US2710780A

US2710780A - Tiltable drawing table top counterbalance structure

Info

Publication number: US2710780A
Application number: US402215A
Authority: US
Inventors: Lawes Francis George Ryland
Original assignee: LAWES BROS Ltd
Current assignee: LAWES BROS Ltd
Priority date: 1953-01-05
Filing date: 1954-01-05
Publication date: 1955-06-14
Anticipated expiration: 1972-06-14

Description

June 14, 1955 F. G. R. LAWES TILTABLE DRAWING TABLE TOP .COUNTERBALANCE STRUCTURE 3 Sheets-Sheet 1 Filed Jan. 5, 1954 Inventor a (/47 V AltorneyJ June 14, 1955 F. G. R. LAWES 2,710,780

TILTABLE DRAWING TABLE TOP COUNTERBALANCE STRUCTURE Filed Jan. 5, 1954 s Sheet s-Sheec 2 Inventor Attorneys June 14, 1955 i w s 2,710,780

TILTABLE DRAWING TABLE TOP COUNTERBALANCE STRUCTURE Filed Jan. 5, 1954 s sheets-sheet 3 4/ [I l [1/ A I A Inventor W Z fit! 2 Attorneys United States Patent" TILTABLE DRAWING TABLE TOP COUNTER- BALANCE STRUCTURE Francis George Ryland Lawes, Esher, England, ,assignor to Lawes Bros. Limited, Weybridge, Surrey, England, a company of Great Britain Application January 5, 1954, Serial No. 402,215

Claims priority, application Great Britain. January 5, 1953 2 Claims. (Cl. 31137) This invention comprises an improved drawing stand adapted for carrying a drawing board and having means for counterpoising the drawing board and drafting apparatus which may be mounted thereon. I

According to the invention, a drawing stand comprises an upstanding post, a drawing board (or mount for carrying the same adjustably or otherwise) pivotally connected to the post so that it may be tilted as desired, a tension spring housed within the post, one end of the spring being anchored to the post and the other end being connected to a cable which passes over a guide or pulley and is connected to the drawing board, or its mount, to one side of the pivotal point, the guide or pulley being carried by the post and being disposed at a point below the pivotal point, the arrangement being such that the said cable pulls on the drawing board or its mount on the said side of the pivotal point to counterbalance excess of weight of the drawing board, and/or of any apparatus mounted thereon, on the other side of the pivotal point.

Preferably the post is mounted in a base so as to be adjustable up and down, means being provided for locking the post in a plurality of positions relative to the base. The drawing stand may comprise weight counterbalancing means urging the post upwards and means for locking the drawing board or its mount in a plurality of positions relative to the post.

The invention is illustrated, by way of example, in the accompanying drawings in which:

Fig. l is a sectional elevation of a drawing stand according to the invention,

Fig. 2 is a section taken on the line II-II of Fig. 1,

Fig. 3 is a side elevation of the features illustrated in Fig. 2,

Fig. 4 is a section taken on the line IVIV of Fig. 1,

Fig. 5 is a part plan detail view of Fig. 4, and

Fig. 6 is a sectional elevation of a modified form of drawing stand according to the invention.

Referring to Figs. 1-5, a drawing stand comprises a hollow base casting 1 to the inside of whose front wall 2 is secured a bearing member 3. Slidably mounted within the bearing member 3 is an upstanding tubular post 4. The weight of the post 4 is balanced by a counter-weight 5 carried by a pair of cables 6 which pass over a pair of pulleys 7 which are rotatably mounted in an extension 8 of the bearing member 3, the other ends of the cables 6 being secured to a bridge piece 9 which bridges the base of the post 4. The provision of two cables 6 prevents undue swinging of the counter-weight 5.

The post 4 is provided with a pair of flats 10 (see Fig. 2) with which co-operate pads 11 carried by spigots 12, mounted in levers 13. One of the spigots 12 is provided with a left hand thread, the other being provided with a right hand thread. The spigots 12 are threaded within bushes 14 mounted within the bearing member 3, the bushes 14 being prevented from rotating within the bearing member 3 by grub screws 15. The levers 13 are pivoted to pull rods 16 (see Fig. 3) which are secured at their lower ends to an operating pedal 17. The

ing the casting to a floor.

2,710,780 Patented June 14, 1955 operating pedal 17 passes through an opening in the front wall 2 of the base casting 1 and is pivoted within the base casting at 18. The arrangement is such that downward pressure on the operating pedal 17 will cause the spigots 12 to rotate within the bushes 14 so as to withdraw the pads '11 from contact with the flats 10 on the post 4, thus enabling the post 4 to be moved vertically with respect to the base casting 1. Tension springs (not shown) are fitted to the operating pedal 17 and pull rods 16.so that when the said downward pressure is relieved, the pads 11 co-operate with the flats 10 to clamp the post 4 in position.

It will be appreciated that the clamping action of both pads 11 may be equalised. This may be effected by slackening olf the grub screws 15, adjusting the positions of the bushes 14 in the bearing member 3, and then re-tightening the grub screws 15.

