GB2434526A

GB2434526A - Bed scissor lifting apparatus

Info

Publication number: GB2434526A
Application number: GB0601704A
Authority: GB
Inventors: Mike Wilkinson
Original assignee: Genie Care Ltd
Current assignee: Genie Care Ltd
Priority date: 2006-01-27
Filing date: 2006-01-27
Publication date: 2007-08-01
Anticipated expiration: 2026-01-27
Also published as: GB0601704D0; GB2434526B

Abstract

Bed lifting apparatus (1) comprising a base frame (2), an upper frame (3) adapted to support a bed (4) and lifting means (5) disposed between the base frame and the upper frame adapted to raise and lower the upper frame in relation to the base frame, in which the lifting mean comprises at least a first pair of crossed arms (6 and 7) pivoted together at a mid point (8), first ends (9) of which are attached to the base frame in a pivoted relationship, and second ends (10) of which are attached to the upper frame in a pivoted relationship, such that rotation of the arms about the mid point raises and lowers the upper frame, and in which a portion of the base frame extending between the first ends of the first pair of crossed arms is adapted to allow passage of a wheeled chassis (not shown). The base frame may be adapted to have a D shape profile (Fig 4) where the curved portion (26) is on an upper surface. The bed may be provided with skirts (27) around the periphery. The lifting means may be powered by a motor (not shown). Gas struts (31) may be provided to assist in raising the bed from the ground. The apparatus may be moved on wheels (28).

Description

Bed lifting apparatus This invention relates to bed lifting apparatus

for use particularly, but not exclusively, in conjunction with a hoist in hospitals, care centres or homes.

Some patients require a bed which is low to the ground, so if they fall or climb out of it they will not be injured. However, many of these patients also require assistance in positioning themselves in bed, or in being moved to and from their bed, and such assistance is far more readily provided if the bed is the height of a regular hospital bed. Therefore, it is known to provide lifting apparatus which raises and lowers a bed as required.

There are numerous constructions of lifting apparatus for beds, but the present invention is concerned with those comprising a base frame, an upper frame supporting the bed, and a so-called "scissor lift" mechanism between them. Scissor lift mechanisms comprise at least one, and usually two, pairs of crossed arms which are pivoted together at a mid point, and which are attached at one end to the base frame and at the other to the upper frame, in a pivoted manner. One or other of the ends of the arms are attached to the base frame or the upper frame in a sliding manner. Usually a motor is provided to operate the scissor lift, which forces the arms to rotate about the mid point so the upper frame is raised or lowered in relation to the base.

Scissor lift arrangements of this type suffer from a number of problems. The first is that because the base frame must have a particular size and strength to support the arms and the upper frame, they are often constructed from large components, like metal box members. This causes a problem when it is desired to manoeuvre wheeled equipment under the bed. Such a requirement arises with most known patient hoists. Such devices comprises a wheeled base chassis carrying a crane device which supports the hoist. In use the wheeled chassis is positioned underneath the patient so their weight is carried as close as possible to the centre of gravity of the device. This usually means that the wheeled chassis, or part of it, is positioned under the bed. However, this is prevented if the base frame of a scissor lift bed is positioned on the ground. In such cases it becomes more awkward and potentially hazardous to use any of the known hoists because the centre of gravity of the hoist must be positioned some distance from the patient.

The above problem can be overcome if the base frame is supported off the ground high enough to allow the wheeled chassis of a hoist to be manoeuvred under it. This is achieved in some cases when the base frames are provided with wheels.

However, when wheels are provided, or when the base frame is supported off the ground in any other way, the primary purpose of the bed is compromised. The upper frame, and therefore the bed, can only be lowered to the level of the base frame. If this is raised off the ground then the bed is also raised off the ground when it is positioned at its lowest point. Although this may not be a problem for some patients, it is obviously not ideal if the idea is to prevent injury as much as possible.

The object of the present invention is to provide a scissor lift bed which allows the wheeled chassis of a hoist to be positioned under the bed, but which also lowers the bed to the ground, and which also has wheels.

