WO2009136359A1

WO2009136359A1 - A handling system for goods, burdens or disabled persons

Info

Publication number: WO2009136359A1
Application number: PCT/IB2009/051832
Authority: WO
Inventors: Henrik Nøhr KOFOED; Mogens Ilsted Bech; Niels Tvergaard Haagh
Original assignee: Borringia Industrie AG
Current assignee: Borringia Industrie AG
Priority date: 2008-05-05
Filing date: 2009-05-05
Publication date: 2009-11-12
Anticipated expiration: 2010-11-05

Abstract

A lifting device comprises a carriage (1, 2) and at least three mutually spaced rollers or wheels (3) for supporting the carriage on a ground or floor surface so as to define a polygon. A lifting mast (5) for lifting and carrying a load (L) extends upwardly from the carriage. A supporting device (12) is movable vertically in relation to the carriage and arranged at or adjacent to a vertical axis (a) extending through a gravity center (G) of the combined lifting device and a load (L) carried thereby. The supporting device (12) may be biased against the supporting surface by biasing means so as to reduce the weight carried by the supporting rollers or wheels (3). This facilitates turning of the lifting device by manual forces. Furthermore, the supporting device may comprise a motor driven driving device comprising a driving wheel or roller (12) for driving the lifting device. In this case the biasing means may secure sufficient friction between the driving wheel and the floor surface.

Description

A handling system for goods, burdens or disabled persons

Background of the Invention

A large number of wheeled structures, vehicles or systems are used to transport and handle a variety of goods, burdens or even disabled persons. Many such systems have three principal functions:

1. Lifting and lowering of the burden or person to the desired level above the ground.

2. Manipulating the burden or person in order to place it or him/her precisely at a given point of reception. (For goods, one example could be to place a heavy reel of film at a precise angle & height in a packing line. For a person, one example could be to move a disabled person e.g. from a bed and place him/her correctly in a wheelchair.)

3. Transporting the burden or person from one site to another.

Most such handling systems comprises a wheeled undercarriage, where the front part is kept as low as possible in order to be able to driven under machines, pallets, beds, wheel chairs etc. At the back end of the undercarriage, most known handling systems have a lifting mast with a motorised lifting function. Some systems have the ability to manipulate (tilt in space or turning) the lifted burden or person, a few of these electrically. However, for most of the handling systems, transporting it from one point to another involves a person, who takes on the function as a human engine, manually pushing the system. When transporting heavy objects on a wheeled system, the person pushing is exposed to severe physical strain both to initiate movement, to control the movement and in order to brake the system as and when desired. For this reason a number of "assistive drive technologies" have been developed. Typically, such technologies help the person pushing the handling system by supplying the force needed to propel the handling system either forwards or backwards. The person normally supplies the steering force, by pushing directly onto the handling system or onto a steering handle supplied.

Most of the handling systems have a plurality of free swivelling wheels placed in a rectangular formation in order to give the system stability. If traction is supplied by motorizing, e.g. the two rear wheels of the vehicle - as known from many assistive drive systems - the vehicle will have a pattern of movement similar to that of a car, which means that the vehicle needs a lot of space to manoeuvre, turn around corners etc. More importantly, moving such a vehicle sideways will involve "kerb side parking". Free space for manoeuvring is seldom readily available. On production sites, in warehouses etc. free space is unproductive space. Therefore handling systems, which can move omni-directionally and turn on the spot, can help turning unproductive square metres into productive ones.

When moving a mobility impaired person into/out of e.g. a bed either in a hospital, in a nursing home or even in a private household, there is seldom enough free space to manoeuvre with a motorised handling system if it cannot drive sideways and turn on the spot.

To overcome these disadvantages a number of handling systems described e.g. in WO2006/119769 and in US Patent no. 5,758,371 have two motorized rear wheels, which can be rotated around a vertical axis. In this way, these systems obtain the ability to drive sideways and in some instances also the ability to turn on the spot with the power being supplied by the motorized drive wheels rather than by a person manually pulling and pushing the system. Motorized driving is particularly important when driving a heavy wheeled structure sideways or turning it on the spot, as these types of movement cause a very severe asymmetrical loading of the musculoskeletal system if the necessary power is supplied manually by a person.

