A lifting device to be attached to a wheel assembly, suitable for lifting the wheel assembly onto an obstacle; the wheel assembly comprises a supporting wheel, rotating around a wheel axis, the wheel axis being mounted in a fork; the lifting device comprises a lifting brace that rotates in the vertical plane parallel to the plane of the supporting wheel around a pivot axis, which axis is attached to the fork, parallel to the wheel axis; furthermore, the lifting device comprises a spring element that forces the lifting brace to stay in the upper position of rotation.

A similar device is known from the European patent application nr. 1 279 392 describing the front wheels of a wheelchair being provided with a lifting device comprising a pivoting brace, mounted onto the fork of the front wheel, and on the front side fitted with a curved surface or circle segment. This construction has the disadvantage of having only one contact surface or contact point with the obstacle, like a threshold, making it difficult, unless a strong force is applied, for the brace to start rotating in order to lift and support the front wheels. Therefore this type of lifting device is experienced as not being comfortable by a person displacing itself in a wheelchair. Furthermore this construction may easily cause damage to the object being surmounted as a result of the force applied. As a result of having only one point or surface of contact with this device the risk of slipping on the object is significant which is undesirable. Therefore this type of lifting device is configured and dimensioned in such a way that the wheel is only surmounted for a part of the height of the obstacle by the brace, whereas the wheel still has to be pushed upon the obstacle for the rest of the height.

From the German patent application DE 30 39 611 a lifting device is known that is mounted upon a protruding arm at the front side of the frame of a carriage, like a wheelchair. This lifting device comprises a tiltable brace, provided with two arms connected at an angle; both arms having guide wheels at their ends. This construction also has disadvantages. Because the lifting brace is mounted on a protruding arm far in front of the supporting wheel, the wheel can only be lifted over part of the height of the obstacle. Both arms have to be fitted with guide wheels because the lifting device has to move forward over the obstacle in order to bring the supporting wheel to the obstacle. Therefore the construction only is useful if the obstacle has a considerable width, like a sidewalk, because in the case of smaller obstacles the guide wheels already descend from the obstacle before the support wheel has reached the top of the obstacle. Also this construction can only be used in one direction of movement because it is mounted onto the frame of the carriage. This makes the device to be expensive and complicated and causes the protruding brace to be inconvenient when not in use.

The object of the present invention is to provide a compact, universal, low cost lifting device for a wheel assembly without the aforementioned disadvantages; which is connected to the wheel assembly and is operable with little force, without the need to roll on and over the object or the need to use guide wheels; suitable for crossing over low obstacles as well as high obstacles; comfortable for a person being transported, without the risk of slipping on or damaging the object.

These objectives are achieved with the lifting brace comprising a support arm and a guide arm, whereby the support arm and the guide arm both are extending in a direction opposite to the pivot axis; the support arm and the guide arm having a mutual angle to each other, in such a way that the support arm and guide arm in the upper position of rotation of the lifting brace, in the direction of movement, are projecting out of the front side of the wheel assembly.

With this lifting brace the supporting wheel of the wheel assembly can always be lifted on or over an obstacle in the driving direction without having to apply much force and without applying much force onto the obstacle. This construction is compact, easy to camouflage or hide and not protruding outside the frame. It can be manufactured at low cost and can be applied universally on wheel assemblies with a fork such as in swivel wheels or castors.

In a preferred embodiment a lifting brace is provided on each side of the fork of the wheel assembly; the braces being rotably mounted upon the pivot axis in such a way that the lifting braces will rotate in a parallel manner around the pivot axis. In this way the wheel assembly can be lifted more easily upon the obstacle and the forces acting upon the wheel assembly and exerted upon the obstacle are less than with a single lifting brace. In addition, in a preferred form, the support arms of both lifting braces are connected to each other on both sides of the fork and the supporting wheel. This way a strong lifting device is obtained that can be used to move heavy loads.

