US3848544A

US3848544A - Drafting tables

Info

Publication number: US3848544A
Application number: US00324839A
Authority: US
Inventors: J Douglas
Original assignee: Individual
Current assignee: Individual
Priority date: 1973-01-18
Filing date: 1973-01-18
Publication date: 1974-11-19
Anticipated expiration: 1991-11-19

Abstract

Drafting tables for schools and colleges having steel frames with rear leg arrangements which ensure stability on uneven floors without special adjustment. The tables also all include a single ratchet associated with the frame, engageable by the lower end of a rod the upper part of which extends horizontally under the drawing board, and which is rotatable by a handle to release the lower end of the rod from the ratchet and to thus allow adjustment of the board angle. One embodiment includes a single rear leg and ratchet foldable into the plane of the front legs so that the whole table can be folded flat.

Description

United States Patent [191 Douglas [4 1 Nov. 19, 1974 1 1 DRAFTING TABLES [21] Appl. No.: 324,839

283,083 5/1952 Switzerland 108/6 142,745 11/1903 Germany 108/4 63,830 5/1913 Switzerland 108/9 210,074 3/1924 Great Britain..... 248/1882 28,941 12/1902 Great Britain 108/6 1,239,237 10/1959 France 1 108/8 Canada 108/6 Primary Examiner-Paul R. Gilliam Attorney, Agent, or Firm-Stevens, Davis, Miller & Mosher [57] ABSTRACT drawing board, and which is rotatable by a handle to release the lower end of the rod from the ratchet and to thus allow adjustment 'of the board angle. One embodiment includes a single rear leg and ratchet foldable into the plane of the front legs so that the whole table can be folded flat.

3 Claims, 14 Drawing Figures i/ /3Z /3 I E J 35 l 26 [52] U.S. Cl. 108/6 [51] Int. Cl. A47f /12 [58] Field of Search 108/1-10, 115;

[56] References Cited UNITED STATES PATENTS 196,381 /1877 Plluegner .1 248/397 418,687 1/1890 Collins 656,256 8/1900 Leisenring 987,113 3/1911 Cooley 1,184,594 5/1916 Nagy 1,399,706 12/1921 Ellison 2,016,571 10/1935 Barrett 2,630,360 3/1953 McGinley 2,686,094 8/1954 Terry 2,912,046 11/1959 Fuerst 3,473,491 10/1969 Grzywacz 108/6 FOREIGN PATENTS OR APPLICATIONS 205,642 10/1923 Great Britain 108/9 PATENTtLmvlslsm 3,848,544 SHEET 30F 6 DRAFTING TABLES This application is a continuation-in-part of my US. Pat. application Ser. No. 172,184 filed Aug. 16, 1971, now abandoned.

The present invention relates to a table, and particularly to a drafting table for use in schools and colleges.

Drafting tables at present in use generally have four fixed legs. Such tables are apt to rock either due to inaccuracies of manufacture, or due to uneveness of the floor on which they rest, so that normally such drafting tables require adjustment means for one leg in order to be satisfactory.

An object of the present invention is to provide a table, particularly a drafting table, of simple construction which is quite stable on uneven floors, and requires no adjustment of its legs.

Other objects of the invention are to provide tables with improved ratchet arrangements for adjusting the angle of the table top or board means, and to provide a foldable table having these features.

In accordance with one aspect of the present invention, in a table having a support frame and board means mounted on the support frame by pivot means allowing tilting of the board means about a horizontal axis, said board means is adjustable to a variety of angular positions relative to the support frame by means including a single ratchet mounted on the frame, a rod having an upper shaft portion extending horizontally under the board means and rotatably attached thereto, the rod having a lever portion extending downwardly from said upper shaft portion and having ratchet engaging means at its lower end engageable and disengageable with said ratchet on rotation of said shaft portion, and handle means for rotating said shaft portion.

Preferably, the support frame includes a front cross member rigidly connecting upper portions of the front leg members, and a further member extending rearwardly from the cross member and having the rear leg means connected onto its rear end. The rear leg means may be a simple single rear leg, or may include a rear upright member extending downwardly from the rearwardly extending member, a rear cross member mounted for limited angular movement on said upright member, and rear feet attached to the outer ends of said rear cross member.

