Bearings – Linear bearing – Ball bearing for drawer
Reexamination Certificate
1999-01-11
2001-08-28
Footland, Lenard A. (Department: 3682)
Bearings
Linear bearing
Ball bearing for drawer
Reexamination Certificate
active
06280086
ABSTRACT:
The invention relates to a telescopic rail including at least two substantially C-shaped sections of which a first section is slidably mounted in a second section with interposition of a first ball cage. Such a telescopic rail is generally known and offered for sale by Thomas Regout BV, Netherlands.
This known telescopic rail comprises first and second section, slidable mounted to each other with an interpositioned ball cage. The first section is movable relative to the second section, thereby extending or retracting the rail between a fully extended first position and a fully retracted second position. Two of such rails are used as a pair for suspension of for example a drawer in a cabinet. In order to prevent damage to the rails, the drawer or the cabinet and to prevent noise generation when the rails reach the first or second position, buffer means are provided on the ball cage and the first and second sections. The first section is provided with an inward extending tab near the front and the rear of the section. The second section is provided with at least an inward facing tab near the end of the second section. A plastic or rubber buffer element is positioned on the rearward tab of the second section. The ball cage is furthermore provided on each end with a second buffer element.
When the rail is in the fully extended first position the front tab of the second section is in abutment with the front buffer element on the ball cage, the rearward tab of the first section in abutment with the rear buffer element of the ball cage. When the rail is in the fully retracted second position the rear tab of the first section is in abutment with the rear buffer element of the second section.
This known telescopic rail has the disadvantage that the first ball cage has to be provided with said buffer elements, as well as at least one of said tabs, which is time consuming and costly. Assembling this known telescopic rail is relatively difficult. The buffer elements are difficult to reach when the rail is in use, which can be a disadvantage, for example for maintenance. Furthermore, the first and second sections have to be relatively long in order to provide for tabs near the rear end of the first and second sections, on the opposite side of the ball cage from the first tab and furthermore since a locking mechanism has to be positioned at the rearward end of the sections. Therefore a relatively large amount of material is necessary and relatively much space for movement of the rail, which means that the rail is relatively heavy and needs a large building volume.
One object of the invention is to provide a telescopic rail in which the said problems are avoided, without loss of the advantages thereof.
The stop block according to the invention incorporates in itself the buffer elements for both the fully retracted as the fully extended position, co-operating with the first and second projections on the first section. The first inward facing projection, that is the projection nearest to the rear of the rail can be brought forward over about the length of the first ball cage in comparison to the known telescopic rail with a similar extension length. The first section can therefore be relatively short. Furthermore only the stop block has to be positioned within the second section in order to obtain both buffer functions. Since the ball cage has no essential buffer or stop function in a telescopic rail according to the invention, the buffer elements on the ball cage can be dispensed with, as can the buffer elements on the tabs. Assembling a telescopic rail according to the invention is easy. The first section is, together with the ball cage, slid into the second section, and the stop block is connected to the second section. The first projection can be formed prior to assembly, the second projection either prior to or after assembly, depending on the flexibility of the stop block and the mode of attachment thereof. When the stop block is sufficiently flexible the first tab on the first section can be pushed over the stop block, deforming the stop block resiliently. The said tab can not pass the stop block in the opposite direction. Either way only assembling steps have to be performed near the front side of the rail, which enables quick and easy assemblage.
A ball cage has to be interpreted in this application as bearing means provided in raceways on the respective rail sections. These ball cages can be constituted as separate series of balls, for example embedded in strips, a strip positioned in each race way or as series of balls embedded in a cage comprising two rows of balls, one for each raceway, the rows being interconnected by a connecting part. Furthermore ball cages can comprise sliding means besides or instead of balls.
At least one guide projection stabilizes and supports the first section relative to the second section, especially in a partly or fully extended position. The or each projection prevents relative movement of the first to the second section in a direction inclined to the direction of extension and retraction. Furthermore the projections can have a stabilizing function for the stop block relative to the second and/or first section. Preferably the stop block is provided with two guide projections, one in the upper and one in the lower raceways of the first and second sections. Furthermore, the stop block centers the first and second sections relative to eachother.
Known three section telescopic rails have an inward facing tab near the front as well as near the rear of the third section, at least the rearward one being provided with a resilient plastic or rubber buffer element. The second ball cage between the second and third section in these known rails is again provided with a second buffer element on the front and rear side thereof. In the fully extended position of the rail the front buffer element of the ball cage is in abutment with the front tab of the third section while the rearward buffer element of the second ball cage is in abutment with the rearward tab of the second section. In this known telescopic rail the distance over which the second section can move relative to the third section is thus determined by the distance between the front and rear tab on the third section and the length of the second ball cage between the buffer elements.
A three section telescopic rail according to the invention has the advantage that it can be extended over a relatively long distance, wherein the stop block provides for a stop and buffering function of the second and first section, whereas in the fully retracted position the stop block provides for a stop and buffering function for all three sections. The buffer part extending through the second, intermediate rail and providing for buffering means for the third section has the advantage that there is no need for a tab near the rear end of the third section. In the fully retracted position of the second and third sections the third projection, positioned near the front of the third section abuts the resilient means of the buffer part, thus limiting movement of the second section relative to the third section in rearward, retracted direction. The third section can therefore be relatively short compared to the third section of a known telescopic rail with similar possible extension length. The length of the third section can for example be limited to approximately the length of the path of travel of the second ball cage and the length of the second ball cage itself.
A further advantage of a telescopic rail according to the invention in such embodiment is that assembly of this rail is very easy. This can be done for example as follows. The first, second and third sections can be manufactured separately, except for the second, front projection on the first section. The second ball cage and the second section are slid into the third section, after which the stop block is placed in the second section, thus locking the second section to the third section. In the fully extended position the front side of the second ball cage abuts th
Footland Lenard A.
Thomas Regout B.V.
Weingarten, Schurgin Gagnebin & Hayes LLP
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