Secured to the top of the post 4 is a tubular member 19 within which is journalled a tube 20 to which are pinned mounts 21 for a drawing board 22. The drawing board 22 is provided with drafting equipment 23.

The member .19 is provided with a slot 24 at its front. Within the slot 24 is disposed a pulley 25 which is partially disposed within a slot 26 in the post 4. A cable 27 is secured to a bracket 28 pinned to the tube 20, the cable passing over the pulley 25 and being connected to the top of a tension spring 29 housed within the post 4. The base of the tension spring 29 is secured to a nut 30 which is threaded on a screw 31 passing through the cross-piece 9, rotation of the screw 31 thus serving to alter the tension of the spring 29.

A dog clutch mechanism is provided for adjusting the position of the drawing board with respect to the post 4. The dog clutch mechanism comprises a toothed member 32 (see Fig. 4) pinned to the tube 20 and a toothed member 33 secured to the tubular member 19. The member 33 is urged into mesh with the member 32 by a compression spring 34 interposed between the member 33 and the bracket 28. Pivotally mounted on the member 32 is a lever 35 carrying a roller 36 adapted to bear against a flange 37 on the member 33. Pivotal movement of the lever 35 in the direction of arrow 38 will thus serve to disengage the

members

32, 33. The tube 20 may then be rotated within the tubular member 19 so as to bring the drawing board into a different position with respect to the post 4. When the lever 35 is released the spring 34 will cause the

members

32, 33 to mesh with each other. The teeth on the

members

32, 33 are so formed that the drawing board may be clamped in a plurality of angular positions relative to the post 4, the said angular positions being separated from each other by 10.

Referring to Fig. 6, which shows a modified and simpler form of the invention, a base casting 40 is provided with holes 41 for the passage therethrough of bolts for secur- The casting 40 is provided with an upstanding tubular portion 42 within which is housed the base of a tube 43. Mounted within and coaxial with the tube 43 is a tube 44 which is spaced apart from the tube 43 by a split collar 45. The tube 44 may be moved vertically within and clamped in a number of positions with respect to the tube 43 by means of a clip 46, the tube 43 being split in the region of the clip 46.

A drawing board 47 is secured, by means not shown, to a tube 48 rotatably mounted within a member 44' mounted in the top of the tube 44. Secured to the drawing board 47 is a quadrant 49 having an arcuate slot 50. A screwed pin (not shown) mounted on the tube 44 passes through the slot 50, the drawing board 47 being clamped in a desired position with respect to the tube 44 by means of a wing nut (not shown) threaded on the pin and bear ing against the quadrant 49.

A plate 51 is secured to the underside of the drawing board 47. Passing through a hole in the plate 51 is a cable 52 which passes over a pulley 53 and is secured to a tension spring 54 anchored to a member 55 secured to the base of the tube 44. The pulley 53 is disposed partially within a slot 56 in the tube 44 and is rotatably mounted in a clip 57 encircling the tube 44. The tension of the spring 54 may be adjusted by moving the cable 52 through the hole in the plate 51 and clamping the cable in a desired position by means of a grub screw 58.

The drawing board 47 carries a straight edge 59 which may be moved parallel to itself up and down the drawing board, the weight of the straight edge being balanced by a counterweight 60 secured to the straight edge by wires 61 passing over

pulleys

62, 63 at the top and bottom of the drawing board 47 respectively.

I claim:

1. A drawing stand comprising an upstanding post, means for mounting a drawing board, said mounting means being pivotally connected to the post so that it may be tilted as desired, a tension spring housed within the post, one end of the spring being anchored to the post, a guide carried by the post and disposed below the point at which the mounting means is pivoted to the post, and a cable connected to the mounting means to one side of the pivotal point, the cable passing over the said guide and being connected to the other end of the said spring, whereby the cable pulls on the mounting means on the said side of the pivotal point.

2. A drawing stand comprising an upstanding post, a drawing board pivotally connected to the post so that it may be tilted as desired, a tension spring housed within the post, one end of the spring being anchored to the post, a guide carried by the post and disposed below the point at which the drawing board is pivoted to the post, and a cable connected to the drawing board to one side of the pivotal point, the cable passing over the said guide and being connected to the other end of the said spring, whereby the cable. pulls on the drawing board on the said side of the pivotal point so as to counterbalance excess of weight on the drawing board to the other side of the pivotal point.'

References Cited in the file of this patent UNITED STATES PATENTS 520,630 Bramwell May 29, 1894 660,868 Reid Oct. 30, 1900 867,024 Egelin Sept. 24, 1907 1,354,743 Hang "Oct. 5, 1920 1,564,358 Elein Dec. 8, 1925 1,859,456 Nestler May 24, 1932 2,539,700 Piper Jan. 30, 1951 2,605,156 Laxo July 29, 1952 2,646,322 Laxo July 21, 1953 2,649,345 Hubbard Aug. 18, 1953