US2709481A

US2709481A - budai

Info

Publication number: US2709481A
Authority: US
Publication date: 1955-05-31
Anticipated expiration: 1972-05-31

Description

May 3% R5 s. G. umm

EOLDING CHAIR Filed Oct. 22, 1953 3 Sheets-Shem. 1

S. Q. 'UDAII FOLDING CHAIR Filed Oct. 22, 1353 3 Sheets-Swat 2 FQLDHNG CHAIR Steve G. Budai, Cincinnati, Ohio, assignor to Ealcranlr, inc, a corporation of Ohio Application ilctober 22, 1953, Serial No. 387,618

7 Claims. (Ct.155139) This invention relates generally to light weight folding chairs having frames constructed of metal tubing and having cloth or flexible plastic panels attached to the frames and providing the seat and back rest surfaces. The invention is directed particularly to improvements in the frame structure which increase its strength and facililate handling of the chair.

Chairs of this character are intended for general outdoor use and are known in the industry as deck chairs; as such, the chairs are moved about from one location to another quite frequently. For this reason it is highly important that the chairs be light in weight and also that they be capable of being folded to a flat compact condition for convenience in carrying them about and for compact storage when not in use.

One of the primary objects of the invention has been to provide a folding chair of simplified construction having tubular frame members which may be articulated to collapsed or erected position in a simple and convenient manner, the frame members being geometrically arranged to form a self-locking structure which remains in erected position without any possibility of accidental collapse, even under rough usage.

Essentially, the chair frame comprises front and rear legs which are pivotally connected to a seat frame along opposite sides, the legs having portions rising upwardly above the seat frame. A back rest is pivotally connected to the rearward edge of the seat frame in common with the rear legs and a pair of arm rests reside in parallelism above the seat frame, each arm rest being pivotally connected at opposite ends to the back rest and to the upper ends of the front legs which project above the seat frame. The seat frame and arm rest along each sideof the chair thus delineate two sides of a parallelogram, while the interconnected portions of the back rest and front legs delineate the other two sides. Since the members are pivotally connected at the four points of intersection, the frame members are free to be articulated ,selectivelyto an erected or to a fiat collapsed condition and remain relatively parallel in either condition.

To provide the self-locking structure for holding the chair in erected position, the upper end ,of each rearward leg, which projects upwardly above the seat frame, is slidably connected to the arm rest whereby, in erected position, the leg portion on opposite sides acts as a linkage truss member extending at an angle across the pivotally connected portions of the arm rest and back rest, the three triangulated members cooperating to lock the frame members in their parallelogram relationship. In order to provide the slidable connection to the truss member, each arm rest is provided with a longitudinal slot extending forwardly from the back rest, the upper end of the truss member being slidably confined in the slot by a slide bearing. The slide hearing resides against the forward end of the slot when the chair is in erected condition and thus provides a positive stop. When collapsed to folded condition, the framing members articulate in parallelogram fashion while the slide bearing of the truss member traverses the slot to its opposite end and concurrently swings the rear leg into alignment with the back. rest.

By virtue of this arrangement, practically no additional structure is required to provide the folding and locking functions; instead, the arm rests perform their normal function as part of the chair and additionally cooperate with the framing members as part of the self-locking structure. Moreover, geometric arrangement of the parts distributes the weight load to the several pivot points and increases the strength and durability of the structure.

Another object of the invention has been to increase the lateral stiffness and stability of the chair frame by the provision of a transverse stiffener which extends between the front legs to lock them firmly in parallel relationship. A further object has been to utilize the stiffener for the additional functions of spacing the seat frame between the legs and to reinforce the pivotal connection between the legs and seat frame. The stiffener is generally U- shaped as viewed from the front and has vertical limbs engaged against the inner surfaces of the legs and attached by screws spaced one above the other. The upper screws pass through the seat frame at opposite sides to provide the pivotal connection and since the limbs are attached to the legs by the lower screws, the pivot screws are supported in cantilever fashion by the two tubes through which they pass so as to support the seat frame with greater rigidity.

