US3099479A - Chair structure - Google Patents

Description

Jul-Y 1963 H. c. BANKE 3,099,479

CHAIR STRUCTURE Filed Feb. 27, 1961 3 Sheets-Sheet 1 g5 Jmhfjm H. C. BANKE CHAIR STRUCTURE July 30, 1963 5 Sheets-Sheet 2 Filed Feb. 27. 1961 July 30, 1963 H. c. BANKE 3,099,479

CHAIR STRUCTURE Filed Feb. 27, 1961 5 Sheets-Sheet 3 Wf/W gj lOO +7, I a-8 93 @Z United States Patent 3,899,479 CHAlllR STRUCTURE Henry C. Banks, Chicago, llll., assiguor to Clarin Mfg. (10., Chicago, ill, a corporation of Illinois Filed Feb. 27, 1361, Ser. No. 91,695 2 Claims. (Cl. 297-36) The present invention relates to a chair with a tablet arm, and more particularly to structure for more effectively mounting such a tablet arm on a l air.

The tablet arm for a chair is generally a flat member attached to the chair and positioned so that the person seated in the chair may use it to support materials, and in particular, as a writing surface. This is a useful and convenient way of providing these facilities with obvious saving in expense and space, and chairs with tablet arms are used a great deal in schools, lecture halls and the like. Of course, it is highly desirable that the tablet arm be firmly supported during use, even after a period of service which involves repeated raisings and lowerings, so that it will provide a solid stable surface on which to write. At the same time, it is desirable that the structure operate in cramped quarters, i.e., move so as to avoid interference with adjacent chairs. It is further desirable that the person who will be using the chair can easily and quicldy tilt the arm to get in and out of the chair and can lower it when the tablet arm is not needed. Further, in addition to simplicity of operation, the operation should be as smooth and quiet as possible, and while a of effort should be required, jammed fingers and bruised shin bones can result from a completely free swinging arm.

Accordingly, the principal object of the present invention is to provide an improved chair with tablet arm. More specific objects include providing such a chair which more effectively combines easy and simple operation with firm and stable support. In this connection, an object is to provide operation which is directly pressure responsive and does not require preliminary unlocking or other preparatory steps. A further specific object is to provide such an improved chair having a tablet arm which, while easy to move, is provided with restraining means which prevents the arm from falling and thereby create noise and possible injury. It is another object to provide such .a structure which is durable and sturdy, yet economical.

Further objects and advantages will become obvious from the following description and accompanying drawings (3 sheets).

In the drawings:

FIGURE 1 is a perspective view of a folding chair having a tablet arm and embodying various features of the invention, the chair being extended and the arm being shown in phantom in its raised or operative position;

FIGURE 2 is similar to FIG. 1, with the arm in a lowered position;

FIGURE 3 is a front view (with parts broken away) of the chair structure shown in FIG. 1, with the chair folded and the arm in the storage position;

FIGURE 4 is a side view of the chair structure shown in FIG. 3;

FIGURE 5 is an enlarged fragmentary front view (with parts broken away and in section), showing the front connection means between the tablet arm and the support member of the chair shown in FIG. 1, the arm being in the raised position;

FIGURE 6 is generally similar to FIG. 5, the arm being in a lowered position;

FIGURE 7 is a sectional view taken generally along line 7--7 of FIG. 6;

FIGURE 8 is a sectional view taken generally along "ice 2 line 8-8 of FIG. 5, showing the pressure responsive locking means;

FIGURE 9 is a view parts broken away and in section) taken generally along line 99 of FIG. 5.

FIGURE 10 is an enlarged perspective view of the double-pivot bracket of the tablet arm front connection means;

FIGURE 11 is an enlarged perspective View of the sleeve bracket of the front connection means, together with the associated roller sleeve and the spring and ball bearings of the pressure responsive means;

FIGURE 12 is an enlarged perspective View of a mounting bearing for the tablet arm support member; and

FIGURE 13 is an enlarged perspective view of the rear support bracket for the tablet arm, as viewed when the tablet arm is lowered alongside the Briefly, the illustrated chair 21 includes a frame on which a tablet arm 25 is mounted for ready movement between a firmly supported raised or use position (FIG. 1) and a lowered or non-use position (FIG. 2), the movement being accomplished by first tilting the arm and then swinging it downwardly. Pressure responsive locking or holding means 27 releasably maintain the arm 25 in the raised position until sufiiciently and properly directed pressure is applied to the arm to move it to a lowered position. No preliminary unlatching, unbolting, or the like is required to lower the Retarding means 29 are also provided to prevent the arm from falling from the tilted position to a lowered position (FIG. 2). The illustrated chair 21 may itself be folded, and the tablet arm 25 then moved relative to the chair into a storage position (FIGS. 3 and 4).