Therefore, according to the present invention bed lifting apparatus comprises a base frame, an upper frame adapted to support a bed and lifting means disposed between the base frame and the upper frame adapted to raise and lower the upper frame in relation to the base frame, in which the lifting means comprises at least a first pair of crossed arms pivoted together at a mid point, first ends of which are attached to the base frame in a pivoted relationship, and second ends of which are attached to the upper frame in a pivoted relationship, such that rotation of the arms about the mid point raises and lowers the upper frame, and in which a portion of the base frame extending between the first ends of the first pair of crossed arms is adapted to allow passage of a wheeled chassis.

With this arrangement a hoist can be positioned under the bed, and the bed can be lowered right down to the ground.

In a preferred construction the base frame can comprise a substantially rectangular frame with two long sides and two short sides, and the first ends of the first pair of crossed arms can be attached to a first of those long sides. Further, the lifting means can also comprise a second pair of crossed arms identical in construction to the first pair and attached to a second of the long sides, on the opposite side of the base frame.

Preferably a portion of the base frame extending between the first ends of the second pair of crossed arms can also be adapted to allow passage of a wheeled chassis. Thus, a hoist can be positioned on either side of the bed.

It will be appreciated that the portions of the base frame adapted to allow passage of a wheeled chassis could be formed in several ways, including a raised section, or a receding section. However, in a preferred construction the portions of the base frame adapted to allow passage of a wheeled chassis can comprise members with a curved or chamfered upper surface. Thus, the portions can be adapted to allow a wheeled chassis to be readily driven over them. With this arrangement, the structural shape of the base frame remains rectangular, and is therefore not compromised strengthwise.

Preferably these portions of the base frame can comprise sections formed with a substantially D-shaped cross-section. Such sections are commonly referred to as "D section bars".

In a preferred construction both pairs of crossed arms can have a first arm attached to the base frame in a sliding pivoted relationship and to the upper frame in a stationary pivoted relationship, and a second arm attached to the base frame in a stationary pivoted relationship and to the upper frame in a sliding pivoted relationship.

The upper frame can carry a skirt which contacts the ground when the upper frame is at its lowest point. This ensures that there is no gap between the bed and the ground when the upper frame is at its lowest point.

As mentioned above, it is preferable to provide a scissor lift bed with wheels, and in the present invention this can be done without compromising the position of the base frame.

Therefore, in a preferred construction the upper frame can be provided with wheels, which are adapted to move between a stowed position in which they do not contact the ground when the upper frame at its lowest point, and an unfurled position in which they contact the ground at a point when the upper frame is higher than its lowest point.

Thus, if the apparatus is to be moved, the wheels are moved to their unfurled position when the upper frame is in a raised position, then the upper frame is lowered until the wheels reach the ground. From there, the scissor lift mechanism continues to operate, lifting the base frame off the ground.

Preferably the wheels can be carried on arms which can be pivoted to the upper frame. In the stowed position the arms can be substantially parallel with the upper frame, and in the unfurled position the arms can be substantially perpendicular to the upper frame. This is a simple and expedient way to stow and unfurl the wheels. A locking mechanism can be provided to lock the wheels in either position.

The lifting means of the invention can be mechanically operated by a motor.

There are numerous known arrangements of motor for scissor lift beds, and the invention can be used with any of them.

However, in one construction gas struts can be provided on the upper frame, which are compressed when the skirt contacts the ground, and which provide lift during the initial stages of raising the upper frame from the base frame.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings, in which: Figure 1 is a cross-sectional side view of bed lifting apparatus according to the present invention in a first arrangement; Figure 2 is a cross-sectional side view of the bed lifting apparatus as shown in Figure 1 in a second arrangement; Figure 3 is a cross-sectional side view of the bed lifting apparatus as shown in Figure 1 in a third arrangement; and, Figure 4 is a cross-sectional end view of a component of the bed lifting apparatus as shown in Figure 1.