However, the known drive systems including the ones described in WO2006/119769 and in US Patent no. 5,758,371 have a number of disadvantages, which are overcome by the present invention. The three principal disadvantages are:

1. In that the known systems replace one or more of the supporting castors or wheels with (a) motor driven wheel(s), these systems cannot be pushed manually when they are unloaded, which is often desired, or in the case of the drive system malfunctioning.

2. In order to maintain a low height at the front of the undercarriage, the known systems have to place the drive wheel(s) at the back of the undercarriage, well behind the lifting mast. As the weight of the burden or person to be handled is placed in front of the mast, the known handling systems are prone to have insufficient friction between the drive wheel(s) and the floor to transmit the drive force needed to move such handling systems when loaded. In order to partially overcome this problem, the known handling systems add weight to the structure over the motor driven rear wheels, leading to unnecessarily heavy handling systems and increased energy consumption during motorized driving. 3. In the known handling systems the combined weight of the system proper and the burden to be handled is distributed on all the supporting wheels. This means that the torque needed on the motorised rear drive wheels in order to make the handling system pivot on the spot increases by the distance-ratio of the drive wheels to the centre of gravity of the total system relative to the distance between the centre of gravity and the free swivelling front wheels. The consequence is that larger, heavier and more expensive drive motors are needed. Also, the energy consumption for pivoting is unnecessarily high.

Summary of the Invention

The present invention provides a lifting device comprising a carriage, at least three mutually spaced rollers or wheels for supporting the carriage on a supporting surface, such as a ground or floor surface, and defining a polygon, and a lifting mast extending upwardly from said carriage and for lifting and carrying a load, the combined lifting device and load having a common gravity center, and the lifting device according to the invention is characterized in a supporting device, which is movable vertically in relation to the carriage and arranged at or adjacent to a vertical axis extending through said gravity center, and biasing means for biasing the supporting device against said supporting surface so as to reduce the weight carried by said supporting rollers or wheels.

When the supporting device, which may consist of or comprise a spherical member or another rounded projection, is biased downwardly in relation to the carriage so as to support a substantial part of the weight of the lifting device and the load carried thereby, an operator may easily manually turn the lifting device around the turning point formed by the contact point between the supporting device and the ground or floor surface. In the preferred embodiment the supporting device comprises a motor driven driving device for driving the lifting device. Such driving device may, for example be of the type disclosed in WO2006/059200 and arranged close to the vertical axis trough the centre of gravity, for example directly under or adjacent to the base of the lifting mast, surprisingly the new lifting device shows none of the disadvantages described above.

The assistive driving device may function as "a 5^th wheel", which can be retracted at will, meaning that the new lifting device can be pushed manually when it is not heavily loaded or in case the driving device is malfunctioning. Furthermore, the present lifting device may utilise the fact that the assistive driving device in question may adjust the force with which the driving wheel is pressed towards the floor according to the combined weight of the handling system and the burden lifted.

When the driving device is activated, the driving wheel may be lowered until it touches the floor. Subsequently, the pressure of the driving wheel against the floor may gradually be increased until approximate 80% of the total weight of the handling system and burden is carried by the driving wheel. The remaining 20% of the total weight is distributed on the supporting rollers or wheels, preferably castor wheels. This ensures that the lifting device according to this invention always has sufficient traction to safely drive and brake regardless of the weight of the burden or load. In this manner no additional weight has to be added to obtain traction and hence the lifting device may be optimised both with regard to weight, motor sizes and power consumption.

