EP0689410B1 - Wheelchair - Google Patents

Abstract

The invention concerns a wheelchair with a seat, two side-located drive wheels and front and rear running wheels which are free to rotate about substantially vertical axes. The drive wheels are mounted at least approximately coaxially with each other about an axis which extends across the wheelchair below the central area of the seat. Together with its respective axle bearing, each drive wheel can be individually rotated, about a substantially vertical axis, between a fixed position for straight-line travel and a pivoted position for sideways travel. A first part of the wheelchair frame, comprising the chassis and the drive wheels and rear running wheels, and a second part of the wheelchair frame, comprising the seat and back (if any) and the front running wheels, can be rotated with respect to each other about a transverse horizontal axis.

Description

The invention relates to a wheelchair with a seat, two side drive wheels and front and rear wheels freely pivotable about respective substantially vertical axes, the drive wheels of which are mounted at least approximately coaxially on an axis line which runs transversely beneath the seat surface.

With known wheelchairs, even with so-called active wheelchairs, which are also suitable for sports, the mobility and maneuverability is very limited by design. In particular, thresholds and steps, even if they are only a few centimeters high, prove to be an insurmountable obstacle in many cases. If they are overcome with momentum and strength, the situation easily arises in a three-axle wheelchair with drive wheels on the middle axle that they lift off the ground and driving on without assistance is no longer possible. In addition, especially in small apartments and also on larger work surfaces such as tables where the wheelchair user wants to reach for things that are outside his immediate range, the required maneuvering with the wheelchair requires too much free space and consumes time.

The problem of thresholds and levels is still in practice unsolved. To increase the flexibility of movement, an electrically powered wheelchair is known ("LEM", brochure from Sanitätshaus Wißmann & Co., Düren), which on the underside of a frame has five wheels distributed around the circumference, each pivotable about a vertical axis and coupled in this pivot and has a central drive wheel, the pivoting position of which is also coupled to the running wheels and, moreover, is coupled to the seat located above the frame, which can therefore rotate on the spot and continue in any direction. The design effort for this wheelchair is very high. Also, a transverse displacement of wheelchairs is known per se (DE-A 31 33 636), namely with the aid of rollers which are extended in such a way that the drive wheels rigidly arranged for forward travel are lifted off the ground for the transverse displacement. However, the patient cannot do the operation by hand and the ability to move the auxiliary casters does not provide him with any particular maneuverability of the chair, especially since the changeover is energy-intensive and no rapid rolling movement is possible on the auxiliary rollers. A wheelchair is also known (DE-A 30 05 871) which comprises two large drive wheels on an axis which runs approximately centrally under the seat surface and further comprises a frame cross with four wheels, the cross point of which is also centrally below the seat surface. This wheelchair is already relatively manoeuvrable, since it can turn on the spot by turning the two drive wheels in opposite directions, but maneuvering for a change of location takes a certain amount of time and it is not possible to overcome thresholds and steps. The stability of the wheelchair against tipping forward and backward is also questionable. In another known wheelchair (FR-A 2 383 822) of the type mentioned, the construction of which basically resembles that according to DE-A 30 05 871, the axis of the drive wheels can still be rotated overall about a vertical central axis of the wheelchair. However, such a construction is not possible with large-wheeled hand-operated wheelchairs and also leads to stability problems and difficulties in contact with the ground in the event of unevenness.

In contrast, the invention is intended to enable quick maneuverability and easy mobility of the wheelchair. This is achieved by two measures which are particularly effective in combination, but to a certain extent also individually, namely first of all in that the wheelchair comprises a first frame part comprising a chassis with the drive wheels and the rear or front wheels and a seat surface with possible backrests and the second frame part, which does not comprise the first frame part and which comprises front or rear wheels, can be pivoted relative to one another about a transverse horizontal pivot axis, and preferably also in that the drive wheels including their respective axle bearings individually about a respective substantially vertical axis between a created position for Straight ahead and a transverse position for transverse travel are pivotable.