As shown in Figure 1 bed lifting apparatus 1 comprises a base frame 2, an upper frame 3 adapted to support a bed 4, and lifting means 5 disposed between the base frame 2 and the upper frame 3, and adapted to raise and lower the upper frame 3 in relation to the base frame 2, as discussed below. The lifting means 5 comprises two pairs of crossed arms, only one pair of which 6 and 7 are visible in the Figures, which are pivoted together at a mid point 8. First ends 9 of the arms 6 and 7 are attached to the base frame 2 in a pivoted relationship, and second ends 10 of the arms 6 and 7 are attached to the upper frame 3 in a pivoted relationship, such that rotation of the arms 6 and 7 about the mid point 8 raises and lowers the upper frame 3. A portion 11 of the base frame 2 extending between the first ends 9 of the pair of crossed arms 6 and 7 is adapted to allow passage of a wheeled chassis (not shown), as discussed below.

Figures 1 to 3 show a cross-section of bed lifting apparatus i according to the invention. The cross-section is taken from a central line down the longitudinal axis of the apparatus. Thus, half of the apparatus is visible, as viewed from within. The other half is identical in construction, and where features of the visible side of the apparatus 1 are discussed below, it is to be understood that the same features are present on the opposite side.

The base frame 2 comprises a number of structural members formed into a rectangular shape. The long sides of the rectangular shape comprise D-section members 12, which carry support members 13 and 14 at each end. The short sides of the rectangle are formed by structural members 15 and 16, which are welded to the support members 13 and 14 respectively.

The upper frame 3 also comprises a number of structural members formed into a rectangular shape. The long sides of the rectangular shape comprise support members 17, which are braced by four structural members 18, and structural member 19.

In order for a scissor lift mechanism to work, at least one end of each arm must be able to move laterally. This can be achieved in various ways, but in apparatus 1, the first end 9 of arm 6 is mounted to support member 13 in a slidable relationship, while its second end 10 is mounted to the structural member 19 in a stationary -is not slidable -relationship. Conversely, the first end 9 of arm 7 is mounted to structural member 16 in a stationary relationship, which the second end is mounted to support member 17 in a slidable relationship.

The support members 13 and 17 are provided with channels 20 and 21, in which slide pins 22 and 23 are arranged. The arms 6 and 7 are attached to the slide pins 22 and 23 in a pivotal relationship. It will be appreciated that when the arms 6 and 7 rotate about the mid point 8 to raise the upper frame 3, the slide pins 22 and 23 slide through the channels 20 and 21, and the arms 6 and 7 rotate about the slide pines 22 and 23.

The other ends of the arms 6 and 7 are attached to structural members 16 and 19 by pivot pins 24 and 25, about which they pivot when the upper frame 3 moves up and down.

Figure 1 shows the upper frame 3 at its highest point in relation to the base frame 2, at which the slide pins 22 and 23 are at one end of the channels 20 and 21. Figures 2 and 3 show the upper frame 3 at its lowest point in relation to the base frame 2, at which the slide pins 22 and 23 are at the opposite end of the channels and 21.

As is clear from the Figures, the support members 13 and 14 are of a certain height, in order to provide for the channel 20, and the structural member 16, which support the pins 22 and 24. In all known scissor lift mechanisms a single support member is provided which extends the length of the base frame 2. In other words, the support members 13 and 14 are formed from one single support member, like support member 17 on the upper frame 3. This is done because the first ends 9 of the arms 6 and 7 must be structurally held together, when the upper frame 3 is raised, otherwise the scissor lift mechanism will collapse on itself; and the simplest and most cost effective way to do this is to provide a single support member as described. However, as mentioned previously, this type of construction prevents the wheeled chassis of a hoist from being manoeuvred under the bed, or situated under the bed's edge.

However, the construction shown in the Figures allows a wheeled chassis (not shown) to be manoeuvred under the bed 4, because there is a gap between the support members 13 and 14, which is only bridged by the D-section member 12. As is shown in Figure 4, the D-section member 12 has a curved upper surface 26, which can readily be traversed by the wheeled chassis of a hoist (not shown). The D-section member 12 is also strong enough along its longitudinal axis to carry the forces exerted on the first ends 9 of the arms when the upper frame 3 is raised in use.

