The present invention relates to a vertically adjustable work table comprising a pair of mutually parallel link arms at each side of a stand, said pairs being connected by a crossbar, each said pair of parallel link arms being journalled at a first end to said stand and at a second end to a respective side piece arranged either side under a table top, said side pieces connecting to a frame arrangement positioned under the table top, which each sidepiece enclosing a gas spring means, each gas spring means being journalled between the upper link arm and the upper edge of the side piece or the frame arrangement under the table top, whereby the gas spring means arranged on one side is lockable and the gas spring means on the other side is adapted to accommodate various loads on the work table.

It is previously known to design vertically adjustable work tables in which gas spring means are used for the vertical positioning. The utilization of fixed gas spring means and a parallel linkage is previously known from, for example, SE- -B-9003607-0 , with one end of respective gas spring means being attached to said parallel linkage. The attachment points can be placed so that good functioning is achieved within the whole positioning range of the table, but this is only valid for a certain predetermined load. If a variation of this load is desired, the filling pressure of the gas spring means must be altered in order to achieve a satisfactory function.

It is also previously known to adapt the design according to the above variable loads. This is achieved by making the attachment points of one or both pistons movable. This design however only works satisfactorily within certain lifting ranges. The table top usually has to be lifted to bring it to an elevated position and pressed down in order to transfer it to a low position or vice versa. This is mainly due to

shortcomings in the gas spring means which, in an extended position, lose power.

The object of the present invention is to provide a vertically adjustable work table employing gas spring means, which eliminates the above problems and which allows the height of a loaded work table to be varied using minimal positioning force, even when the load is varied. This object is fulfilled according to the invention by means of each respective gas spring means at each respective side is attached to different attachment points so that the gas spring means seen in a side elevational view essentially form a cross ans that the spring constants of the gas spring means differ substantially.

In order to enable the work table to be adapted to different loads, according to a special feature of the present invention, the lower attachment point of the gas spring means which is adaptable to the work load is moveable along the upper link arm.

According to another special feature of the present invention, the lower attachment point of the lockable gas spring means is displaced in relation to the upper link arm by means of a protruding attachment section on the upper link arm, which section preferably displaces the attachment points vertically upwards.

According to a preferred embodiment of the present invention, the spring constant of the lockable gas spring means is lower than the spring constant of the gas spring means adaptable to the workload, whereby the relationship between these spring constants is preferably 1:3.

The invention will be further described in the following, with reference to the attached drawings, in which Fig. 1

shows the assembled vertically adjustable work table, Fig 2 is a side elevational view of the work table in which a side piece has been removed in order to more clearly show the positioning of the gas spring means, and Fig 3 is the corresponding side elevational view of the other side of the table.

In the drawing, 1 generally denotes a work table according to the invention comprising a table top 3 supported by a frame 2.

The above mentioned frame comprises i.a. a stand 4 and, at its upper end, a pair of mutually parallel pivotally arranged link arms 5, which are connected via a crossbar 6 and, at a second end, pivotally attached to side pieces 7 on each side, which are arranged under a table top. The table top 3 is placed on a frame 8, which connects to the upper edge of the side pieces and represents the last essential part of the framing.

Gas spring means 9, 10 are arranged diagonally at the side of the work table, inside the side pieces, in a way which will become evident from Fig. 2 and Fig.3.

One of the gas spring means 10 is equipped with a locking mechanism 11 whereby the table can be locked in a specific position after adjustment. This gas spring means is fixedly attached at both its ends 10a, 10b, though the attachment at each end is journalled in order to enable said positioning. The attachment point 12 of the lockable gas spring means is displaced in relation in relation to the upper link arm so that this attachment point lies somewhat above the upper link arm.

The other gas spring means is fixed at its upper end 9a but has a moveable lower attachment point for adjustment to the

desired load on the work table. The gas spring means is journalled at both these attachment points. The displacement of the lower attachment point is made along the upper link arm, preferably by means of an adjustment screw 13, so that unwanted changes do not occur.

As can be seen from Fig.2 and Fig.3, the gas spring means 9,

10, are arranged so tat they form an angle , β with the table top 3, which lies in the horizontal plane. The adjustment of the gas spring means adaptable to the workload

9 causes this angle to vary. In order to achieve the object of the invention, the two gas spring means have different attachment points so that when the lockable gas spring means

10 forms an angle α with the table top, the corresponding angle β for the adaptable gas spring means 9 varies between

180°-α and the 90° which corresponds to the end position of the adjustment screw 13. The two gas spring means 9, 10 are thus arranged so that in a side elevational view they essentially form a cross.

In order for the invention to work satisfactorily, the spring constants of the gas spring means must differ. The lockable gas spring means preferably has a low pressure, while the gas spring means with the adjustable attachment has a substantially higher pressure. In a preferred embodiment of the invention this relationship is 1:3.

When the work table is in its normal state, its position is locked. In order to carry out an adjustment of the table height, the locked gas spring means 10 must first be released. This is done via a control handle 11 which is preferably placed at the front edge of the work table. A "weightless" adjustment of the table height can thereafter be performed. When the desired position is reached, the control handle 11 is released, whereby the locking of the design is reinstated. The table thereafter once again works as an

ordinary work table. In order for the height adjustment to work satisfactory, the gas spring means 9, 10 must be adapted to meet the load on the table. This is achieved by altering the adjustment screw 13 of the adaptable gas spring means 9. With a change of load on the work table and a subsequent desired height adjustment, the table must first be adjusted to the right load by means of the adjustment screw 13, after which the height adjustment can be performed as above.