Due to the tiltable pivoting of the frame parts and the transverse adjustability of the wheels, the patient sitting in a wheelchair can overcome thresholds up to a few centimeters in height without losing the contact of the drive wheels with the floor for a short time, and without having to turn the chair and himself, for example Roll back and forth along a furniture edge, even on uneven floors, but it can also turn on the spot if necessary.

The wheelchair can be a hand-driven or a motor-driven wheelchair; the measures according to the invention prove to be advantageous in both cases. However, they are preferably used in a hand-operated wheelchair, which is particularly suitable for agile movements and quick adjustments due to its smaller dimensions and lower weight. Likewise, the invention is applicable to both a rigid and a collapsible wheelchair, but the application of the measures according to the invention to a rigid wheelchair, such as the active and sports wheelchairs corresponds, preferably, because these wheelchairs are more suitable for fast movements due to their greater stability compared to the weight and the wheelchair according to the invention is particularly suitable for narrow apartments and the like, while its maneuverability, for example outdoors, is less of an issue.

The rear and front wheels are naturally used for support, whereby tipping over backwards is particularly avoided. The tiltable pivoting of the frame and thus the possibility of lifting the front and / or rear wheels without losing contact with the other wheels and the drive wheels, allows thresholds to be passed over. However, the mutually tiltable frames also prove to be advantageous when driving on the side with transverse drive wheels, in particular with slightly different ground levels between the front and rear wheels. In such a constellation, in which the drive wheels are located above a type of trough or just above a floor recess, the drive would be interrupted in a rigid frame.

The pivotability of the frame parts relative to one another is, however, preferably limited in terms of angle, in order to prevent the entire frame part comprising the seat surface from tilting backwards by 90 ° due to awkward movements. With a swivel range of up to 10 °, a threshold of 5 cm in height can be overcome in a wheelchair of normal size. The provision of driving over higher thresholds is only of limited use in hand-operated wheelchairs, since the driving force required for this is very high.

When driving sideways, a step that has to be overcome in this transverse direction is less problematic, especially since the two drive wheels successively overcome the step and, with the appropriate wheel arrangement, always represent the front or rear wheel, so that the wheels stand out in between, which is what however due to the mutual pivotability of the frame parts in connection with the weight of the user sitting on the wheelchair does not act as a back and forth swing of the seat.

The construction is particularly expedient in that the pivot axis of the frame parts lies against one another behind the patient's center of gravity and the frame part, which contains the seat surface, carries the front wheels; in this case, the patient can easily raise the front wheels by throwing his upper body backwards and bring them over a threshold. If it is reversed, that is, so that the pivot axis lies in front of the center of gravity and the rear wheels are connected to the seat frame part, he can lift the rear wheels by tilting the seat forward, for example by tilting the upper body forward then to overcome a threshold in reverse. Also possible, albeit less preferred, are constructions in which the pivot axis of the frame parts is close to the center of gravity, for example also in the wheel axis of the drive wheels in their straight-ahead driving position. In this case, springs must be provided between the frame parts and it is more difficult for the patient to lift the front or rear wheels.

A design in which the tilt pivot axis of the frame parts can be adjusted so that it is either further forward or further back, it is possible to adapt the wheelchair to the individual requirements of different patients. And with a construction that includes a cam or thumb that engages the seat from below to raise it, the pivoting of the frame members can be accomplished by twisting the cam, thereby allowing other force to be actuated.

The line of the axes of the drive wheels in the applied position, in which these wheels are essentially coaxial to one another, preferably runs transversely below the central region of the seat surface, that is to say in front of the center of gravity of the seat User, and the pivot axis of the frame parts against each other is preferably just below the seat and slightly behind the patient's center of gravity, which improves the possibility of turning on the spot with minimal traffic space and also the pivoting of the frame part caused by the patient's upper body movement, which the Seat and preferably includes the front wheels, is facilitated.

