1. Field of the Invention
The invention concerns wheel spindle and hub assemblies, preferably for use in a non-driven axle of an automobile or trailer, the assemblies including fastening means for securing a hub and anti-friction bearings on the spindle, and lubrication means for replenishing lubricant to the hub and bearings.
2. Description of the Related Art
Wheel spindle and hub assemblies are typically comprised of a spindle, one or more (typically two) antifriction bearings for rotatably supporting a hub, a hub, and lubrication means. Generally, wheel spindle and hub assemblies can be classified as either an oil lubricated or grease lubricated type.
In any grease lubricated wheel spindle and hub assembly, grease must be periodically added to make up for grease which is lost during normal operation. Further, grease should be routinely added in order to exchange grease which has been oxidized or has lost it's lubricating properties due to prolonged exposure to high temperature, contact with air, contacted with fresh or salt water, etc.
Typical grease-lubricated spindle assemblies are disclosed in U.S. Pat. No. 4,262,978 (Everett) and U.S. Pat. No. 5,259,676 (Marti), the disclosures of which are incorporated herein by reference. A longitudinal bore is drilled generally along the axis of the spindle beginning at one end and extending inward along the axis of the spindle shaft to a point generally transverse with the bearing, or in the case of two or more bearings, the outboard bearing. A grease fitting such as a zirk fitting is provided in communication with the longitudinal bore. A transverse bore is provided in communication with the longitudinal bore in the area of the bearing for providing grease to the bearing(s) and/or interior of the hub.
Such a construction permits the resupplying of grease without requiring disassembly of the wheel spindle and hub assembly. The grease spindle assembly also includes a passageway which vents the lubricating medium. Grease can be injected at the outboard end of the assembly using a conventional grease gun, and passes through the longitudinal bore along the axis of the spindle, then radially through the transverse bore, and into a lubricating cavity. As new grease is injected, older grease is displaced and caused to be expelled from the lubricating cavity through the vent passageway. This expulsion indicates that the hub and bearings are packed with grease. The vent passageway also allows the grease to purge any air trapped in the lubricating cavity.
Normally, the hub and bearings are mounted on the spindle and held in a preset relationship, i.e., the bearing preload adjustment, by a nut screwed onto the end of the spindle, engaging threads machined onto the outside surface of the spindle. In order to prevent rotation of the nut once the preload adjustment has been set, resort may be made to a retaining means comprising a castellated nut and a cotter pin or other type of pin which is inserted through a bore hole drilled laterally through the centerline of the threaded end portion of the spindle. There is a general familiarity with, and acceptance of, this system wherein the castellated nut is positioned by lining up a slot and hole on one side of the spindle with a slot and hole 180.degree. on the other side of the spindle, and bending the cotter pin projections around the shaft. See, for example, U.S. Pat. No. 1,540,055 (Chilton).
Although there is general acceptance respectively of the lubrication supply system having an axial bore hole as a lubrication supply channel, and also of a hub retaining system comprising a castellated nut, retaining pin, and retaining pin bore hole drilled through the centerline of the spindle, a problem occurs when attempting to employ both systems at once. Namely, both the longitudinal axial lubricant bore hole and the lateral diametrical retaining pin would intersect, resulting in leakage of the lubricant out of the retention pin hole.
Attempts have been made in the past to construct a wheel spindle and hub assembly having a lubricant channel provided in the spindle, a nut for retaining the hub on the spindle, and a pin for retaining the nut in place on the spindle.
U.S. Pat. No. 5,259,676 solves the problem by providing the grease fitting and axial lubricating channel at the outboard end of the spindle, and a nut for retaining the hub and a D-washer with locking tabs for securing the D-washer at the inboard end. However, serviceability would be improved if both the grease fitting and the nut securing the hub were provided on the readily accessible outboard end of the spindle.
It is also possible to provide the D-washer and lubricating channel on the same axial end of the spindle, since the locking finger or tab of the D-washer can be constructed so as to not interfere with the grease fitting. However, the locking finger or tab is made of thin metal which is easily broken or sheared off during normal operation. Further, specialized replacement washers may not be readily available.
Another proposed solution is disclosed in U.S. Pat. No. 5,120,170, in which a cotter pin cordal passageway is provided spaced from the axial lubrication passageway extending along the longitudinal axis of the spindle. However, a disadvantage of such a solution is the requirement to plane or flatten the threaded surface, or take other steps, so that the bore for the cotter pin may be readily and accurately drilled. A further problem resides in the fact that the end of the axle, through which the axial lubrication channel bore must be drilled, usually presents a "nipple" at the center of the end face of the spindle, making positioning of the drill difficult and causing wandering of the drill tip. Yet a further problem with such a system is that the tangential cotter pin has an unconventional appearance, and thus requires an end user to overcome an initial unfamiliarity and mistrust.
In view of the foregoing, it is an object of the present invention to provide a novel hub and spindle assembly lubrication and fastener retention system which eliminates or minimizes the above-mentioned and other problems, limitations and disadvantages typically associated with conventional systems. It is a further object of the invention to design a system which is simple to manufacture, easy to use, inexpensive, and reliable. Still other objects will become apparent in the following description of the invention.