US2899772A

US2899772A - Drafting board mechanism with automatic retraction means

Info

Publication number: US2899772A
Authority: US
Publication date: 1959-08-18
Anticipated expiration: 1976-08-18

Description

Allg- 18, 1959 I P. l.. PAULSEN ETAL 2,899,772

DRAFTING BOARD MECHANISM WITH AUTOMATIC RETRACTION MEANS fnvenfof" faul 5..Faulserp and Zaad? ffc'zfjelefjger Allg- 18, 1959 P. l.. PAuLsEN ET AL 2,899,772

DRAFTINC BOARD MECHANISM WITH AUTOMATIC RETRACTION MEANS Filed Feb. 6, 1958v 6 Sheets-Sheet 2 Nbl fraz/e nim-'5.' Paul L. fczus's-n Victor E Hier-:s ma Claude '.V fa'fzjele/jger @,'Qmm LA r @3 GNN ' P. l.. PAuLsEN vx-:T AL

Aug. 18, 1959 2,899,772

DRAFTING BOARD MECHANISM WITH AUTOMATIC RETRAC'TION MEANS Filed Feb. 6, 195e e sheets-sheet 5 d A i A A A 3%@ um E WJ?, ^AQ AMM ww e QH ma f 0 .K/M M IT n .H .0 Al ff@ f 0 A @ima fy u@ QA, .kvm wwwwmnwwww ,|||||,|||||||||\|1l||||l|||MIMINMM: hwwww www in .1| WMIHMIMIIMMMH Hwwmwmm P. L. PAULSEN ETAL Aug. 18, 1959 DRAFTING BOARD MECHANISM WITH AUTOMATIC RETRACTION MEANS Filed Feb. 5, 1958 6 Sheets-Sheet 4 fnverzors" faul l. ,Paulien Aug. 18, 1959 P. l.. PAuLsEN ETAL DRAFTTNG BOARD MECHANISM WITH AUTOMATIC RETRACTTON MEANS Filed Feb. e, 195e 6 Sheets-Sheet 5 fm@ ..fauzek Aug. 18, 1959 P. 1 PAULSEN ET AL- DRAFTINC BOARD MECHANISM WITH AUTOMATIC RETRACTION MEANS Filed Feb. 6, 1958 6 Sheets-Sheet 6 m. a r 3. n @MMV w JmL L ,JW fm1/J m Y @ff/M JL rfv, i LT! www @NN NS h v .S

NNN QNN DRAFTING BOARD MECHANISM WITH AUTO- MATIC RETRACTON MEANS Paul L. Paulsen, Victor H. Hiers, and Claude G. Kanzelberger, Two Rivers, Wis., assignors to Hamilton Manufacturing Company, Two Rivers, Wis., a corporation of Wisconsin Application February 6, 1958, Serial No. 713,677

14 Claims. (Cl. 45-131) This invention relates to drafting board mechanism.

For some time past there has been a demand for a desk and drawing board unit for engineers and draftsmen that permits the Worker to sit at a desk while having a drawing board readily available and accessible and to which he may turn by merely rotating his chair without interference by the desk. Features of such a unit are disclosed and claimed in copending patent application of Paul L. Paulson et al. Serial No. 691,774 liled October 22, 1957.

The present invention is a further development of and improvement on the disclosure of said patent application and aims to provide a drawing board in such an arrangement which may not only be rotated angularly but may also be moved inwardly and outwardly on a pivoted frame so as to elevate the board, in vertical or near vertical positions thereof, sufficiently to permit working thereon in a standing position, if desired, degrees of elevation being made possible 'by improved and simplified mechanism therefor.

An important object of the present invention is the provision that when the drawing board and its frame are rotated toward the horizontal position the board is positively and automatically retracted on the frame.

Further objects of the invention are improved counterbalancing means for the board in its selective reciprocal adjustments on the frame, and means counterbalancing the frame and board in angular movements thereof.

A still further object of the invention is a provision for releasably locking the frame and board in a predetermined reciprocable position and for locking the frame in a predetermined angular position on the stand.