The pivoting angle of the drive wheels about the respective vertical axis is preferably 90 °, the wheels in the position for straight travel (0 °) and for transverse travel (90 °) and if necessary also in one or more intermediate positions by simple measures, for example with the help a perforated sheet should be lockable. The wheels can also be coupled to one another for pivoting, which is advantageous, for example, for one-armed paralyzed patients, since the two drive wheels (except when cornering) must be parallel to each other in every pivoting position for driving. The possibility of the transverse position, however, means that if the wheels are not to be mounted very far outwards, the size of the wheels is limited, since they partially pivot under the seat. A preferred construction is that of claim 12, in which the ratio of the wheel diameter to the seat width is such that the transverse wheels overlap on both sides in segments. If, on the other hand, the wheels have a common central plane in the transverse position, the distance between their vertical pivot axes cannot be less than the wheel diameter unless the pivot angle is to be limited to an angle below 90 °. This version is therefore most suitable for mechanically, especially electrically powered, wheelchairs in which the wheel size is not a critical size. The drive wheel pivoting can also be designed to be electrically controllable.

It should be pointed out that the features and variants mentioned can be combined with one another as desired in order to create embodiments of the wheelchair according to the invention which are particularly suitable for specific applications.

Fig. 1

eine Seitenansicht eines erfindungsgemäßen Rollstuhls;

Fig. 2

eine Vorderansicht des Rollstuhls nach Fig. 1;

Fig. 3

eine Vorderansicht des Rollstuhls nach Fig. 1 in einer anderen Arbeitsstellung;

Fig. 4

eine Draufsicht auf den Rollstuhl in der ersten Arbeitsstellung, mit teilweise ausgeschnittener Sitzfläche zur Sichtbarmachung der darunterliegenden Teile;

Fig. 5

eine Draufsicht auf den Rollstuhl in der zweiten Arbeitsstellung;

Fig. 6

in verkleinertem Maßstab eine Seitenansicht des Rollstuhls entsprechend Fig. 1, jedoch teilweise in getrennter Darstellung seiner Rahmenteile;

Fig. 7

eine Teilansicht entsprechend der Darstellung von Fig. 2 einer abgewandelten Ausführungsform, in gleichem Maßstab wie Fig. 2;

Fig. 8

eine Ansicht entsprechend Fig. 4 einer abgewandelten Ausführungsform;

Fig. 9

Ansichten entsprechend Fig. 6 des Rollstuhls nach Fig. 8, wobei ein Teil des linken Antriebsrads weggeschnitten ist;

Fig. 10

eine Ansicht entsprechend Fig. 1 noch einer weiteren Abwandlung.

Further details, advantages and developments of the invention result from the description of preferred exemplary embodiments with reference to the drawing. Show it:

Fig. 1

a side view of a wheelchair according to the invention;

Fig. 2

a front view of the wheelchair of FIG. 1;

Fig. 3

a front view of the wheelchair of Figure 1 in a different working position.

Fig. 4

a plan view of the wheelchair in the first working position, with a partially cut-out seat to make the parts underneath visible;

Fig. 5

a plan view of the wheelchair in the second working position;

Fig. 6

in a reduced scale a side view of the wheelchair according to Figure 1, but partially in a separate representation of its frame parts.

Fig. 7

a partial view corresponding to the representation of Figure 2 of a modified embodiment, on the same scale as Fig. 2.

Fig. 8

a view corresponding to Figure 4 of a modified embodiment.

Fig. 9

Views of Figure 6 of the wheelchair of Figure 8, with part of the left drive wheel cut away.

Fig. 10

a view corresponding to FIG. 1 yet another modification.

