US2863497A - Back adjustment for office chairs - Google Patents

Description

1958 H. w. PARROTT ET AL 2,863,497

BACK ADJUSTMENT FOR OFFICE CHAIRS Filed March 5, 1957 3 Sheets-Sheet 1 V": I: I 3 34 31 I37 INVENTOR s. Q Tm'eiw BY umm ATTORNEYS Dec. 9, 1958 H. w. PARROTT ET AL BACK ADJUSTMENT FOR OFFICE CHAIRS 3 Sheets-Sheet 2 Filed March 5, 1957 INVENTORS I I5 ll IHIIIIII ATTORNEYS 1958 H. w. PARROTT ETAL 2,863,497

' BACK ADJUSTMENT FOR OFFICE CHAIRS Filed March 5, 1957 I 5 Sheets-sheaf :s

v 43 4? ,44 K. i 23 INVENTORS W- w r ATTORNEYS 2,863,497 Patented Dec. 9, 1958 2,863,497 BACK ADJUSTMENT Fon OFFICE CHAIRS Henry Wheeler Parrott, Shelton, and Sidney Albert Ericson, Bridgeport, Coun., assignors to The Bassick Company, Bridgeport, Conn., a corporation of Connecticut Application March 5, 1957, Serial No. 644,046 Claims. (Cl. 155-157) This invention relates to back adjustments for ofiice chairs and particularly to those for chairs in which the back is pivotally mounted and vertically adjustable with respect to a non-tiltable seat.

In chairs of this type it has been the practice to equip a chair iron supporting the seat with an assembly comprising a two-part bracket, one part of which is a forward member pivoted in relation to the seat-supporting post and the other part of which is a member pivoted at its upper end to the first part and carrying a guide or trackway in which a chair-back-supporting member is adjustable vertically. This provides for the vertical adjustment of the chair back by permitting the desired raising or lowering of the part to which the chair back is fixed, and by swinging the rearward part of the two-part bracket the inclination of the chair back can be adjusted.

One of the principal objects of this invention is to provide improved means whereby the member or element carrying the chair back and vertically adjustable can be easily and securely fixed at the desired elevation.

Another object is to provide a clamping screw arrangement for the purpose of clamping the back carrier in the desired position which will operate without binding of the screw in its associated nut.

To these and other ends the invention consists in the novel features and combinations of parts to be hereinafter described and claimed.

In the accompanying drawings:

Fig. l is a side, elevation of an oflice the invention;

Fig. 2 is an elevation on a larger scale showing certain portions of the chair illustrated in Fig. 1; V

Fig. 3 is a top plan view with certain parts omitted showing a chair iron embodying the invention;

Fig. 4 is a section on line 4-4 of Fig. 3;

Fig. 5 is a section on line 5-5 of Fig. 4;

Fig. 6 is a section taken on the same section line as Fig. 4 but looking in the opposite direction;

Fig, 7 is a section similar to Fig. 5 showing another position of the clamping screw appurtenant to the chair back;

Fig. 8 shows in detail the tiltable nut associated with the said clamping screw; and

Fig. 9 is a section on line 9-9 of Fig. 6.

In the drawings there is shown by way of example an ofiice chair of the swivel type having a non-tiltable seat and a pivoted tiltable back which is vertically adjustable. By referring to a tiltable back it is intended to indicate that the back can be swung on a lower pivot to dilferent inclinations. In the chair illustrated, the base of the chair has an upwardly extended post carrying at its upper end a bracket or frame which is secured to longitudinal bars to which the chair seat is affixed. Extending rearwardly from thesaid frame or base member is a twopart element, the forward part of which is pivoted to said base member or frame and under the control of a tensioning bolt or screw. Pivoted to the forward part pf this two-part bracket is a second part which is tiltable chair embodying bracket parts serves as a pivot.

2 in a vertical plane and which has at the rear part thereof an upright guide or trackway in which is adjustable a channel-shaped element carrying the chair back. At the lower portion of this second bracket part the same is operatively connected to an adjusting screw operable to vary inclination of the chair back. Also mounted upon the second bracket part is a clamping screw arrangement involving a clamping screw or stem operable from one side of the chair for clamping the back-carrying element after the latter has been moved vertically to the desired position.

In the drawings, the upwardly extended supporting post is indicated at 10, the bracket or frame at the upper end of this post at 11, the longitudinal bars to which the seat is aflixed at 12, the forward part of the two-part element or bracket at 13, the tensioning screw connection to part 13 at 14, the second or rear bracket part at 15, the channel-shaped element carrying the chair back at 16, the adjusting screw operable to vary inclination of the chair back at 17, and the clamping screw arrangement for clamping the back carrier element after vertical adjustment at 18.

The bracket or frame 11 connected to the upper end of the seat-supporting post has parrallel horizontal side bars that are fastened in any suitable manner to the longitudinal bars 12 that are applied in the usual manner to the lower face of the chair seat. The forward bracket part 13 is extended between the rear end portions of bars 12 and at 19 is a pivotai connection between the lower forward end portion of bracket part 13 and the frame 11. The part 13 is of generally U-shaped cross section presenting a downwardly facing channel, and the upper wall of this member has an upstanding flange: 20 connected in the usual or any preferred manner with the tensioning screw 14, a coil spring 21 being interposed between the wheel-carrying nut 22 and a part of the frame 11.

