Brakes – With condition indicator – Wear
Patent
1995-10-17
1997-09-02
Graham, Matthew C.
Brakes
With condition indicator
Wear
F16D 6602, F16D 65097, F16D 65092
Patent
active
056621914
DESCRIPTION:
BRIEF SUMMARY
The subject of the present invention is friction pads, equipped with springs and wear indicators, particularly intended to be installed on disc brakes for motor vehicles.
Such friction pads include, in a known fashion, a carrier plate received with anchorage and sliding in a torque-withstanding member of the disc brake, and a friction lining is fixed to a part of the surface of a first face of the carrier plate to enter into frictional contact with a rotating disc when a force is applied to a second face of the carrier plate opposite the first face. Usually, an anti-rattle spring is associated with the friction pad, as is a device indicating the state of wear of the friction lining, warning the driver of the vehicle, by means of a signal, generally a light signal, that the friction lining through wear has reached a predetermined thickness and needs to be replaced.
Very many documents illustrate this type of friction pads, such as U.S. Pat. No. 4,056,174, FR-A-2,433,676 or FR-A-2,567,601. According to the latter document, corresponding to the preamble of the main claim, a through-opening is formed in the carrier plate for fixing a helical part of the anti-rattle spring, this part being formed of at least one turn, and of a fitting part of an indicator for indicating the state of wear of the friction lining passing through the helical part of the spring.
Such a design does, however, exhibit drawbacks. Firstly, a cutout has to be formed in the friction lining to accommodate the wear indicator. It follows that the surface for friction with the rotating disc is reduced commensurately, as is the effectiveness of the disc brake thus equipped. What is more, the spring includes two turns housed respectively in two U-shaped housings made in the carrier plate and separated by a projection of the latter. In order to give a means for fastening the friction lining wear indicator, this projection includes an opening so that it forms a closed annulus around a bore.
The circumferential edge of the projection includes a U-shaped recess for guiding the part of the spring forming the link between the two turns situated on either side of the projection. A holding part of the wear indicator extends through one of the turns and includes a groove equipped with a ring which comes into abutment on a shoulder formed in the bore of the projection.
This design therefore involves a relatively complicated, and therefore expensive, shape of the carrier plate, and in particular of the projection used to fasten the spring and wear indicator. What is more, the spring is held on the carrier plate only when the fitting part of the wear indicator is itself in position in the opening of the projection, this giving rise to a risk of the spring being lost during assembly operations of the friction pad, this risk being aggravated by the fact that it is possible to fit the wear indicator onto the carrier plate without having fitted the spring beforehand.
SUMMARY OF THE INVENTION
The object of the present invention is therefore to provide a friction pad for a disc brake of the type recalled above, in which the carrier plate is simple to manufacture, in which the anti-rattle spring and the wear indicator can be fitted easily and remain fixed reliably, the wear indicator moreover giving a warning signal when the thickness of the friction lining, through wear, has reached a predetermined value.
This objective is achieved, according to the present invention, by ensuring that the spring includes end parts situated on either side of the carrier plate, the helical part of the spring being received in the opening in the carrier plate, and the fitting part of the wear indicator being formed with a screw thread which interacts with the helical part of the spring.
The anti-rattle spring is thus fixed to the carrier plate, the wear indicator is fixed to the spring by screwing and locks it in place, so that it is impossible to fit the wear indicator on the carrier plate without having fitted the spring beforehand.
Other objectives, features and advantages of
REFERENCES:
patent: 3592295 (1971-07-01), Kennel
patent: 4643277 (1987-02-01), Bangert
patent: 5048645 (1991-09-01), Thiel et al.
Gerard Jean Louis
Le Deit Gerard
AlliedSignal Europe Servives Techniques
Graham Matthew C.
McCormick Jr. Leo H.
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