Another feature of the invention resides in the utilization of nonmetallic slide bearings comprising bushings attached to the swinging ends of the truss members and slidably confined in the slots of the arm rests at opposite sides to protect the metal surfaces of the slot against galling under the sliding action of the truss member. The bushings are formed from a plastic material which is highly resistant to wear and friction and are in bearing contact with the metal surfaces of the slot and the surfaces of the arm rest on opposite sides of the slot to distribute the bearing load and take up any looseness between the metal parts.

Various other features and advantages will be more fully disclosed in the following detailed description taken in conjunction with the drawings.

In the drawings:

Figure l is a side elevation of the chair in erected position, the frame being shown partially collapsed in broken lines.

Figure 2 is a front view of the chair in erected position as projected from Figure 1.

Figure 3 is a side elevation showing the chair folded to completely collapsed position.

Figure 4 is an enlarged sectional view taken on line l-4, Figure 1, detailing the attachment means of the seat frame cross bar.

Figure 5 is an enlarged sectional View taken on line 5-5, Figure l, detailing the nylon slide bearing connection between the arm rest and upper end of the rear leg.

Figure 6 is an enlarged sectional view taken on line t5-- 6, Figure l, detailing the pivot screw connection of the forward end of the seat frame to the front leg and reinforcement limb.

In the preferred embodiment of the invention as disclosed in the drawings, the several framing members of the chair, with the exception of the arm rests, are fabricated from tubular metal stock such as seamless aluminum tubing or :1 similar light weight alloy. The framing .members are generally U-shaped and are susceptible to economic and rapid production by the use of power operated tube bending machines. Cloth or woven plastic panels are applied to the fabricated seat and back frames and the chairs are assembled in a simple manner by applying pivot members to the holes which are formed in the framing members at their hinge points.

The use of light weight tubular stock, combined withthe geometric arrangement of the several framing members, as explained in detail later, provides a folding chair which is exceptionally light in weight but which is possessed of a high degree of strength and rigidity in proportion to its mass. In order to control the tightness of the joints between the framing members, they are connected together by means of pivot screws which include self-locking nuts; the nuts are adjusted at assembly to provide a firm joint having controlled frictional resistance to allow the members to articulate smoothly and to retain them in folded position by friction.

Described with reference to Figure l, the metal frame essentially comprises a pair of front legs -40, a U- shaped composite rear leg 11, a seat frame 12, a back rest frame 13, and a pair of arm rests 1414. The arm rests are formed from flat metal stock and the remaining frame members are formed of tubular metal stock, the several members being pivotally connected together to provide relative articulation and sliding motion. Thus, as indicated in broken lines in Figure 1, the chair is folded to its flat collapsed position by swinging the seat and arm rests upwardly toward the back rest, causing the rear leg frame 11 to pivot toward a position generally aligned with the back frame 13.

When viewed from the side in erected position (Figure 1), the seat frame 12 and arm rest 14 delineate two sides of a parallelogram while the interconnected portions of the front legs 10 and back rest 13 form the opposite two sides. Since these members are pivotally connected at the four intersecting points of the parrallelogram, the several members are normally free to change their angular relationship while remaining relatively parallel with one another. In order to lock the pivoted framing members in the erected position, the rear leg frame 11 has its intermediate portion pivoted as at 15 to the seat frame and lower end of the back rest and includes an angular portion 16 bisecting one corner of the parallelogram and acting as a truss member. The free end of the truss member 16 is slidably connected as at 17 to the arm rest which is slotted as at 18 for this purpose. It will be seen therefore that the weight load of the chair acting upon the rear leg frame tends to swing the leg frame about its pivot point 15 and to urge the free end of the truss member 16 in an are generally toward the front of the chair. This forces the slide bearing 17 against the end of slot 18, the three members at the corner forming a triangular truss structure which locks the chair firmly in erected position.