As mentioned above the bed 4 is carried on the upper frame 3. It is supported by structural members 18. The bed 4 is provided with a skirt 27 which depends from the bed 4, and surrounds the upper frame 3. As shown in Figure 2, the skirt 27 meets the ground when the upper frame 3 is at its lowest point, and the base frame 2 is in contact with the ground. Thus, when the upper frame 3 is at its lowest point the skirt 27 completely envelops all the moving parts of the apparatus 1, preventing any entrapment.

The upper frame 3 is provided with wheels 28, one situated at each corner.

Each wheel 28 is mounted on an arm 29, which is movable between a stowed position as shown in Figures 1 and 2, and an unfurled position as shown in Figure 3.

As shown in Figure 2, in the stowed position the wheels 28 do not contact the ground when the upper frame 3 is at its lowest point. However, as is clear from Figure 3, in the unfurled position the wheels 28 contact the ground at a point when the upper frame 3 is higher than its lowest point in relation to the base frame 2 when the base frame 2 is on the ground. (Figure 3 actually shows the upper frame 3 at its lowest point in relation to the base frame 2, because the lifting means 5 has continued to operate from the point at which the wheels 28 contacted the ground, and the base frame 2 has been raised off the ground.) The arms 29 are mounted to the upper frame 3 via a hinge plate (not visible) which has an integrated locking means. The hinge plate comprises a pivot socket, and a circumferential channel arranged around it which extends through 90 degrees.

The arm is provided with two pins, a first of which is disposed in the socket, and forms the central axis of rotation. The second is disposed in the circumferential channel, and slides through it when the arm 29 is moved between positions. The pivot socket is provided with a vertical recess and a horizontal recess, and the circumferential channel is provided with a vertical recess at the end at which the second pin is disposed when the arm 29 is unfurled, and a horizontal recess at the other end. Thus, when the arm 29 is rotated up into the stowed position, it can be pushed back so the pins slide into the horizontal recesses, and hold it in position.

Likewise, when the arm 29 is rotated into the unfurled position, and takes the weight of the apparatus 1, the pins are pushed up into the vertical recesses, which locks the arm 29 in a vertical position.

A motor (not shown) is provided to operate the scissor lift mechanism. The motor is a screw mechanism which is mounted between the structural member 15 and structural member 30, which is mounted between arm 7 and its opposite number. The motor extends an arm to raise the upper frame 3, and retracts it in order to lower the upper frame 3. Such motors are known in the art and are not further described here.

However, the particular arrangement of apparatus 1 means that the motor (not shown) can struggle to operate efficiently. As shown in Figure 2, when the upper frame 3 is at its lowest point in relation to the base frame 2, structural member 30 is at a very low angle to structural member 15. At such an angle a great deal of force is required to initially lift the upper frame 3 off the base frame 2. This problem is overcome in known systems by mounting the motor at a greater angle, with the lower end below the level of the base frame 2. This is possible because the base frame is mounted off the ground on wheels. Obviously that is not the case here, so an alternative solution is required.

Thus, gas strut 31 is provided on the outside of support member 17. The gas strut 31 is a pressurised ram, which compresses against the ground when the upper frame 3 is brought down onto the base frame 2 when the base frame 2 is on the ground, as shown in Figure 2. When the motor (not shown) is operated to lift the upper frame 3, the lift provided by the gas strut 31 assists the motor (not shown) in the initial stages of lift, and allows the scissor lift mechanism to operate efficiently.

In use the apparatus 1 has three arrangements. In the first shown in Figure 1 the bed 4 is raised off the ground to the height of a regular hospital bed. The apparatus I can be arranged in this fashion if it is to be used as a normal hospital bed. In addition, the apparatus I can be arranged thus when a patient who requires a lower bed for safety, needs to be treated by medical staff or moved to or from the bed 4.

