US 3364881 A
Description (OCR text may contain errors)
DRAFTING TABLE, WITH SINGLE PEDAL CONTROL OF E J. P. E. KOOI Jan. 23, 1968 VERTICAL MOVEMENT AND TILTING Filed April l2,- 1966 2 Sheets-Sheet 1 INVENTOR- JOHAN F! E. KOOI BY M lyn4 PATENT AGENTS J. P. E. KOOI 3,364,881 DRAFTING TABLE, WITH SINGLE PEDAL CONTROL OF BOTH Jan. 23, 1968 VERTICAL MOVEMENT AND TILTING Filed April 12, 1966 2 Sheets-Sheet 2 INVENTOR.
PATENT AGENTS United States Patent Oflfice 3,364,881 DRAFTING TABLE WITH SINGLE PEDAL CON- TROL OF BOTH VERTICAL MOVEMENT AND TILTING Johan P. E. Kooi, Ancaster, Ontario, Canada, assignor to Keuftel & Esser of Canada Limited, Montreal, Quebec, Canada Filed Apr. 12, 1966, Ser. No. 542,162 13 Claims. (Cl. 108-10) This invention is concerned with improvements in or relating to drafting tables, and especially to such tables which are adjustable so that an operator can change at will the inclination and/ or the height of the table.
A number of problems are encountered in the construction of an adjustable drafting table. It is usually desired that both the inclination and the height of the table be adjustable individually or simultaneously, preferably without one adjustment affecting the other, and yet the table top must be held securely at all times in the position to which it was last adjusted. The table top is usually comparatively heavy, and its weight must therefore be counter-balanced in some way. It has been known to use springs as counterbalances, but difiiculty is often experienced since the loading of the springs may vary with the position of the table, and means must be provided to adjust the spring loading to accommodate different types of top, and ditferent additional equipment that may be fastened to the top. In addition, the drafting table should have the usual commercial requisites of attractive external appearance, robust and trouble-free construction, and low initial cost.
It is an object of the present invention to provide a new adjustable drafting table.
It is another object to provide a new adjustable drafting table that permits ready adjustment of the inclination and/ or height of the table top by operation of a single control.
In accordance with the present invention there is provided a drafting table comprising a table body, a leg assembly mounted by said body for generally vertical movement with respect thereto, a table top mounted by said leg assembly for corresponding generally vertical movement with respect to the body and also for tilting movement with respect to the body about a generally horizontal axis, the leg assembly comprising a first leg member pivotally connected to the table top about the said horizontal axis, a second leg member movable relative to the first leg member and connected to the table top at a point spaced from said horizontal axis, and retaining means mounted by the table body and comprising first retaining means releasably retaining the leg assembly against said movement with respect to the table body and second retaining means releasably retaining the two leg members against the said relative movement for releasably retaining the table against the said tilting movement.
A drafting table which is a particular preferred embodiment of the invention will now be described, by way of example, with reference to the accompanying drawings wherein:
FIGURE 1 is a general perspective view of a drafting table, with parts thereof shown broken away as necessary for the opearting mechanism to be seen,
FIGURE 2 is a cross-section of a detail, taken on the line 22 of FIGURE 1,
FIGURE 3 is a view of a specific part of the table, namely a support leg thereof, with part broken away to show its interior,
FIGURE 4 is a view similar to FIGURE 1, of the lower part of the table, to show the said first and second releasable retaining means,
3,354,881 Patented Jan. 23, 1968 FIGURE 5 is a section taken along the line 55 of FIGURE 4, and
FIGURE 6 is a section taken along the line 66 of FIGURE 5.
In general, the new drafting table comprises a table body 19 mounted on two spaced elongated parallel feet 11, the body it supporting a table top 12 by means of an intervening leg support structure, which comprises two spaced leg assemblies 13. The arrangement is such that the table top can be raised or lowered relative to the body (as indicated by the arrows 14 in FIGURE 1), and can be also tilted at different inclinations relative thereto (as indicated by the arrows 15 in FIGURES l and 3).