These and other objects of the invention will be apparent from the following `description taken together with the accompanying drawings, showing an illustrative embodiment of the invention, and in which drawings:

Figure 1 is a side elevational view, of a drawing board and mechanism therefor, a stand being shown in section, a horizontal position of the board and frame being shown in full line and selective angular position in broken lines; v

Figure 2 is a back view of the board and frame in vertical position, the board being retracted on the frame;

Figure 3 is an enlarged view, broken away to save space, taken on the line 3 3 of Fig. 2;

Fig. 4 is a further detailed section on the scale of Fig. 2 taken on the line 4 4 of Fig. 2;

Figure 5 is an enlarged vertical section on the line 5 5 of Fig. 2;

Figure 6 is a further enlarged cross-section of one of the tracks, taken on the line 6 6 of Fig. 2;

Figure 7 is a vertical section on the scale of Fig. 3, taken on the line 7 7 of Fig. 6;

Figure 8 is a vertical section, at right angles to Fig. 7, taken on the line 8 8 of Fig. 6, and being also a section taken on the line 8 8 of Fig. 7;

Figure 9 is an enlarged fragmentary side elevational view of the support rod and frame locking mechanism, showing in broken lines adjustable Aselective positions of the parts;

nited States Patent ICC Figure 10 is a face View of parts shown in Fig. 9;

Figure 11 isan axial section taken on the line 11 11 of Fig. 10 still further enlarged;

Figure 12 is a perspective view of parts shown in Figs. 9, 10 and ll;

Figure 13 is an enlarged fragmentary face view of parts of the board locking mechanism Igenerally shown also in Fig. 2, with the mechanism in released position;

Figure 14 is a plan view of the locking mechanism of Fig. 13 in locked position, being a section taken on the line 14-14 of Fig. 2 and also a section on the line 14 14 of Fig. 15;

Figure 15 is a face View of the board locking mechanism in locked position with the cover cut away;

Figure 16 is an enlarged longitudinal sectional view of the cable bob;

Figure 17 is a fragmentary enlarged axial View taken on the line 17 17 of Fig. 3;

Figure 18 is a reduced perspective view showing the board and the frame therefor mounted on the stand; and

Figure 19 is a somewhat schematic view showing the retractor cable for the drawing board.

Referring 'in detail to the illustrative construction shown in the drawings, the numeral 20 indicates a base for the drafting board which in this instance is shown in the form of a stand 21 that is angularly related to a draftsmans or engineers desk 22 (Fig. 18). The stand 21 mounts the angularly adjustable or rotatable frame 23 that slidingly carries the drawing board 23a, the combination of the desk, angled stand and drafting board being described, and features thereof claimed, in said pending application Serial No. 691,774.

The stand 21 rotatably mounts the frame 23 thereon by means of bifurcated

brackets

24 and 25 each secured to a corner of the stand as at 26 and 27 (Fig. 3) and which at each end, on their inner furcations, journal the torque tube 28. The latter is an operative integral part of and rigid with the frame 23, the whole providing distortion resisting structural support for the drawing board. As best seen in Fig. 17, the torque tube 28 rotates on bearings 29 that are bolted to the

brackets

24 and 25 as at 30, on inner furcations thereof.

Welded to 'the torque tube 28, adjacent each end thereof, and between the

brackets

24 and 25 are a pair of

leg members

31 and 32 that have attachment lingers 33 that embrace and are rigidly secured to the torque tube 28. Rigidly secured to the

leg members

31 and 32 are the frame track members 34 and 3S` respectively that are shown screwed to the leg members as at 36 and 37. The track members 34 and 3S are therefore also rigid with the torque tube 28 to constitute a non-distortable U-structure with the torque tube. To enhance the rigidity of the frame parts referred to and for other purposes later pointed out, a cross bar 38 connects the

track members

34 and 35 intermediately of `their length, secured thereto as by screws 39, the bar 38 being in the form of a channel member with its channel facing the

members

34 and 35 and its outer face conveniently carrying rubber bumpers 40 that may engage the top surface 21a of the stand 21 (Fig. 18). At the outer ends of the

track members

34 and 35 is another cross bar 41 screwed to the track members as at 42 and being of reverse channel formation in cross-section, the one of the said channel formations through which the screws 42 pass facing outwardly as at 43 (Fig. 5) and 'the other facing inwardly as at 44, that is, toward the

track members

34 and 35. Y

The.