It will be recognized that the arm rest and leg interconnection provides the necessary locking action without adding separate members to the structure since the arm rest serves as a locking member in addition to its normal function; moreover the arrangement provides a positive look when in erected position and allows the chair to be folded to collapsed condition in a simple manner without manipulating separate locking members.

When the chair is to be folded to collapsed position, the outer end of the arm rest is swung upwardly toward the back rest, causing the slide bearing 17 of the truss member 16 to traverse the slot rearwardly toward the back rest as the arm rest progressively swings toward the back rest. In other words, the slide bearing 17 at the swinging end of the truss member moves through a fixed are about its pivot point 15, while the slot swings in its own are about a pivot point 20 located above pivot point 15. The two arcs of motion are so correlated to one another that the slide bearing 17 abuts the forward I it will be noted that the front legs 10 have their upper ends pivoted to the arm rests 14 by means of rivets 21- 21 on opposite sides. The arm rests 14 are formed of relatively heavy sheet aluminum stock bent to right angular shape in cross section providing a horizontal top flange 22 and a vertical side flange 23 (Figure 5). langc 23 resides against the inner sides of the front legs and the rivets 21 pass through the flange and through the tubular legs. A washer 24, which is formed from fibrous material is interposed between the flange 23 and front leg to provide clearance between the parts and also to apply a slight frictional resistance to their relative pivotal motion.

The lower end of each front leg is provided with a cap 25 formed of rubber or other suitable material to provide a frictional engagement with the supporting surface and to prevent excessive wear upon the lower ends of the tubular legs. Since the weight load of the front legs is concentrated more or less in a localized area, the lower ends of the tubes include metal closure caps 26 which seat within the tube and provide a backing for the rubber cap (Figure 1). The closure caps have a slightly round-. ed edge overlying the end of the tube to protect the bottom of the rubber cap.

The front legs are held rigidly in spaced relationship by a tubular cross member 27 which is generally U- shaped as viewed from the front (Figure 2), providing vertical limbs 2828 which reside against the inner surfaces of the front legs. The vertical limbs are each attached to the legs by screws 30, one at each side, the screws passing through the limbs and front legs. A second screw 31 which forms a pivot point for the forward end of the seat frame, passes through the seat frame at opposite sides and projects outwardly through the limbs and chair legs (Figure 6). Both sets of

screws

30 and 31 include nuts 32 applied upon their outer ends, the nuts being of a commercial self-locking type to hold the partspermanently in engagement under controlled pressure. I

The preferred form of lock nut is known in the trade as an elastic stop nut and includes an insert washer formed of fibrous material which engages the threads of the screw to frictionally lock the nut in its adjusted position. With the exception of the rivets 21, the several pivot connections of the frame assembly consist of similar screws and nuts. At assembly, the nuts are adjusted to eliminate any looseness in the structure; thereafter they can be adjusted conveniently to take up for any wear which may become evident after the chair has been in service for a prolonged period.

As detailed in Figure 6, washers 33 are confined on each screw 31 between the seat frame 12 and limb 28 to form a bearing surface therebetween and to space the members so as to prevent interference with projecting parts of the frames when in collapsed condition. Similar washers, providing the required clearances, are utilized at other pivot connections as noted later. The upper ends of the limbs 28 include closure caps 26 similar to those of the front legs.

It will be observed at this point, that the cross brace 27, by virtue of its two point connection to the front legs, is effective to stiffen the legs and enable them to resist the lateral strains which are imposed upon them when the chair is occupied. In addition to stiffening the legs, the limbs 28 function as fillers or spacers between the front legs and seat frame and strengthen the pivotal connection of the seat to the legs.

As viewed in Figure 2, the rear leg frame 11 is generally U-shaped, with its cross member 34 converging upwardly toward center from the curved portions 3535 which rest upon the support surface, thus providing a more stable support. As disclosed in Figure 5 the upper truss members 16 of the rear leg frame 11 have their upper ends slidably connected to the arm rest slot 18 by the slide bearings previously indicated at 17. Each slide bearing is mounted upon a screw 36 which includes a lock nut 32 on its threaded end as described earlier. The surfaces of the slot have a tendency to become chalfed and worn if metal to metal contact exists between the screw and slot surfaces; therefore a nonmetalic bushing indicated generally at 37 surrounds the portion of the screw which passes through the slot. The bushing is formed from a plastic material, preferably nylon, which is found to provide a smooth sliding fit and which exhibits a very high resistance to wear. Rigid testing of the bushing under conditions equivalent to actual use of the chair, caused no measurable wear upon the bearing surfaces of the plastic bushings.