The limited angular movement of the rear cross member is preferably of the order of 1.

Where the rear leg means is a single rear leg, the rearwardly extending member may be hingedly attached to the cross member, to allow the whole table to be folded flat.

It will be understood that the term front" refers to the side of the table at which the person using the table normally stands, the rear ofthe table being the opposite side.

A further feature of tables in accordance with the invention is that the board means comprises a flat board, for example of wood or plastic, supported by stiffening means including two brackets spaced apart and extending fore-and-aft of the board, the brackets being rigidly connected by a bar which is sufficiently stiff in torsion to prevent warping of the board itself. The brackets each include a depending flange which also serves to connect the board means with hinge means carried by the support frame.

The invention will be particularly described with reference to the accompanying drawings, in which;

FIG. 1 shows a perspective view of a first embodiment of drafting table in accordance with the invention,

FIG. 2 shows a front view of the table,

FIG. 3 shows a side view of the table,

FIG. 4 shows a top, plan view of the table,

FIGS. 5 and 6 show detailed side views of part of rear leg means,

FIG. 7 shows a perspective view of a second, simpler drafting table using a similar board and hinge arrangement,

FIGS. 8 and 9 show, respectively, front and side views of the table of FIG. 8,

FIG. 10 shows a top plan view of the table of FIG. 8,

FIGS. 11, 12 and 13 show respectively side, rear and top plan views of a third embodiment of drafting table, and

FIG. 14 shows a perspective front view of the third embodiment of drafting table when folded flat.

Referring to FIGS. 14 of the drawings, a drafting table is shown having drawing board means 10 mounted for tilting movement about a horizontal axis on a support frame 11, this axis being adjacent the front edge of the board means. The support frame comprises two upright front leg members 13, a cross member 14 connecting the upper portions of the leg members 13, a member 15 extending rearwardly from the center of cross member 14, and a single, central, rear leg means 17 extending downwardly from the rear end of member 15. The rear leg means comprises a rear upright member 18 extending downwardly from the member 15, a rear cross member 19 mounted at 20 for limited angular movement on member 18, and rear feet 21 attached to the outer ends of the rear cross member. The members 13, l4, l5 and 18 are all formed of 1 inch square section 18 gage steel tubing, securely welded together to make a rigid structure. The top of leg member 18 extends above the level of the

horizontal members

14 and 15, and is capped with a resilient cap to form a support for the rear edge of the board means 10.

The drawing board means 10 comprises a flat board 24 of 5/6 inch thick Macrolite (trademark), fixed to stiffening means comprising two

angle member brackets

25 and 26 extending fore and aft of the board and adjacent to the side edges of the board, and joined at their rear ends by a torsion bar 27 of 1 inch steel tubing securely welded to the brackets. The brackets have their horizontal flanges securely fixed to the board, and the bar 27 is sufficiently stiff in torsion to prevent any substantial warping of the board. The

brackets

25 and 26 each have a vertical flange which increases in depth towards the front edge of the table. The lower front corner of each of the vertical flanges is pivotally secured to the outside of a front leg member at a point just above the cross member 14, in such manner as to allow tilting movement of the board about a horizontal axis parallel to the cross member. The pivot means attaching the brackets to the leg members 13 include a fibre, friction washer, and a conical, resilient pressure washer, which are tightened to give sufficient frictional resistance to pivoting of the board to prevent the board dropping under its own weight.

Beneath the rearwardly extending member 15 is attached a single vertical ratchet 29, comprising a sheet steel member having a vertical slot with a series of notches in the rear edge of the slot. As will be clear from the drawings, the ratchet is located in a central position between the side edges of the board means 10. The ratchet is engageable by means at the end of a lever formed by the lowest part 30 of a rod 31 which is pivotally mounted on the board means. The rod 31 has an upper shaft portion 32 extending horizontally under the board means, parallel to the front edge of the board, and held by small brackets 33 so as to be rotatable about its own axis. The lever portion 30 of the rod is bent at 90 to the shaft portion and extends downwardly from one end of the upper shaft portion and terminates in ratchet engaging means constituted by a bent-in end which engages with the notches of the ratchet 29. The outer upper end of the rod is bent to form a handle 35 situated under the right hand side of the board, so as to be convenient to the user of the board.