1 to 6 consists of a first frame part 1 and a second frame part 2, which are connected to one another in a hinge-like manner. 6 are the two Frame parts are shown in a separate state in addition to the assembled state. On the first frame part 1, which represents a type of chassis, there are a left drive wheel 3, a right drive wheel 4 and a single rear wheel 5. In the embodiments that are not shown, two rear wheels can also be provided, for example. Since the wheelchair shown is a manual drive, a handrail ring 6 is attached to the drive wheels 2 and 3, respectively. The second frame part 2 comprises a seat 10 and a backrest 11 - any side rests that may be present are not shown - and two front wheels 12 arranged approximately on the line of the drive wheels 3 and 4. The wheels can be pivoted in the usual way about respective vertical axes, which correspond are designated by 13.

In the example shown, the frame part 1 consists essentially of square tube and the frame part 2 essentially consists of a round tube, which in places is covered with fabric.

The frame parts 1 and 2 are connected to one another via a pivoting or hinge axis 16, which in the example shown is determined by two ball joints 17. To hold the ball joints 17 on both sides of the second frame part 2 there is a tab 18 which protrudes from the underside of the circumference of the seat surface 10, so that the axis 16 runs just below the seat surface in the transverse direction, that is at 90 ° to the straight forward direction. The ball joints 17 lie at a distance of 10 to 15 cm from the edge between the seat surface 10 and the backrest 11, that is to say still behind the perpendicular line running through the center of gravity of an average patient, which is indicated at 19 in FIG. 1.

A cross member 23 belonging to the second frame part 2 and running under the seat 10 extends in the position according to FIG. 1 on a cross member 24 of the first frame part 1 on. The cross members 23 and 24 are, in relation to the normal direction of travel of the wheelchair, in front of the hinge axis 16, in the example described also in front of the center of gravity line 19. If the cross members 23 and 24 lie one on top of the other, the frame parts have a pivoting angle of 0 ° relative to one another. By pressing the patient sitting on the wheelchair with his back against the backrest 11, the second frame part 2 can be pivoted clockwise about the axis 16 relative to the first frame part 1, as shown in FIG. 1, whereby the front wheels 12 lift off the floor. The pivoting is limited by stop elements 25 indicated in the drawing, which limit the pivoting angle to an order of magnitude of 10 °. Such pivoting is sufficient to raise the front wheels 12 about 5 cm above the ground.

In the embodiment described, the first frame 1 consists of a frame welded construction made of metal with a bracket 29 which supports the rear wheel 5 and which extends obliquely from an edge region into the region of the longitudinal center plane of the wheelchair. The rear wheel 5 lies in the layout behind the backrest 11 and thus in any case a sufficient distance behind the plumb line 19, even when the frame part 2 is pivoted back. Sit on both sides on a frame-like inner frame part of the first frame part 1 - in FIGS. 2 and 3 hidden by the spars of the second frame part - bearing 30 (Fig. 1) with a substantially vertical axis of rotation in the vertical plane of the axes of the drive wheels 3 and 4. In the bearings 30 stub axle bolts 31 are mounted, which in turn are the stub axles for the bearing 32 Wear drive wheels 3 or 4. The drive wheels 3 and 4 can thus be pivoted about the respective bearing axis of the bearing 30 in question, namely by a pivoting angle of 90 °, starting from the straight-ahead position according to FIGS. 1, 2 and 4. In FIG. 1, the two bearings 30 and the two halves of the kingpin 31 for the wheel 3 above and below the Wheel bearing 32 visible.

The bearings 32 are located approximately at a distance from the wheel radius below the level of the seat surface 10, even if in plan laterally next to the seat surface, and are approximately coaxial to one another in the working position for straight travel. In the floor plan they are located approximately below the center of the seat surface 10, that is to say in front of the line 19 running through the patient's center of gravity. The center of gravity thus acts in the triangle between the bearings of the drive wheels 3 and 4 and the rear wheel 5 in the floor plan.

The pivoting is carried out for each drive wheel by a pivot lever which is connected to the relevant kingpin 31, namely a pivot lever 33 for the left drive wheel 3 and a pivot lever 34 for the right drive wheel 4. To simplify the illustration, the pivot levers 33 and 34 are shown in FIG Figures 2, 4 and 5 are not shown. They are in the working position according to FIGS. 1 and 2, that is to say for driving straight ahead, in the area between the drive wheels 3 and 4, the pivoting lever 33 being directed towards the front and the pivoting lever 34 towards the rear.

