GB1258592A - - Google Patents

Abstract

1,258,592. Indicating brake lining wear; discbrake linings. SOC. ANON. FRANCAISE DU FERODO. 14 May, 1969 [15 May, 1968], No. 24675/69. Heading F2E. A wear indicator device for friction linings includes warning means 12 arranged to act when the wear of the lining is sufficient to establish contact between the warning means and the member or material against which the friction lining operates, the warning means being essentially linear and extending over or around a substantial area of the lining 11 and having portions positioned close to or in contact with the (metal) support 10 on the side of the support on which the lining is situated, the whole of the warning means or at least their parts most distant from the support surface being in a plane parallel to the support surface, and at least part of the warning means being inserted in passage means provided in the lining; the distance of the above-mentioned plane from the support surface represents a predetermined "warning reserve". As shown in Fig. 1, an electrically conductive wire 12 of copper or brass arranged in the form of a fork and covered by an insulating sheath 13 is inserted into passages 17 drilled in the finished lining 11. A connector (not shown) applied to the central loop enables the wire to be incorporated in a circuit incorporating a warning lamp or bell. The warning may be consequent upon the "making" of the circuit by contact between the wire 12 and the member, e.g. a brake disc, against which the lining operates, when both lining and insulation have been worn away at any position. Alternatively, the circuit may be normally complete and energized, the warning being consequent upon such wear of the lining, insulation and wire itself that the wire is completely worn through, the circuit being thereby broken. This second alternative has the advantage that if a spurious warning is given by faulty operation of the circuit, the user will be alerted to check the circuit. Instead of the sheath 13, the wire 12 may be insulated by being arranged in an insulating layer of the lining. In Fig. 4, at least part of the wire 12 is accommodated between the support and a cut-away edge of the lining 11. The wire 12 may have a frame shape, or a grid-like pattern resembling a grating; the latter configuration serves also as a reinforcement of the lining. The wire may have a wavy outline so as to provide at least three widelyspaced points at a distance from the plane of the support equal to the "warning reserve".