GB1384492A - Disc brake having a switching device for the electrical circuit of a warning device - Google Patents

Abstract

1384492 Brake-lining-wear warning devices DEUTSCHE BENDIX AUSRUSTUNGS GmbH 1 Feb 1973 [3 Feb 1972] 5159/73 Heading F2E In a disc brake having a disc 2, at least one spring 9 for moving apart and/or holding down two friction pads 4, 4<SP>1</SP>, and a switching device adapted to close a circuit including a warning device for indicating excessive brake lining wear, one electrical contact member of the switching device is the spring 9 itself or a member mounted directly on the spring, the other electrical contact member being the disc, these two members coming into contact on braking with excessively worn linings. As shown in Figs. 1, 2, spring 9 is a hold-down spring consisting of wire covered with insulating sheathing in the form of approximately a flattened coil having one-and-a-half turns. The central portion 9 lies above pins 8, 81, Fig. 2, on which backing plates 6, 6<SP>1</SP> of brake pads 4, 4<SP>1</SP> are slidable by bores 7, 71; the outer portions 11, 11<SP>1</SP> are in contact with the brake linings 5, 5<SP>1</SP>, and are held apart by stops 10, 10<SP>1</SP>, integral with the brake housing 1. One end of the spring 9 is formed into a plug pin 15 for engagement with a connector socket (16, Fig. 3, not shown) connected through an optical warning device and a battery to a chassis terminal; the disc 2 is also connected to a chassis terminal. In operation, by the time the brake linings 5, 5<SP>1</SP> have been worn down to the admissible limit, the backing plates 6 have pushed the central zones 19, 19<SP>1</SP>, Fig. 1, of the spring portions 11, 11<SP>1</SP> into contact with the brake disc 2, the disc then abrades the sheathing, and the wire makes contact with the disc; thereby completing the warning circuit. During subsequent braking operations, if the linings are not replaced, the backing plates 6, 6<SP>1</SP> bear (through spring 9) against the fixed stops 10, 10<SP>1</SP>, reducing the braking action. In the modification of Fig. 6, spring 9 is not insulated and does not form part of the circuit. Instead, a separate contact member 21 comprising an injection-moulded synthetic plastics body 27 incorporating a conduction core 26 is clamped around the outer arms of the spring to provide contact zones 22, 22<SP>1</SP>.