The motor (not shown) has forced the structural member 30 away from the structural member 15, and as a result the arms 6 and 7 have rotated about the mid point 8 and raised the upper frame 3, and therefore the bed 4. The motor (not shown) is adapted to hold its extended position to lock the arms 6 and 7 in this position.

If the patient requires the assistance of a hoist in order to change position, or to move to and from the bed, the wheeled chassis of the hoist can be manoeuvred through the gap between the support members 13 and 14, and positioned as best as possible under the weight of the patient. Other ground-going articles of equipment can also pass through this gap if required.

If the bed 4 needs to be lowered to prevent a user falling from it and injuring themselves, the apparatus 1 can be arranged as shown in Figure 2. The motor (not shown) retracts its arm and moves the structural member 30 towards the structural member 15, and as a result the arms 6 and 7 rotate about the mid point 8 and lower the upper frame 3, and therefore the bed 4, until the upper frame 3 rests on top of the base frame 2. In this position the skirt 27 extends down to the ground, and there is no clearance between the bed 4 and the ground.

In normal use the apparatus 1 will be moved back and forth between the positions shown in Figures 1 and 2 as required. The motor (not shown) is adapted to allow the bed 4 to be positioned at any position between those shown in Figures 1 and 2 as required.

If the apparatus 1 is to be moved to a new location, it can be arranged as shown in Figure 3. In order to arrive at this position, first the apparatus must be arranged as shown in Figure 1, or at least with the upper frame 3 high enough to allow the arms 29 to be readily unfurled. The user reaches around under the skirt 27 and pushes each arm 29 inwards towards the centre of the apparatus until the locking means is released, and it rotates under its own weight into the unfurled position shown in Figure 3. When each arm 29 is positioned thus, the motor (not shown) is operated to lower the upper frame 3, until the weight of the apparatus 1 is taken by the wheels 28. As described above, when this happens the arms 29 become locked in a vertical position. From there the motor (not shown) continues to force the structural member 30 towards the structural member 15 and as a result the base frame 2 is lifted from the ground. This is continued until the upper frame 3 and the base frame 2 are as close together as possible, as shown in Figure 3. In this position the gas strut 31 is also raised off the ground. The apparatus can now be transported on its wheels 28.

Once the apparatus is in its new position the motor (not shown) can be operated in the opposite direction, forcing the structural member 30 away from the structural member 15. (It will be appreciated that it is not necessary to provide any assistance to the motor (not shown) to initially separate the base frame 2 and the upper frame 3 in this position, because of the force of gravity acting on the base frame 2.) Once the base frame 2 contacts the ground, the upper frame 3 is raised upwards from it. The arms 29 can then be rotated back into the stowed position, and fixed there.

The embodiment shown in the Figures can be altered without departing from the scope of Claim 1. For example, in alternative embodiments (not shown) the portion of the base frame which is adapted to allow passage of a wheeled chassis comprises a raised section, or a receding section.

Thus, a bed lifting apparatus is provided which does not hinder the use of a hoist, but which also extends right down to the ground, and has its own wheels.

Claims

Claims 1. Bed lifting apparatus comprising a base frame, an upper frame

adapted to support a bed and lifting means disposed between the base frame and the upper frame adapted to raise and lower the upper frame in relation to the base frame, in which the lifting means comprises at least a first pair of crossed arms pivoted together at a mid point, first ends of which are attached to the base frame in a pivoted relationship, and second ends of which are attached to the upper frame in a pivoted relationship, such that rotation of the arms about the mid point raises and lowers the upper frame, and in which a portion of the base frame extending between the first ends of the first pair of crossed arms is adapted to allow passage of a wheeled chassis.

2. Bed lifting apparatus as claimed in Claim I in which the base frame comprises a substantially rectangular frame with two long sides and two short sides, in which the first ends of the first pair of crossed arms are attached to a first of said long sides, in which the lifting means further comprises a second pair of crossed arms identical in construction to the first pair of crossed arms, and in which the first ends of the second pair of crossed arms are attached to a second of said long sides.

