Patent GB-1446845-A (GB)
Title: Collapsible volume frame structures
IPC: B60G11/22
Filed: 1973-03-02
Abstract: 1446845 Folding chairs GANNET HOLDINGS Ltd 31 Oct 1973 [1 Nov 1972 2 March 1973] 50331/72 and 10246/73 Heading A4J [Also in Division B7]  In a folding volume frame, particularly for a wheel chair or a chair without wheels or with some form of runners other than wheels, collapsible in horizontal and vertical senses, a pair of opposite sides are inter-connected by a collapsible X-frame extending in the lateral sense and by tie means having two ends of maximum separation which in the extended condition hold the volume frame erected. In one embodiment Fig. 2 the parts 4C, 4D of seat back parts constituting extensions of rear legs 4A, 4B are connected by pivots to extensions of base elements 1, 1 A, by an X-frame 11'. A collapsible toggle strut 12 inter-connects rods 11, 11A of the X-frame 11' and a similar collapsible toggle strut 13 inter-connects the front legs 3, 3A. A second X-frame 14' pivotally inter-connects the front legs 3, 3A to rear legs 4A, 4B. In another embodiment, Fig. 3, a third X-frame 15 has rods 15, 15A pivotally connected at their upper ends to legs 3, 3A and at their lower ends pivoted at 150 to slides 16 movable along base elements 1. Also pivoted to slides 16 are toggle struts 17A, 17B the strut 17B being pivoted to rear legs 4A, 4B. The struts 17A extend to provide handles 17D. A lock such as a plastics spring latch or a slidable ring may hold the struts 17A, 17B together when extended. Fig. 10 shows a spring lock in which a plunger 16C is retractable by a wire 16D connecting it to a trigger (16E) Fig. 5 (not shown) near the handle 17D for releasing the locked slide 16. Collapse of the structure shown in Fig. 3 is effected by pulling handles 17D forwardly thus breaking struts 17A, 17B for slides 16 to move rearwardly taking with them the bottom ends of the X-frame 16; thus producing a bundle Fig. 6 (not shown) in which all the main elements of the frame are nearly parallel. The parts 8 of arm rest 9 can be fitted into open ends at the top of legs 3, 3A, the arm rest 9 being pivoted to back rests 4C, 4D, thus the arm rests can be detached at their forward end and pivoted upwardly, Fig. 4 (not shown) for the occupant to sit sideways. As shown in Fig. 9 a crooked handle 90 may be inserted into the top end of seat back parts 4C, 4D in any one of four positions made possible by slots in the forked end 93 which correspond with pivot pin 10A. The structure is provided with four "wheel pairs". As shown in Fig. 10 fully castoring front wheel pair of resiliently tyred wheels 100 are borne on an axle 101  which is fixed in two side plates 102 of a rocking element pivoted at 102A thus attaching it to a square section tube 103 which is rotatable for castoring in a hollow pin 106. The assembly 105, 105C is held resiliently by the flange 105A being sandwiched between rubber pads 106, 107, all held in compression within fitting 2A riveted to element 1. The tube 103 has pivoted at 108 a fitting 109 housing, in compression, rubber block 109A which acts as a resilient cushion between fitting 109 and tube 103 when wheel 100 is urged upwards. A rubber pad 102C carried on the extension-of plates 102 controls resilient rebound of the wheel 100. Fig. 11 shows the controlled suspension of the back wheels in which brackets 114 are rigidly attached to the members 11 and hold, in compression, rubber bushes 115 in which are embedded cantilever arms 116 which support axles 117 which bear a rear wheel pair 118. The tyres 119 are preferably of sponge plastics material with a resilient but smooth tread, all formed as one moulding and secured to the moulded plastics wheels by adhesive or by being formed and cured in situ. In a further embodiment, Fig. 12, an X-frame of cross members A30, A31, is provided, interpivotted at A32, the ends of cross members A30, A31 being pivoted via members such as A30A to four pivots A33, A34 on the front legs A21, A22. The members A30A, A31A are extended past their respective pivots and linked by rods A35 to their corresponding parts A31B, A30B. The cross members are further linked by a toggle bar A37 having a knob A37A which is pulled upwards and the handles A9 are moved forward for collapsing the frame. In a further embodiment Fig. 14 (not shown) the same basic volume frame as shown in Fig. 12 has a single lever mechanism (C41), (C43), (C46) which may collapse and  extend the toggles (C20) of rear X-frame (C11), (C10) and the toggle (C37) of the forward X-frame simultaneously. The beam (C43) is pivotally attached to the seat bearers (C23), (C24), by struts (C48) so that as an occupant sits down his weight taken through the bearers (C23), (C24) pushes the beam (C43) down thus "making" rear toggles (C20) and forward toggle (C37). Fig. 17 shows a variant of an X-frame which braces front legs A' 21, A<SP>1</SP>22. The frame has a rigid cross element A<SP>1</SP> 30, A<SP>1</SP>31 rotation of which in the clockwise sense in Fig. 17 breaks the corresponding toggle connections and permits the legs A'21, A'22 to approach one another.