Slip Bearing for a Sway Bar Clamp

The invention relates to clamps, especially clamps with slip bearings that are used to mount metal sway bars to automobile frames. Such clamps are normally comprised of a U-shaped bolt and plate which hold a split, annular rubber innerliner in compressive engagement with the sway bar, when the clamp and sway bar are properly secured to the automobile frame. The rubber innerliner may be a separate part, or integrally molded to the inside of the U-shaped bolt and plate assembly.

In either case, the rubber to metal contact of the innerliner and sway bar produces an annoying squeaking noise, when the automobile is in operation. To combat this, the inner periphery of the rubber innerliner is coated with Teflon which has a lower coefficient of friction than the rubber of the innerliner. This has proven to be a rather expensive solution to the problem. Moreover, the sway bars are oftentimes forged with rough outer surfaces which can quickly destroy the Teflon coating and cause the problem to reappear. The invention is designed to shift the interface of slippage between the clamp and sway bar away from the unfriendly metal surface of the sway bar to a friendly interface of the clamp.

Briefly stated, the invention is in a sway bar clamp which comprises an assembly of a U-shaped metal bolt and plate with a rubber innerliner and an elastomeric sleeve which is separately mounted around the sway bar. Either the outer periphery of the sleeve, or the inner periphery of the innerliner, or both, may be coated with a low friction material so that any slippage, caused by movement between the clamp and sway bar, occurs between the elastomeric materials in radially spaced relation from the metal sway bar.

The following description of the invention will be better understood by having reference to the accompanying drawing, wherein:

FIG. 1 is a cross-section of a sway bar clamp which is made in accordance with the invention, and shows the clamp in relation to an automobile frame; and

FIG. 2 is a section of the clamp viewed from the line 2--2 of FIG. 1.

With particular reference to the drawing, there is shown a sway bar clamp which comprises a U-shaped bolt 78 in juxtaposed relation to a matingly configured cylindrical plate 8, which is sandwiched between the bolt 7 and a generally cylindrical innerliner 9 which is composed of any suitable elastomeric material, e.g. rubber, and which is split longitudinally and normally designed to surround and compressively engage a sway bar 10, when the clamp 6 and attached sway bar 10 are fastened by nuts 11 to an adjacent automobile frame 12. The innerliner 9 may be molded to the bolt 7 and plate 8, both of which are covered by an outer layer 13 of the elastomeric material during the molding process to form an integral clamp assembly for easy handling.

A separate, hollow cylindrical sleeve 14 is interposed between the rubber innerliner 9 and metal sway bar 10. The sleeve 14 is composed of any suitable elastomeric material, e.g. plastic, and may also be split longitudinally for easy mounting on the sway bar 10, prior to the placement of the innerliner 9, plate 8 and bolt 7 around the elastomeric sleeve 14 and sway bar 10.

It is important to shift the interface of slippage between the clamp 6 and sway bar 10 away from the unfriendly metallic surface of the sway bar 10. This is accomplished by increasing the frictional engagement between the sway bar 10 and elastomeric sleeve 14 and decreasing the frictional engagement between the rubber innerliner 9 and elastomeric sleeve 14, so that the difference between the two will be sufficient to shift the interface of slippage away from the metal-to-elastomer interface of the sway bar and sleeve to the elastomer-to-elastomer interface of the sleeve and innerliner. Accordingly, the inner cylindrical surface 15 of the elastomeric sleeve 14 which contacts the sway bar 10, is molded or extruded with knurls or serrations to provide a rough inner surface with a high coefficient of friction. The outer cylindrical surface 16 of the elastomeric sleeve 14 which contacts the rubber innerliner 9 is treated in an opposite manner, i.e. it is coated with any suitable material which has a low coefficient of friction, such as Teflon, silicone, etc. Thus, the differences in the coefficients of friction of the two interfaces will be substantial and sufficient to cause slippage between the clamp 6 and sway bar 10 to occur at the interface of the two elastomers; namely, the rubber innerliner 9 and elastomeric sleeve 14.

The elastomeric compositions of the sleeve 14 and low friction coating on the outer surface 16 of the sleeve 14 are not detailed, since they depend on the design requirements which vary from application to application. For example, these compositions would probably differ depending on whether the clamps are used on small passenger vehicles, or large heavy trucks. Whichever the case, it is necessary to shift the interface of slippage between the clamp 6 and sway bar 10 away from the unfriendly metal surface of the sway bar to a friendlier interface for longer wear and better performance.

Thus, there has been described a sway bar clamp with a unique slip bearing which is simple and inexpensive to manufacture. This slip bearing eliminates the undesirable squeaking noise and is less susceptible to destruction by the sway bar to which the elastomeric sleeve clings and acts as a protective shield for the rubber innerliner of the clamp.