For purposes of assembly, each bushing is composed of two parts consisting of a collar 38 having a flange 40, in bearing engagement with the inner surface of the arm rest flange 23 (Figure 5). A washer 41 is located upon the outer end of collar 33 between the head of the screw and the outer surface of the flange 23. The limbs of the rear leg frame 11 are bent slightly toward one another such that the truss members 16 are sprung apart when their ends are connected to the arm rests. Thus the truss members exert a constant preload pressure toward the flanges of the arm rests, forcing the flange 40 of the bushing against the metal surface of the arm rest. This condition provides a constant frictional resistance which aids in maintaining the chair in folded condition and also partially decreases the bearing pressures which are localized along the relatively narrow surfaces of the slot. As

shown in Figure 5, the collar 38 is slightly longer than the thickness of the arm rest flange 23 to provide the clearance i2 between the arm rest surface and washer 41. This allows the lock nut to be drawn up tight without causing the slide bearing to clamp the arm rest flange.

As explained earlier, the limbs of the leg frame are pivotaliy connected intermediate their length as at 15 to the seat frame 12 and back rest frame 13. This connectlon is also provided by a screw i3 and lock nut 32, the rew passing in common through the seat frame, bacl'. rest and rear leg. The tube of the back rest frame is held in spaced relationship at opposite sides between the scat frame and rear leg limb by means of the fiber washers ted at 44- and 4. 5 (Figure 2). The washers are r to those shown in Figure 6 except that their thickness is regulated to provide a slightly different spacing at opposite sides of the back rest tubes, as required by the relationship of the parts.

The seat frame 12 also constitutes a U-shaped memin the present example, the cross member or bight 46 of the U extends across the forward edge of the seat. As best shown in Figure l, the forward portion of the frame 12, including the cross member, is bent downwardly at an angle to the plane of the seat frame as indicated at 47. By this arrangement, the forward edge of the seat assembly flares downwardly below the legs of the user to provide a more comfortable seat. The rearward portion of the seat in the present structure is also reinforced by a tubular cross member 48 as detailed in Figure 4. The opposite ends of the cross member are flattened and bent to a radius corresponding to the diameter of the tubular seat frame, as indicated at 59. The curved ends 50 are attached to the seat frame by the screw 51 and lock nut 32.

The seat frame includes a seat panel formed of canvas or a woven plastic material. closure two panels are utilized, one panel indicated at 52 extending transversely across the limbs of the seat frame, while a second panel 53 extends longitudinally from the bight 46 to the cross member 48 (Figure 1). The marginal edge portions of each panel at opposite sides are doubled over upon the panel to provide loops 54 and the looped portions are confined around the respective tubular members of the frame. The longitudinal panel 53 preferably overlies the transverse panel 52 and they are applied to the seat frame before assembly of the chair.

In the present dis- Should the panels become worn or damaged they are replaced by demounting the seat frame and removing cross bar 48.

In another form of the chair following the principles herein disclosed, a simplified seat structure is utilized. in this structure a U-shaped seat frame: is provided but the cross bar 48 is omitted and the position of the frame is reversed, the open end of the frame being disposed to the front of the chair.

The back rest 13 of the chair is also of U-shaped tubular construction having generally vertical limbs connected across the top by a horizontal connecting portion 56. As viewed in Figure 1, the limbs 55 are bent rearwardly intermediate their length to provide the inclined portion 37. A canvas or woven plastic back panel 58 having looped marginal edges 54, similar to the seat panels, is anchored between the limbs 55 and resides across the upper portion of the back rest. The back panel is removable for replacement by detaching the back rest frame in the manner described with reference to the seat frame. The fiber washers interposed between the articulated frame members provide sufficient clearance to allow the components of the frame to be folded to flat condition without interfering with the heads of the screws or the looped portions of the panels.