The present invention has application to various types of chairs, including rigid structures, but since it is especially advantageous for use in a folding chair, it will be described in connection with a folding chair 21.

The illustrated folding chair 21 comprises a conventioual construction, generally similar to that shown in United States Patent No. 2,548,098 issued April 10, 1951. As shown in FIGS. 1 through 4, the chair 21 comprises a frame including an inverted, generally U-shaped section 23 which is formed from a strip of metal that has had its lateral edges rolled inwardly to form parallel beads with a flat portion in between. The bight portion of the section 23 supports a chair back rest 31, and the downwardly extending portions provide a pair of front legs 33 for the chair. The front legs 33 are interconnected a short distance from their lower ends by a cross brace 35 of a similar construction to that of the section 23. The cross brace 35 is preferably rigidly and firmly secured to the legs 33 by welding, bolting, or the like, as it provides support for the tablet arm 25 in a manner to be described. A pair of rear legs 37 of similar construction to the front legs 33 are pivotally connected to them, as indicated at 39, to form an X construction on either side of the chair 21. The rear legs 37 may be reinforced by having a pair of cross braces 49 connected between them. The upper ends of the rear legs 37 are pivotally connected to either side of a chair seat 41. The seat 41 is further pivotally supported by a pair of links 43 which are in turn pivotally connected to the section 23. Further support is provided for the seat 41, when the chair 21 is in the extended position shown in FIGS. 1 and 2, by a cross brace 45 connected between the front legs 33 above the pivots 39. The construction just described permits the chair 21 to be folded so that the upper surface of the seat 41 faces forwardly when the chair is folded into the position shown in FIGS. 3 and 4. The ends of the legs 33 and 37 are each provided with a pad 47 of a suitable material, such as rubber or plastic.

The illustrated tablet arm 25 is a generally elongated platform or plate made of wood or other suitable material. It is formed so that, when it is in the raised or use position shown in FIG. 1, with its upper surface lying in a generally horizontal plane, its forward end, which 18 enlarged relative to its rearward portion, provides a writing surface, while the rearward portion provides an arm rest while affording ample room for the occupant of the chair.

In the illustrated device, the tablet arm is pivotally connected at its rearward end to the upper portion of the section 23 by a rear support means in the form of a bracket 49 (shown particularly in FIG. 13), and it is also pivotally connected by front connection means 51 to a generally L-shaped, rigid support member 51 which has one leg thereof rotatably mounted on the cross brace between the front legs 33.

The illustrated structure will now be described with some particularity, after which the operation of the device will be considered.

The rear bracket 49, which connects the rear end of the tablet arm 25 to the section 23 in the illustrated device, is shown best in FIG. 13, and includes a fixed plate 52 which is riveted, welded or similarly secured to the left side of the fname 23 (as viewed in the drawings). Pivotal-1y connected to the fixed plate 52, as by a rivet 53, for rotation about a generally horizontal axis, is first section 55 of a generally L-shaped plate or angle 54, having a second section designated 56. Hinged along its edge to the outer edge of section 56 by means of a hinge pin 57 is a plate 58 which is suitably securely fixed to the underside of the tablet arm 25, as by means of screws (not shown) passing through the holes 59 provided in plate 58.

This construction of the rear support bracket 49 provides firm, solid support for the rear end of the tablet arm 25 when the arm is being used, contributing to the overall stability and elfective performance of the writing surface. In particular, when the arm 25 is in the raised position, as shown in FIG. 1, the plate 58 is folded back upon section 56 of plate 54 to provide a relatively broad support surface for the arm. This broad support surface tends to eliminate wobble or tilting and provides a firmer support for the rearward end of the arm 25.

