AU586560B2 - Workstation height adjusting device - Google Patents

Description

WORKSTATION HEIGHT ADJUSTING DEVICE

This invention relates to a device which may be used to adjust the height of workstations such as desks for typists, clerks or computer keyboard operators, tables for draftsmen and others, or factory benches. The device of the invention is particularly applicable to workstations in which the top member of the workstation providing a working surface is supported on a framework which includes hollow legs. For example, desks used in many offices are constructed with a top member of wood or other appropriate material supported on a steel framework including tubular steel legs.

It is obvious that while workstations such as desks are generally, for reasons of economy, produced in a limited number of standard sizes and in particular with relatively few different heights for the working surface of the top member, the height of the person using a workstation may vary considerably. Particularly in recent years, it has been realized that in order to provide a comfortable and efficient working surface for persons spending most of their time at a particular workstation, the height of the workstation should be adjusted to suit the height of the person concerned. Various proposals have been made to enable adjustment of the height of a workstation but many of these are expensive and complicated to produce and/or install. It is therefore an object of the present invention to provide a device which is relatively simple in construction, may be readily fitted to an existing workstation and which will allow simple and convenient adjustment of the height of the workstation to which it is fitted.

Accordingly the present invention provides a workstation height adjusting device for a workstation said device including a threaded shaft extending coaxial with a drive shaft, at least one internally threaded fixing nut on the threaded shaft and rotational movement within a workstation leg; adjustment means adapted tocooperate with the drive shaft allowing axial movement of the drive shaft but turning the drive shaft and its associated threaded shaft about their common axis, a locating sleeve within which the adjustment means is axially rotatable but which is mounted relative to the adjustment means so that relative axial movement between the locating sleeve and the adjustment means is minimised, said adjustment means being keyed for cooperation with an adjustment key which when fitting into the adjustment means enables the means to be turned about its axis.

The height adjusting device of the invention includes a two part height adjustment shaft. For convenience of description and ease of understanding the device will be described in its position of use so that relative terms such as "lower" and "upper" refer to this position. Thus, in use, the lower part of the height adjustment shaft is a threaded shaft which extends coaxially with the second part of the height adjustment shaft. The second part of the shaft is a drive shaft which may be in the form of a rod or tube as hereinafter described.

The device of the invention further includes at least one fixing nut which is internally threaded to cooperate with the threaded shaft which is threaded within the fixing nut(s) . The periphery of the or each fixing nut is formed so as to allow press fit assembly within the base of a workstation leg. Preferably, a single fixing nut is formed with an outwardly extending flange on its lower portion, the flange forming a shoulder which in the assembled position of the device abuts against the lower edge of the workstation leg. As indicated, the fixing nut is adapted to be press fitted within the workstation leg and should be fixed against rotational movement within the leg. If necessary, for example in a round leg, the fixing nut may be held in position within the workstation leg. For example, a grub screw may be fitted to extend through the leg and into the fixing nut thereby holding the nut against rotation within the leg.

The device of the invention further includes an adjustment means which is adapted to cooperate with the drive shaft, allowing axial movement of the drive shaft but turning the drive shaft and its associated threaded shaft about their common axis. For example, an adjustment means may be formed by a tube of substantially square cross-section surrounding a drive shaft of rod-like form. The rod-like drive shaft may be of square cross-section which is not- rotatable, but is slidable, within the surrounding tube. Alternatively, abutments may be formed on a rod-like drive shaft of circular or other cross-section which allows rotation of the shaft within the tube to prevent such rotation but still allow relative axial movement between the shaft and tube. As a further alternative, an adjustment means of rod-like form can be provided to move axially but not rotationally within a tubular drive shaft.

In accordance with the invention, the adjustment means is maintained, throughout movement of the adjustment shaft, at a fixed height relative to the workstation. This is achieved by the provision of a locating sleeve within which the adjustment means is axially rotatable but which minimises relative movement between the adjustment means and the fixing nut when the device is installed.

For example, the locating sleeve may consist of a bush which surrounds the upper end portion of the adjustment means and internally abutting shoulders on the bush and the adjustment means respectively, minimise prevent relative axial movement between these two members. When the bush is fixed relative to the workstation, for example by press fitting within the top member of the workstation, relative movement between the adjustment means and the fixing nut press fitted within the workstation leg is also minimised. Alternatively, the locating sleeve may extend between the upper end of a tubular adjustment means and the fixing nut. The upper end of the tubular adjustment means may be flared radially outwardly in this form of the device so as to minimise axial movement of the sleeve and to provide a point at which the sleeve may provide support for the adjustment point. As a variation on this form of the device where the locating sleeve extends between the upper end of the adjustment means and the fixing nut, a washer may be slipped over the upper end of the height adjustment means and welded to the adjustment means adjacent its upper end to minimise axial movement of the sleeve and to provide a point for the sleeve to support the adjustment point. Since either variation of this, form of device minimizes axial movement of the sleeve between the upper (outer) end of the adjustment means and the fixing nut, the outer end of the adjustment means is maintained, in use, at a fixed height relative to the workstation. In order to enable its rotational movement, the adjustment means is keyed for cooperation with an adjustment key which when fitted into the adjustment means enables the means to be turned about its axis. The key in the adjustment means is preferably at its outer end for easy access. For example, a square- or hexagon- headed plug key may be fitted within a corresponding socket at the upper end of the adjustment means. Alternatively, a slotted key may be formed in the adjustment means for cooperation with a screw¬ driver-type adjustment key. As a further alternative, the upper end of the adjustment means may be in the form of a square- or hexagonal-section plug and cooperate with a corresponding socket of an adjustment key. Preferably the cooperation portions of the adjustment means and the adjustment key are hardened to minimise wear.