From the foregoing analysis of the structure and principles of the invention, it will be apparent that the tri- M ation of the several framing members at opposite sides 18 effective to lock the chair rigidly in erected position. When the chair is in use, the major portion of the weight load at each side is imposed upon. the pivot screw 43 at the rear of the seat frame and acts upon the rear leg frame, tending to swing the frame about the pivot screw. The sliding end of the truss portion 16 thus is forced in an are about the pivot screw 43 toward the front of the chair, the major force being generally parallel to the longitudinal axis of the arm rest and to a minor degree, at right angles to the rest. These forces are imposed by the slide bearing 37 upon the end portion of the slot, whereby the major force is resisted in tension by the arm rest. The self-locking triangulation of the parts is such that the chair remains firmly locked in erected position even though the user tilts with the chair to a rearwardly inclined position with a corresponding change in the distribution of forces.

To collapse the chair, the back rest and arm rest (or forward edge of the seat frame) are forced toward one another; in collapsed condition, the frictional resistance of the slide bearings and other pivot points prevents relative motion of the framing members, such that the chair may be carried conveniently in folded condition.

As explained earlier, the cross brace 27 at the front of the chair resists lateral deflections to the chair, spaces the seat frame, and also reinforces the pivotal attachment of the seat frame. Although chairs have been constructed in the past having a cross member extending transversely across the lower ends of the front legs, similar to the rear legs of the present disclosure, such construction fails to stiffen the legs to the same degrgee. Moreover, a cross member extending across the supporting surface forms an undesirable obstuction which tends to trip the user of the chair.

Having described my invention 1 claim:

1. A collapsible chair comprising a seat frame, a pair of front legs pivotally connected to the forward portion of the seat frame at opposite sides, the front legs having linking portions which rise upwardly above the plane of the seat frame, a back rest pivotally connected to the rearward portion of the seat frame at opposite sides, a pair of arm rests extendin along opposite sides of the seat frame, the arm rests being spaced above the plane of the seat frame generally in parallelism therewith, each of said arm rests having its respective opposite ends pivotally connected to the back rest and to the linking portions of the front legs, a pair of rear legs pivotally connected to the rearward portion of the seat frame at opposite sides, said rear legs having truss portions above the pivotal connections thereof which extend angularly above the plane of the seat frame toward the forward portion of the chair, and slide means slidably connecting said angular truss portions to the arm rests on opposite sides, said slide means including abutment means engaging the truss portions at a limit of angulation toward the forward portion of the chair, thereby to lock the arm rests and pivotally connected members thereof in erected position, said slide means adapting the arm rests and pivotaily connected members thereof to be pivoted toward the back rest to a collapsed position by providing relative sliding motion between the arm rests and slidably connected truss portions.

2. A collapsible chair comprising a seat frame, a pair of front legs pivotally connected to the forward portion of the seat frame at opposite sides, the front legs having linking portions above the pivoted connections thereof which rise upwardly above the plane of the seat frame, a back rest having its lower ends pivotally connected to the rearward portion of the seat frame at opposite sides, a pair of arm rests at opposite sides of the seat frame, the arm rests being spaced above the plane of the seat frame and generally parallel therewith, each of said arm rests having its respective opposite ends pivotally connected to the back rest and to the linking portions of the front legs, a rear leg frame pivotally connected to the rearward portion of the seat frame at opposite sides, said leg frame having truss portions above the pivotal connection thereof extending above the plane of the seat frame angularly toward the forward portion thereof, said arm rests each having a slideway extending longitudinally and outwardly toward the forward portion of the seat frame, and respective slide bearings connected to the free ends of said truss portions and confined in said slideways, said slide bearings normally engaging the outer ends of said slideways, whereby the truss portions lock the chair in erected position, the slideways providing sliding motion of the slide bearings toward the inner ends of the slide ways, whereby the arm rests and pivotally connected parts thereof may be pivoted upwardly relative to one another toward the back rest to a collapsed position.