The illustrated support member 51 (FIGS. 1-4) is an elongated, generally tubular, L-shaped part having legs or sections 60 land 61. Member 51 is mounted with section 60 disposed with its axis generally horizontal and parallel with the cross brace 35, and With section 61 extending upwardly in a generally vertical direction from the end of section 60, on the left side of the chair 21 as viewed in FIGS. 13. Horizontal section 61 is rotatably received within (one of which is shown in detail in FIG. 12) which are fixed upon the forward face of the cross brace 35. Each bearing 62 is solidly fixed to the cross brace 35 by a pair of rivets, bolts or the like (not shown) which pass through spaced holes 62' provided in the bearings. Also, the cylindrical bearing surface, which each bearing 62 provides, extends for a substantial length (indicated by L in FIG. 12) along the horizontal section 60. Thus, the two spaced apart bearings 62 provide firm, steady and rigid support for the support member 51.

Vertical section 61 has an angularly bent portion 63 provided at its lower end to allow section 61 to assume a position adjacent the chair legs (as shown in FIGS. 2 through 4), and the latter is connected at its upper end to the tablet arm 25. A brace or strap 64 in the form of a tube of metal or the like is fixedly connected between intermediate points on the two sections 60 and 61 of the support member. The strap 64 provides reinforcement, and also provides a stop to the rearward pivoting of the support member 51 in the bearings 62, as shown in FIG. 2. The section 61 is also provided with a stop pin 48 whose function will be explained below.

Now to describe the front connection means between the tablet arm 25 and the support member 51 in the illusa pair of spaced apart mountings bearings 62 trated device. As shown in FIGS. 5 through 7, the tubular vertical section 61 is provided with a sleeve bracket 67 (shown in detail in FIG. 11), having a lower sleeve section 66 which slidably engages the Vertical section 61, and an upper, U-s'haped section 65, which extends around and beyond section 61, so as to provide a pair of spaced apart vertical plates 69. I

There is a slot 68 provided in the bight of U-shaped section 65, which slot extends downwardly from the upper edge of the section 65. The upper end of the tubular vertical section 61 is provided with an end plug 70 (FIG. 5) which is secured in place by a pin or nivet 68' having an enlarged head 71. The pin 68' is positioned so as to enter slot 68 when sleeve bracket 67 moves upwardly relative to vertical section 61 into the relative positions shown in FIG. 5, the arm 25 thereby being positioned in its raised position as seen best in FIG. 1. In that position, the shank of the pin 68 engages the bottom of the slot 63 to prevent the bracket 67 from becoming disengaged from the vertical section 61, while the head 71 of the pin 68 overlaps the edges of the slot 68. The seating of the pin 68 within the slot 68 and the overlapping of the head 71 aid in providing firm and sturdy support between the bracket 67 and the section 61, and so contribute to the overall stability of the structure when it is in the raised position (FIG. 1).

The rearward portion of the lower edge of the bracket 67 is provided with a pair of downward extensions 48 and 43". Extension 48 is positioned to engage the stop pin 43 on the vertical section 61, when the device is in the lowered position shown in FIG. 6, to prevent arm 25 from swinging outwardly from the position generally parallel to the side of the chair shown in FIG. 2. Extension 48 is circumferentially spaced from extension 48', allowing rotation of the arm inwardly of the chair to the position shown in FIGS. 3 and 4, at which place extension 18" acts as a stop against further rotation in that direction.

A generally U-shaped double pivot bnacket 72 (shown in detail in FIG. 10'), having an intermediate portion 73 and a pair of spaced apart vertical plates 74, is disposed, as best seen in FIG. 7, with its vertical plates 74 positioned immediately outwardly of and pivotally connected to the vertical plates 69 of the sleeve bracket 67. As seen in FIG. 7, a suitable pivot pin, shaft or rod 76, having an enlarged head 75 on one end and a threaded portion 77 at the other end to receive a nut 78, passes through aligning apertures in the vertical plates 6 and 74 to connect the brackets 67 and 72 for rotational movement relative to one another about the axis of that pin 76. The axis of the pivot pin 76 is in substantial alignment with the axis of the pivot hinge 57 of the rear connection bracket 49 to provide a common axis for arm 25 to tilt or rotate about as will be further explained. The axis of the pivot pin 76 is also disposed generally perpendicular to and spaced-apart from the longitudinal axis of the elongated vertical section 61. The bracket '72 has a pair of vertical slots 79* extending into its center portion 73. These slots 79 are positioned to receive a pair of cars or extensions 80 on the lower ends of the vertical plates 69 when the arm is moved to the vertical position shown in FIG. 6.