The device of the invention preferably includes a movable foot having a mounting stem attached to the base of the threaded shaft. The foot is preferably rotatable about the axis of the shaft and is further preferably tiltable relative to the shaft axis. This movement of the foot can be achieved by connecting the foot to its mounting stem by a ball joint.

In one preferred form of the invention a cover is provided to conceal the exposed portion of the threaded shaft after the adjustment of the workstation height has been made. For example, a flexible sleeve, preferably of concertina-like formation, can be placed between the foot and the fixing nut respectively.. In order to install the device of the invention within the leg of a workstation, the lower portion of the workstation leg is preferably cut off to enable the height of the workstation to be reduced. Thus, the normal height for an office desk is between 710 to 720 mm but the study of keyboard ergonomics indicates that a height around 620 mm is desirable. Adjustment of the height of a desk using the device of the present invention can readily accomodate height variation for the working surface of a normal desk within the range of 560 to 740 mm.

Another preliminary step in the installation of a device according to the present invention is the formation of a hole in the top member of the workstation so as to provide access to the top of the device and/or to permit the top of the device to be located within or adjacent to the top member. Accordingly, a hole of appropriate diameter is drilled or otherwise formed with its centre on the longitudinal axis of the leg within which the device is to be inserted. The device can then be inserted from the bottom of the leg with the top portion of the device being located in accordance with the design of the particular device at or adjacent the top surface member of the workstation.

The upper portion of the device may be recessed within the working station top member or within the tubular leg of the workstation. Alternatively the device may be designed so that its top edge is mounted flush with the working surface of the workstation top member. One preferred design for flush mounting with the working surface of the top member uses a bush as the locating sleeve and the bush is fitted tightly within the hole formed in the top member.

In the installation procedure the fixing nut is press fitted within the base portion of the leg and, if necessary, secured against rotation within the leg.

Devices according to the invention may be installed in one or more legs of a workstation depending upon the adjustment required and on the number of legs on the particular workstation. For example, if the working surface is to be sloped, it may be necessary to insert the devices of the invention only in the leg or legs on the far side of the workstation from the operator's working position. On the other hand, if a flat working surface is required a device of the invention should be inserted in all legs of the workstation. Installation of a device in all legs will, of course, allow adjustment of height and/or slope of the working surface.

Whatever the location of the upper portion of the device at or adjacent the top member of the workstation, the Iff hole formed in the top member can be concealed by an appropriate press-in plug after installation of the device has been completed. When adjustment of the device is required, any press-in plug can be readily removed and reinserted after adjustment has been made.

In order to increase or decrease the effective length of the leg in which the device is installed, and thus raise or lower the height of the workstation in the area of that leg, an adjustment key is fitted within the adjustment means and turned to extend or retract the threaded shaft until the 20 desired effective length of the leg is reached. The height of the workstation may thus be altered by appropriate adjustment of each leg within which a device is fitted until the desired workstation height is achieved.

In order to assist a further understanding of the invention, two preferred embodiments of the device will now be described with reference to the accompanying drawings in which:

Figure 1 is a section on a vertical plane showing a preferred form of device installed within one leg of a 0 workstation;

Figure 2 is a cross-sectional view on an enlarged scale taken through the device on the line II-II in Figure 1;

Figure 3 is a cross-sectional view on an enlarged scale taken on line III-III in Figure 1;

Figure 4 is a view similar to that of Figure 1 but showing an alternative form of device, not installed;

Figure 5 is a cross-sectional view on an enlarged 8 scale taken through the device on the line V-V in Figure 4. Figure 1 shows a workstation leg 1 secured to a workstation top 2 in the normal manner. One embodiment of a device in accordance with the present invention is installed within the workstation leg 1 and top 2. The height adjusting device of the invention illustrated in Figure 1 includes threaded shaft 3 which extends coaxially with drive shaft 4. As seen in Figure 2, drive shaft 4 is a rod of square cross-section. The upper end portion of drive shaft 4 is an axial sliding fit within adjustment means 5. Adjustment means 5 includes a square tubular section within which drive shaft 4 can move axially and is keyed at its upper portion to enable rotational movement of the adjustment means and hence the drive shaft about their common axis.

