GB1598980A - Drafting board support - Google Patents

Description

(54) DRAFTING BOARD SUPPORT (71) We, REPPISCH-WERKE AG, a Swiss Body Corporate, of 23 Bergstrasse, Dietikon,Switzerland, do hereby declare the invention. for which we pray that a patent may be granted to, and the method by which it is to be performed, to be particularly des cribed in and by the following statement: The invention relates to a drafting board support. The support includes an upright column which supports the drafting or draw ing board proper. Conventionally, the board forming the working surface is adjustable about a horizontal axis and the board can be locked after proper adjustment.

The rigid locking devices which have been employed heretofore are subject to damage if the board should be exposed to excessive loads.

An object of the invention is to construct a support for a drawing or drafting board wherein the adjustment mechanism may not be damaged even if heavv loads should be applied thereby extending the useful life of the support.

A further object is to provide an adjust ment mechanism for a drafting or drawing board which is of simple and light con struction and which permits rapid adjust ment to substantially improve the useful life of a drafting apparatus according to the invention.

According to the invention there is pro vided a support for a drafting board com Xrisino a pair of opposite support members for s connection to the board, said members in cluding resilient extensions. a hollow support shaft having a conical surface at each end, means for mounting said hollow shaft on a horizontal axis to extend between said mem bers. brake bushings having conical surfaces engaging the conical surfaces of the shaft.

said bushings being carried by said resilient extensions. a rod extending through said shaft, abutment means on the ends of the rod engaging the outer surfaces of said resilient extensions. one of said abutment means in cluding a cam member, the arrangement being such that in the operative position of the cam member, the cam member, through the said one abutment means, presses against the associated resilient extension and causes the brake bushings and conical surfaces to tightly engage and frictionally restrain movement of the support members relative to the shaft; and that in the released position of the cam member, the resiliency of the extension causes the brake bushings to move away from the associated conical surfaces so as to allow tilt adjustment of the horizontal members relative to the shaft about said horizontal axis.

In order that the invention may be clearly understood, it will now be described, by way of example, with reference to the accompanying drawings, wherein: Figure 1 illustrates the drawing or drafting board base according to the invention in a vertical, axial section, whereby the board is shown in its loweed position; Figure 2 illustrates the upper portion of the base and parts of the board whereby the latter is in its elevated position; Figure 3 is a longitudional section through the horizontal tilting bearing of the drafting board or table along the section line III-III in Figure 1; Figure 4 is an elevational view of an arm of a pedal for operating the height adjustment device of the drafting board, including a sectional view through respective brake elements: and Figure 5 is a horizontal sectional view through the upright column shown in Figure 1 along section line V-V.

Referring to Figure 1 there is shown an upright column 1 secured to a pedestal 2 forming together the base proper. The upright column 1 is a hollow sectional member inside of which there is arranged a hollow column 4 carrying at its top the table or board 3. The hollow column 4 is adjustable in its elevational position and secured against rotation by guide means inside the upright column 1. The guide means comprise two longitudinal guide grooves 5 arranged in the hollow column 4 at two oppositely positioned longitudinal edges thereof. Adjacent corners of the hollow column 4 form corner guide grooves 6 which receive balls 7, whereby the inner hollow column 4 is guided without anv play. Two brake plates 9 rest against the hollow column 4 which is adjustable in its elevational position.These brake plates 9 make it possible to block the hollow column 4 relative to the upright column 1 when the hollow column 4 is in its extended position.

The brake pressure is exerted by means of a spring bail X having a U-configuration. The bail 8 is constructed as a brake pedal. The bail 8 is provided at its upper end with legs into which there are inserted pressure bolts 18 forming the lilting axis of the bail 8. The pressure bolts 8 extend through a respective ore in a bearing plate 39. The brake plates 9 are guided in openings 17 arranged opposite each other in the outer hollow upright column 1. The spring elastic legs 8' of the bail 8 press the bolts 18 against the brake plates 9 which in turn rest against the inner hollow column 4. Conical discs 19 are arranged on the bearing plate 39 below the pressure bolts 18 and on the outer surface of the upright column 1.In operation, when the bail 8 is tilted toward the upright column 1, that is in the direction of the arrow A. the bail legs 8' are spread apart by the discs 19 and the brake dilates 9 are relieved from the brake load.

us, the elevational position of the drafting board 3 is adjustable. Upon release of the bail 8. the latter simultaneously tilts back into the original position due to its inherent spring characteristic. whereby the brake plates 9 are again subjected to the full brake load. Incidentally. in Figure 1 the brake position of the bail 8 is shown in full lines and the release position of the bail 8 is shown in dash-dotted lines.