A hollow cylindrical roller spacer or sleeve 81 is rotatably disposed about the pivot pin 76 and extends between the vertical plates 69 of the sleeve bracket 67. The outer surface of the sleeve 81 serves as a positioning roller, having a groove 81. which extends around its circumference and is positioned to engage the vertical section 61, as seen best in FIG. 7, to guide the bracket 67 at its upper end for movement relative to .the section 61. The sleeve 81 also aids in maintaining the proper spacing and disposition 'of the spaced-apart vertical plates 69 and '74.

The pressure responsive locking or holding means 27 of the illustrated device, shown in FIG. 8, includes a hollow, cylindrical tube or housing 83 extending between the plates 69 of bracket 67 at a location below the pivot pin 76. The tube 83 extends through opposed apertures in the plates 69 and is secured in that position to provide an open passageway between the plates 69. A pair of ball-bearings 85 are received in the passageway of the tube 83, and are urged outwardly in opposite directions by a small coil spring 87 positioned between them within the tube 8-3. The ball-bearings 85 are retained within the tube 83 by the inner surfaces of the plates 74 of the bracket 72, which surfaces overlay the openings to the passageway. These plates 74- are each provided with an outwardly curved, generally circular depression 8-9. The two depressions 89 are positioned generally opposite from one another and are located relative to the pivot pin 76 so as to align with the tube 83- and receive the ball-bearings 85 (FIG. 8) when the parts are in the respective positions shown in FIG. 5, wherein the arm 25 is in its raised position. The spring 87 urges the ballbearings 85 outwardly and into the depressions 8 9, thus maintaining the parts releasably fixed in that position until sufiicient pressure tending to rotate the bracket 72 in a counter-clockwise direction (as seen in FIG. 5) moves the ball-bearings 85 inwardly against the spring 87 to allow the rotation.

A second pair of similarly constructed, opposed depressions 90 in the plates 74- serve to releasably lock the tablet arm 25 in the tilted position. As the arm moves from the position shown in FIG. 5 to that tilted position, the ball-bearings 85 are in rolling contact with the inner surface of the plates 74 so as to retain them within the tube 83-. The two positions are extreme positions, further rotation in either direction about pin 76 being restricted as will be described.

As shown in FIGS. 5, 6 and 9, the illustrated bracket 72 is pivotally connected to a flanged housing 93, which is fixed to the underside of the tablet arm 25, for relative rotation therebetween about an axis which is generally perpendicular to the upper surface of the arm 25 and intersects the axis provided by pivot pin 76. More particularly, the mid or intermediate portion 73 of the bracket 72 includes a generally circular, centrally disposed hub 95 (FIG. The housing 93' has a main wall 97 disposed generally parallelly spaced from the undersunface of the arm 25, and having a peripheral skirt or flange 99 which engages the u-ndersurface and is fixed thereto as by means of screws 100. The main wall 97 has a central, circular opening 101 which receives the hub 95 of the bracket 72 for rotation therein. The main wall 97 adjacent the opening 101 is offset to provide a circular shoulder 102 which maintains the part of the intermediate wall 73 of the bracket 72 which is outwardly of the shoulder 102, spaced slightly from the main Wall 97. The hub 95 is held in the opening 101 by a formed, generally discashaped spring 103 which is disposed centrally over the hub 95 and connected to it by means of a centered rivet 105, having its shank passing through aligned apertures in the hub 95 and the spring 103 and its enlarged ends disposed on either side thereof. A disc-shaped washer 107 is disposed inside the housing 93 around the opening 101. The disc spring 103 has a larger diameter than the opening 101 so that its marginal portion abuts the washer 107. The spring 103 is formed so as to tend to position its center portion away from the washer 107. The rivet 105 restricts this center portion of the spring 103, the result being that the spring 103 urges the bracket 72 into abutting engagement with the raised shoulder 102 of the housing 93. The spring 103 thus cooperates with the other parts to act as a retarding means, i.e., create abutting, high friction contact to retard the relative rotation between the bracket 72 and the housing 93 to prevent falling of the arm. In addition to its retarding function, this spring structure will compensate for wear to the parts caused by the relative movement therebetween, and serves to reduce wobble in the device. a

Now to consider the operation of the device. FIG. 1 shows the chair 21 extended, and the tablet arm 25 is in the raised position in a generally horizontal plane and the tablet arm support section 61 is in a generally vertical extending position. The rear support bracket 49, together with the front connection means 50 and the support member 51, provide firm, solid, stable support tor the tablet arm 25 to provide the desired writing surface. Since the pivot pin 76 is positioned well toward the outside of the chair 21, downward pressure on the writing surface of the arm incident to its normal use will urge the arm downwardly against its supports to provide a solid, steady surface. The pressure responsive means 27 maintains the arm 25 in the desired position, and further tends to remove Wobble.