At the rear of the bracket part 13 there is an upper pivotal connection between this part and the rear bracket part 15 whereby the rear bracket part is pivotally mounted so that the chair back may be placed at different inclinations. The rear bracket part has side walls 23 interconnected by a web 24 and this member is extended into the space between rearwardly projecting wall portions of part 13, and a pivot pin 25 extending across the bracket structure and passing through overlapping lugs of the two This pin 25 is rigid with the forward bracket part, and the lugs of the rear part can turn relatively to this pin. Adjusting movement of the rear bracket part on its pivot can be produced by rotation of an adjusting screw shank 26 located longitudinally of the bracket parts 13, 15 and disposed horizontally at the lower part of this bracket structure. This screw shank is rotatably supported and held against longitudinal movement in a downwardly extending flange 27 carried by part 1.3 at the lower portion thereof, said screw being engaged intermediate of its ends in a U-shaped nut 28 engaged over the lower edge of the transverse wall of bracket part 15. This nut 28 is provided interiorly with a spring 29 arrangedin the manner shown in Fig. 6, and a clearance aperture 30 in part 15, through which screw 26 passes, permits part 15 to swing relatively to the screw. The arrangement is such that when screw 26 is rotated in one direction the lower part of the rear bracket member is swung rearwardly and when the screw is rotated in the opposite direction this part is swung forwardly. At the forward end of the screw 26 a universal coupling 31 is provided, this being connected to a rotary adjusting stem 32 having an end wheel 33 accessible at one side of the chair seat. The rotary element or stem 32 is arranged at an acute angle to the longitudinal axis of the chair iron and this rotary element has its inward end supported by means such as a yoke 34 extending downwardly from a lower wall provided interiorly of I bracket part 13.

The clamping screw arrangement 18, previously mentioned, is associated with the rear bracket part at an ele-' vation where the clamping screw is somewhat above the adjusting screw 17. This clamping screw arrangement comprises a threaded clamping screw or stem 35 extended through an aperture 36 in one side wall of the bracket part and serving to clamp the channel element 16 in its adjusted position. The channel element 16 is suitably mounted at the lower extremity of the chair back and, as shown herein, it comprises a relatively wide rear member 37 to which is fixed a forward part 38. The side walls of part 15 present at their outer faces V-shaped grooves so that there is provided on this member a vertical guide or trackway,'and member 38 has inwardly bent flanges engaging these grooves. The threaded stem 35, which is arranged at an acute angle to part 15, has an inner conical extremity that is adapted to enter the space between one of the V-shaped parts of the bracket and the flat forward face on the body of member 38. For supporting the stem 35 adjacent its inner extremity, a yoke 39 having upper and lower prongs engaging the stem is rigidly fastened to the adjacent bracket wall.

t the opposite side of the bracket part, where the clearance opening 36 is provided, the stem 35 has threaded engagement with a nut that is supported from the adjacent wall of the bracket in a manner such that the nut can move relatively to the bracket for purposes hereinafter mentioned. In the form herein shown, a nut 40, shown in detail in Fig. 8, is provided, the same consisting of an interiorly threaded nut body 41 rigidly fixed to an elongated plate structure 42 in such a manner that the nut body lies at an acute angle to the palne of the supporting plate. The supporting plate is an elongated plate having intermediate of its ends a nut-body-carrying portion 4. 3 lying at an angle to the plane in which the end portions of the end plate are disposed. The end portions of the plate are each provided with an integral lug 44 in the same plane as the end portion of the plate. These lugs 44 serve for movably supporting the nut, said lugs being projected through slots 45 of greater width than the thickness of lugs 44 to provide clearance for pivoting. After insertion into slots 45 the extremities of the lugs are deformed by staking or swaging to present on the lugs enlargements by which the nut plate will be prevented from displacement from its supporting wall. The nut plate extends in a vertical direction and the nut portion engaging the threaded stern can swing in a horizontal plane for the purpose of facilitating proper engagement of the stem extremity with the angular space or socket presented respectively by the chair back carrier and the rear bracket part.

It will be noted that the plate 42 of the nut device is applied to the wall having the aperture 36, one end of the plate being above the aperture and the other end below it. When the stem 35 is withdrawn from its cooperating angle or socket, as shown in Fig. 7, the stem can be swung laterally to a certain extent, as shown by the broken lines in Fig. 7, the aperture 36 providing a clearance that permits this. When the stem 35 is swung in this manner, its pivoting axis coincides Vertically with the pivotal mountings of the lugs 44 in the slots d5. At the outer ends of the lugs 44 the lugs are enlarged or provided with heads, as above described, and at the inner face of the bracket wall, shoulders 44a on the plate 42 abut the wall, the stem 35 when in the disengaged position being freely swingable laterally to a certain extent. The conical end of the. stern, when the stem is moved inwardly, is free to engage one side or the other, or both, of the receiving angle for the stem and on continued rotation of the stem the latter is free to go home in an accurately lined up position.

