Bearings – Linear bearing – Plain bearings
Reexamination Certificate
1999-08-20
2001-01-30
Hannon, Thomas R. (Department: 3682)
Bearings
Linear bearing
Plain bearings
Reexamination Certificate
active
06179468
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of Invention
The present invention relates generally to accessory apparatus for use with a plain bearing located in a housing and slidably positioned on a shaft or guide member. More particularly, the invention relates to apparatus adapted for adjusting the running clearance between the bearing and the shaft, and for optionally provide a frictional drag and/or braking force between the bearing and shaft; and which, while suitable for other uses, is particularly useful in connection with adjusting the running clearance and/or braking linear slides provided with plain bearings sliding on a guide rail.
2. Description of Prior Art
Plain bearings are often used for either slidably or rotatably supporting a shaft member in a stationary housing, or slidably or rotatably supporting a housing member on a stationary shaft. In such arrangements, it is desirable at times to stop the relative motion between the housing and the shaft, or to provide a frictional drag to resist the relative motion. At present, suitable friction and braking apparatus may be embodied in a separate unit, or may involve a clutch or conventional braking arrangement, and may be relatively complicated and expensive. Thus, there is a need for a simple, relatively inexpensive means for applying a frictional drag between the bearing and shaft, and for optionally applying sufficient friction to act as a braking force.
It is also well known that plain bearings have a limited life as a result of wear. Bearings are installed with an initial shaft clearance which tends to increase from extended use. Accommodation of an acceptable level of wear is typically taken into account in design of any particular arrangement, and the bearing is then typically replaced when the wear exceeds an allowable limit. It is apparent that a simple, relatively inexpensive apparatus adapted to adjust the clearance between the bearing and shaft, to accommodate wear and prolong the useful life of the bearing, would reduce bearing replacement costs, and in many instances, reduce the overall long-term cost of operation.
One common use for plain bearings is in connection with linear slides. A typical linear slide arrangement includes a stationary shaft or other stationary guide rail, and a housing slidably positioned on the guide rail with one or more plain bearings. For example, Komiya, U.S. Pat. No. 5,297,873 discloses a linear motion slide with generally rectangular guide rail and a separate slide stop assembly.
Osawa, U.S. Pat. No. 4,941,758 discloses a linear slide and guide rail arrangement in which the slide housing is provided with a slit defining outer and inner side wall portions, and a pressing bolt adapted to elastically deform the inner wall portion for adjusting the gap between the bearing and the guide rail. While the Osawa arrangement is an improvement for certain arrangements over the prior art, a simpler arrangement which avoids the need to form the slotted sidewall, but which is adapted to adjust the clearance between the bearing and shaft is desirable to further reduce the cost of clearance adjustable sliders.
From the foregoing, it is clear there is a need for a simple, and relatively inexpensive arrangement adapted to adjust the clearance between a plain bearing and associated shaft, and which is further adapted to apply a frictional drag and optionally a braking force between the bearing and the shaft.
SUMMARY OF THE INVENTION
The general aim of the present invention is to provide a new and improved apparatus adapted for adjusting the running clearance between a plain bearing and a shaft or guide rail, and for applying a frictional drag or braking force as desired.
A detailed objective is to achieve the foregoing by providing apparatus connected to the housing and operatively engaging a split bearing located in the housing for effecting closure of the bearing to reduce the clearance or impart a friction between the bearing and the shaft.
These and other objectives and advantages of the invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
Briefly, in a preferred embodiment, a plain bearing is slidably positioned substantially surrounding a guide rail for sliding linear movement therebetween. A slider assembly includes a housing, the plain bearing positioned in the housing and provided with an axially extending slit, and the closure apparatus grounded to the housing and operatively engaging the bearing for adjustably closing the slit in the bearing to effect clearance reduction and/or braking between the bearing and the guide rail.
REFERENCES:
patent: 1285628 (1918-11-01), Craley
patent: 3095247 (1963-06-01), von Zelewsky
patent: 4518205 (1985-05-01), Heathe
patent: 4773769 (1988-09-01), Church
patent: 4941758 (1990-07-01), Osawa
patent: 5297873 (1994-03-01), Komiya
Thorstens Dale
Woodworth Donn
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