At the junction between the shaft portion 32 and the lever portion 30 of the rod there is welded one end of a flexible thin rod or wire 36, the other end of which is bent at 90 and secured to the underside of the board. Before being secured in this manner, the wire 36 is subjected to torsion, in such direction as to urge the lever 30 against the notches of the ratchet 29, so that this wire 36 forms a spring which holds the lever in the appropriate notches of the ratchet.

FIG. and 6 show details of the joint between the rear upright member 18 and the rear cross member 19. The joint includes two side plates 38 welded to the lower end of member 18 and extending below this lower end to form a recess for receiving the cross member 19. The member 19 is secured to the plates 38 by a pivot pin 39 passing horizontally fore-and-aft through holes in the plate 38. Thin washers are mounted between the plates 38 and the member 19, to prevent looseness in the assembly. The clearance space between the top of member 19 and the lower end of member 18 is sufficiently small (about l/64 of an inch), so that the angular movement of the cross member is limited to a few degrees, and preferably is of the order of l.

In operation, the tilted position of the drawing board can be adjusted by holding the board with two hands, with the fingers of the right hand holding the handle 35 and pressing this upwards, towards the board, to disengage the lower end of the lever 30 from the ratchet, so that the board can readily be adjusted to any tilted position.

The self-levelling nature of the rear leg means in practice ensures that the drafting table is steady even when placed on somewhat uneven floors, and no special adjustment of the leg means is necessary.

FIGS. 7 to 10 illustrate a somewhat similar drafting table to that of FIGS. 1 to 6, but in which a simple, single rear leg is provided instead of the self-levelling rear leg means of the first embodiment.

Referring then to FIGS. 7 to 10, the drafting table has a drawing board means 110 mounted for tilting movement about a horizontal axis on a support frame 111. The support frame comprises two upright front leg members 113, a cross member 114 connecting the upper portions of the leg members, a member 115 extending rearwardly from the center of cross member 114, and a single, central rear leg member 117 extending downwardly from the rear end of member 116. The

members

113, 114, and 117 are all formed of 1 inch square section 18 guage steel tubing, securely welded together to make a rigid structure. The top of leg member 117 extends above the level of the

horizontal members

114 and 115, and is capped with a resilient cap 118 to form a support for the rear edge of the board means 110.

The drawing board means 110 comprises a flat board 20 of 5/8 inch thick Macrolite (trademark), fixed to a stiffening means comprising two

angle member brackets

121 and 122 extending fore and aft of the board, and joined at their rear ends by a torsion bar 123 of 1 inch steel tubing securely welded to the brackets. The brackets have their horizontal flanges securely fixed to the board, and the bar 123 is sufficiently resistant to torsional deflection to prevent any substantial warping of the board. The

brackets

121 and 122 each have a vertical flange which increases in depth towards the front edge of the table. The lower front corner of each of the vertical flanges is pivotally secured to the outside of the front leg at a point just below the cross member 114, in such manner as to allow tilting movement of the board about a horizontal axis parallel to the cross member. The pivot means attaching the brackets to the leg members 113 include a fibre, friction washer, and a conical, resilient pressure washer, which are tightened to give sufficient frictional resistance to pivoting of the board to prevent the board dropping under its own weight.

Inside the rear leg member 117 is attached a vertically extending ratchet comprising a sheet steel member having a vertical slot with a series of notches in the rear edge of the slot. The ratchet is engageable by means at the end of a lever formed by the lowest part 125 of a rod 126 which is pivotally mounted on the board means. The rod 126 has an upper shaft portion 127 extending horizontally under the board means, parallel to the front edge of the board, and held by small brackets 128 so as to be rotatable about its own axis. The lever portion 125 of the rod is bent at 90 to the shaft portion and extends downwardly from the board and terminates in a bent-in end which engages with the notches of the ratchet. The outer upper end of the rod is bent to form a handle 129 situated under the 'right hand side of the board, so as to be convenient to the user of the board.

