Patent Application
20130112036
None.
The present invention relates to drum brake systems, and more particularly to S-cams for use in such systems. The invention provides for a two-piece S-cam, which can be used in drum brake systems.
Disclosed are both a method for manufacturing a split-shaft S-cam, and the split-shaft S-cam itself. The method for converting a one-piece S-cam into a two-piece S-cam comprises: cutting an S-cam along a non-bearing-surface portion of its length resulting in an S-cam inner portion and a head portion; machining a coupling means for releasably joining the inner and head portions into each of the cut ends; providing a nipple having, cooperating coupling means for engaging with the coupling means machined into each cut end of the S-cam, and a shoulder having a width equivalent to a length of material removed in the cutting step, the shoulder disposed between the cooperating coupling means and adapted to engage a cooperating shoulder on each of the ends; and mating the coupling means with the cooperating coupling means; whereby, a one-piece S-cam is converted into a two-piece S-cam adapted to allow replacement of at least a portion of an S-cam without requiring complete disassembly of a trailer brake. The coupling means and cooperating coupling means may be threaded, splined, or other well-known mechanical-type connections disclosed by the prior art.
The S-cam according to the present invention comprises: an S-cam inner portion having a means for engaging a brake activator and a length of shaft terminating before a bearing-surface portion begins; an S-cam head portion having an S-cam disposed at one end thereof and having at least one bearing surface; and a coupling means for releasably joining the inner and head portions; whereby, either section may be replaced separately and replacement can take place without complete disassembly of a trailer brake. The coupling means and cooperating coupling means may be threaded, splined, or other well-known mechanical-type connections disclosed by the prior art.
There having thus been outlined, rather broadly, the more important features of the invention in order that the detailed description thereof that follows may be better understood, and in order that the present contribution to the art may be better appreciated. There are, of course, additional features of the invention that will be described hereinafter and which will form the subject matter of the claims appended hereto.
In this respect, before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in this application to the details of construction and to the arrangements of the components set forth in the following description or illustrated in the drawings. The invention is capable of other embodiments and of being practiced and carried out in various ways. Also, it is to be understood that the phraseology and terminology employed herein are for the purpose of description and should not be regarded as limiting. As such, those skilled in the art will appreciate that the conception, upon which this disclosure is based, may readily be utilized as a basis for the designing of other structures, methods and systems for carrying out the several purposes of the present invention. Additional benefits and advantages of the present invention will become apparent in those skilled in the art to which the present invention relates from the subsequent description of the preferred embodiment and the appended claims, taken in conjunction with the accompanying drawings. It is important, therefore, that the claims be regarded as including such equivalent constructions insofar as they do not depart from the spirit and scope of the present invention.
Further, the purpose of the foregoing abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientist, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
S-cams are well known in the mechanical industry with respect to drum brakes, generally on larger trucks and trailers. The construction of a typical S-Cam is illustrated generally in
There will be at least one bearing section along the length of the S-Cam 100, and there are generally two or more. As shown in
The S-cam 112 has a first arm 114 and second arm 116 for engaging the drum in a brake. The S-Cam 112 is closer to the wheel, and the gears 102 are disposed away from the wheel along and near the axle.
Also typically defined on an S-Cam 112 is at least one keeper channel. As shown, a first keeper channel 118 is located between the gears 102 and the first end 122. A second keeper channel 120 is shown between the second bearing section 106 and the third bearing section 108. The purpose of the keeper channels 118 and 120 is to receive a keeper (not shown) to hold the S-Cam 112 in place to ensure that it does not move further toward the wheel or away from the wheel than is desired in operation.
Once the S-Cam has been cut into two pieces, or if it is originally manufactured in two pieces, there needs to be a means for mating the two pieces together in operation which also allows for them to be released for service or to be replaced. As shown, two different configurations for the connections are described: A first threaded connection; and a second splined connection. It is well known in the art to use other methods to releasably connect two metal pieces together. Splines are an option as are threads of various sorts. However, connectors for two pieces in the machining arts an old and well established art and the invention incorporates any of the various methods for joining two metal pieces together that are available in the machine arts.
Once a one-piece S-Cam has been cut into two parts, a means for connecting them must be machined. As shown in
S-Cam if the width of the saw blade cut being removed from the overall S-Cam shaft length is not critical to the operation of the braking system. Shown in
Inherent in the discussion above about threaded sections is the concept that the threads are biased in a way that when the S-Cam operates, the threads are biased in a tightening direction. Thus, if the alternate were true, when the S-Cam operated, the threads would tend to become unscrewed and the S-Cam would be unstable in operation. Therefore, it is key that the threads all be biased in favor of tightening the threads by operation of the S-Cam in the braking system.
The purpose of the abstract is to enable the U.S. Patent and Trademark Office and the public generally, and especially the scientist, engineers and practitioners in the art who are not familiar with patent or legal terms or phraseology, to determine quickly from a cursory inspection the nature and essence of the technical disclosure of the application. The abstract is neither intended to define the invention of the application which is measured by the claims, nor is it intended to be limiting as to the scope of the invention in any way.
While the invention has been shown, illustrated, described and disclosed in terms of specific embodiments or modifications, the scope of the invention should not be deemed to be limited by the precise embodiment or modification therein shown, illustrated, described or disclosed. Such other embodiments or modifications are intended to be reserved especially as they fall within the scope of the claims herein appended.
