Brakes – Wheel – Transversely movable
Patent
1979-03-23
1986-06-17
Halvosa, George E. A.
Brakes
Wheel
Transversely movable
188196B, F16D 6554
Patent
active
045950822
DESCRIPTION:
BRIEF SUMMARY
The invention relates to a drum brake of the type comprising two brake shoes, operating means situated between two first adjoining ends of the shoes, and adjusting means designed to increase automatically the distance separating the first ends of the shoes as a function of the wear on linings carried by the shoes, the adjusting means comprising a lever pivoted at one end on a first one of the shoes in the vicinity of the operating means, a pawl pivoted on the first shoe and meshing with a toothed sector formed on the other end of the lever under the influence of resilient means, and an operating member responsive to the distance between the said first ends of the shoes so as to pivot the lever in a direction corresponding to adjustment of the brake.
In such drum brakes, when the linings of the shoes are worn, pivoting of the adjusting lever controlled by the spacing of the shoes can cause the pawl to escape circumferentially from the teeth of the toothed sector formed on the lever. Also, even if the deflection of the adjusting lever is not enough to make the pawl escape, it may bring the free end of the lever into engagement with the hub of the vehicle wheel on which the brake is mounted. In either of these situations, the components of the adjusting means and other parts of the brake and hub may be seriously damaged.
To overcome these disadvantages, the invention proposes a drum brake of the type described above, characterized in that abutment means are provided to prevent pivoting of the lever through more than a predetermined angle relative to the position occupied by the lever when idle and when the linings carried by the shoes are new, second resilient means being associated with the operating member to absorb the force transmitted by the latter when the lever is abutting on the abutment means.
With such a feature, of course, the lever cannot pivot when it comes into contact with the abutment means, the position of which is so selected as to prevent the pawl escaping from the teeth in the toothed sector on the adjusting lever and also to prevent the latter from making contact with the wheel hub.
According to another feature of the invention, the abutment means comprise at least one rigid member associated with the first shoe. Preferably, such a member is pivoted at one end on a pivot pin bearing the pawl, the other end of the said member comprising an abutment portion capable of engaging a corresponding abutment surface defined on the lever.
According to still another feature of the invention, the said member cooperates with those faces of the pawl and lever remote from the first shoe irrespective of the position occupied by the lever, so preventing any axial offset between the pawl and the toothed sector formed on the lever. Such a feature also makes it possible to prevent the teeth in the toothed sector on the lever from escaping in a direction parallel to the drum axis from the teeth on the pawl. A member so designed can therefore prevent both circumferential escape when the components have reached the limit of their travel and axial escape of any time of the teeth in the toothed sector from the pawl, while ensuring that the adjusting lever does not touch the wheel hub. A drum brake having these features is therefore even more reliable than known drum brakes of the type defined above.
A particular embodiment of the invention will now be described by way of example with reference to the accompanying drawings, in which:
FIG. 1 is a general view of a drum brake embodying the principles of the invention;
FIG. 2 represents a section along a line 2--2 in FIG. 1; and
FIG. 3 represents a section along a line 3--3 in FIG. 1.
The drum brake illustrated in FIG. 1 comprises a support plate 10 designed to be attached to a non-rotary part (not shown) near one wheel of a vehicle and defining a substantially circular rim 12 on its outer periphery. Operating means, for example a wheel cylinder 14, and a fixed fulcrum block 16 are mounted at two diametrically opposite places on the support plate 10. The wheel cylind
REFERENCES:
patent: 2378662 (1945-06-01), Shuman
patent: 3991861 (1976-11-01), Hayashida
patent: 4121701 (1978-10-01), Gestkoff
Decker Ken C.
Halvosa George E. A.
Palguta Larry J.
Societe Anonyme D.B.A.
LandOfFree
Drum brake does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Drum brake, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Drum brake will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2268720