At the junction between the shaft portion 127 and the lever portion 125 of the rod there is welded one end of a flexible thin rod 130, the other end of which is bent at 90 and secured to the underside of the board. Before being secured in this manner, the rod is subjected to torsion, in such direction as to urge the lever portion 125 of the rod 126 against the notches of the ratchet, so that this flexible rod 130 forms a spring which holds the lever in the appropriate notches of the ratchet.

In operation, the tilted position of the drawing board can be adjusted by holding the board with two hands, with the fingers of the right hand holding the lever 129 and pressing this upwards, towards the board, to disengage the lower end of the lever 125 from the ratchet, so that the board can readily be adjusted to any tilted position up to the nearly vertical position shown in FIG. 9.

The drafting table shown in FIGS. 11 to 14 is somewhat similar to the previously described embodiment, but is adapted to be folding.

right front leg members 213 and a cross member 214.

rigidly connecting upper portion of these by members. The frame also includes, as in the previous embodiment, a rearwardly extending member 215 from the rear end of which extends a single central rear leg member 217, these latter members together constituting rear leg means for the table. However, in this embodiment, the member 215 is hingedly connected to cross member 214 for movement relative to the cross member about a vertical axis (i.e., an axis which is vertical when the table is in its operating position), the member 215 being hinged to the cross member by bolt means 215a at a position near to one of the upright front leg members, and in the operating position both the member 215 and the rear leg member 217 extend obliquely away from the cross member so that the lower end or foot of the member 217 is underneath the centre of the rear of the board means (see FIG. 13).

,The rear leg member 217 is also'oblique to the member 215 when seen in side view, and the

members

215 and 217 can be pivoted about bolt means 2150 into the folded position shown in FIG. '14 in which the

members

215 and 217 are parallel to the plane of the front leg members and in which foot-of member 217 is adjacent the foot of thatupright member on the opposite side of the table from bolt means 215a. It will also be apparent from FIG. 14 thatv the

members

215 and 217, when in the folded'position, are wholly within the outer boundaries of the plane of the front leg members 213. Furthermore, since member 215 folds underneath member 214,

the'members

215 and 217 are contained entirely within the space bounded by the front leg members and the cross member so that the folded support frame has a thickness substantially the same as the fore-and-aft width of the leg members.

The board means 210, and the rnanner of attachment of the board meansto the frame, are similar to those of the previously described embodiments, except for the use of short brackets 225a connected to the upper ends oflegs 213 by pivot means, and the absence of any torsion bar. These pivot means permit folding of the board means flat against the folded frame as illustrated in FIG. 14. g

The means for maintaining the board means in a variety of angular positionsincludes a ratchet 229 attached to the rear leg member 217 and having rearwardly facing notches. The ratchet is engageable bya lowermost, horizontal portion 230a of the lever portion 230v 'of a bent rod 231. The rod 231 includes two upper horizontal portions 232 extending horizontally under the board means and connected thereto by small brackets 233 which allow rotation about the axis of portions 232; two legs of .lever portion 230 extending downwardly from the board when the table is in use; and the connecting. lowermost portion 2300. In addition, the outer ends of rod 231 provide two handles 235 for rotating the portions 232 and disengaging portion 230a from the ratchet. I v r [n this embodiment, no spring is needed to urge the ratchet engaging rod portion 230a into the notches of the ratchet, since the slope of the ratchet ensures-that such movement occurs under gravity. v v

The table is used in similar manner to that of FIGS. 7 to 10. However, for shipping or storing the table, this can be folded into the flat condition of FIG.114. This is achieved simply by release of the rod portion 230a from the ratchet and then folding this rod flat against the board means, folding of the rear leg member 217 about the vertical axis of bolt means 215a into the plane of leg members 213, and finally folding of the board means 210 flat against the leg members 213 by pivoting it about its pivoted axis which is parallel to cross member 214.

It is not of course essential that the rearwardly extending member 215 be connected directly to the cross member 214; indirect connection via a bracket attached to a'front leg member 213 would also serve the purpose.

It may be noted that the drafting tables are of extremely simple construction, using a frame work having few joints, but which are nevertheless quite stable. The means for maintaining the board in a number of tilted positions is also simple in construction and operation,

particularly by virtue of the association of the ratchet means with the rear leg means. The provision of a single, central, ratchet means is in contrast to many previous designs for drafting tables, which require the use of two ratchets, one at each side of the table,'which have to be operated simultaneously.