track members

34 and 35 as seen in Figs. 6, 7 and 8, are of box form and carry channel members 45 secured within the track `as by screws 46 and which in turn receive an outer ball race channel 47 also secured by the same screws 46. The outer race 47 has transversely curved sides 47a providing inwardly facing longitudlnal grooves 47h and slidingly contains a ball cage channel 4S that has at intervals spaced therealong, in its opposite side walls, round holes'49 for anti-friction b earmg balls 50. An inner race channel for the balls 50 v1s provided by the channel member 51 attached to the drawing board 23a and that has transversely curved sides 51a that provide outwardly facing longitudinal grooves 51h. The longitudinal grooves 47b in the outer race and the longitudinal grooves 51h -in the inner race provide complementary raceways for the balls 50 guidedrby the ball cage 4,8. Channel members 51 project into the

track members

34 or 35 through a longitudinal opening 52 in the latter. Channel member 45 reinforces the outer race 47 and an inner filler strip 53, of wood, reinforces the inner race 51. Screws 54 pass through the filler strip 53, through the channel 51, throughspacing washers 55 and into the drawing board 23a to secure the inner race channel rigidly to the board. It will be understood that the ball cage 43 rides back and forth in the tracks and channels on the frame and board respectively rin response to relative movement thereof to minimize friction therebetween.

By means of the two anti-friction track means thus provided on the frame 23, at each side of the drawing board 23a, the board is reciprocable by sliding movements with respect to the frame Within the limits of a pair of stops 56 on the board adjacent its inner edge and 57 adjacent its outer edge, at each side of the board, for engagement respectively with faces 58 and 59 alternatively on a bumper 60 tixed on each of the

track members

34 and 35 on the frame. Figure 2 shows the board in its innermost or retracted position with respect to the frame with the outer board stops 57 abutting the faces 59 of the bumpers 60. It will be understood that in the outermost reciprocated position of the board on the frame, the stops 56 of the board will contact the opposite faces 58 of the track bumpers'.

To releasably lock the board in selective reciprocated or sliding adjustment with respect to the frame, the frame carries a central cylindrical bar 61 secured at its inner end to the torque tube 28, as at 62, and at its outer end secured to the frame cross-bar 41, as at 63, and thus extending inthe direction of reciprocation of the drawing board. For cooperation with the bar 61,V

the drawing board carries manually releasable clamping mechanism indicated generally by the numeral 64 and which includes a pair of

pressure jaws

65 and 66 actuatable by a hand lever 67. Details of the mechanism are shown in Figs. 13, 14 and 15, as next described.

Secured to the board 23a, as by screws 68a, adjacent the rod 61 is a base plate 68 having return bent

flanges

69 and 70 along its upper and lower edges respectively. On the base plate 68 are iixed a plurality of

studs

71, 72 and 73 having heads 74 that pass respectively through laterally

elongated slots

75, 76, and 77 in a sliding plate 78 carried on the face of the base plate. Over the sliding plate 78 is another sliding plate 79 that has elongated

slots

80 and 81 therein registering with the

slots

75 and 76, the heads 74 of the studs being large enough to hold the sliding plates together in relatively slidable arrangement on the

studs

71 and 72. The sliding plate 78 is rigid ywith and carries the pressure jaw 65 and the sliding plate 79 is rigid with and carries the pressure jaw 66. These jaws desirably are lined with a yielding elastic material such as rubber or plastic, as indicated at 82 and 83 respectively (Fig. 14) for frictionally engaging the rod 61. By relatively moving the sliding

plates

78 and 79 in given opposite directions it will be apparent that the jaws will be moved together and will be clamped onto the rod, while, by relatively moving them in the reverse opposite directions, the rod will be released for sliding movement of the drawing board. For manipud lation of the sliding

