Wheelchair

A collapsible wheelchair having a pair of opposed side frames connected by scissors cross bars and having a pair of vertical shafts, which terminate in handles connected to the rear end of the side frame. A pair of seat-supporting members telescope into the side frames and move up and down as the side frames are brought together to collapse the wheelchair. To reduce the frictional forces in the telescoping members, rollers are provided on the telescoping members which bear against the vertical shafts and roll up and down as the chair is folded from use to non-use positions and back again.

PRIOR ART 
The brochure MEYRA Wheelchairs and Rehabilitation Equipment from MEYRA 
Wilhelm Meyer GmbH & Co. KG, Meyra-Ring, D-4925 Kalletal-Kalldorf, 
describes a wheelchair of the type in question. If such a wheelchair is to 
be folded up from the use position into the non-use or stored position, 
the side frames must usually be pressed together by means of handles 
mounted at the rear of the frames and which are normally used to move the 
wheelchair. This often poses problems because of the frictional forces in 
the telescoping guides, and this effect is even worse because of clamping 
and jamming effects due to misalignment of the side frames by the 
application of closing forces at the rear of the chair. Therefore, it is 
often possible to collapse the wheelchair only by raising manually the 
telescoping top parts of the side frames, which necessitates special 
handling or reaching around. 
SUMMARY OF THE INVENTION 
The object of this invention is to solve the problem inherent in the prior 
structures and to provide a collapsible wheelchair which folds from the 
use position to the non-use position with ease. 
The object of this invention is accomplished by reducing the frictional 
forces in the telescoping guides, by supporting the tops of the side 
frames by contact rollers which bear against tubes or shafts that rise 
above the side frames and serve as handles for the wheelchair. The rollers 
run parallel to the vertical movement of the telescoping guides which move 
up from the side frames as the chair collapses. These rollers absorb a 
considerable portion of the compression forces applied to the side frames 
when the wheelchair is folded up and transmit these forces in a rolling 
fashion with a diminishing frictional force. Reduction of frictional 
forces in the guides facilitates the entire operation of collapsing the 
wheelchair. 
The vertical bearing tubes against which the rollers bear extend upward 
above the side frames and are curved down to form handles. The bearing 
tubes thus do not result in any increase in cost and the cost of the 
contact rollers is very low. The rollers may be rotatably mounted on the 
ends of the seat-supporting tubes with their axes of rotation parallel to 
the axis of the seat-supporting tubes, which tubes are connected to the 
telescoping guides. 
The invention will now be illustrated according to one embodiment.

The wheelchair which is shown schematically in FIGS. 1 and 2 has a pair of 
opposed side frames, each of which consists of spaced upper and lower 
horizontal tubes 1 and 4 and 2 and 3, respectively. The horizontal tubes 
are connected by vertical tubes 13, 14 and 11, 12, respectively. These 
vertical tubes also serve as sleeves which telescopically receive posts or 
guides 7, 8, 9, 10 as shown in FIG. 2. Seat-supporting tube 19 is 
connected to the tops of posts 7 and 8 for vertical movement therewith. In 
like manner, tube 20 is connected to the tops of posts 9 and 10. The upper 
ends of posts 7 and 8 or 9 and 10 preferably are welded to end sleeves 15 
and 16 or 17 and 18 in which the center sections of the seat-supporting 
tubes 19 and 20 rotate. The axes of these short end sleeves run at right 
angles to the axes of the guide posts 7 to 10. 
In the same manner as seat-supporting tubes 19 and 20 rotate in end sleeves 
15-18, lower horizontal tubes forming part of the side frames have middle 
sections 21 and 22 which rotate in end sleeves 23 and 24 or 25 and 26 
consisting of short tube segments. A pair of cross bars 27 and 28 are 
connected together in the middle like scissors by means of a mid point 
rotary bearing or pivot 29. The upper end of bar 27 is welded to rotatable 
tube 19 of the right side frame and its lower end is welded to rotatable 
lower tube 22 of left side frame as viewed in FIGS. 1 and 2. The other 
member of the scissors, bar 28, is welded to rotatable tubes 20 and 21 in 
opposed side frames. 
Wheels 31 and 34 support the chair with the usual design and arrangement, 
which need not be explained further, and attach to the side frames at the 
bottom thereof. 
Vertical shafts or tubes 35, 36 are secured to the rear of the upper and 
lower horizontal tubes comprising part of the side frames. Rollers 37 and 
38 are mounted on offset axles welded to the outer ends of sleeves 16 and 
18. The rollers roll in contact with the inside surfaces of the bearing 
shafts. Bearing shafts 35 and 36 continue upward over the guide segment 
and the curve down or are bent down so they form handles 39 and 40. A seat 
41 in the form of a flexible belt extends between seat-supporting tubes 19 
and 20 and is wrapped at the ends around tubes 19 and 20. 
In FIGS. 1 and 3 of the drawings, the wheelchair is in its ready-to-use 
position where side frames are essentially the maximum distance apart as 
determined by the width of seat 41. In this position cross bars 27 and 28 
are at the maximum spread; and scissors are open. In order to bring the 
wheelchair into the collapsed position illustrated in FIGS. 2 and 4, 
handles 39 and 40 are moved toward each other. Contact rollers 37 and 38 
roll on the inside surfaces of bearing shafts 35 and 36, as the 
seat-supporting tubes move from the position in FIGS. 1 and 3 to the 
position in FIGS. 2 and 4. Thus all essential forces due to the folding 
action are transmitted largely without any friction, with the result that 
the wheelchair can be collapsed from the ready-to-use position into the 
non-use position with little effort. 
Rectangular side frames and their respective horizontal and vertical 
members, as well as seat-supporting tubes 19, 20 need not necessarily 
consist of bent or welded steel tubes. They may also be flat plate-shaped 
side frames. The guides for the vertical posts that belong together in 
pairs may also have any other design with which those skilled in the art 
are familiar.