Another preferred embodiment is characterized by the wheel assembly comprising two supporting wheels and the lifting brace being centrally mounted within the fork between both supporting wheels. By mounting the lifting device in between the supporting wheels, the wheel assembly can be lifted upon obstacles in a stable way with one lifting brace.

Preferably the angle, between the support arm and the guide arm of the lifting brace, is in the range of 15 to 60 degrees. Applying this range of angles, a lifting device is accomplished that can lift a wheel assembly over obstacles of varying height.

Also, in a preferred form, the lifting brace is configured and dimensioned in such a way that in the upper position of rotation of the lifting brace the distance between the end of the guide arm and the ground is in the range of 5% to 15% of the diameter of the supporting wheel and the distance between the end of the support arm and the ground is in the range of 30% to 60% of the diameter of the supporting wheel. By these measures the lifting brace of the lifting device will not already start to turn if small objects or bumps on the ground pass by, while the lifting device is able to lift the wheel assembly upon obstacles of considerable height.

Preferably the lifting brace is configured and dimensioned in such a way that the ends of the support arm or the guide arm will not contact the ground in any position of the lifting brace. That way it is secured that the lifting brace will always return to its upper position of rotation when the wheel assembly has reached the top of the obstacle.

Alternatively, the end of the support arm at the lifting brace may be equipped with an auxiliary wheel. Also in a preferred embodiment the end of the guide arm at the lifting brace is equipped with a wheel or guide roller. By adding rolling elements to the ends of the support arm and the guide arm, the tilting and lifting movements will be more smooth and the forces exerted upon the obstacle will be smaller thus reducing the risk of damaging the obstacle. The invention will be explained in more detail hereafter using the drawings of some examples of an embodiment of the wheel assembly with lifting device, revealing characteristic features and advantages.

Fig. 1 shows a side view of a wheel assembly with lifting brace comprising a support arm and a guide arm according to the invention;

Fig. 2A shows in perspective view a wheel assembly with a double lifting brace;

Fig. 2B shows a front view of the wheel assembly with the lifting brace of figure 2A;

Fig. 3 A - D show in a series of side views in detail how the lifting brace lifts the wheel assembly upon an obstacle;

Fig. 4 shows in side view a wheel assembly with a lifting brace comprising an auxiliary wheel at the end of the support arm;

Fig. 5 shows a front view of a wheel assembly with two lifting braces and two auxiliary wheels; Fig. 6 A - E show in a series of side views in detail how the lifting brace of Fig. 4 lifts the wheel assembly upon an obstacle;

Fig. 7 shows the lifting brace mounted upon the bottom of the frame in the proximity of a wheel assembly;

Fig. 8 shows the lifting brace of Fig. 4 comprising a wheel at the end of the guide arm; Fig. 9 A - B show a lifting device for a wheel assembly with two supporting wheels.

In Fig. 1 the lifting device according to the invention is shown comprising a lifting brace 1, attached to a fork 5 of a wheel assembly. The wheel assembly comprises a supporting wheel 2 that can rotate freely around wheel axis 20. The wheel axis 20 is attached to the fork 5. The purpose of the lifting device is to lift the supporting wheel and the wheel assembly upon an obstacle 12, like a threshold or curb. The wheel assembly may be fixedly positioned, non-displaceable and non- rotatable, upon a frame but preferably the wheel assembly is of the swivel type being freely rotatable connected through a vertical axis to a frame whereby the vertical axis is not positioned exactly above the wheel axis.