plates

78 and 79, the hand lever 67 is pivoted as at 84 on the sliding plate 78 by one end of T-head 85 of the lever, the other end of the T-head being articulated as at 86 with a link 87 that is pivoted as at 88 on the sliding plate 79, thus constituting a toggle device. When the lever 67 is swung to the right as shown in full lines in Fig. 13 and in dotted lines in Fig. 15, the sliding plates 78 and '79 are moved relatively oppositely to open the jaws 65-66, while, when the lever 67 is moved to the left, in this instance, to a vertical position, the sliding plates 7S and 79 are moved relatively in opposite directions to clamp the jaws 65-66 together as by a toggle action of the lever head S5 and link 87. A stop 89 welded to the base plate 68 as at 89a and having a portion 89h overlapping the sliding

plates

73 and 79 in adjacency with the lever head 85 and link 87 when the latter are in clamping position prevents the lever from being further moved to the left from the vertical position to overrun the dead center of the lever head. The proximal end of the lever 67 desirably passes under a metal guard 90 secured to the drawing board by screws 91 at each end, which further limits undesired movement of the lever. The overhanging

flanges

69 and 70 of the base plate 67 have holes 93 drilled therein at each end respectively for screw securement thereto of a cover plate 94, the lower ange 70` and the cover being interrupted as at 70a to permit the lever 67 to pass oscillatably therethrough. When it lis desired to move the drawing board with respect to the frame, -the lever 67 is swung to the right, the board is then moved, and then the lever is brought back to the normal position with respect to the clamping device 64 thereby locking the drawing board to the frame ina given adjusted sliding position. The lower end of` lever 67 desirably depends below the lower edge of the drawing board for ready accessibility from the front of the board, as seen in Fig. 18.

Since the frame and drawing board are rotatable as a unit on the stand 21 -to tilt the board to a desired angle and since in vertical positions of the unit with respect to the stand, or positions approaching the vertical, the weight of the drawing board is considerable, thus tending to retract the drawing board toward the proximal or pivoted end of the frame, counterbalancing means are provided for otfsetting at least a part of the weight of the drawing board, such means being here represented by the strap and spiral spring mechanisms 95 carried at the back of the board on struts 96 axed to and between the cross bars 38 and 41 of the frame, as by screws 97 to the cross bars 33 and screws 98 to the cross bar 41, the struts 96 having an angular portion 99 to which the llange 100 of the spring mechanism housing 101 is ksuitably secured as by welding. Within the housing 101 is the usual clock type spring 102, one end of which is centrally anchored to a housing post 103 and to the free end of which as at 104 is secured one end of a flexible strap 105. The outer ends of the eXible straps 105 are led to clips 106 secured as by screws 107 to lthe back of the board adjacent its lower or inner end and to which the strap ends are respectively anchored. The struts 96 are desirably permanently tilted toward the clips 106 so as to facilitate free play of ythe strap 105 in the opening 108 in the base of the spring housing and a registering slot 109 in the llange 99 through which the strap 105 passes into and out of the housing as it, is wound up or released by its spring. The springs 102 ofthe mechanisms respectively are pre-tensioned so as to be under `greater potential stress when the drawing'board is at its innermost position with respect to the frame as seen in Fig.k2, and so as to wind up the straps as the drawing board'is moved oulwardly on the frame, but desirably the springs are also under tension when the board is in its outermost position on the frame so as at all times to'tend to resist inward movement thereof which might cause the drawing board to drop suddenly when the board and the frame are in vertical position and the lever 67 is released. The clamping mechanism 64 of course overcomes the tendency of the spring mechanism to move Ithe board outwardly when such outward movement is not desired.

