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1. Field of the Invention
The present invention relates to height adjustable tables. More particularly, the present invention relates to an improved height adjustable table that provides a plurality of legs that are simultaneously adjustable. A specially configured gear and drive shaft configuration telescopes all of the legs simultaneously to either raise or lower a table top supported by the legs responsive to rotation of a single crank.
2. General Background of the Invention
Adjustable tables have been in use for many years. There are several adjustable height tables that are commercially available. Several of these adjustable height tables were patented as drafting tables. Several of these patented commercially available tables were sold under the trademark Hamilton. Patents relating to Hamilton® drafting tables that have been sold for many years are U.S. Pat. Nos. 3,140,559 and 3,273,517).
One of the primary uses for adjustable height tables is the support of a heavy object such as a computer and/or monitor at a comfortable elevation for the user. Because computers and monitors are relatively heavy, a problem exists when the table is at a maximum elevational position such as when the user chooses to stand. In such a situation, adjustable height tables can become top heavy and suffer from lateral instability. The weighted table top of the table tends to deflect when it is elevated to a high position and when it is loaded with a heavy object such as a monitor, computer or the like. In order to stabilize a table top, often three or more legs are placed in triangular position. When a table top is extremely large, three legs are preferably employed rather than two legs having laterally extending feet. For a table with three legs, height adjustment requires that all three legs either elevate or lower simultaneously. Many patents have issued that are directed to elevating or height adjustable tables. Early patents that show adjustable height tables are shown for example in U.S. Pat. Nos. 5,448,36; 1,243,750; 2,532,342; and 2,642,996;
The May Patent discloses an adjustable support for a drafting table. In the May U.S. Pat. No. 2,982,050, an adjustable drafting board support that includes a pair of links that swing to elevate and lower the board and an improved arrangement for counterbalancing the board to apply a substantially uniform lift to the board in all operative positions.
The Grow U.S. Pat. No. 3,140,559 discloses a drafting table that uses a rack and pinion arrangement in combination with a locking or braking mechanism which is adapted to lock the vertically adjustable table in any selected position when the operating linkage has been released and which lock will become even more securely locked upon the application of downward pressure on the table top occurring in normal use.
The Kooi U.S. Pat. No. 3,364,881 discloses a drafting table with a single pedal control of both vertical movement and tilting. U.S. Pat. No. 3,638,584 discloses a drafting table that includes a pedestal, support columns associated with the pedestal for vertical movement and a drafting board on an upper portion thereof. An elevating table is disclosed in the Feiertag U.S. Pat. No. 3,820,176.
A telescoping support arm of quadrangular cross-section is disclosed in the Bertalot U.S. Pat. No. 3,887,115. The apparatus provides roller bearings in corner spaces between each tube surrounding each other, the rollers in one corner rolling over separate braces supported on resilient means urging the rollers and the inner tube toward the other corner so as to exclude backlash.
The Horner U.S. Pat. No. 3,908,560 discloses a counter balancing system for a drafting table.
A vertically adjustable drafting table is disclosed in the Evans U.S. Pat. No. 4,130,069.
The Raymond U.S. Pat. No. 4,469,029 discloses a workstation comprised of support legs with a stable support base and the uprights on which pivoting elbows are adapted to form adjacent arms which are positioned and locked in place in an adjustable angular manner at one of these end of the arms, the other end bearing supports are work tops positioned and locked in place in a manner which can be angularly adjusted at will, so that these supports or work tops allow effects and uses which are multiple and can be combined together.
U.S. Pat. No. 4,591,214 issued to Reuter discloses a cabinet closure assembly that includes a panel which is pivotable between opening-blocking and opening-unblocking positions. The Kurrasch U.S. Pat. No. 4,619,208 discloses a work surface height adjustment mechanism.
An adjustable computer work table is disclosed in U.S. Pat. No. 4,637,322. Vertically actuating scissor arms are provided for moving the support shaft upward and downward whereby providing a vertical adjustment.
The Ball U.S. Pat. No. 4,751,884 discloses a height adjustable work top. The work top is adjustable and may tilt about a horizontal axis near the front edge. The work top may be mounted in an open office beam system or an office screen or partition in cantilever fashion or it may be a free standing unit.
A table lift mechanism is disclosed in the Watt U.S. Pat. No. 4,981,085. The '085 patent discloses furniture having a top or the like supported for vertical movement by telescoping legs supports with a counter balance for exerting a relatively uniform counter balance force from the top throughout its range of vertical movement. A latch mechanism is provided for latching the top in the selected vertical positions, and an adjustable roller guide mechanism as provided for coupling the telescoping elements of the legs supports.
An apparatus for adjusting a computer work station to individual needs is disclosed in the Seiler U.S. Pat. No. 5,041,770.
An adjustable height table is disclosed in the Rizzi U.S. Pat. No. 5,289,782. The '782 patent discloses a table having a top that can be vertically adjusted to various heights by a pair of telescoping legs and a counter balance weight mechanism which includes a weight box and weights that can be easily added or removed by the user depending on the weight carried by the table top. A locking mechanism including a spring urged threaded half nut and a stationary threaded rod enables the table top to be locked in place once a desired height is achieved.
An adjustable dual work surface support is disclosed in the Sherman, et al, U.S. Pat. No. 5,332,025. The Borgman, et al, U.S. Pat. No. 5,323,695 discloses a method of using a work station having separate and back tops having separate power drive arrangements while permitting independent height adjustment. A controller, which is programed by an operator, permits storage of a number of predetermined height locations each defining distinct heights for the tops. The operator effects programed movement of the tops to predetermined height locations for predetermined times in a predetermined sequence, with the rear top moving initially and a front top moving thereafter.