By placing the driving device directly underneath the lifting mast and close to the centre of gravity of the combined lifting device and load an added advantage is obtained. With approximately 80% of the weight carried by the drive wheel and only 20% by the supporting castors, the drive wheel effectively becomes a pivot point and the entire lifting device can manually be turned on the spot with surprisingly little effort, even when loaded with a burden of 300+ kilograms. In this way, only a tiny fraction of the force or torque needed to make prior art handling systems pivot of the spot is sufficient to pivot a lifting device according to this invention. This leads to significant improvements in the form of lower total weight, smaller motors, less energy consumption and consequently smaller batteries.

The present invention provides a handling system including a drive wheel system, an undercarriage comprising a centre house with a receiver for the lifting mast and two legs, which undercarriage is supported by supporting rollers or wheels, a lifting mast with a lifting sledge, which is driven up and down inside the lifting mast on a motorised spindle, said lifting sledge functioning as a connection point on which burden or patient handling systems of the user's choice can be mounted, said drive wheel system comprising a wheel frame adapted to be mounted on or form part of the undercarriage, a sub-frame mounted on the wheel frame which can be turned 90 degrees a drive roller or wheel with a reversible drive motor and transmission means mounted on the sub-frame allowing for traction in the forwards/backwards direction or sideways when the sub-frame is turned 90 degrees, a system for deploying and retracting the drive roller or wheel from the floor and, a system for regulating the pressure of the drive roller or wheel against the floor depending on the total weight of the handling system and burden to be handled. In a preferred embodiment of the invention the drive system is described in WO2006/059200 is utilized, but other drive systems with the ability to regulate the wheel pressure against the floor could be used in the present invention.

In a preferred embodiment of the invention the lifting mast includes an internal motorised spindle along which a lifting sledge is moved up and down. The said sledge functions as a connection point for various burden or patient handling systems. Most such burden or patient handling systems will incorporate some sort of a substantially horizontal beam or arm in order to keep the burden or patient at a distance from the lifting mast. A functioning handling system could be achieved by using a more traditional design with a substantially horizontal beam pivotally hinged around a substantially horizontal axis at the top of the lifting mast, the said beam being moved up and down by traditional means, such as e.g. a linear actuator, motor or hydraulic system.

The driving device may comprise steering means for rotating the driving device about a vertical axis. Such steering means may position the driving device in any angular position or selectively position the driving device in steering positions, which are mutually angularly spaced by 90°.

Due to the ability of the drive system to turn the drive roller or wheel 90° the invention will allow very precise manoeuvring using minimum space. If one wants to place e.g. an object at a given position in a production line and one does not approach at the exactly right spot from a horizontal perspective, one would have to "kerb-side-park" with traditional handling systems until the right spot is hit. This often involves several attempts. With the invention, however, one would simply give a drive command via the man machine interface to go left or right horizontal spot is hit.

On most motorized handling systems - even those with the ability to drive sideways as e.g. the system described in WO2006/119769 - the man machine interface (MMI) is placed in such a way that the operator has to walk behind the handling system. This adds substantially to the overall space requirements needed for such handling systems to function. In the present invention, this problem is overcome by providing two MMIs for the drive system placed on the two push handles at such an angle that they be operated equally well and from an ergonomically correct posture regardless of whether the operator is controlling the handling system from behind or standing on either side. In this way the total length of the handling system and the operator can be limited to the length of the handling system proper, allowing it to operate with very limited free space.

In order to place either burdens or persons correctly and precisely, one needs to be able to not only lift the burden or patient but also to tilt and/or turn the burden or patient. On most known handling systems such manipulation has to be carried out manually with the operator supplying the force needed. Just as manual pushing of heavy wheeled objects exposes the operator to severe strain, so does manual turning or tilting of a heavy burden or patient. Therefore, the present invention includes a system whereby electrical power is supplied at the front side of the lifting sledge allowing users of the invention to design burden or patient handling systems with one or more electrically powered manipulation systems.

In that the invention utilises a power drive system, which can retract the drive roller or wheel, the invention can also be pushed manually, should the operator desire to do so. In order to minimise the strain on the operator during manual driving and turning of the present invention, push handles are provided, which are placed at a substantial distance to the lifting mast, giving the operator good leverage and hence optimal utilisation of his/her body weight during pushing.