Turning now to the means for supporting the drawing board and frame in selective angular or tilted position with respect to the stand 21, the frame 23 has `secured thereto at one side and intermediately thereof, in this instance on the track member 34, a bail 110 that rotatably journals a thimble 111 that is secured to the upper end of a support rod 112, the bail 110 being secured by ears 110a and screws 11013 to the track member extending laterally therefrom. The other or lower end of the support rod 112 passes downwardly through an elongated opening 113 in the stand top 21a, and, downwardly into the pedestal part 114 of the stand, Where it passes through a clamping mechanism indicated generally by the numeral 115 (Fig. 9) that is carried by and within the stand pedestal and which is manually actuatable by a knob or hand wheel 116 accessible on the outer face 117 of the stand pedestal 114 as next more particularly described.

The upright or pedestal part 114 of the stand 21 is of box formation and has the

parallel side walls

117 and 118. In the Wall 117 is an opening 119 (Fig. ll) reinforced by the collar 119a in which is a bushing 119b. lournaled in bushing 11912 is the reduced end 120 of an arbor 121 that has passed threadedly therethrough the screw shank 122 of knob 116. A retaining nut 123 is screwed onto the threaded reduced arbor end 120 on the outer face of wall 117. The inner end of the arbor 121 has secured thereto one end of a tubular bearing member 124, the other end of which is secured to a plug 125 that is centrally tapped to receive a cap screw 126 carried by the pedestal wall 118. Cap screw 126 turns in opening 127 that is reinforced by collar 128 on the inner face of the wall 118. Tube 124 may thus rotate in the

walls

117 and 118 while the knob 116 may be at the same time rotated with respect to the tubular member 124. Telescoped within the tubular member 124 is an inner tube 129 that has a closure 131) at its end adjacent the screw shank 122 and normally abutting the inner end of the latter. In the telescoped

tubes

124 and 129 are pairs of registering diametrically opposite holes 131 and 132 through which the lower end of the support rod 112 passes. When the knob 116 is rotated in a counterclockwise direction (Fig. 18), the shank 122 is unscrewed from the arbor 120 and the inner tube 129 is then free tomove, under the inuence of the support rod 112 to register the pair of holes 131 with the pair of holes 132, respectively, so that the support rod may move freely therethrough. Since the tubes 124-129 are rotatable in the

stand walls

117 and 118 they adjust themselves to angular movements of support rod 112, as indicated in Figs. l and 9. When, however, the knob 116 is rotated in a clockwise direction the shank 122 is screwed inwardly into abutment with the closure 138 of the inner vtube 129, which moves the latter axially of the outer tube 124 to tend to place the pairs of holes 131 and the pairs of holes 132, respectively, out of register and thus to pinch the support rod 112 and grip it against movement, thereby causing it to support the frame and drawing board in any selective angular or tilted position, from a horizontal position as shown in full lines in Fig. l to a vertical position as shown in broken lines in Fig. l. Other registering pairs of holes 131a and 132a in

tubes

124 and 129 permit free and ready passage therethrough of a cable 146 later described.