It is understood that the chair back carrier can be adjusted vertically through a range of substantial .extent and that it is very desirable that this carrier be capable of secure clamping in all of its adjusted positions. In prior height adjustments for chair backs where a clamping screw or stem was intended to engage in an angle presented between the carrier element and the bracket there has been serious malfunctioning and failure in firmly securing the carrier element due, for one reason, to the fact that in different height adjustments the receiving angle or socket for the stem would be in different positions laterally of the bracket structure. This serious drawback is overcome by the structure presently described. Another important advantage arises from the fact that where the nut supporting the threaded stem is rigidly fixed to the bracket there is likely to be serious binding of the stem in the nut because the stem is not accurately lined up with its receiving angle, and this defect is overcome by the herein described improvement.

The receiving angle referred to here is that presented by the vertically elongated parts of the bracket wall and the back carrier having planar surfaces at an acute angle to each other and adapted for engagement by the conical extremity or nose portion of the clamping screw. in the form described these surfaces are provided respectively on the forwardly facing channel portion of the back-supporting carrier or slide and by the rearward lip portion at one side of the bracket.

Various modifications and detail changes may be made without departing from the principles of the invention and the scope of the claims.

What we claim is:

1. In a chair iron, a post-supported frame, a twopart bracket member extending laterally from said frame having forward and rear bracket parts, the rear bracket part being tiltable in a vertical plane relatively to the forward bracket part, a back-supporting element movable vertically on said rear bracket part and forming in conjunction With one side of said rear bracket part an elongated acute angle or socket formation, a rotary clamping screw extending through an aperture in a side wall of said rear bracket part and having a pointed extremity to engage in the angle or socket of said formation, said screw lying in a substantially horizontal plane and-extending outwardly of said bracket part and the aperture through which said screw passes allowing clearance for lateral movement of said screw, a nut in threaded engagement with said screw having a movable mounting within said bracket part to permit accurate lining up of the screw with said angle or socket and a hand stern disposed outwardly of said rear bracket part and fixed to said screw.

2. In a chair iron, a post-supported frame, a two-part bracket member extending laterally from said frame having forward and rear bracket parts, the rear bracket part being swingable in a vertical plane relatively to the forward bracket part, the rear bracket part having a channel formation facing rearwardly with one of its side walls apertured intermediate of the upper and lower ends of said bracket part, a back-supporting element movable vertically on said rear bracket part, a rotary clamping screw disposed substantially horizontally and extending from the exterior of said bracket part through the aperture of said bracket part with clearance, said screw having within said bracket part a pointed end engageable in an acute angle provided between said backsupporting element and a wall of said rear bracket part, amounting nut for said screw located within said bracket part and having pivotal connection with the latter at points above and below said aperture whereby said screw can have a horizontal swinging movement to line it up with said angle, and a hand stern disposed outwardly of said rear bracket part and fixed to said screw.

3. In a chair iron, the combination of a back-supporting member provided with a forwardly facing channel uprightly disposed, a bracket part to which said backsupporting member may be fixed in a number of vertical adjustments and formed as a rearwardly facing channel providing guide grooves at the sides in which said back-supporting channel member is engaged, said bracket part having a side wall with an aperture therein located forwardly of said back-supporting element, a nut member comprising a threaded nut body and a plate at an angle to said nut body, said plate being mounted from said bracket part at points above and below said aperture in a manner such that said nut body can have a limited lateral swing, a clamping screw extending into said bracket part through and with clearance in said aperture and provided with threads engaging those of said nut body, said screw having a pointed interior extremity for engaging an angle or socket created between an inner surface of said back-supporting element and an inner surface of said bracket part and a hand stem disposed outwardly of said rear bracket part and fixed to said screw.

4. In a chair iron, a mounting nut for the clamping screw of a chair-back-adjusting assembly, said nut having an interiorly threaded nut body and rigid therewith a plate provided with opposite end portions in a plane 'at an acute angle to the intermediate part of said plate,

said intermediate part carrying said body, and said end portions each being provided with an integral lug adapted for projection through a slot in a supporting wall.

5. In a chair iron, a post-supported frame, a two-part bracket member extending laterally from said frame having forward and rear bracket parts, the rear bracket part being swingable in a vertical plane relatively to the forward bracket part, the rear bracket part having a channel formation facing rearwardly with one of its side walls apertured intermediate of the upper and lower ends of said bracket part, a back-supporting element movable vertically on said rear bracket part, a rotary clamping screw disposed substantially horizontally and extending from the exterior of said bracket part through the aperture of said bracket part with clearance, said screw having within said bracket part a pointed end engageable in an acute angle provided between said back-supporting element and a wall of said rear bracket part, and a mounting nut for said screw located within said rear bracket part and having rigid therewith a plate provided with lugs loosely mounted in slots formed in said rear bracket part to establish pivotal connection with the latter at points above and below said aperture whereby said screw can have a horizontal swinging movement to line it up with said angle.

References Cited in the file of this patent UNITED STATES PATENTS

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