To lower the arm 25, the user may simply grasp it by its inner edge and tilt or rotate it about the generally horizontal axis defined by pivot pin 76 ot the front connection means 50 and the hinge pin 57 of the rear support bracket 49, by merely applying suflicient pressure against the releasable, pressure responsive, locking or holding means 27 to release it, i.e., disengage the ball bearings 05 item the depressions 89. The arm 25 is thus tilted or rotated to a position wherein its upper surface lies in a generally vertical plane. The engagement of the ears in the bottoms of the slots 79 of the bracket 72 serves to prevent over tilting of the arm. The arm is maintained in the vertical position by the engagement of the ball bearings with the depressions which additionally serve to reduce wobble.

Then the front end of the arm 25 may be lowered to the position shown in FIG. 2: the arm 25 pivots or swings about rivet 53 of the rear support bracket 49, sleeve bracket 67 slides relative to the vertical section 61 or the support member 51, said section 61 moving through an are as member 51 pivots in mounting bearings 62, and the bracket 72 pivots relative to the housing 93. As already pointed out, this last relative pivoting motion is retarded by the spring 103, thereby slowing down this movement to prevent the arm 25 from falling suddenly and rapidly to cause a noise or to possibly injure someone. In the illustrated chair 21, the downward swing of the arm 25 is limited by the strap 64 engaging a front leg 33 of the chair (FIG. 1), and by the engagement of stop pin 48 with the lower edge of the sleeve bracket 67, as seen best in FIG. 6. When the arm 25 is in this lowered position, it is out of the way and the chair 21 may be used as any other chair. It may be noted that the vertical section 61 moves through a relatively small angle in going from its position in FIG. 1 to its position in FIG. 2.

If it is desired to store or carry the chair 21, the legs 33 and 37 are brought together, raising the seat 41 so that the section 23 (including the front legs 33), the seat 4-1, and the rear legs 37 are all in general alignment with one another as shown in FIG. 4. Then, the arm 25 may be rotated to lie generally flush against the chair, as shown in FIGS. 3 and 4, the plate 58 of the rear support bracket 49 pivoting about hinge pin 57, while the sleeve bracket 67 and the parts connected to it are rotating about vertical section 61. In this latter position, the chair 21 is ready for transportation or storage.

Thus, the illustrated chair has a firmly and stably supported tablet arm which may be readily lowered in direct repsonse to pressure. It requires no preliminary step such as unlatching, etc. The structure provides firm stable support for the arm at all times, and particularly when it is in the raised or use position. The retarding means eliminate the noise of falling arms and guard against injury. The operation of the arm is easy and uncomplicated, and requires a minimum of time and also a minimum of space.

Obviously many modifications and changes may be made to the illustrated chair structure without departing from the spirit and scope of the invention. Various teatures of the invention are set forth in the following claims.

I claim:

-1. In combination with a chair including a chair frame providing a pair of front legs, a pair of rear legs, and a back rest, a tablet arm assembly comprising, a tablet arm, a pivotal connection securing a rearward portion of said tablet arm to said back rest adjacent one side of the chair for relative movement about a pair of transverse axes, and means connecting a forward portion of said tablet arm to said frame comprising'a support member carried at its lower end by the frame for swinging movement through a generally vertical plane along said one side of the chair from a generally vertical position and in a direction toward said back rest to a rearwardly inclined position, and a universal connection between the tablet arm and said support member including a bearing means on the underside of said tablet arm, a yoke-like element connected with said bearing means for pivotal movement about an axis disposed at right angles to the plane of said tablet arm, a sleeve element slidably engaging said support member for movement axially thereof and connected with said yoke-like element for relative pivotal movement about an axis transverse to and spaced from the axis of the sleeve and support member, whereby said tablet arm may be rotated about said transverse axis of said universal connection and one of said axes of said rearward pivotal 25 connection to move between a generallyhorizontal position of use and a generally vertical position along said one side of the chair, and when in said generally vertical position the tablet arm may be moved vertically downward about the other transverse axis of said rearward pivotal connection and said axis of said bearing means to cause said sleeve to slide along said support member and place said tablet arm in its lowered position alongside the chair with said support member disposed in its rearwardly inclined position with respect to its connection with said frame, and a biasing means in position to urge the adjoining surfaces of said bearing means and yokelike element together to resist relative rotation therebetween, whereby said tablet arm is maintained in any selected position along said support member when the tablet arm is positioned in said generally vertical position along said one side of the chair.