I claim: l 1. A drafting table comprising: r

a. a support frame including two upright front leg members and. a cross member rigidly connecting upper portions of said leg members and single rear leg means extending downwardly and rearwardly ,from said cross member in an operative position thereof, I

. a single normally vertical pivotconnecting said single rear leg means to said cross member, the upper 7 forward end of said rear leg means being mounted underneath said cross member and said rear leg means being dimensioned to allow said rear leg means to be folded by movement about said pivot into a position parallel to the front leg members and wholly within the outer boundaries of the front leg members and said cross member,

c.- means-defining a series of notches spaced along said rear leg means so that said notches have openings rearwardly of the rear leg means when the rear leg means is in its operative position,

d. board means mounted on the support frame by pivot means allowing tilting of the board means about a horizontal axis adjacent a front edge of the board means, said pivot means allowing adjustment of the angular position of the board means to a variety of sloping operative positions and also allowing folding of said board means into a position close to and parallel to said front leg members, and

e. adjustment means mounted on said'board means for adjustment thereof relative to said rear leg positions, and said rod having handle means at the other end of said shaft portion for rotating said shaft portion to control engagement of the lower horizontal portion with said notches, said lever portion being disengageable from said notches and pivotal against the underside of said board means for folding of the t able, W

whereby said table can be folded by disengagement of the lower horizontal rod portion from the notches, folding of the rear leg means parallel to the plane of the front leg members, pivoting of the rod lever portion against the board means and then pivoting of the board means flat against the leg members.

2. A table according to claim 1, wherein said rear leg means is pivoted to said cross member at a position near to one of said upright front leg members, and wherein, with the rear leg means in the folded position, the lower end of the rear leg means is adjacent the lower end of the other upright front leg member.

3. A table according to claim 1, wherein, in the folded condition, the rear leg means is contained entirely within the space bounded by the frontleg members and the cross member, whereby the folded support frame has a thickness substantially the same as the foreand-aft width of the front leg members.

Claims

1. A drafting table comprising: a. a support frame including two upright front leg members and a cross member rigidly connecting upper portions of said leg members and single rear leg means extending downwardly and rearwardly from said cross member in an operative position thereof, b. a single normally vertical pIvot connecting said single rear leg means to said cross member, the upper forward end of said rear leg means being mounted underneath said cross member and said rear leg means being dimensioned to allow said rear leg means to be folded by movement about said pivot into a position parallel to the front leg members and wholly within the outer boundaries of the front leg members and said cross member, c. means defining a series of notches spaced along said rear leg means so that said notches have openings rearwardly of the rear leg means when the rear leg means is in its operative position, d. board means mounted on the support frame by pivot means allowing tilting of the board means about a horizontal axis adjacent a front edge of the board means, said pivot means allowing adjustment of the angular position of the board means to a variety of sloping operative positions and also allowing folding of said board means into a position close to and parallel to said front leg members, and e. adjustment means mounted on said board means for adjustment thereof relative to said rear leg means, said adjustment means including a rod having an upper shaft portion extending horizontally under the board means, said upper shaft portion being positioned close to the board means and rotatably mounted thereon, said rod having a lever portion extending downwardly from one end of said shaft portion and having a lower horizontal portion at its lower end, said lower horizontal portion being suitable for engagement with the notches of said rear leg means when the board means and the rear leg means are in their operative positions, and said rod having handle means at the other end of said shaft portion for rotating said shaft portion to control engagement of the lower horizontal portion with said notches, said lever portion being disengageable from said notches and pivotal against the underside of said board means for folding of the table, whereby said table can be folded by disengagement of the lower horizontal rod portion from the notches, folding of the rear leg means parallel to the plane of the front leg members, pivoting of the rod lever portion against the board means and then pivoting of the board means flat against the leg members.

3. A table according to claim 1, wherein, in the folded condition, the rear leg means is contained entirely within the space bounded by the frontleg members and the cross member, whereby the folded support frame has a thickness substantially the same as the fore-and-aft width of the front leg members.