The lifting brace 1 in the lifting device may rotate around the pivot axis 8, connected to the fork 5, enabling the lifting brace 1 to rotate in the vertical plane parallel to the plane of the supporting wheel 2. The pivot axis 8 is oriented mainly parallel to the axis 20 of the supporting wheel. Furthermore the lifting device comprises a spring element 10 that forces the brace to stay in the upper position of rotation or presses the brace against cam 9, fixed onto fork 5. The lifting brace 1 comprises two arms that point downwards in the upper position of rotation: one support arm 14 and a guide arm 13. In this preferred embodiment the guide arm 13, at its end 6, is provided with a round shape, easing the guidance of the guide arm 13 against the side of the obstacle 12. At its lower end the support arm 14 comprises a support surface 11. Both the support arm 14 and the guide arm 13 are extending in a direction opposite to the pivot axis 8, the arms enclosing a mutual angle C. In this way both arms 13, 14 form a V-shape and the side face 3 of the lifting brace 1 forms a Y-shape. The angle C between both arms 13, 14 preferably is in the range of 15 to 60 degrees. The distance A between the end 6 of the guide arm 13 and the ground, whereupon the supporting wheel 2 is resting, preferably is in the range of 5% to 15% of the diameter D of the supporting wheel 2. The distance B between the end 7 of the support arm 14 and the ground is preferably in the range of 30% to 60% of the diameter D of the supporting wheel 2. In that way a lifting device is obtained that has optimal dimensions to lift wheel assemblies upon obstacles for every wheel diameter. The lifting device in Fig. 1 comprises one lifting brace 1 on one side of the fork 5 of the supporting wheel 2.

In Fig. 2A and 2B an embodiment is shown whereby the lifting device is provided with two lifting braces 1' and 1" that rotate parallel by means of the mutually interconnected support arms 14' and 14" and the common pivot axis 8. In that way the support surface 11 at the ends 7' and 7" of the support arms 14' and 14" is extending over the entire width of the supporting wheel 2. By attaching a lifting brace 1 on both sides of the wheel assembly, the forces on the fork 5 are reduced and distributed in a better way so that the lifting device can be constructed in a lighter way using a thinner material.

In Fig. 3A - 3D is shown how a wheel assembly, provided with the lifting device according to the invention, is lifted upon an obstacle 12 like a threshold. When the wheel assembly with the lifting device reaches the obstacle 12, the lower protruding arm (guide arm 13) of lifting brace 1 will be moved backwards in reaction to the forward movement of the supporting wheel 2. This causes the lifting brace 1 to tilt or rotate around the pivot axis 8 so that the support arm 14 with support surface 11 will rest upon the top of the obstacle 12 (Fig. 3B). When the lifting brace 1 is tilted further (Fig. 3C) the load of the supporting wheel 2 is transferred to the support arm 14 with support surface 11 and as a result of the tilting movement of the lifting brace 1 around the pivot axis 8 the wheel assembly is lifted. In this way the supporting wheel 2 is lifted that far so as to bring the running surface of the wheel on the level of the upper side of the obstacle 12 so that the wheel can roll over the obstacle. The moment the supporting wheel 2 rests upon the upper side of the obstacle 12, the wheel assembly is not supported any more by the support arm 14. The lifting brace 1 then is no longer forced backwards and comes loose from the top surface of the obstacle 12. As a result the lifting brace 1 will return to its upper position through the action of spring element 10 (See Fig. 3D).

To ensure that under normal conditions of use of the wheel assembly the lifting brace 1 does not contact the ground, the lifting brace 1 is configured and dimensioned in such a way upon the fork 5 of the wheel assembly that in the upper position of the lifting brace 1 the end 6 of the guide arm 13 is positioned at a distance from the ground. In a lower position of the lifting brace, whereby the guide arm 13 extends vertically relative to the pivot axis 8, the end 6 of the guide arm 13 is positioned at a distance from the surface on which the wheel 2 rests. In other words, the end 6 of guide arm 13, when the lifting brace 1 rotates around pivot axis 8, follows a path that does not contact the ground.