The invention is designed for maximum versatility. The connection point and power outlet on the lifting sledge allows users of the new handling system to design their own burden or patient manipulation systems to meet each specific set of needs. It is impossible to list all types of burdens, which need manipulation. A few examples could be reels, bowls, drums, crates, pallets etc.

As many of these burdens require tilting in space, the centre of gravity of the burden may change from a point, which is substantially in front of the lifting sledge to a point, which is to either side of the lifting sledge and closer to either of the legs on the undercarriage. Prior art lifting masts with lifting sledges moving up/down e.g. on a motorized spindle, run on rollers inside the mast, which absorb the longitudinal forces relative to the handling system's forward/backward axis. In the present invention an extra set of rollers are introduced, which can absorb any horizontal forces in the athwart direction of the handling system potentially caused by a change in the burden's centre of gravity. In this way a much more sturdy, safe and thereby versatile design is achieved.

One preferred embodiment of the invention includes a patient handling system for lifting and correct positioning of a mobility impaired patient either in a bed or in a chair. For the comfort of the patient, most patient handling systems lift the patient in a soft body harness or "sling", which is suspended from a fixed spreader bar or "yoke" in a plurality of hooks, normally three or four. In that the sling is a soft piece of cloth, the patient tends to be suspended in semi-sitting / semi-lying position. This makes it extremely difficult for the carer or operator to position the patient correctly both in chairs and in beds. For correct positioning in a bed, the patient should ideally lye flat in the sling. For correct positioning in a chair - i.e. with the buttocks close to the backrest - the patient should ideally sit upright in the sling with back vertical, the thighs horizontal and the calves vertical. The same positions are ideal out of a bed or a chair. By providing a new type of motorized spreader bar, the invention obtains the ability to transfer a patient in the two preferred positions and any position between the two. The motorized spreader bar includes a motor driven axel around which two sets of straps or lines with hooks are wound up & unwound synchronously in pairs. The two outer straps or lines are hooked into two receivers on the sling supporting the torso portion of the patient. The two centre straps or lines are hooked in the receivers of the sling supporting legs of the patient. If operator wants to position the patient in a substantially horizontal position, the straps or lines supporting the patient's torso are unwound and the straps or lines supporting the patient's legs are wound up. In this position the patient will be lying flat in the sling, which is ideal for lifting him/her into or out of a bed. If the process is reversed and the two centre straps or lines are fully unwound and the outer straps are fully wound up, the patient will be sitting substantially upright in the sling with the back vertical, the thighs horizontal and the calves vertical, which is ideal for lifting him/her into or out of a chair.

Should the operator not desire the option of actively positioning the patient, the invention can be equipped with a fixed spreader bar or yoke. This gives the operator the freedom to use specialised slings from a large number of sling manufacturers. In a even further preferred embodiment of the invention a patient handling system is provide where a weighing scale is inserted above the spreader bar - whether motorized or not. This allows care givers to monitor the weight of the patient during transfer, which is often desirable in hospitals as a sudden change of body weight can be an indication of dehydration, which can have severe consequences if undetected.

Further preferred embodiments of the invention include a "tilt-in-space" shower- and commode chair (not shown), a "tilt-in-space" shower trolley (not shown), a "tilt-in- space" examination or treatment table (not shown) and even a "tilt-in- space" operating table(not shown).

