GB2112279A

GB2112279A - Counter balanced work tables

Info

Publication number: GB2112279A
Application number: GB08235765A
Authority: GB
Inventors: Hans Bertil Nilsson
Original assignee: SPACIO SYSTEM AB
Current assignee: SPACIO SYSTEM AB
Priority date: 1981-12-16
Filing date: 1982-12-15
Publication date: 1983-07-20
Also published as: FR2517942B3; ZA829043B; GB2112279B; FR2517942A3; SE444258B; CH659371A5; SE8107530L; DE8235050U1; IT8254066V0

Abstract

A balancing device for work tables, preferably drawing tables, comprises a stand 2, one or more lever arms 7, 8 pivotally mounted on the stand, a work-table top 14 mounted on the lever arm or arms and one or more balancing means for balancing items, including the work- table top, mounted on the stand via the lever arm or arms. The balancing means comprises a telescopic spring means 18 extending between the stand and the lever arm or arms. In order to reduce the risk of misadjustment of the spring means and at the same time quickly and easily carry out the mounting and adjustment operations necessary, each spring means 18 is pivotally journalled at its bottom end 19 on the stand 2 and at its top end on the lever arm 7,8 in one of a number of positions provided along an arcuate line CB, the centre C of which coincides with the lower support point of the spring means. <IMAGE>

Description

SPECIFICATION Improvements relating to work tables The present invention relates to a balancing device for work tables, particularly drawing tables, of the type comprising a stand, one or more lever arms pivotally mounted on the stand, a work-table top arranged on the lever arm or arms and one or more balancing means for balancing members, including the work-table top, mounted on the stand via the lever arm or arms, said balancing means comprising telescopically functioning spring means extending between the stand and the lever arm or arms.

It is known in height adjustable work tables, e.g. of the drawing-table type, to use gas springs for balancing the equipment such as the drawingtable top, drawing apparatus and lamp mounted on the table. While the weight of this equipment may vary within wide limits, e.g. 1 5-60 kg, it is necessary to vary the force by which the gas spring or springs affects the drawing table. In drawing tables in which height adjustment is provided by means of pivotable lever arms, it is known to mount one or more gas springs between the lever arm and the stand of the drawing table.

Adaptation to various loads is often very circumstantial, since it is necessary to mount gas springs with different pressure in order to make the adaptation possible.

It is also known to mount the gas spring or springs in various fixed positions along said lever arm such that different moments are obtained from the gas springs. The upper end of the gas spring is then pivotally mounted in one of several holes in said arm and the lower end thereof is mounted in a corresponding hole of an identical series of holes in the stand of the drawing table.

Hereby, it is possible to parallelly move the gas spring towards or away from the centre of rotation of the lever arm in the stand and thus attain the desired moment from the gas spring or springs.

However, this movement of the gas springs is circumstantial, since the position of the upper as well as the lower mounting of the gas springs must be adjusted. While it is generally necessary to search for the proper position for a satisfactory balancing of the drawing table, the position of the gas springs must be adjusted several times. Since the position of the gas springs in the series of holes present is not controlled, it is easy by mistake, to mount one or more gas springs in the wrong holes in the stand of the drawing table. The person working at the drawing table may perhaps not notice it immediately since correct balancing has been achieved, but the erroneously mounted gas spring limits the vertical movement of the drawing table such that the table does not achieve the intended function.To be able to move the gas springs in said series of holes, they must be carefully arranged parallel to each other, which means difficulties in manufacturing and the parallel movement of the gas springs generally also complicates a suitable building in thereof.

The present invention seeks to reduce or eliminate said drawbacks and provide in a device of the above type by simple means a suitable arrangement from various aspects, which primarily eliminates or at least to a great extent eliminates the risk for misadjustment of the spring means and at the same time shortens and simplifies the mounting and adjustment operations.

In accordance with the invention there is provided a balancing device for work tables, said device comprising a stand, one or more lever arms pivotally mounted on the stand, a work-table top arranged on the lever arm or arms and one or more balancing means for balancing the items, including the work-table top, mounted on the stand via said lever arm or arms, said balancing means comprising telescopic spring means acting between the stand and the lever arm or arms, the or each spring means being pivotally journalled at its bottom end on the stand and pivotally journalled at its top end on the lever arm in one of a number of positions, provided along an arcuate line on the lever arm, the centre of which coincides with the pivotal support point of the bottom end of the spring means.

In order that the invention may be better understood, an embodiment thereof will now be described by way of example only and with reference to the accompanying drawing in which: Figure 1 is a side view of a drawing table incorporating a device according to the invention; Figure 2 is a side view on a larger scale than Figure 1 of an upper mounting device for a spring means forming part of the device of Figure 1; and Figure 3 is a section of a lower mounting device for the same spring means, on the same scale as Figure 2.

Figure 1 illustrates a drawing table 1 comprising a stand 2 with two lateral members 3 (only one member is shown since they look the same). The lateral members 3 are connected to each other through a connecting spar (not shown) and each lateral member comprises a foot spar 4 and a tubular stand leg 5 which is open on top. A parallelogram-type linkage 6 is pivotally arranged on top of the stand leg 5 and said linkage includes two lever arms 7 and 8 which are pivotally mounted on said leg 5. These lever arms 7, 8 are pivotally connected to an inclining device 10 having a spring 11 for inclining load and a brake segment 12 which together with said spring 11 is connected to so called mounting rules 13 for a drawing-table top 14.The drawing table 1 also comprises a brake lever 1 5 for height adjustment and a brake wheel 1 6 for adjusting the inclination, but these units have no connection with the present invention.