The pivoting range of the wheels 3 and 4 is limited by stops so that each of the wheels can be pivoted by 90 ° from the initially parallel position according to FIGS. 1 and 2, namely the wheel 3 to the rear and the wheel 4 to the front, wherein they are in the end positions again have parallel center planes that have a mutual distance corresponding to twice the length of the steering knuckle between the axis of the bearing 30 and the center of the wheel bearing. This distance is sufficient not only to allow a segment-wise overlap of the two wheels, as can be seen in FIG. 3 in the area 38, but also between the wheels 3 and 4 thus placed there is still space for the load-bearing frame part of the first frame part 1.

In the manner not detailed in the drawing, the drive wheels 3 and 4 are in their pivoting end positions and possibly also lockable in one or more intermediate positions. For this purpose, for example, on the one hand on the frame part 1 and on the other hand on the kingpin 31 or on the lever 33, 34 circular ring segments 40 with holes or resilient or retractable projections are seated in the holes. The withdrawal may e.g. B. can be controlled by depressing the relevant lever 33 or 34. Intermediate pivot positions between the end positions can have the advantage that a larger number of directions of travel is made available thereby and in a given intermediate position there is also the minimum of the traffic area requirement. The detents are advantageous in that the drive wheels 3 and 4 must always be exactly parallel in each straight-ahead driving position in order to produce a defined direction of travel. On the other hand, a non-parallel wheel position allows a quick correction of the angular position of the wheelchair relative to the edge of the work surface or the like.

In a further embodiment, the pivoting movements of the wheels 3 and 4 can also be coupled to one another in a manner not shown, for example by means of a cable or chain hoist, by a connecting shaft which engages via bevel gears on bevel gears sitting on the steering knuckles, or, if there is a corresponding reduction, also via Tension and push rods. In the case of such a coupling, one of the levers 33 and 34 can optionally be omitted, for example if the patient is only able to operate on one side anyway.

The drive wheels 3 and 4 have a diameter which in the example shown is slightly smaller than the height of the underside of the seat surface 10 above the floor. The pivoting of the wheels 3 and 4 is possible so that their vertical diameter just comes to rest under the seat 10. If the wheel diameter is larger, the axes of the bearings 30 must be moved further outwards. For the hand drive there are on the one hand near handrail rings 6 and on the other hand, large diameters of the drive wheels 3 and 4 are desired. The training shown represents the optimum between these opposite demands.

If necessary, the wheelchair can be built collapsible, e.g. B by the horizontal struts of the frame can be telescopically pushed together or folded like scissors in a manner known per se.

The following maneuvers can be carried out with the wheelchair according to Fig.n 1 to 6: Driving straight on a flat route is easy. If the wheelchair approaches a threshold or step, the patient leans against the backrest 11, if necessary suddenly, causing the front wheels 12 to lift off the floor. With simultaneous feed by means of the drive wheels 3 and 4, the wheels 12 come over the threshold and possibly behind them back to the ground, whereupon the drive wheels 3 and 4 also take the threshold through vigorous drive via the handrail rings 6, without lost the frictional contact to the ground in between to have. The front wheels 12 then rise again briefly from the ground, but come back to it when the rear wheel 5 is also pulled over the threshold.

If it is now a narrow aisle that the wheelchair user wishes to reverse, he can do so in the usual way by reversing. However, it is also possible for him to turn on the spot by turning the drive wheel 3 forwards and at the same time turning the drive wheel 4 backwards - or vice versa - and thus to reverse the narrow gear forward. Driving down over the threshold previously overcome in the opposite direction does not cause any difficulties, since the drive wheels always maintain contact with the ground.