Brief Description of the Drawings The invention will now be further described with reference to the drawings, which show a presently preferred embodiment of the handling system according to the invention, and wherein

Fig. 1 is a view of the handling system without any burden or patient handling system attached to the lifting sledge,

Fig. 2 is a bottom perspective view, showing the inside of the centre house of the undercarriage and the position of the drive wheel system exactly under the lifting mast,

Fig. 3 is a bottom view of the invention showing the drive wheel in the engaged position and drive direction being forwards/backwards,

Fig 4 is a bottom view of the invention showing the drive wheel in the engaged position and drive direction being sideways, Fig. 5 is top view of the lifting mast, where the upper mounting plate has been removed and the lifting sledge has been extracted from the mast in order to show the rollers as well as a view of the mast design,

Fig. 6 is a view of the lifting sledge and the spindle,

Fig. 7 is a bottom perspective view of the lifting mast showing the female part of the clutch used to transmit power from the lifting motor to the spindle as well as connectors for transmission of power and drive control from the two man machine interfaces,

Fig. 8 is a view into the receiver for the lifting mast on the centre house showing the male part of the clutch used to transmit power from the lifting motor to the spindle as well as connectors for transmission of power and drive control from the two man machine interfaces,

Fig. 9 is a bottom perspective view, showing the inside of the centre house of the undercarriage without the drive wheel showing the position of the lifting motor,

Fig. 10 is a view of the invention equipped with a patient handling system including a weighing scale and the motorized spreader bar,

Fig. 11 is a view of the invention equipped with a patient handling system including a fixed spreader bar,

Fig. 12 is a view of the man machine interface, which controls the drive functions.

Detailed Description of a Preferred Embodiment of the Invention: Figs. 1 - 12 offer a detailed description of the invention and examples of different patient handling systems. In Fig. 1 the invention is shown without any burden or patient handling system. The invention comprises an undercarriage made up of a centre house (1) and one or more legs (2). The undercarriage is supported by a plurality of rollers or castors (3). The centre house is equipped with a receiver (4) which holds the lifting mast (5). Inside the lifting mast a lifting sledge (6, Fig. 5) is driven up and down on a motorized spindle (7, Fig 6). A protruding part (8) of the sledge (6) serves as a connection point, which can be used to apply a burden or patient handling system. The mast is equipped with handle bars (9) on which man machine interfaces (10) are mounted at such an angle that they can be used to control the invention's drive functions both standing/walking behind the invention and to the side of it.

Fig. 2 shows the invention seen from the bottom with the bottom cover removed so as to show the position of the drive system (11) mounted directly under the foot point of the lifting mast (5). The drive wheel (12) is shown at its retracted position i.e. inside the drive system. A linear actuator (13) connected to the legs (2) via a system of arms and levers (14) allows for electrical spreading of the legs allowing the invention to approach wide objects.

Fig. 3 shows the invention from the bottom with the drive wheel (12) deployed and positioned for forwards/backwards driving.

Fig. 4 shows the invention from the bottom with the drive wheel (12) deployed and positioned for sideways driving

Fig. 5 shows the lifting sledge (6) partially extracted from the lifting mast (5). On the lifting sledge four rollers or wheels (15) which absorb the longitudinal forces relative to the handling system's forward/backward axis. An extra set of rollers or wheels (16) are introduced, which can absorb any horizontal forces in the athwart direction of the handling system potentially caused by a change in the burden's centre of gravity. In this way a much more sturdy, safe and thereby versatile design is achieved.

Two spring loaded sliding contacts (17) are mounted on the back of the lifting sledge. When the sledge is driven up and down said contacts have continuous contact to two power rails (not shown) and said contacts are connected to a power outlet (not shown) at the front of the connection point (8). This allows the users of the invention to design burden or patient handling systems with electrically powered burden or patient manipulation.

Fig. 6 shows the spindle (7) with the lifting sledge (6) outside of the lifting mast.

Fig. 7 is a bottom perspective view of the lifting mast (5) showing the female part of the clutch (18) used to transmit power from the lifting motor to the spindle as well as connectors for transmission of power (19) and drive control (20) from the two man machine interfaces (10). This design allows the mast to be removed for transport purposes, service, etc. without having to unplug cables. When the mast is inserted into the receiver (4) the connectors will make contact with corresponding contacts in at the bottom of the receiver, just as the female part of the clutch will connect and lock with the male part of the clutch in the receiver. In this way, all driving and lifting motors can be placed inside the centre house (1), where they are protected against accidental, physical damage.

