Patent Application
20080087508
While the present invention may be embodied in different forms and there may be some variations in the preferred form in which the invention is carried into practice, a description will be given of a presently preferred embodiment of the invention.
Referring now to the drawings in greater detail, there is shown in
The shoes and brake linings are normally actuated by a pair of oppositely disposed pistons (only one shown) 24, which are received within a slave cylinder generally designated 26 for actuation. The slave cylinder 26 receives its fluid 28 under pressure from a master cylinder (not shown) as is well known in the art. The pistons each have end portions 30, 32 adapted to push the shoes 16, 18 apart and into engagement between the linings 20, 22 and the drum 12 when the brake pedal (not shown) is actuated. There are two return springs 34, 36 to return the shoes 16, 18 and their linings 20, 22 to their retracted positions whenever the brake pedal and master cylinder have not put the slave cylinder(s) 26 under pressure.
Each upper portion of the shoes 16, 18 has a pocket 38, 40 for receiving the end portion 42, 44 of the adjuster mechanism generally designated 46. The adjustment mechanism 46 includes a rotary toothed adjusting wheel or nut 47 for engagement by the flat blade portion of an adjusting tool (e.g., a “spoon”) a screwdriver or the like (not shown). This moves the adjuster mechanism to cause the pockets 38, 40 and hence the shoes 16, 18 to move slightly farther apart.
The adjustment mechanism generally designated 46 (
The adjuster 46 also includes, at one end, a first fork generally designated 64 having a longitudinal notch 66 in the body and an end portion 68 of enlarged width. The adjuster 46 also includes a cut-out central opening 60, a spring groove 72 cut in an angled portion 74 with a slight inward enlargement 76.
Moreover, the adjuster assembly includes a threaded insert generally designated 71 having a bifurcated end portion 73 adjusted to snugly engage the pocket 44 in the brake shoe 18, a plain shank portion 75 and a threaded portion 77. The adjusting nut 47 engages the threaded portion. The insert fits snugly within the tubular portion 48 of the adjuster assembly. A spring 53 holds the two elements 46, 71 together by engaging the spring groove and the shoe 16 and urging them together.
Referring now to
First, a rectangular impact area 82 is stamped from one section of the sheet 80. The next operation involves piercing the drain opening 84 in the being-formed sheet 80. The outline cut 86 is next, and this forms a partial edge portion of the blank.
The next step is an elimination of the border and manufacture of a partial end portion within the outline 88. The individual flat blank 92 is then formed, except for the edge portion binding the blank 92 to the sheet 80, and with the tongue and groove portions in place within the flat blank 92. The next operation calls for slightly forming a curl in the blank 94, and then a somewhat more curved or moderately curved blank 96 is formed. A deeply curved blank 98 is then formed, and finally the sheet 100 is formed into a complete tube with the side portions interlocked.
Next, the schematic shows coining 102 of these seamed components, thus adding considerable strength and work hardening the material. The next stage consists of forming a flat end portion 104 with the tongue and groove in the tube and end portions being intact.
In the next section, additional cuts are made, thus forming the spring groove and the longitudinal notch in the blank 106. Additional notches 108 are cut from this blank, in the next station, and the material assumes its penultimate form. The final station 110 involves bending upwardly one of the fork tines thus formed.
Thereupon, the last step shows the adjuster removed from the tabbed portion 112, having been eliminated from the continuous formation strip.
The parts of the prior art previously were made from seamless steel tubing that was then flattened on the end, and cut to produce the current design. The basic flaw with that method is that the finished part proved to lack the desired strength, particularly column strength. During tests, which consisted of an offset column loading, the parts buckled relatively easily within the applicable strength range. Thus, the prior art design had a column loading requirement of 13,500 Newtons. A part made according to the prior art was tested. This part failed at 12,422 Newtons. This was well short of the requirement of 13,500 Newtons.
Two additional specimens made according to the instant method were tested, and these gave what was believed to be satisfactory results. Thus, second part failed at 14,130 Newtons and the third part failed at 15,618 Newtons.
These two parts, which failed at just over 14,000 to 15,600 Newtons, would exceed the strength requirement that was mandated; however, higher values were believed within easy reach.
Consequently, when it was discovered that these test samples were erroneously placed in the fixture, new tests were made, and four samples were created. Against the load requirement of at least 13,500 Newtons, the new samples were tested. The least strong failed at 17,137 Newtons and the other three all exceeded 18,000 Newtons. Hence, this was considered an excellent success and this design was then settled upon.
The material from which the test specimens were made was grade 1010 (mild steel) which also exceeded substantially the force requirements. 1010 steel, while meeting the requirements, is considerably less expensive than some of the other steels which were used. In addition, an HSLA (high strength, low alloy) steel could be used for even greater strength.
There are several instances in which these parts are plated for appearance and/or for reduction of rust and other reasons. The plating of these parts is carried out in an immersion bath coating the interior as well as the exterior. The parts are thoroughly wetted and current is then passed through the tubular unit in one instance. In some cases, however, the liquid plating bath was inadvertently retained within the interior of the unit, even after the plating was supposedly completed.
Consequently, it was determined that a drain hole 62 should be placed in these units so that, during handling, any liquid which was retained in the interior because of the orientation of the parts would drain from the material. If a unit were placed in one way, the liquid would be drained from the bottom. If they were placed in a slightly different environment, then the drain hole would be necessary to relieve the accumulation of plating bath in the interior of the parts.
It will thus be seen that the present invention provides a novel product and method of making it, having a number of advantages and characteristics including those specifically pointed out and others which are inherent in the invention.