An intermediate angular position for the frame and drawing board also shown in broken lines in Fig. l is one at say 55 from the horizontal, this being an angular or tilted adjustment frequently used, and its has been found desirable to provide a releasable stop for the frame and drawing board in this position. To this end, the rotatable tube 124 has passed thereonto a hanger member 13341 having two parallel sides `133 and a front piece 134 that is of channel shape and isrwelded to the sides 133 as at 135. Circular perforations 136 in the sides 133 permit the hanger 133g to ride loosely on the cylindrical tube 124, the sides 133 of the hanger straddling the support rod 112. A washer 137 on the rod 1'12 that rides between the sides 133 keeps the hanger 133a aligned with the rod. The front piece 134 of the hanger is continued longitudinally in the direction of the rod 112, in both directions from the tube 124, and has an elongated slot 138 in its lower face. At the lower end of the rod 112 is a ferrule 139 that is held on the rod by a set screw 140 and that carries a button 141. Slot 138 is in the path of the button 141, the portion of the hanger front 134 that has the slot 138 therein thus providing a detent portion 142 for cooperation with the button 141. The lower end of this detent portion 142 is turned outwardly as at `142g so that as the frame and drawing board are raised from the horizontal position shown in full lines in Fig. l to the 55 or more position shown in broken lines in Fig. l, the button 141 engages the cam surface 143 of the detent and swings the detent away from the support rod until the button 141 rides in the slot 138. Since the lower end of the detent is heavier than its upper end and since in this angular position of the board the support rod oscillates at its lower end on its bearing 124 in the direction of the detent, the slot 138 and the button 121 are interengaged so that the board may then be lowered to the 55 position and held in that position so long as the detent `142 is engaged with button 141 as best seen in full lines in Figs. 9 and l0. Slot 138 is long enough so that the button 141 may ride therein while permitting raising of the drawing board to the vertical position. When it is desired to lower the drawing board to less than a 55 angle from the horizontal, the upper end of the detent 142 is manipulated by a finger of the draftsman acting upon the ngerpiece 144 of the detent 142 to rock detent 142 into dotted line position in Fig. 9. Fingerpiece 144 extends upwardly through the opening 113 in the stand in the 55 degree position of the frame (Fig. 9). By drawing the ingerpiece 144 toward the rod the button 141 is released from the slot 138, permitting lowering of the drawing board further toward the horizontal. As the drawing board moves toward the horizontal from the 55 angle the rod 112 oscillates in the opposite direction depressing the finger piece 144 below the upper surface of the stand, but this is not objectionable since the finger piece 144 need only be manipulated when the support rod 112 is in the position which it occupies when the drawing board is at the 55 angle.

1n the lowermost position of the drawing board and frame as shown in full lines in Fig. l, the detent 142 may, by gravity, swing away from the support rod 112, the lower end of the support rod '112 being at this time swung to the left from its position shown in Fig. 9 to its position as shown in full lines in Fig. l.

Since Va large size board is here contemplated, having considerable weight, means are provided for counterbalancing at least a part of the weight of the `drawing board and frame as the board and frame are lowered to the horizontal, such means being here illustrated by the coil spring 145 carried by encirclement von the rod 112 in abutment with the washer 137 which is between the hanger sides 133, this washer 137 thereby serving a dual purpose. At its other end the coil spring 145 in its expanded state, extends upwardly on the rod 112 in position to be contacted by the thim-ble 111 with which the upper end of the support rod 112 is articulated with the frame 23, so that, when the frame and board are droppsd, the spring 145 is placed under compression, resisting but not preventing ldownward movement of the frame and board and thereby cushioning the drop of the latter, spring 145 being placed under fuither compression as ythe frame is moved to the horizontal.

Moreover, for the reason that the drawing boardV may be of large area as here contemplated, it is desirable to provide positive and automatic means for retracting the drawing board on the frame 23, if it be in outwardly extended position thereon Vwhen the drawing vboard and frame are lowered from the vertical to the horizontal position, and representative means for this purpose will next be described.

A cable 146 or other flexible strand having Iat its lower end a stirrup 147 is hooked thereby onto a lug 148 carried yby the ferrule 139 at the lower end of the rod 112, the cable 146 from there running up parallel with the support rod 112 and passing over an idler pulley 149, to another idler pulley 150, from thence parallel with the frame 23 and board 23a, then over another idler pulley 151 at the outer end of the frame 23, and thence across the frame to a spring takeup device 152 carried on the frame 23. Pulley 149 as best shown in Figs. 9 and l() is rotatively carried on a bracket 153 welded or otherwise secured to the rotatable tube 124, the pulley 149 thus oscillating with the tube 124- and with the support rod 112 in their movements in accommodation to the angle of the drawing board and frame. Pulley 150 is rotatable on a pintle 154 carried on the outer furcation of bracket 24, the other furcation of lwhich supports one end of the torque tube 28 of the frame 23. Pulley 151V is `axled as at 155 on an extension 156 of the frame cross-bar 41. The takeup device 152 includes a spring housing 157 that is screwed as at 153 to the end of the frame cross-bar 41 opposite pulley 151 and to the reverse channel part 43 of the cross-bar. The terminal 146a (Fi-g. 4) of the cable 146 is connected to the clew 160k of the flat spiral spring 160 of the takeup mechanism and runs from there to the pulley 151 through the reverse channel portion 44 of the cross-bar 41. Strap 160:1 connects clew 1601) to spring 160.