The table top 12 can be of any conventional construction, and is rigidly secured to two spaced parallel supporting members 16 of channel form, the mouths of the channels opening downwards. Each member 16 is pivotally connected by a pivot pin 17 about a generally horizontal pivot axis, to a respective downwardly-extending hollow main leg member 18 of the associated assembly 13. Each member 16 is also pivotally connected, by a pivot pin 19 about a corresponding horizontal pivot axis generally parallel to the pivot axis of the pin 17, to a respective subsidiary leg member 29 which is capable of telescoping motion relative to and Within the associated main leg member 18. Each main leg member has a major straight portion thereof generally rectangular transverse cross section, with the two sides that constitute the shorter sides of the rectangle bifurcated by respective longitudinal slots 21, so that the furcations constituting the said two longer sides are capable of some freedom of movement towards and away from one another in directions parallel to the said shorter sides. A flat plate 22 extends between the longer sides parallel thereto and approximately midway between them, being mounted for limited sideways floating movement on three spaced pins 23 (FIGURES 2 and 3).
Each subsidiary leg member 21 is also bifurcated, comprising two spaced solid bars which extend on either side of the plate 22, each bar being generally in easy rubbing sliding contact with the plate and with the immediately adjacent longer side, A pin 24 extends between the two bars, engages the rear edge of the plate 22, and is constrained to move in the gap between the said rear edge and the immediately adjacent shorter edge of the member 18.
The tilting motion of the table top is specifically illustrated in FIGURE 3, and it will be seen that the pivot pin 17 may be regarded as fixed, while the pin 19 moves in an are on the centre provided by the pin 17 (as indicated by the arrow 15), The pin 24 constrains the bottom end of the subsidiary leg to follow a straight line pa th, while the hollow main leg 18 is sulficiently long or deep in its transverse cross-section to accommodate the transverse motion of the subsidiary leg upon the said relative telescoping motion.
Each leg assembly 13 is individually mounted for free vertical movement in the table body 10 by means of two pairs of grooved rollers 25, the pairs being spaced vertically from one another, and the two rollers of each pair engaging respective shorter sides of the main leg member. The rollers are mounted by conventional means in two spaced parallel channel members 26, disposed with their mouths facing one another, the members 26 in turn being securely mounted in any suitable manner in the frame 27 of the table body. In this particular embodiment the frame 27 comprises rigid members connected in a boxlike structure, to which decorative panels such as 28 are fastened, but in other embodiments other arrangements may be employed, as will be apparent to those skilled in the art.
A bracket 29 is fastened to the lower end of each main leg member and has connected thereto one end of a respective chain 30. Each chain passes over a respective sprocket 31 that is fixed to and rotatable with a shaft 32 rotatably mounted in bearings carried by a plate 33 fastened to the members 26. The other end of each chain is fastened to arespective end of a counterweight 34. This counterweight is mounted for free vertical movement in the table body by two pairs of rollers 35, each pair being mounted at a different end of the counterweight, and engaging one web of an L-section member 36 fastened to the adjacent member 26. It will be seen that the members 26 and 36 are somewhat inclined to the vertical, so that the rollers 25 are held in engagement with the said web by gravity. As the two leg assemblies move upward, the counterweight 34 moves downward, and vice versa, the chains 30, the sprockets 31, and the common axle 32 constituting a positive connection between the assemblies which causes them to move together and ensures that the table pivot axis will remain horizontal for all positions of the table.
In this embodiment the counterweight 34 is in the form of an open-topped box into which Weights of various types may be loaded, e.g. metal or cement pieces, or even sand, until the desired counter balance with the table top and leg assemblies is achieved. The effective weight of the counterbalance remains constant for all positions of the table, and its effective weight can be adjusted with precision at any time. if the weight of the table top is changed, e.g. by substituting a top of a different size, or adding a drafting instrument, the counterbalance weight can quickly and simply be changed correspondingly.