For example, if the long corridor is between an elongated work surface and the wall, the wheelchair user can turn in front of the work surface by turning on the spot and turning 90 ° again position. This is quicker, however, if he puts the drive wheels 3 and 4 crossways and can now drive to the right or left as desired without turning the seat 10. The wheels 5 and 12 each set themselves in the new direction of travel.

If there is an incomplete parallelism of the wheelchair to the edge of the work surface at the start of the transverse travel, the wheelchair user can not only adjust his basic orientation again by swiveling back and turning the drive wheels in the opposite direction, but also by moving the drive wheels into different swivel positions, in particular one in a straight-ahead position and one in the transverse position, and then by a small rotation of the straight drive wheel cause the wheelchair to rotate about the base point of the transverse drive wheel. If the wheel axes are not at right angles and not parallel to each other, the base point of the transverse drive wheel also performs a certain rolling movement with this adjustment.

If, during the transverse movement, a floor step runs parallel to the seat surface or the floor is not completely level, for example in the form of a carpet edge, a channel or a grate or in the case of hollows or bumps in the floor, the second frame part takes a slight one compared to the first frame part Incline without affecting the ability of the wheelchair to move sideways. The drive wheels always stay on the ground due to the frame that can be folded in at right angles to the direction of travel.

In the case of an L-shaped worktop edge, for example, intermediate pivoting angles of ± 45 ° can be helpful. In this case, however, the total swiveling of the drive wheels by 90 ° is not sufficient; at least 135 ° is required for this.

In the preferred embodiment according to FIGS. 1 to 6 drive wheels 3 and 4 sit on steering knuckles and can therefore overlap in area 38. In particular, in cases where the wheel size is less important, for example in the case of electrically powered wheelchairs, smaller wheel diameters can also be used and the wheel can be pivotable about an axis that coincides with the vertical wheel diameter or the vertical axis. A corresponding embodiment is shown schematically as a partial representation in FIG. 7. A drive wheel 43, which is seated on the first frame part 1 as in the first embodiment, can be pivoted about a pivot axis 44 which lies in the center plane of the wheel. Accordingly, it sits on a swivel bracket that is angled at the end over the wheel. A motor 46 with a reduction gear also sits on the swivel bracket 45 and can be swiveled together with the wheel 43. In a further embodiment of this embodiment, the pivoting movement can also be electrically driven, which may be necessary depending on the type of disability of the wheelchair user.

The modification according to FIGS. 8 and 9 serves the purpose of adapting the wheelchair to the personal dimensions of the patient. The force to be exerted on the backrest 11 for pivoting the frame depends on the distance between the plumb line 19 and the hinge axis 16. If line 9 is shifted forward from an average value due to the individual figure of the patient, it could result that the force required for lifting the running wheels 12 is too high for the patient. According to FIGS. 8 and 9, this distance can be adjusted. The first frame part 1 has instead of the fixed ball joints 17 a bracket-like support body 51, which - in the example shown - has five holes 52, and the second frame part 2 has two support brackets 53 which surround the support bracket 51 and each of which also has five holes 54 , which are arranged in the same way as the holes 52 and are aligned in pairs for the two brackets 53. In this respect, the arrangement could also be reversed.

The row of holes 52 and the row of holes 54 are aligned and one of the holes 52 and a pair of holes 54 are connected by a bolt 55 which then forms the hinge axis. In the present example, which has 1 and 2 rows of holes with five successive holes in each of the frame parts, five different positions of the hinge axis relative to the frame parts 1 and 2 and specifically relative to the backrest 11 can be selected, while their mutual position in the normal, untilted position of the frame parts remains unchanged. Fig. 8 shows the position of the pin 55 for a heavy patient and Fig. 9 for a slim patient.