Fixed on the cable 146, between the

pulleys

150 and 151 is a bob stop 161, that, in the outermost position of the drawing board 23a with respect to the frame 23, is abutted by a finger 162 on the drawing board that has an eye therein passing the cable 146 freely therethrough and which is rigid with a bracket 163 secured as by screws 164 to the underface of the drawing board 23a. As best seen in Fig. 16, the bob 161 has limited adjustability with respect to the cable 146 by being threaded onto the screw spool 165 through which the cable 146 passes, the e spool having reduced ends 166 and 166a that are crimped onto the cable to firmly secure the spool and cable together. A set screw 167 in the bob engages the spool 165 to x the adjustment of the bob 161 thereon. Since the lower end of the cable 146 moves with the lower end of support rod 112, as illustrated in Fig. 19, when the frame 23 is swung from the vertical position toward the horizontal, the bob 161 is drawn toward the pivot of the frame or torque tube 28 by the lower end of the support rod 112 acting through the cable 146. lf the drawing board is projected outwardly on the frame as in Fig. 19, the bob 161 engages the finger 162 and simultaneously draws the drawing board toward the pivot. By the adjustability of the bob 161, minor variations may be made in the point at which the bobengages the finger 162 and the point t0 which the drawing board is re tracted, to coincide with the action of board stops 56 and 57 and frame bumper 58 that determines the extreme positions of the board with respect to the frame. By the arrangement just described the board is retracted as it is swung down, thus avoiding hitting another adjacent object, which might be the head of another draftsrnan, where the desks are closely arranged in groups. Also, since the board is under tension by reason of the spring mechanisms 95 accidental outward movement of the board by release of lever 67 in the horizontal position, that might otherwise cause the board to strike an extraneous object by being propelled outwardly thereagainst, is prevented.

' In angular movements of the frame and drawing hoard, the spring takeup mechanism 152 not only maintains tension on the cable 146 :at all times but also moves the bob 161 out of theway of finger 162r to the limit permitted by the position of the lower end of the support rod 112. It will be observed from Fig. l, that only in the vertical position of frame 23 can the board be slid outwardly on the frame to its outer limit of movement thereon. In all other positions, outward movement of the board is limited by the bob 161. In the 55 tilt for example, shown intermediately in Fig. l, further outward movement of the board is prevented by the bob stop 161 engaging the finger 162, while, in the horizontal position of the frame, no outward movement of the board is permitted. In the innermost position of the board it desirably overhangs the pivot of the frame for enhanced convenience of the draftsman In the vertical position of the frame full upward and downward (outward and inward) movement of the board is permitted while the outward position of the board is progressively limited as the frame is moved nearer the horizontal. At the same time, the frame and board may be locked in selected positions, iboth with respect to the board and frame relatively to the stand and also with respect to the board and frame relatively to each other. 1n the locking means for the last mentioned purpose, the

slots

80, 81 and 77 (Figs. 13, 14 and 15) are so arranged as to require reciprocal movement of both plates 79 :and 7S in order to equalize pressure on

jaws

65 and 66 to ensure maximum efficiency.

The invention is not intended to be limited to details of construction shown for purposes of illustration. Furthermore, it may not be essential in all aspects of the invention to use all features thereof conjointly since various combinations and sub-combinations may at times =be :advantageously employed. For example, the stand and drawing board may tbe used Without the desk, by providing any suitable support therefor.

Such changes may be made as fall -within the scope of the appended claims without Ideparting from the invention.

See also application of Victor H. Hiers and Claude G. Kanzelberger, Serial No. 790,743, filed February 2, 1959, for Tiltable Drafting Board Support Means.