A counterbalance problem is also encountered in the tilting of the table top, in that sometimes a bare top is used, while at other times a relatively heavy drafting machine is clamped to the top edge thereof and unbalances the top, causing it to try to tilt as soon as the clamp means are released. To provide the necessary balance a channel member 37 is screwed to the under side of the top, as by screws 38, to provide an open-ended passage into which a counterbalance weight 39 of suitable size can be slid and retained therein by set screws such as 49. It will be understood that the appropriate Weight 3? is first chosen, and then the counterweight 34 adjusted for the total weight of the table top etc. A portion 41 of the member 37 extends beneath the lower edge of the table and provides a pencil trough.
Means for releasably retaining the table top at any in clination and height to which it has been set by an operator will now be described. A relatively massive fixed clamp bar 42 is mounted at each side of the table body at the top thereof, between the two channel members 26. Two spaced parallel pins 43 extend from the fixed bar 42 and a movable clamp bar 44 is mounted for free sliding movement on the pins 43, the bars 42 and 44 and the pins 43 constituting a clamp assembly which embraces the part of the leg assembly at which the two leg members are bifurcated and are telescoped together. If a suitable releasable clam ing force is applied to the movable bar 44 then the main leg members 13, the two bars of the subsidiary leg member 20 and the plate 22 are clamped tightly in contact with one another, preventing simultaneously the said vertical and tilting movements of the table. It will be seen that the plate 22 has a function in addition to guiding the pin 24 of providing two additional surfaces for frictional clamping engagement with the bars of the leg member Ztl.
In this embodiment the means for providing the releasable clamping force comprises two push rods 45, mounted with their longitudinal axes coextensive in respective cross bars 46, one end of each rod being connected to a'respective movable bar 44, while the two immediately adjacent ends a e engaged with a wedge cam 47, Referring especially to FIGURE 6, the wedge cam 47 comprises a wedge member 48 mounted in a U-shaped member 49 and clamped rigidly therein by a pushrod which has a screw-threaded portion passing through the base of the U-member 4% and the cam member 48. The position of the wedge cam longitudinally of the rod 50 can be adjusted by means of two nuts 51, while the length of the push-rods can be adjusted by nuts 52 thereof. The other end of the rod Stl'is connected by a pivot pin 53 to a lever 54, which is in turn pivoted by a pin 56 to uprights 57 of the body 10. The lever 54 is biased or urged in the upward direction (as seen in the drawings) by a plurality of tension springs 58 (only two shown) connected between a movable transverse bar 59 of the lever 54 and a fixed transverse bar 6% mounted in the uprights.
The springs 58 urge the rod upward in the direo tion of the arrow 61 in FIGURE 6, causing the wedge cam 47 to urge the rods 45 outward in the direction of the arrows 62, so that the required clamping force is applied to the a bars 44. An operator wishing'to change the height and/or the inclination of the table top steps on a foot pedal 63 of the lever 54 and depresses the lever in the direction of the arrow 64 against the action of the springs 58, thereby moving the rod 51} downwards in the direction of the arrow 65 and permitting the rods 45 to move in the directions of the arrows 66. The operator at this time has both hands free to adjust the table, which is virtually weightless because of the action of the counterweight 34, and has virtually no tendency to tilt about its pivot axis because of the action of the counterweight 39; when the table position is adjusted to his satisfaction, the
operator merely releases the foot pedal 63, whereupon the table is clamped securely in its new position.
Various modifications are possible. For example, al though in this embodiment the two members of each leg assembly telescope one within the other, it is contemplated that in other embodiments they will simply move verti cally relative to one another side by side. Other forms of retaining means can be provided, such as movable retaining pins which enter holes in the leg members, but such means do not provide such a wide range of adjust ment as those particularly illustrated. Other forms of clamping means may also be provided, for example, pivoted pads which are individually spring engaged with the leg assemblies, and are released from a single operators control by means of connecting flexible cables. Other em bodiments within the scope of the appended claims will be apparent to those skilled in the art.
What we claim is:
1. A drafting table comprising a table body, a leg as sembly mounted by the body for generally vertical movement with respect thereto, a table top mounted by said leg assembly for corresponding generally vertical movement .with respect to the body and also for tilting movement with respect to the body about a generally horizontal axis, the leg assembly comprising a first leg member pivotally connected to the table top about the said horizontal axis, a second leg member movable relative to the first leg member and connected to the table top at a point spaced from said horizontal axis, and retaining means mounted by the table body and comprising first retaining means releasably retaining the leg assembly against said movement with respect to the table body and second retaining means releasably retaining the two leg membersagainst the said relative movement for releasably retaining the table against the said tilting movement.