The Smies U.S. Pat. No. 5,339,750 discloses an adjustable work table. The '750 patent table comprises a base and at least one movable extensible vertical column attached to the base having a table top carried on the vertical column. A pivot is provided for moving the table top into any of a range of pivoted positions, preferably on both sides of the horizontal position of the table top. A motor is provided for holding the table top in any of the range of pivoted positions.
A non-binding cantilevered table lifting device disclosed in the Childers U.S. Pat. No. 5,370,063.
The Winchell U.S. Pat. No. 5,408,940 discloses an adjustable height work surface with rack and pinion arrangements.
The present invention provides an improved height adjustable table apparatus that includes a table top having an underside to which legs are affixed and an upper surface that provides a work area or work surface.
A plurality of telescoping legs attach to and support the table top. The legs each include a fixed section and a moving section. Each leg provides a lower end portion and an upper end portion. The upper end portion of each leg attaches to the table top underside with a gear box arrangement interface. This gear box arrangement includes a gear cluster that is mounted at the top of each leg that includes a plurality of gears that can be bevel gears.
Each leg provides a hollow interior that holds a generally vertically extending, externally threaded rod. The rod provides an upper end portion with a bevel gear that forms part of the gear cluster and a lower end portion that threadably engages a lower leg section.
A single crank is attached to a drive shaft. A gear that forms a part of the gear cluster is mounted on one end portion of the drive shaft and generally opposite the crank.
A plurality of connecting rods connect each gear cluster to another of the gear clusters. When the single crank is rotated, all of the connecting rods rotate, each connecting rod having a gear at a connecting rod end portion that forms part of the gear cluster. The gear clusters and connecting rods are so configured that when the single crank is rotated by a user in a first rotational direction, all three legs elevate the table top. To lower the table top, a user rotates the crank in the opposite rotational direction.
For a further understanding of the nature, objects, and advantages of the present invention, reference should be had to the following detailed description, read in conjunction with the following drawings, wherein like reference numerals denote like elements and wherein:
Each of the telescoping legs 13, 14, 15 is comprised of an inner section and an outer section. The leg 13 has an inner section 19 and an outer section 22. The leg 14 has an inner section 20 and an outer section 23. The leg 15 has an inner section 21 and an outer section 24. Connecting braces 25, 26 can be provided for stabilizing each of the legs 13, 14, 15 as shown in
A single rotary crank 27 is provided for simultaneously elevating each of the outer sections 22, 23, 24 of the legs 13, 14, 15 relative to the inner sections 19, 20, 21 so that the table top 11 rises or falls uniformly. The table work surface 12 remains level and preferably defines a substantially horizontal plane at all times during elevation or lowering.
Crank 27 is preferably manually operated using handle 28. Crank 27 can be motor (eg. electric) operated. The handle 28 and crank 27 connect to drive shaft 29 as shown in
A feature of the present invention is that when the crank 27 is rotated, a provided gear arrangement simultaneously rotates a vertical, threaded shaft 36 located inside of each of the legs 13, 14, 15. The detail shown in
In
At its upper end portion, threaded shaft 36 extends to gear housing 31 and connects with bevel gear 34. At an opposing, lower end portion, the elongated vertical threaded shaft 36 connects with internally threaded nut 41 that is mounted to the top of sleeve 42. The sleeve 42 extends from nut 41 downwardly to an attachment 44 that joins leg inner section 21 to foot 18 at circular plate 45. Sleeve 42 is hollow, having interior 43. The connection of sleeve 42, plate 45, and foot 18 can be an attachment 44 that is either bolted or welded, as examples. As table top 11 is lowered, shaft 36 extends into interior 43 of sleeve 42.
For each of the legs 13 and 15, the thread pattern for the threads on vertical threaded shaft 36 are the same. A reverse thread is provided for the threaded shaft 36 that occupies the center leg 14. A reverse threading of the threaded shaft 36 is provided for the center leg 14 to insure that all three legs 13, 14, 15 elevate at the same time when crank 27 is rotated in a first rotational direction. Similarly, all three legs 13, 14, 15 are lowered (see
There are three gear housings, one at the top of each leg 13, 14, 15. In
An elongated, generally horizontally positioned connecting rod 48 spans between the gear housings 46, 47. Similarly an elongated, generally horizontally positioned connecting rod 49 spans between the gear housings 47, 31. Each rod 48, 49 has end portions that attach to a bevel gear mounted next to each of its end portions. In the preferred embodiment, rods 48 and 49 have hexagonally shaped ends that fit into a hex shaped socket or opening in the bevel gear to which rod 48 or 49 attaches.
When crank 27 is rotated in a first rotational direction, the table top 11 elevates as the legs 13, 14, 15 extend and elongate. When crank 27 is rotated in an opposite rotational direction, the table top lowers as the legs 13, 14, 15 retract and shorten. Connecting rod 49 is a linkage that has bevel gears 35, 54 at its end portions (see
Rod or linkage 48 has gears 55, 56 at its end portions (see
As an alternate location for crank 27, a socket 50 in table top 11 (see
The following is a list of suitable parts and materials for the various elements of the preferred embodiment of the present invention.
The foregoing embodiments are presented by way of example only; the scope of the present invention is to be limited only by the following claims.
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