As best seen in Figure 2. the drawing or drafting board 3 which is rotatable about the vertical axis X-X. shown in Figure I. reaches with a vertically extending, conical brake piston 10 into a respectively shaped conical recess formed with a vertical axis in a support member 11 which is rigidly secured to the hollow column 4. The axially upwardly facing end of the brake piston 10 is provided with an axiallv extending recess 20. A spring element 12 functioning as a clamping disc is located in the recess 20. A clamping screw 21 extends through the spring element 12 and is threaded into member 11. The spring element 12 is effective against the bottom of the depression 20 of the brake piston 10 through the head 21' of the clamping screw 21 and through an axial bearing 12'.The conical brake piston 10 is thus pressed into the hollow conical recess in the support member 11.

whereby the brake pressure is produced. The brake pressure may be adjusted as desired by adjusting the clamping screw 21. The piston 10 and the member 11 function as an over load clutch so that the drafting or drawing board held normally rigid with the column 4 may be rotated about the vertical upright column axis as desired by the user.

As shown in Figure 3 a horizontally ex tending tubular support shaft 13 is rigidly connected to the conical brake piston 10 by welding. The support shaft 13 has conically tapering ends 15 which reach into respectively shaped hollow conical recesses in brake bushings 36 secured to the surfaces of supporting sectional members 34 which surfaces face each other. The board 3 is fixed to the members 34. Depending legs 35 of the members 34 exhibit a degree of resiliency for a purpose to be described.

A rod 22 extends axially through the support shaft 13. An abutment member 23 is located at one end of the rod 22 and rests against the leg 35 of the supporting sectional member 34. The abutment member 23 is tiltable about a bolt 23' out of its normal position substantially across said pull rod into a position substantially axial relative to said pull rod 22 so that the rod 22 may be pushed from one side into the support shaft 13. An actuating lever 14 is arranged on the left side or on the right side of the structure. An eccentric abutment member 25, forming part of the actuating lever 14, is rotatbly secured by means of a journal bolt 26 at the other end of the rod 22. The eccentric member 25 is effective for cooperation with a support member 24 which rests against the outer surface of the leg 35 of the support sectional member 34.An abutment 27 serves for location of the horizontal position of the table.

Under normal load or stress applied to the board 3 during use, the brake pressure produced bv the eccentric member 25 is sufficient to prevent tilting of the drawing board 3 about the support shaft 13. The resilient extensions or legs 35 of the support sectional members 34 bend slightly intermediate the clamping position and the non-clamping position. Said resilient legs 35 extend approximately at right angles relative to the drawing board 3. The resilient extensions or legs 35 of the support sectional members 34 tend to pull the two brake bushings 36 with their conical recesses into their positions in which they do not provide a brake clamping action when the eccentric member 25 is released.

As shown in Figure 1. a piston cylinder arrangement 29 is located inside the hollow column 4. The piston cylinder arrangement 29 rests on the pedestal 2 to which the outer upright column I is secured, for example, by a bushing 2'. The piston 30 of the piston cylinder arrangement 29 is spring supported and operatively connected to the support member 11 with its conical recess. Since the latter is connected through the conical bear ing member 10 to the shaft 13 and is also connected to the inner hollow column 4, the piston cylinder arrangement 29, 30 provides a support also for said inner column in the manner of a gas spring. Thus, the gas spring support of the just described components assists in an effortless elevational adjustment of the drafting board 3.The assistance or load relief could be achieved by other well known means not necessarily of the gas spring type as just described. A disk spring element 31. for example of the bellville type.

serves as an end stop for limiting the stroke of the drawing board 3 in the downward, lowered direction.

In operation, the above described brake plates 9 secure the inner hollow column 4 against an elevational displacement except when the vertical force applied to the board 3 exceeds the frictional force between the brake plates 9 and the hollow tube 4 or when the ball 8 is moved to relieve pressure on the brake plates.The clamping disk spring element 12 and the clamping screw 21 secure the board 3 against rotation about the vertical axis X-X. except when during normal adjustment the respective forces applied to the board 3 bv the user exceed the force determined by the disk spring element 12 and the friction between the conical member 10 and the conical surface of the recess in the support member II. The third braking action is accomplished by the friction between the tapering ends 15 of the support shaft 13 in the conical recesses of the brake bushings 36 in cooperation with the eccentric member 25.

This third braking action prevents a tilting of the board 3 about the horizontal axis of the support pipe 13 unless an applied force exceeds the braking force or unless the lever 14 is actuated to release the clamping member 25 thereby relieving pressure on the resilient extensions 35.