The parallelogram-type linkage 6 is mounted on each lateral member 3 and the support means of the linkage on the stand leg 5 are covered from the outside by lateral plates 1 7 screwed onto said stand leg 5.

For balancing the drawing-table top 1 4 and various accessories arranged on said drawing table top 14, balancing means are mounted between the stand 2 and the linkage 6. Said means comprise, more specifically, telescopic spring means 18, e.g. of gas spring type, which is journalled at its bottom end within the stand leg 5 and at its top end on a flange 7a, which latter is mounted on the lever arm 7 adjacent to said stand leg 5.

In order to facilitate the mounting and/or adjustment of the spring means 1 8, it is journalled at its bottom end to pivot about at point C. At its top end, the spring means 1 8 is set at a position L3 of a number of positions L1--L8, provided along an arcuate line CF3, the centre of which coincides with the point C, i.e. the lower support point of the spring means 1 8.

In the embodiment shown, the positions LI -L8 are defined by holes, the centres of which coincide with the arcuate line CB. As an alternative to the holes, a longitudinal slit (not shown) may be provided, the centre of which coincides with the arcuate line CB, but such an arrangement may in certain cases create problems, since retainment of the spring means at a certain point in the slit may require clamping of the joint.

For each mounting of spring means 18, the stand leg 5 is equipped with a bracket 1 9 which is open in an upwards direction and which permits downwards insertion of the spring means 1 8 therein and setting without being locked against extraction in upwards direction but against sideways sliding. Hereby, the spring means 1 8 is easily extracted from the stand leg 5, when required, without previous release and a new spring means 18 may be inserted into the stand leg 5 until it engages the bracket 1 9 without the need to anchor it at the bottom end.

The bracket 1 9 has preferably the shape of a yoke and is vertically adjustable relative to the stand leg 5. This vertical adjustment may be brought about by means of an eccentric knob having a handle 20 arranged outside the stand leg, said handle having an axle neck 21 protruding into a hole in said stand leg 5. An axle 22 is eccentrically arranged on said neck 21 and carries the bracket 1 9. This arrangement means that the upper clamping position of the spring means 1 8 is quickly and easily adjusted. This is achieved by locking the linkage 6 after setting thereof in an upper position relative to the stand 2, whereafter the handle 20 is rotated to thereby move the bracket 1 9 downwards. Thereafter, the spring means 1 8 may be moved to another upper clamping position.When the spring means 1 8 has reached a new upper clamping position, the bracket 1 9 is moved upwards to starting position.

It is apparent from the drawing, that the spring means 1 8 is for the most part hidden in the tubular stand leg 5 and protrudes therefrom.

Only one spring means 1 8 is shown in the drawing, but preferably, one spring means 1 8 is provided in each stand leg.

The invention is of course not limited to the embodiment described above and shown in the drawing, but may vary within the scope of the following claims. Thus, the invention may be used with other types of drawing tables and with a wide variety of work tables for different purposes.

Instead of cooperating with the lever arm 7, the spring means 1 8 may cooperate with the lever arm 8. The lever arm 7 forms a part of a parallelogram system as shown, but this is not necessary while the lever arm 7 may be arranged in another way. The upper and lower mounting points of the spring means 1 8 may of course also be provided in another way while maintaining the features essential for the invention. Finally, it may be noted that the definitions stated with regard to the centre point C, arcuate line CB and positions L1-L8 are desired ideal positions which in practice are difficult to attain. Therefore, said definitions should be interpreted to lie within practicable limits that are reasonable in this regard.

Claims

1. A balancing device for work tables, said device comprising a stand, one or more lever arms pivotally mounted on the stand, a work-table top arranged on the lever arm or arms and one or more balancing means for balancing the items, including the work-table top, mounted on the stand via said lever arm or arms, said balancing means comprising telescopic spring means acting between the stand and the lever arm or arms, the or each spring means being pivotally journalled at its bottom end on the stand and pivotally journalled at its top end on the lever arm in one of a number of positions, provided along an arcuate line on the lever arm, the centre of which coincides with the pivotal support point of the bottom end of the spring means.

2. A balancing device according to claim 1, wherein each position on the lever arm for the spring means is obtained by providing a hole, the centre of which coincides with said arcuate line.

3. A balancing device according to claim 1, wherein a plurality of positions for the top end of the spring means on said lever arm is obtained by providing a longitudinal slit, along which said spring means may be anchored in various positions, the centre of the slit coinciding with the arcuate line.

4. A balancing device according to any one of the preceding claims, wherein the stand is equipped with at least one bracket into which the spring means is insertable and settable without being locked against extraction in upwards direction but against sideways sliding.

5. A balancing device according to claim 4, wherein the bracket is vertically adjustable on the stand.

6. A balancing device according to either one of claims 4 or 5, wherein the bracket has the shape of a yoke.

7. A balancing device device according to any one of the preceding claims, wherein said stand takes the form of a tubular leg.

8. A balancing device according to claim 7, wherein the most part of said spring means is positioned within said tubular leg and protrudes therefrom.

9. A balancing device according to claim 8, wherein the upper end of said spring means is connected to a lever arm forming part of a parallelogram system of arms.

10. A balancing device for work tables substantially as hereinbefore described with reference to the accompanying drawing.

11. A work table when fitted with a balancing device as claimed in any one of the preceding claims.