10 shows, in addition to the displaceable hinge axis, a possibility for lifting the impeller 12 not by throwing the upper body backwards, but by actuating a lever 61 which is fastened on an axis 62 which is rotatably mounted on a bracket 63 of the frame part 1 and when rotating the frame part 2 pivoted relative to the frame part 1 against the weight of the patient via a cam, a curve or a thumb 64. The axis 62 runs horizontally under the seat 10. Such a device for lifting the frame part 2 is particularly useful for patients who suffer from multiple sclerosis and no longer have enough strength to pivot the frame parts of the embodiments according to FIGS. 1 to 6 against one another. If the patient's performance is even lower, the bracket 63 can also be rotated by an electrical or other drive.

All of the previously described embodiments can be combined with one another as desired based on their characteristics, which results in special variants that are particularly suitable for different purposes.

Claims (14)

1. A wheelchair having a seat (10), two lateral drive wheels (3, 4) and front and rear trailing wheels (5, 12) which pivot freely around respective vertical axes (13), the drive wheels supported approximately coaxially on and rotating around an axis line (of 32) which passes transversally under the seat, characterized in that the wheelchair consists of a first frame part (1) comprising a chassis with the drive wheels (3, 4) and with the rear or front trailing wheels (5, 12), and a second frame part (2) comprising the seat (10) including back and arm rests (11) if any, and the front or rear trailing wheels (12, 5) which are not comprised by the first frame part, the frame parts being tiltable against each other about a transversal horizontal axis (16).
2. The wheelchair of claim 1, characterized in that the front trailing wheels (12) are mounted at the second frame part (2).
3. The wheelchair of claim 2, characterized in that it has five wheels (2, 3, 5, 12), the first frame part (1) carrying besides both of the drive wheels (3, 4) the only rear trailing wheel (5) and the second frame part (2) carrying two front trailing wheels (12).
4. The wheelchair of claims 1 or 3, characterized in that the mutual tilting axis (16) of the frame parts (1, 2) is positioned in close distance beneath the seat (10) and in close distance behind the vertical transversal plane (19) containing the point of gravity of the patient sitting on the seat.
5. The wheelchair of claims 1 or 4, characterized in that the mutual tilting of the frame parts (1, 2) is limited by stops (25) to a maximum tilting angle of 8° to 12°.
6. The wheelchair of any of claims 1 to 5, characterized in that a rotatable axis (62) supported by the first frame part (1) is secured to a lever (61) turnable by the patient and to a cam means (64) engaging at one hand from below the seat (10) and at the other hand the other frame part (2) at a point forwards of the tilting axis (16).
7. The wheelchair of any of claims 1 to 5, characterized in that the transversal horizontal axis (55) is adjustable to be selected between several positions differently spaced from the plane of the back rest (11).
8. The wheelchair of claim 7, characterized in that the first frame part (1) and the second frame part (2) each have a row of holes (52, 54), the holes of the frame parts being aligned to each other in pairs, one of the aligned pairs of holes being penetrated by a bolt (55), which is releasable for the purpose of being mounted in another pair of holes.
9. The wheelchair of any of claims 1 to 8, characterized in that the drive wheels (3, 4) including their respective axial bearing (32) are each turnable around a respective vertical axis (of 30) between an alongside position for driving forwards and a transversal position for driving sideways.
10. The wheelchair of claim 9, characterized in that the axis line in the alongside position of the drive wheels (3, 4) passes transversally beneath the central area of the seat (10).
11. The wheelchair of claims 9 or 10, characterized in that the wheel diameter is equal or smaller than the free height under the seat (10).
12. The wheelchair of claim 11, characterized in that the drive wheels (3, 4) are mounted at axle swivels rotatable about the respective generally vertical axis and in the transversal position are parallel to each other and, seen from front to back, overlap each other.
13. The wheelchair of claim 11, characterized in that the turning axis (44) of the preferably electrically (by 46) driven drive wheels (43) coincides with the vertical wheel diameter.
14. The wheelchair of any of claims 9 to 13, characterized in that the drive wheels (3, 4) are mounted at wheel supports (31) rotatable about parallel generally vertical axes and being interlocked for this movement about the generally vertical axes.

Images