3. A collapsible chair comprising a seat frame, a pair of front legs pivotally connected to the forward portion of the seat frame at opposite sides, the front legs having linking portions above the pivoted connections thereof which rise upwardly above the plane of the seat frame, a back rest having its lower ends pivotally connected to the rearward portion of the seat frame at opposite sides, said back rest having linking portions on opposite sides which are parallel to the linking portions of the front legs, a pair of arm rests at opposite sides of the seat frame, the arm rests being spaced above the plane of the seat frame in parallelism therewith, each of said arm rests having its respective opposite ends pivotally connected to the linking portions of the back rest and to the linking portions of the front legs, said arm rests and seat frame delineating two sides of a parallelogram and the linking portions of the back rest and front legs delineating the other two sides, a rear leg frame pivotally connected to the rearward portion of the seat frame at opposite sides, said leg frame having truss portions above said pivotal connection on opposite sides extending above the plane of the seat frame angularly toward the forward portion thereof, said arm rests each having a slideway extending longitudinally and outwardly toward the forward portion of the seat frame, and respective slide bearings connected to the free ends of'said truss portions and confined in said slideways, said slide bearings normally engaging the outerends of said slideways, whereby the truss portions bisect one corner of the parallelogram and lock the chair in erected position, the slideway providing sliding motion of the slide bearings toward the inner ends of the slideways, whereby the arm rests and pivotally connected parts thereof may be pivoted in parallelogram fashion toward the back rest to a collapsed position.

4. A collapsible chair frame comprising a seat frame, a pair of front legs pivotally connected to the forward portion of the seat frame at opposite sides, the front legs having linking members above the pivoted connections thereof which rise upwardly above the plane of the seat frame, a back rest having lower end portions pivotally connected to the rearward portion of the seat frame at opposite sides, said lower end portions providing linking members which are parallel to the linking members of the front legs, a pair of metal arm rests at opposite sides of the seat frame, the arm rests being spaced above the plane of the seat frame in parallelism therewith, the opposite ends of said arm rests being pivotally connected to the rearward portion of the seat frame at opposite sides, said le frame having respective truss portions above said pivotal connections on opposite sides and extending angularly above the plane of the seat frame toward the forward portion thereof, said arm rests each having a longitudinal slot therein, said slots having inner ends adjacent the back rest and outer ends which terminate outwardly toward the forward portion of the seat frame, respective slide bearings formed of plastic material confined in said slots and in sliding contact with the metallic surfaces of said slots, and means connecting the slide bearings to the upper ends of said truss portions, said slide bearings normally engaging the outer ends of said slots and locking the chair in erected position, the slots providing sliding motion of the slide bearings toward the inner ends of the slots whereby the arm rests and pivotally connected parts thereof may be pivoted in parallelogram fashion toward the back rest to a collapsed position.

5. A collapsible chair frame comprising a seat frame, a pair of front legs pivotally connected to the forward portion of the seat frame at opposite sides, the front legs having linking members above the pivoted connections thereof which rise upwardly above the plane of the seat frame, a back rest frame having lower end portions pivotally connected to the rearward portion of the seat frame at opposite sides, said lower end portions providing linking members which are parallel to the linking members of the front legs, a pair of metal arm rests at opposite sides of the seat frame, the arm rests being spaced above the plane of the seat frame in parallelism therewith, each of said arm rests having a vertical flange extending longitudinally thereof, the opposite ends of said arm rests being pivotally connected to the linking members of the back rest and to the linking members of the front legs, a rear leg frame pivotally connected to the rearward portion of the seat frame at opposite sides in common with the pivot connections of the back rest, said rear leg frame having respective truss portions above said pivotal connection on opposite sides and extending angularly above the plane of the seat frame toward the forward portion thereof, the flanges of said arm rests each having a longitudinal slot therein, said slots having inner ends adjacent the back rest and outer ends which terminate outwardly toward the forward portion of the seat frame, respective slide bearings formed of plastic material confined in said slots and in sliding contact with the metallic surfaces of said slots, and means connecting the slide hearings to the upper ends of said truss portions, said slide bearings normally engaging the outer ends of said slots and locking the chair in erected position, the slots providing sliding motion of the slide bearings toward the inner ends of the slots whereby the arm rests and pivotally connected parts thereof may be pivoted in parallelogram fashion toward the back rest to a collapsed position.

