Relieved tapered roller bearing with true rolling contacts

Details Relieved tapered roller bearing with true rolling contacts Relieved tapered roller bearing with true rolling contacts

1999-01-06

2001-05-29

Bucci, David A. (Department: 3682)

Bearings

Rotary bearing

Antifriction bearing

C384S551000, C384S571000

Reexamination Certificate

active

06238095

ABSTRACT:

CROSS-REFERENCE TO RELATED APPLICATIONS
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable.
BACKGROUND OF THE INVENTION
This invention relates in general to tapered roller bearings, and more particularly to multirow tapered roller bearings in which true rolling contact exists at all critical surfaces during operation of the bearing and in which reliefs exist in the bearing for improving its operation.
Antifriction bearings come in several basic configurations, but irrespective of its configuration, an antifriction bearing includes a pair of ring-like races and rolling elements arranged in at least one row between the races. The rolling elements contact raceways on the races, and when the bearing is set in operation, the rolling elements roll along those raceways and around the axis of the bearing.
When the rolling elements take the form of cylindrical rollers, the bearing has the capacity to take heavy radial loads, but is not very satisfactory for transmitting thrust loads. Moreover, cylindrical roller bearings usually have radial clearances, and thus are not suitable in applications requiring stability, rigidity and a good measure of precision. A ball bearing, in which the rolling elements are balls, may have its raceways oriented obliquely to the axis of the bearing so that the bearing takes radial and thrust loads. When arranged in pairs, these angular ball bearings may be adjusted against each other to eliminate end play—and radial clearances as well—but the load capacity of an angular ball bearing is relatively low. A tapered roller bearing possesses the advantages of both cylindrical roller bearings and angular ball bearings. It has the capacity to carry heavy radial loads and also thrust loads, all through its tapered rollers and the raceways along which they roll. Moreover, a tapered roller bearing may be adjusted to eliminate clearances between its rollers and raceways.
Owing to the geometry of a tapered roller bearing, the tapered rollers tend to move up the raceways and unless restrained will be expelled from the bearing. For this reason, the conventional tapered roller bearing has a thrust rib at the large end of one of its raceways, usually on the inner race which is called the cone. As the rollers roll along the raceways, the large end faces of the rollers bear against the thrust rib, and the rollers remain in place axially. While generally pure rolling contact exists between the tapered side faces of the rollers and the raceways, the end faces of the rollers slide and spin along the face of the thrust rib. In the absence of adequate lubrication, the bearing may fail at this critical area, for here the friction is highest within the bearing. This represents a significant concern, particularly for bearings that operate at high speeds. Moreover, due to the slide and spin motion between the roller ends and the thrust rib, the torque within a tapered roller bearing operating at low speed, is relatively high and, to a measure, wear as well.
BRIEF SUMMARY OF THE INVENTION
The present invention resides in tapered roller bearings that have true rolling contact along all critical load-bearing surfaces and further have reliefs in their rollers or raceways. To this end, each bearing has rollers arranged in multiple rows with the rollers of any row backing the rollers of the adjacent row. Indeed, the end faces of the rollers of adjacent rows contact each other and in these regions of contact pure rolling contact exists. In the absence of their normal supply of lubrication, the bearings will remain operational for sustained periods of time. The reliefs, when in the tapered rollers of at least one row, enable the end faces of the rollers to assume a configuration which facilitates stability, in that it enables contacting rollers to better track each other. When the reliefs are in intervening rollers of a cylindrical configuration, they enable those rollers to carry radial loads, whereas otherwise they may not. The reliefs also facilitate circulation of lubricants. The invention also consists in the parts and in the arrangements and combinations of parts hereinafter described and claimed.


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