c is welded to the part 2 of the cylinder and the cylinder 1, 2 is fixed to the vehicle by a flat ring 4 which also serves to reinforce the annular assembly zone between the two parts 1, 2. In the embodiment of Figs. 2-5 each slot 23 comprises a succession of adjustment parts 24, 26, 28, 30 extending perpendicularly to the sliding centre line of pieces 21, 22 and a series of liaison parts 25, 27, 29 extending parallel to the sliding centre line. Means for locking the pieces 21, 22 in an adjusted position are provided. Such means may comprise at least one point screw (40) screwed into a hole in piece 21 the point (42) of which is engaged in one of a series of holes (43) in the piece 22, see Fig. 8 (not shown); alternatively the means comprises a spring biased pawl (44) fixed to the piece 21 axially guided in a bore (46) in the piece 21 and engageable in one of series of holes in piece 22, see Fig. 9 (not shown). The embodiment of Fig. 6 illustrates a helicoidal slot mechanism 48, the slot being centred on the sliding centre line, with a blocking screw 49. According to the embodiment of Fig. 7 (not shown) the slot (50) is composed of vertical adjustment parts (51, 53, 55, 57) connected by helicoidal liaison parts (52, 54, 56). Marks (58, 59) on the fixed piece 21 and the mobile piece 22 indicate the operator the effective adjustment position of the mechanism, as does lateral observation of the pins 34. A follower 16 fixed to the cylinder 1, 2 attached to an indicator warns the driver of the need for adjustment. In alternative embodiments the cylinder is a cable and spring cylinder with unilateral operation or a cable and bolt cylinder. The piston 5 can be replaced by a diaphragm. The cylinder may be operable directly by fluid pressure with locking of a piston-rod for parking.