Method for measuring vehicle disc brake lining (pad) wear, in particular a method for measuring wear of individual linings

Method for measuring vehicle disc brake lining (pad) wear, in particular a method for measuring wear of individual linings

Field of the invention

The present invention relates to a method for measuring disc brake lining wear, and in particular to a method for measuring wear of individual linings.

Background of the invention

Disc brakes for vehicles, and particularly for heavy vehicles, consist, in general, of a brake disc which is fixedly fastened to a wheel shaft and arranged to rotate with the shaft, and wherein a braking force is applied by frictional engagement with brake pads.

Such a disc brake arrangement is disclosed in fig. 1, in which a brake disc 10 is rigidly fastened to a wheel shaft 11, such as a half shaft or steering shaft. The brake disc 10 is arranged to rotate with the shaft 11, and when braking, brake pads 12, 13 are used to achieve a frictional brake force by pressing the pads 12, 13 against the disc 10. The brake pads 12, 13 consist of a frictional material, lining, affixed to a support or brake block. The brake pad 12 is arranged on the inner side of the disc 10, and the pad 13 is arranged on the opposite side of the disc 10.

Movement of the pads 12, 13 towards (for providing a braking force) and away (for releasing the brakes) from the disc is effected by means of a calliper 14, which straddles the edge of the disc 10, and which is movable in the axial directions A, B so as to allow braking action in a conventional manner, i.e., according to the following. The pad 12 is movable in relation to the calliper in said axial directions A, B of the disc 10, said movement being accomplished in a conventional manner by means of actuating means, such as a hydraulically operatable piston 15. When a chamber 17, formed by a cylinder 16 and the piston 15 is pressurized, the piston 15 will move towards the pad 12 and, when reaching the pad 12, the pad will be pushed towards the disc 10. Simultaneously, or at least when the pad 12 reaches the disc, the calliper will start moving in the direction B until the pad 13 also reaches the disc 10. When the pads have reached the disc, a suitable braking force can be applied to the disc by applying a suitable pressure in the chamber 17.

Obviously, the brake lining is subject to frictional wear, and therefore brake lining wear sensors are often used to measure the wear of the linings in order to automatically alert, e.g., a vehicle control system that, when wear is excessive, the brake pads need replacement.

Preferably, a wear sensor for each brake pad is used since even though the described solution ensures that a substantially corresponding force act on each pad, e.g., misalignment of the pads and/or friction in the sliding of the calliper and/or variations in the surfaces of the disc interacting with the pads can result in differences in the wear of the linings, and thereby the lining of one of the pads can be completely worn off while th...