What we claim as our invention and desire to secure by Letters Patent is:

1. In drafting board mechanism, an angularly rotatable frame tiltable from a horizontal to a vertical position, a drawing board slidably mounted on said frame for inward and outward movement thereon, whereby the drawing board may be elevated in vertical positions of the frame, and means for automatically retracting the 'board on the frame in angular movements of the frame from the vertical toward the horizontal, wherein the retractive movement of the -board is effected progressively, whereby the board may :be moved outwardly a progressively less distance, from full movement in the vertical position of the frame to substantially no movement in the horizontal position of the frame.

2. The structure of claim 1 wherein the frame and board are supported in selective angular positions by a support rod and a traction cable is secured at one end to the lower end of said rod and at its other end to the outer end of said frame and said traction cable is carried on the frame through the intermediation of a spring that takes up the cable as the lower end of the support rod moves upwardly, said cable carrying intermediately thereon a stop that engages a finger on the board to effect said retraction in downward movements of the support rod.

3. Drafting board mechanism comprising .a stand, an angularly rotatable frame on said stand, a pair of tracks carried by said frame, a drawing board movably mounted on said tracks, counterbalancing means carried jointly by said frame and board resisting movement in one direction of the board on said tracks, means carried jointly by said `board and said frame for selectively locking the board in position on said tracks, and means carried jointly by said stand and frame for retnacting the board on said tracks as the frame is lowered to horizontal position.

4. The structure of claim 3 wherein said counter-balancing means includes a pair of flat spiral springs carried by said frame, and straps extending therefrom and secured to the board.

5. The structure of claim 3 wherein the locking means includes a cylindrical bar carried by the frame and a pair of gripping jaws carried by the board for gripping said bar.

6. The structure of claim 5 wherein said jaws are manipulated -by a manual toggle lever carried Iby the board, said toggle lever being articulated with a pair of sli-ding plates each of which carries one of said jaws respectively.

7. The structure of claim 3 wherein the board and frame jointly carry stop elements limiting movement of the board on said track, one of said stop elements being carried by a track.

8. The stnucture of claim 3 including means carried jointly by said stand and frame for counterbalancing at least a portion of the weight of the frame and 'board in angular positions thereof.

9. In drawing board mechanism, a stand, a trame pivotally mounted on the stand for selective angular adjustments with respect thereto, a drawing board movably mounted on the frame for inward and outward positions thereon, a support rod `articulated with the frame, means carried by the stand for releasably gripping the rod to hold the frame and board in selective angular positions, said gripping means being rotatable with respect to the stand to accommodate oscillatory movement of the rod with respect 'to the frame, a cable anchored to the lower end of said rod passing upwardly therealong, an idler pulley on said gripping means passing the cable thereover, another idler pulley of the stand adjacent said pivot,

and a third idler pulley on the frame adjacent the outer end thereof, the side of the frame opposite said pulley carrying a spring takeup mechanism for retracting the cable asy the rod is moved upwardly toward the vertical position of the frame and board, a stop member fixed on the cable, and a linger on the drawing board engageable by said stop member whereby the drawing board is retracted inwardly as the frame and board are moved from the vertical to the horizontal position.

10. The structure of claim 9 wherein the gripping means passes the cable freely therethrough.

ll. The structure of claim 9 wherein the linger passes the cable freely therethrough.

12. The structure of claim 9 wherein the stop member carried fby the cable is` adjustable longitudinally thereon.

13. The stnucture of claim 9 wherein the stop member on the cable is screw threadedly sleeved on a spool to which sections of the cable are secured and a set screw in the side wall of the stop member engages said spool.

14. In drafting board mechanism, a base, a frame angularly rotatably mounted Yon said base whereby to be tiltably elevatable thereon from a somewhat horizontal to a somewhat vertical position, a drawing board slidably mounted on said frame for inward and outward movement thereon in elevated positions of the frame, and means responsive to rotation of the frame toward the horizontal for automatically inwardly retracting the board on 'the frame.

References Cited in the le of this patent UNITED STATES PATENTS 762,530 Holman June 14, 1904 867,024 Egclin Sept. 24, 1907 1,942,727 OFarrell Jan. 9, 1934 1,956,546 Froelich Apr. 24, 1934 2,515,474 Ryder July 18, 1950