Self-Lubricating Cap Nut

My invention involves substitution of a lubricated cap nuts for prior art wing nuts used to secure a cover plate or the like in place. The cap nut comprises a cast metal cylinder having a longitudinal bore extending inwardly from one end thereof towards its closed opposite end. A grease fitting extends through the closed end of the nut and into the bore. The cap nut is cast about a threaded hex nut proximate the open end of the bore. The hex nut is of a size matching the bolt 76 and is of lesser diameter than the bore.

By injecting grease through the grease fitting in the top of the cap nut, the portion of the bolt received into the bore of the cap nut will remain lubricated, thereby preventing the cap nut from seizing to the bolt due to rust or the like.

The foregoing features, objects and advantages of the invention will become apparent to those skilled in the art from the following detailed description of the preferred embodiment, especially when considered in conjunction with the accompanying drawing in which like numerals in the several views refer to corresponding parts.

FIG. 1 is a side elevational view of a prior art transport truck of the type incorporating a gravity tee device with which the present invention finds use;

FIG. 2 is an exploded perspective view of the prior art gravity tee;

FIG. 3 is a partial cross-sectional view of the lubricated cap nut of the present invention; and

FIG. 4 is an exploded perspective view of a gravity tee incorporating the improvements comprising the present invention.

Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words "upwardly", "downwardly", "rightwardly" and "leftwardly" will refer to directions in the drawings to which reference is made. The words "inwardly" and "outwardly" will refer to directions toward and away from, respectively, the geometric center of the device and associated parts thereof. Said terminology will include the words above specifically mentioned, derivatives thereof and words of similar import.

The present invention is described in a typical application where an access cover that is exposed to the elements is to be releasably secured to a container, such as on the gravity tee of a transport truck. However, it is to be understood that the lubricated cap nut may find wider application so that limitation to use on a gravity tee is not to be inferred.

Referring to FIG. 3, there is shown a partially sectioned view of the lubricated cap screw 94 of the present invention. The cap screw is seen to comprise a cylindrical casting 96 made of a suitable metal, preferably aluminum. It includes a central bore 98 having a diameter greater than that of the clamping bolt 76 with which it may be used (see FIG. 4). Fitting into the mold at the time of casting the cap nut cylinder 96 is a hex nut 100 whose threads match those on the bolt 76. The nut 100 preferably includes an annular groove 101 into which metal may flow as the cap portion is being cast. In this way, the cap portion 96 becomes securely attached to the nut 100.

To facilitate rotation of the cap nut 94 onto the bolt 76, there are provided transversely extending arms 102 and 103 that extend radially outward from the body of the cap nut proximate its lower end.

The bore 98 does not extend all the way through the cylinder 96 but, instead, ends short of the top portion 104 of the cap nut 94. A tapered bore 106 extends through the top 104 proximate its center point and fitted into the tapered bore is a conventional Zerk grease fitting 108. A convention grease gun (not shown) can be coupled to the Zerk fitting 108 such that grease under pressure may be injected through the fitting and into the bore 98 to partially fill the bore 98. A breather hole 105 extends through the wall of the casting leading to the bore 98 so that as grease is injected, air can escape to allow the grease to fill the cavity. When the cap nut is advanced on to the bolt 76, it lubricates the mating surfaces of the threads on the hex nut 100 with those on the bolt 76, preventing rusting and seizing thereof.

The length of the cap nut 94 and its internal bore 98 are sufficient to receive the end portion of the bolt 76 on which it is used when the bottom surface 110 thereof is made to press down on the tubular end portion 46 of the projecting ear 42 of the gravity tee of FIG. 4 when the cover plate 50 is abutting the open lower end 52 of the gravity tee. Rotation of the cap nut onto the bolt 76 thus serves to releasibly clamp the cover plate 50 in place.

Because the upper end of the end portion of the bolt 76 is covered with lubricating grease, moisture, corrosive road salt, sand and other debris do not cause the cap nut 94 to "freeze" onto the bolt 76 and it can be readily loosened by hand if earlier only hand-tightened.

While the device of FIG. 3 show the Zerk fitting 108 in the top portion of the cap nut, it is also possible to relocate that fitting to a side wall of the cylinder 96. In fact, the Zerk fitting can be eliminated completely and the cap nut filled with grease via the threaded bore in the nut 100.

The gravity tee incorporating my lubricated clamping nut will also benefit from incorporation of the tubular resilient spring 88 of my provisional patent application Ser. No. 60/077,245, filed Mar. 9, 1998, the substance of which is hereby incorporated by reference into the present application. As is explained in the aforereferenced provisional application, the tubular resilient spring 88 (FIG. 4) is preferably fabricated from PVC tubing and is sufficiently resilient so that the wing nut 74 can be tightened sufficiently to draw the cover plate 50 into contact with the undersurface 52 of the tubular member 32. Now, when the lubricated cap nut 94 is rotated onto the threaded bolt 76, the cover plate will be snugged tightly against the open bottom of the gravity tee with the resilient gasket 62 tightly sealing the opening.

When the lubricated cap nut 94 is loosened, the driver can readily pivot the cover plate 50 about the carriage bolt 70, but the resilient tubular spring 88 placed on the bolt 70 intermediate the ear 56 on the cover plate and the undersurface of the tubular portion 48 of the ear 44 on the gravity tee precludes the cover plate 50 from drooping downward. That is to say, the plate 50 remains in a generally horizontal disposition even when in its rotated, out-of-the-way, disposition relative to the bottom end 52 of the gravity tee.

It can be seen, then, that the present invention offers two advantages. No tools are required to clamp and unclamp the cover plate relative to the gravity tee. Secondly, the cover plate 50 is not permitted to droop due to the action of the resilient tubular spring 88 disposed between the ear 56 and the tubular extension 48. Thus, it cannot be made to dig into the ground and become benched should the driver move his truck before closing and latching the cover plate.

This invention has been described herein in considerable detail in order to comply with the Patent Statutes and to provide those skilled in the art with the information needed to apply the novel principles and to construct and use embodiments of the example as required. However, it is to be understood that the invention can be carried out by specifically different equipment and devices and that various modifications, both as to the equipment details and operating procedures can be accomplished without departing from the scope of the invention itself.