The threaded shaft 3 is threadedly mounted within fixing nut 6. Fixing nut 6 forms a close press fit within workstation leg 1. However, as workstation leg 1 has a circular cross-section, fixing nut 6 is secured against rotational movement within leg 1 by means of grub screw 7. Fixing nut 6 includes an outwardly extending flange 8 against which the lower edge of workstation leg 1 abuts.

The outer end of adjustment means 5 is keyed as shown by securing a hexagon headed nut 9 with its shaft welded as at 10 within the upper portion of the square section tubular portion of the adjustment means 5. A locating sleeve in the form of a bush 11 is fitted at the upper end of the adjustment means 5 so as to allow axial rotation of the adjustment means within bush 11. Bush 11 includes internal shoulders 12 and 13 which minimise axial movement between the bush 11 and the adjustment means, shoulder 12 bearing against the head of nut 9 while shoulder 13 bears against the end of the tubular portion of the adjustment means.

As illustrated, bush 11 fits tightly within the hole which has been drilled for its reception in the workstation top 2. It will also be noted that this form of the invention allows the device to be installed flush with the upper surface of the workstation top.

At the outer end of- threaded shaft 3 which is lowermost when the device is installed in its in use position, is attached a furniture foot 14 which is connected through, ball joint 16 to mounting stem 17. Ball joint 16 allows the workstation to remain on the floor while its height is adjusted by turning a key fitted for this purpose within the keyed portion of the adjustment means.

As indicated above, the key will be of appropriate configuration to cooperate with the keyed portion of the adjustment means so that in the embodiment of Figures 1 to 3 the key will include a male hexagon fitting. The male hexagon fitting can be mounted on any suitable device to assist turning of the adjustment means. For example, the male hexagon fitting can be mounted at the end of a screwdriver shaft or, preferably, to a crank handle to assist the turning which will raise or lower the height of the workstation_*

The alternative embodiment of height adjusting device as illustrated, in Figures 4 and 5 uses similar reference numerals for corresponding parts of the device to the embodiment of Figures 1 to 3. However, in this second embodiment, the outer end of the tube forming adjustment means 5 is flared outwardly to form a stop which prevents axial movement of the locating sleeve 11'. In this embodiment the locating sleeve 11* is a tubular member which extends between the flared outer portion 18 of the adjustment means 5 and the inner edge 19 of fixing nut 6. Adjustment means 5 •may be rotated about its axis within locating sleeve 11^* but while drive shaft 4 and the threaded shaft 3 are able to move axially when the adjustment means is rotated, the adjustment means itself is held by the locating sleeve 11' and cannot move axially.

The alternative form of the device which is illustrated in Figures 4 and 5 and can be fitted similarly to the device of Figures 1 to 3 but the upper end of the device does not need to be retained within the top member of the workstation. The locating sleeve of Figures 1 to 3 also need not be retained within the hole formed in the top member of the workstation or may be recessed below the upper surface of the top member. A press-in plug may be provided to cover the access hole which is formed in the top member, any plug being removed prior to fitting an appropriate key within the keyed portion of the adjustment means to adjust the height of the workstation.

Claims (9)

1. A height adjusting device for a workstation said device including a threaded shaft connected to and extending coaxial with a drive shaft, at least one internally threaded fixing nut on the threaded shaft and having a periphery adapted for press fit against rotational movement within a workstation leg adjustment means adapted to cooperate with the drive shaft allowing axial movement of the drive shaft but turning the drive shaft and its associated threaded shaft about their common axis, a locating sleeve within which the adjustment means is axially rotatable but which is mounted relative to the adjustment means so that in use relative axial movement between the adjustment means and the fixing nut press fitted within the workstation leg is minimised, said adjustment means being keyed for cooperation with an adjustment key which when fitting into the adjustment means enables the means to be turned about its axis.

2. The device of claim 1 wherein the drive shaft is of rod-like form and the adjustment means is tubular.

3. The device of claim 1 wherein the drive shaft is tubular and the adjustment means is of rod-like form.

4. The device of any preceding claim wherein the locating sleeve is a bush which surrounds the adjustment means at its outer end portion and wherein internally abutting shoulders on the bush and the adjustment means respectively minimise relative axial movement between them whereby when the bush is fixed relative to the workstation relative movement between the adjustment means and the fixing nut press fitted within the workstation leg is minimised.

5. The device of claim 2 wherein the outer end of the tubular adjustment means is flared radially outwardly so as to minimise outward "axial movement of a locating sleeve which extends between said flared outer end of the adjustment means and the fixing nut.

6. The device of any preceding claim wherein the fixing nut has an outwardly extending flange which forms a shoulder against which the lower end of a workstation leg will abut when the nut is press fitted within the leg.

7. The device of any preceding claim wherein a movable foot is attached to the base of the threaded shaft through a mounting stem, the foot being rotatable and tiltable in relation to the mounting stem through a ball joint.

8. The device of claim 1 substantially as herein described with reference to Figures 1 to 3 or Figures 4 and 5 of the accompanying drawings.

9. A workstation having at least one tubular leg, said leg containing a height adjustment device as claimed any preceding claim.