Fig. 8 is a view into the receiver (4) for the lifting mast (5) on the centre house showing the male part of the clutch (21) used to transmit power from the lifting motor to the spindle as well as connectors for transmission of power (22) and drive control (23) from the two man machine interfaces (10).

Fig. 9 is a bottom perspective view, showing the inside of the centre house of the undercarriage without the drive wheel showing the position of the lifting motor (24).

Fig. 10 shows the invention with a handling system for transferring and positioning mobility impaired people mounted onto the connection point, which system comprises a beam (25), a weighing scale (26) the motorized spreader bar (27). The motorized spreader bar includes a motor driven axel (not shown) around which two sets of straps or lines with hooks are wound up and unwound synchronously in pairs. The two outer straps or lines (28) are hooked into two receivers on the sling supporting the torso portion of the patient. The two centre straps or lines (29) are hooked in the receivers of the sling supporting legs of the patient. If operator wants to position the patient in a substantially horizontal position, the straps or lines supporting the patient's torso (28) are unwound and the straps or lines supporting the patient's legs (29) are wound up. In this position the patient will be lying substantially flat in the sling, which is ideal for lifting him/her into or out of a bed. If the process is reversed and the two centre straps or lines (29) are fully unwound and the outer straps (28) are fully wound up, the patient will be sitting substantially upright in the sling with back vertical, the thighs horizontal and the calves vertical, which is ideal for lifting him/her into or out of a chair.

Fig. 11 shows the invention with a handling system for transferring and positioning a mobility impaired person or another load (L), which load is indicated in dotted lines. The system comprises a beam (25) and a rigid spreader bar (30) with hooks (31) serving as receivers for a sling (S) of the user's choice for supporting the load (L). The lifting device is adapted to carry a load within certain weight limits, and in Fig. 11 the common gravity center (G) of the lifting device and the load (L) is indicated. A vertical axis (a) extending through the gravity center (G) intersects the floor surface at or adjacent to the point of contact between the drive wheel (12) and the floor surface when the wheel (12) is in its extended position.

Fig. 12 shows the film (32) on the two man machine interfaces (10), which are used for the operator to control the invention's drive functions. By pushing the on/off button (33) the drive system wakes up. It then lowers the drive wheel (12) to the floor, measures the position of the wheel and subsequently increases the pressure of the wheel (12) against the floor, until the drive wheel changes position. At this point the pressure of the drive wheel against the floor is decreased by a pre-determined value, after which approximately 80% of the combined weight of the invention and the burden will be carried by the drive wheel (12). Pushing the on/off button (33) again will turn off the drive system, which retracts the drive wheel from the floor and shots down. Leaving the invention in a state, where it can be pushed manually. After turning on the drive system, the operator has a window of opportunity of a preset number of seconds, during which he can either adjust the desired drive speed by pushing the speed button (34) repeatedly to toggle through 3 pre-set speed options, low, medium and high or pushing and holding down one of the drive buttons (35, 36, 37, or 38). By holding down the "forwards" button (35), the invention will drive forwards at the chosen speed, until the "forwards" button is released, whereby the invention will brake in a controlled manner and come to a complete stop. By holding down the "backwards" button (36), the invention will drive backwards at the chosen speed, until the "backwards" button is released, whereby the invention will brake in a controlled manner and come to a complete stop. By holding down the "left" button (37), the invention will drive left at the chosen speed, until the "left" button is released, whereby the invention will brake in a controlled manner and come to a complete stop. By holding down the "right" button (37), the invention will drive left at the chosen speed, until the "right" button is released, whereby the invention will brake in a controlled manner and come to a complete stop. If the "forwards" or "backwards" button (35, or 36) is pushed whilst the drive wheel is in the position intended for driving sideways, the drive system will first turn the drive wheel 90° and subsequently start driving in the desired direction. If the "left" or "right" button (37, or 38) is pushed whilst the drive wheel is in the position intended for driving forwards/backwards, the drive system will first turn the drive wheel 90° and subsequently start driving in the desired direction. If no button is pushed during the preset window of opportunity, the system will automatically retract the drive wheel and shot down.