Reference may be made to our copending application No. 16758/78 Serial No. 1598979 in which other features of the construction herein described are claimed.

WHAT WE CLAIM IS: 1. A support for a drafting board com rising a pair of opposite support members tor connection to the board, said members including resilient extensions. a hollow support shaft having a conical surface at each end. means for mounting said hollow shaft on a horizontal axis to extend between said members, brake bushings having conical surfaces engaging the conical surfaces of the shaft, said bushings being carried by said resilient extensions, a rod extending through said shaft, abutment means on the ends of the rod engaging the outer surfaces of said resilient extensions, one of said abutment means including a cam member, the arrangement being such that in the operative position of the cam member, the cam member, through the said one abutment means, presses against the associated resilient extension and causes the brake bushings and conical surfaces to tightly engage and frictionally restrain movement of the support members relative to the shaft; and that in the released position of the cam member. the resiliency of the extensions causes the brake bushings to move away from the associated conical surfaces so as to allow tilt adjustment of the support members relative to the shaft about said horizontal axis.

2. A support as claimed in claim 1 wherein the abutment means remote from the cam member is pivoted to the rod so that it can be moved to a position in which it can be pulled through the hollow support shaft whereby the cam member can be located selectively at either end of the hollow shaft.

3. A support as claimed in claim 1 or 2 wherein said means for mounting said hollow shaft provides for vertical adjustment and for swivelling about a vertical axis of said shaft.

4. A support as claimed in claim 1 wherein the hollow shaft and associated rod. abutment means and bushings are constructed substantially as described and substantially as shown in Figure 3 of the accompanying drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (4)

**WARNING** start of CLMS field may overlap end of DESC **. assists in an effortless elevational adjustment of the drafting board 3. The assistance or load relief could be achieved by other well known means not necessarily of the gas spring type as just described. A disk spring element 31. for example of the bellville type. serves as an end stop for limiting the stroke of the drawing board 3 in the downward, lowered direction. In operation, the above described brake plates 9 secure the inner hollow column 4 against an elevational displacement except when the vertical force applied to the board 3 exceeds the frictional force between the brake plates 9 and the hollow tube 4 or when the ball 8 is moved to relieve pressure on the brake plates.The clamping disk spring element 12 and the clamping screw 21 secure the board 3 against rotation about the vertical axis X-X. except when during normal adjustment the respective forces applied to the board 3 bv the user exceed the force determined by the disk spring element 12 and the friction between the conical member 10 and the conical surface of the recess in the support member II. The third braking action is accomplished by the friction between the tapering ends 15 of the support shaft 13 in the conical recesses of the brake bushings 36 in cooperation with the eccentric member 25. This third braking action prevents a tilting of the board 3 about the horizontal axis of the support pipe 13 unless an applied force exceeds the braking force or unless the lever 14 is actuated to release the clamping member 25 thereby relieving pressure on the resilient extensions 35. Reference may be made to our copending application No. 16758/78 Serial No. 1598979 in which other features of the construction herein described are claimed. WHAT WE CLAIM IS:

1. A support for a drafting board com rising a pair of opposite support members tor connection to the board, said members including resilient extensions. a hollow support shaft having a conical surface at each end. means for mounting said hollow shaft on a horizontal axis to extend between said members, brake bushings having conical surfaces engaging the conical surfaces of the shaft, said bushings being carried by said resilient extensions, a rod extending through said shaft, abutment means on the ends of the rod engaging the outer surfaces of said resilient extensions, one of said abutment means including a cam member, the arrangement being such that in the operative position of the cam member, the cam member, through the said one abutment means, presses against the associated resilient extension and causes the brake bushings and conical surfaces to tightly engage and frictionally restrain movement of the support members relative to the shaft; and that in the released position of the cam member. the resiliency of the extensions causes the brake bushings to move away from the associated conical surfaces so as to allow tilt adjustment of the support members relative to the shaft about said horizontal axis.

2. A support as claimed in claim 1 wherein the abutment means remote from the cam member is pivoted to the rod so that it can be moved to a position in which it can be pulled through the hollow support shaft whereby the cam member can be located selectively at either end of the hollow shaft.

3. A support as claimed in claim 1 or 2 wherein said means for mounting said hollow shaft provides for vertical adjustment and for swivelling about a vertical axis of said shaft.

4. A support as claimed in claim 1 wherein the hollow shaft and associated rod. abutment means and bushings are constructed substantially as described and substantially as shown in Figure 3 of the accompanying drawings.