In Fig. 4 an alternative lifting device according to the invention is shown comprising an auxiliary wheel 4 at the end 7 of support arm 14. This auxiliary wheel 4 preferably is attached rotably around an auxiliary wheel axis, onto the lifting brace 1. In that way the support surface 11 of the support arm 14 is formed by the running surface (tread) of the auxiliary wheel, enabling a more gradual and less bumpy lifting movement. Also the risk of damaging the obstacle is reduced. The lifting device can be configured with one lifting brace 1 on one side of the supporting wheel 2 but the lifting device may also be formed by two lifting braces, each provided with an auxiliary wheel 4. When the auxiliary wheel 4 projects outside the end 7 of the support arm 14, the assembly of the support arm 14 with the auxiliary wheel 4 has to be adapted in such a way that the distance B between the ground and the lowest point of the running surface (tread) of the auxiliary wheel 4 has a value between 30% and 60% of the diameter D of the supporting wheel 2.

In Fig. 5 is shown the front view of the embodiment of Fig. 4 whereby the lifting device is provided with two lifting braces 1' and 1" and whereby the support arms 14' and 14" are interconnected by means of the common pivot axis 8 and optional by means of a bridging element like a sheet or strip 15. Both support arms 14' and 14" are each provided with an auxiliary wheel 4' and 4" that are mounted to the outside of the lifting braces 1' and 1". If desired, the auxiliary wheels 4' and 4" may be attached onto the inner sides of the lifting braces I ¹ and 1" or four auxiliary wheels may be used: two on either side of the lifting braces 1' and 1" (not shown).

In Fig. 6A - 6E is shown how by means of the lifting brace 1" of the lifting device as shown in Fig. 4, the wheel assembly is lifted upon an obstacle 12. Due to the forward movement of the wheel assembly, the guide arm 13" makes contact with the front side of the obstacle 12, causing the lifting device to tilt downwards around pivot axis 8 until the auxiliary wheel 4" makes contact with the top of the obstacle 12 (Fig. 6B). The load of the supporting wheel 2 then is transferred to the auxiliary wheel 4" at the end 7" of support arm 14" of the lifting brace 1" and the wheel assembly is lifted by the tilting movement of the lifting brace 1" around the pivot axis 8. The supporting wheel 2 hereby is lifted as far as the running surface reaches the level of the upper side of the obstacle 12 and may roll over the obstacle (Fig. 6C - 6D). As soon as the supporting wheel 2 rests upon the upper side of the obstacle 12 both the guide arm 13" and the support arm 14" do not touch the obstacle any more and the lifting brace 1" will return to its upper position through the action of spring element 10 (See Fig. 6E).

In the figures is clearly shown how the auxiliary wheel 4" rolls over the upper side of the obstacle 12 during the tilting and lifting action, enabling a more gradual and less bumpy lifting movement compared to a lifting brace without an auxiliary wheel.

Fig. 7 shows an alternative embodiment of the lifting device whereby the lifting brace 1 is rotably attached to a frame element 21 whereby the frame element 21 is mounted nearby the supporting wheel 2, sideways or between the two wheels. This requires the lifting device, according to the invention, to be positioned in such a way that the lifting device will be activated when an oblong obstacle, transverse to the direction of movement, is closely approached by the supporting wheels 2.

In Fig. 8 is shown an alternative embodiment of the lifting device as in Fig. 4, comprising a guide roll 22 - like a small wheel - at the end 6 of the guide arm 13 enabling a reduced resistance of the movement of the end 6 of the guide arm 13 against the edge of the obstacle because the guide arm 13 can roll upwards against the front of the obstacle 12 thus preventing damage to the obstacle. When the guide roll 22 projects outside the end 6 of the guide arm 13, the assembly of the guide arm 13 with the guide roll 22 has to be adapted in such a way that the distance A between the ground and the lowest point of the running surface of the guide roll 22 still has a value between 5% and 15% of the diameter D of the supporting wheel 2. In another embodiment the auxiliary wheels 4' and 4" may be replaced by a rotary segment of a circle shaped body that is rotated into the preferred start position by a spring element (not shown).

In Fig. 9A and 9B is shown an alternative embodiment of the wheel assembly and the lifting device; the wheel assembly comprising two supporting wheels 2' and 2" and a lifting device mounted in between both supporting wheels. The lifting device comprises a lifting brace 1 with a support arm 14 and a guide arm 13.

CLAIMS