Claims

1. A lifting device comprising a carriage (1,2), at least three mutually spaced rollers or wheels (3) for supporting the carriage on a supporting surface, such as a ground or floor surface, and defining a polygon, and a lifting mast (5) extending upwardly from said carriage and for lifting and carrying a load (L), the combined lifting device and load having a common gravity center (G), characterized in a supporting device (12), which is movable vertically in relation to the carriage (1,2) and arranged at or adjacent to a vertical axis (a) extending through said gravity center (G), and biasing means

(11) for biasing the supporting device against said supporting surface so as to reduce the weight carried by said supporting rollers or wheels (3).

2. A lifting device according to claim 1, wherein the supporting device

(12) comprises a motor driven driving device for driving the lifting device.

3. A lifting device according to claim 2, wherein the driving device (12) comprises steering means for rotating the driving device about a vertical axis.

4. A lifting device according to claim 2, wherein the steering means may selectively position the driving device in steering positions, which are mutually angularly spaced by 90°.

5. A lifting device according to any of the claims 2-4, wherein the driving device includes a driving wheel or roller (12) for contacting the supporting surface.

6. A lifting device according to any of the claims 1-5, wherein the driving device is located adjacent to or in front of the lower end of the lifting mast (5).

7. A lifting device according to any of the claims 1-6, wherein the lifting mast (5) is inclined upwardly in a backwards direction.

8. A lifting device according to any of the claims 1-7, wherein the biasing means comprises a spring, such as a coil spring or gas spring, the biasing force of which may be changed.

9. A lifting device according to claim 8, wherein the spring has connecting points at opposite ends, at least one of the connecting points being movable so as to change the biasing force of the spring.

10. A lifting device according to any of the claim 1-9, wherein the driving device comprises only one driving wheel or roller rotatable around a substantially vertical axis, the point of contact between the driving wheel and the ground or floor surface being horizontally spaced from the intersection point between said substantially vertical axis and the supporting surface.

11. A lifting device according to any of the claims 1-10, wherein said biasing means is adapted to gradually increase its biasing force, further comprising means for determining the weight carried by the driving device, for detecting when the weight carried has reached a maximum, and for subsequently decreasing the biasing force by a predetermined value.

12. A lifting device according to any of the claims 1-11, wherein the lifting mast (5) comprises a vertically extending stationary frame member defining angularly spaced pairs of opposed guide surfaces, a motor driven carriage or sledge (6) having means (8) for connecting the load thereto, and a rotatable motor driven spindle (7) engaging with the carriage or sledge for moving the same vertically along said guide surfaces.

13. A lifting device according to claim 12, wherein the carriage or sledge comprises guide rollers (15, 16) for engaging with said pairs of opposed guide surfaces.

14. A lifting device according to any of the claims 1-13, wherein the carriage comprises a pair of horizontally spaced legs (2) extending horizontally and in a forward direction from the lower end of the lifting mast (5), further comprising means for adjusting the spacing of said legs.

15. A lifting device according to any of the claims 1-14, further comprising a pair of horizontally spaced handles (9), a man machine interface (10) being arranged at each of these handles.

16. A lifting device according to any of the claims 1-15, further comprising a load suspending device adapted to be connected to and vertically moved by the lifting mast (5), said suspending device including a plurality of horizontally spaced, flexible connecting means (28, 29), such as straps, cords or lines, for suspending a load carrying member, and motor driven means for selectively increasing and decreasing the length of said flexible connecting means, whereby the position and/or shape of the load may be controlled.

17. A lifting device according to claim 16, wherein the load is mobility impaired person and the carrying member is a body harness or sling.

18. A lifting device according to claim 16 or 17, wherein the suspending device comprises one or more motor driven winding devices for winding and unwinding said flexible connecting members.