2. A drafting table as claimed in claim 1, wherein the said first and second leg members are telescoped one within the other.
3. A drafting table as claimed in claim 1, wherein the said first and second releasable retaining means comprise a single clamp means mounted by the table body, releasably clamping each leg assembly to the table body against the said vertical movement with respect thereto, and releasably clamping the said first and second leg members of each leg assembly together to retain them against the said relative movement therebetween.
4. A drafting table as claimed in claim 1, and comprising two spaced leg assemblies, and means connecting the said leg assemblies for simultaneous vertical movement.
5. A drafting table as claimed in claim 1, wherein the second leg member is movable vertically relative to the first leg member and is pivotally connected to the table top about a second axis spaced from and parallel to the first axis, said second releasable retaining means comprising means retaining the two members against the said vertical movement.
6. A drafting table as claimed in claim 1, and comprising means at least adjacent the lower edge of the table top for the reception and retention of a counterbalance weight for balancing the table top in said tilting movement thereof. Y 7. A drafting table as claimed in claim 5, wherein the said first and second leg members are telescoped one within the other for the said vertical relative movement.
8. A drafting table as claimed in claim 5, wherein the second releasable retaining means comprise clamping means which clamp the said first and second leg members together to retain them against the said relative movement.
9. A drafting table as claimed in claim 5, wherein the said first and second releasable retaining means comprise a single clamp means mounted by the table body, releasably clamping each leg assembly to the table body against the said vertical movement with respect thereto, and releasably clamping said first and second leg members of each leg assembly together to retain them against the said relative vertical movement therebetween.
10, A drafting table as claimed in claim 3, wherein each leg assembly comprises a hollow first leg member bifurcated along its length to provide two parts thereof movable toward and away from one another, a second leg member slidably telescoping Within the first leg member, and wherein the said clamping releasable retaining means comprise two clamping members mounted by the table body, each for clamping engagement with a corresponding movable part of the first leg member, and means for urging the two clamping members toward one another.
11. A drafting table as claimed in claim 10, wherein the said second leg member is bifurcated along its length and there is provided a plate member rigidly connected 6 with the first leg member, disposed between the bifurcations of the second leg member and against which the said furcations are clamped.
12. A drafting table as claimed in claim 10, wherein the said urging means comprise a horizontally movable push-rod engaging one of the clamping members, a wedge cam engaging the said push-rod, a vertically movable pushrod for moving the wedge cam, spring means urging the vertically movable push-rod to apply clamping force to the last-mentioned clamping member, and a foot-operated pedal for moving the vertically movable push-rod against the urge of the spring means.
13. A drafting table comprising a table body, a leg assembly mounted by said body for generally vertical movement with respect thereto, first means for releasably retaining the leg assembly against said vertical movement With respect to the table body, a table top mounted by said leg assembly for tilting movement with respect to the body about a generally horizontal axis, the leg assembly comprising a first leg member pivotally connected to the table top about the said horizontal axis, a second leg member movable relative to the first leg member and pivotally connected to the table top about a second axis spaced from and parallel to the said horizontal axis, and second means for retaining the two members against the said vertical movement to releasably retain the table top against the said tilting movement.
References Iited UNITED STATES PATENTS 928,185 7/1909 Dey 108--l47 1,859,456 5/1932 Nestler 1082 1,956,546 4/1934 Froelich 108-2 2,646,322 7/1953 Laxo 108l47 2,710,780 6/1955 Lawes 1082 2,775,497 12/1956 Alvarez 108146 2,860,938 11/1958 Marti 1082 2,924,299 2/ 1960 Kanzelberger et al. 188-67 3,140,559 7/1964 Grow et a1. 1086 3,213,809 10/1965 Kritske 108-146 BOBBY R. GAY, Primary Examiner. GLENN O. FINCH, Assistant Examiner.