2. The combination set forth in claim 1, wherein said front and rear legs are pivotally interconnected intermediate their ends to permit folding of said chair, a cross brace extends between said pair of front legs adjacent the lower end portions thereof, and said support member for the tablet arm includes a lower transverse portion swingably mounted on said cross brace.

References Cited in the file of this patent UNITED STATES PATENTS 2,664,943 Clarin Jan. 5, 1954 2,954,073 Junkunc Sept. 27, 1960 3,024,065 Eves et al. Mar. 6-, 1962

Claims (1)

1. IN COMBINATION WITH A CHAIR INCLUDING A CHAIR FRAME PROVIDING A PAIR OF FRONT LEGS, A PAIR OF REAR LEGS, AND A BACK REST, A TABLET ARM ASSEMBLY COMPRISING, A TABLET ARM, A PIVOTAL CONNECTION SECURING A REARWARD PORTION OF SAID TABLET ARM TO SAID BACK REST ADJACENT ONE SIDE OF THE CHAIR FOR RELATIVE MOVEMENT ABOUT A PAIR OF TRANSVERSE AXES, AND MEANS CONNECTING A FORWARD PORTION OF SAID TABLET ARM TO SAID FRAME COMPRISING A SUPPORT MEMBER CARRIED AT ITS LOWER END BY THE FRAME FOR SWINGING MOVEMENT THROUGH A GENERALLY VERTICAL PLANE ALONG SAID ONE SIDE OF THE CHAIR FROM A GENERALLY VERTICAL POSITION AND IN A DIRECTION TOWARD SAID BACK REST TO A REARWARDLY INCLINED POSITION, AND A UNIVERSAL CONNECTION BETWEEN THE TABLET ARM AND SAID SUPPORT MEMBER INCLUDING A BEARING MEANS ON THE UNDERSIDE OF SAID TABLET ARM, A YOKE-LIKE ELEMENT CONNECTED WITH SAID BEARING MEANS FOR PIVOTAL MOVEMENT ABOUT AN AXIS DISPOSED AT RIGHT ANGLES TO THE PLANE OF SAID TABLET ARM, A SLEEVE ELEMENT SLIDABLY ENGAGING SAID SUPPORT MEMBER FOR MOVEMENT AXIALLY THEREOF AND CONNECTED WITH SAID YOKE-LIKE ELEMENT FOR RELATIVE PIVOTAL MOVEMENT ABOUT AN AXIS TRANSVERSE TO AND SPACED FROM THE AXIS OF THE SLEEVE AND SUPPORT MEMBER, WHEREBY SAID TABLET ARM MAY BE ROTATED ABOUT SAID TRANSVERSE AXIS OF SAID UNIVERSAL CONNECTION AND ONE OF SAID AXES OF SAID REARWARD PIVOTAL CONNECTION TO MOVE BETWEEN A GENERALLY HORIZONTAL POSITION OF USE AND A GENERALLY VERTICAL POSITION ALONG SAID ONE SIDE OF THE CHAIR, AND WHEN IN SAID GENERALLY VERTICAL POSITION THE TABLET ARM MAY BE MOVED VERTICALLY DOWNWARD ABOUT THE OTHER TRANSVERSE AXIS OF SAID REARWARD PIVOTAL CONNECTION AND SAID AXIS OF SAID BEARING MEANS TO CAUSE SAID SLEEVE TO SLIDE ALONG SAID SUPPORT MEMBER AND PLACE SAID TABLET ARM IN ITS LOWERED POSITION ALONGSIDE THE CHAIR WITH SAID SUPPORT MEMBER DISPOSED IN ITS REARWARDLY INCLINED POSITION WITH RESPECT TO ITS CONNECTION WITH SAID FRAME, AND A BIASING MEANS IN POSITION TO URGE THE ADJOINING SURFACES OF SAID BEARING MEANS AND YOKELIKE ELEMENT TOGETHER TO RESIST RELATIVE ROTATION THEREBETWEEN, WHEREBY SAID TABLET ARM IS MAINTAINED IN ANY SELECTED POSITION ALONG SAID SUPPORT MEMBER WHEN THE TABLET ARM IS POSITIONED IN SAID GENERALLY VERTICAL POSITION ALONG SAID ONE SIDE OF THE CHAIR.

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