6. A collapsible chair frame comprising a seat frame, a pair of front legs pivotally connected to the forward portion of the seat frame at opposite sides, the front legs having linking members above the pivoted connections thereof which rise upwardly above the plane of the seat frame, a back rest frame having lower end portions pivotally connected to the rearward portion of the seat frame at opposite sides, said lower end portions providing linking members which are parallel to the linking members of the front legs, a pair of metal arm rests at opposite sides of the seat frame, the arm rests being spaced above the plane of the seat frame in parallelism therewith, each or" said arm rests formed of sheet metal and having a vertical flange extending longitudinally thereof, the opposite ends of said flanges being pivotally connected to the linking portions of the back rest and to the linking portions of the front legs, a pair of rear legs pivotally connected to the rearward portion of the seat frame at opposite sides, said rear legs being inclined upwardly and extending angularly above the plane of the seat frame toward the forward portion thereof, the flanges of said arm rests each having a longitudinal slot, said slots having inner ends adjacent the back rest and outer ends terminating outwardly toward the forward portion of the seat frame, respective slide bearings formed of plastic material confined in said slots, each of said slide bearings comprising a collar passing through the slot, said collar having flanges on opposite ends overlying the opposite sides of the flange adjacent the slot, respective attachment means passing through said collars and through the upper end portions of said rear legs, said slide bearings normally engaging the outer ends of said slots to lock the chair in erected position, the slots providing sliding motion of the slide bearings toward the inner ends of the slots whereby the arm rests and pivotally connected parts thereof may be pivoted in parallelogram fashion toward the back rest to a collapsed position.

7. A collapsible folding chair frame comprising a pair of front legs, a U-shaped bracing member spaced above the lower ends of the legs and extending transversely between said legs, said bracing member having limbs parallel with the legs on opposite sides and attached thereto, a seat frame interposed between the limbs of said bracing member, seat pivot members passing in common through said legs and limbs and through the seat frame at opposite sides, said limbs spacing the seat frame relative to the front legs and reinforcing said seat pivot members, front legs having linking portions extending upwardly above the plane of the seat frame which are stiffened laterally by said U-shaped bracing member, a back rest frame having linking portions at its lower portion parallel to the linking portions of the front legs, back rest pivot members connecting the lower ends of the back rest to the rearward portion of the seat frame at opposite sides, a pair of arm rests disposed along opposite sides of the seat frame spaced upwardly in parallelism therewith, respective arm rest pivot members connecting the respective opposite ends of each arm rest to the back rest and to the linking portions of the front legs on opposite sides, a rear leg frame having inclined limbs pivotally connected to the back rest pivot members on opposite sides, said limbs having upper truss portions extending angularly from the back rest pivot members to the arm rest, respective slideways on the arm rests, slide hearings on the upper ends of said truss portions slidably confined in said slideway and providing relative longitudinal sliding movement of the arm rests and truss portions, the slideways including stop means outwardly from the back rest which limit the forward position of said truss portions, whereby the truss portions lock the chair frame in erected position, said slide bearings adapting the arm rests and pivoted members thereof to be articulated in parallelogram fashion to a collapsed position,

References Cited in the file of this patent UNITED STATES PATENTS 2,072,075 Travers et al. Feb. 23, 1937 2,155,522 Adler Apr. 25, 1939 2,541,664 Pollack et al Feb. 13, 1951 FOREIGN PATENTS 104,079 Great Britain Feb. 22, 1917