3. Bed lifting apparatus as claimed in Claim 2 in which a portion of the base frame extending between the first ends of the second pair of crossed arms is adapted to allow passage of a wheeled chassis.

4. Bed lifting apparatus as claimed in Claim 3 in which the portions of the base frame adapted to allow passage of a wheeled chassis comprise members with a curved or chamfered upper surface.

5. Bed lifting apparatus as claimed in Claim 4 in which the portions of the base frame adapted to allow passage of a wheeled chassis comprise sections formed with a substantially D-shaped cross-section.

6. Bed lifting apparatus as claimed in any of Claims 2 to 5 in which in both pairs of crossed arms, a first arm is attached to the base frame in a sliding pivoted relationship and to the upper frame in a stationary pivoted relationship, and a second arm is attached to the base frame in a stationary pivoted relationship and to the upper frame in a sliding pivoted relationship.

7. Bed lifting apparatus as claimed in any of the preceding Claims in which the upper frame carries a skirt which contacts the ground when the upper frame is at its lowest point in relation to the base frame and the base frame is on the ground.

8. Bed lifting apparatus as claimed in Claim 7 in which the upper frame is provided with wheels, which wheels are adapted to move between a stowed position in which they do not contact the ground when the upper frame at its lowest point in relation to the base frame and the base frame is on the ground, and an unfurled position in which they contact the ground at a point when the upper frame is higher than its lowest point in relation to the base frame and the base frame is on the ground.

9. Bed lifting apparatus as claimed in Claim 8 in which the wheels are carried on arms which are pivoted to the upper frame, in which in the stowed position the arms are substantially parallel with the upper frame, and in which in the unfurled position the arms are substantially perpendicular to the upper frame.

10. Bed lifting apparatus as claimed in any of the preceding Claims in which the lifting means is mechanically operated by a motor.

11. Bed lifting apparatus as claimed in Claim 10 in which gas struts are provided on the upper frame, which are compressed when the upper frame at its lowest point in relation to the base frame and the base frame is on the ground, and which provide lift during the initial stages of raising the upper frame from the base frame when the base frame is on the ground.

12. Bed lifting apparatus substantially as described herein and as shown in the accompanying drawings.

Amendments to the claims have been filed as follows Claims 1. Bed lifting apparatus comprising a base frame, an upper frame adapted to support a bed and lifting means disposed between the base frame and the upper frame adapted to raise and lower the upper frame in relation to the base frame, in which the lifting means comprises at least a first pair of crossed arms pivoted together at a mid point, first ends of which are attached to the base frame in a pivoted relationship, and second ends of which are attached to the upper frame in a pivoted relationship, such that rotation of the arms about the mid point raises and lowers the upper frame, and in which a portion of the base frame extending between the first ends of the first pair of crossed arms is adapted to allow passage of a wheeled chassis when the base frame lies on the ground and the upper frame is in a raised position.

2. Bed lifting apparatus as claimed in Claim I in which the portion of the base frame extending between the first ends of the first pair of crossed arms is adapted to allow a..

passage of a wheeled chassis over it when the upper frame is in a raised position. * *

* *:. . Bed lifting apparatus as claimed in Claim I or 2 in which the base frame comprises a substantially rectangular frame with two long sides and two short sides, in which the * first ends of the first pair of crossed arms are attached to a first of said long sides, in * : which the lifting means further comprises a second pair of crossed arms identical in construction to the first pair of crossed arms, and in which the first ends of the second pair of crossed arms are attached to a second of said long sides.

4. Bed lifting apparatus as claimed in Claim 3 in which a portion of the base frame extending between the first ends of the second pair of crossed arms is adapted to allow passage of a wheeled chassis when the base frame lies on the ground and the upper frame is in a raised position.

5. Bed lifting apparatus as claimed in Claim 4 in which the portion of the base frame extending between the first ends of the second pair of crossed arms is adapted to allow passage of a wheeled chassis over it when the upper frame is in a raised position.

6. Bed lifting apparatus as claimed in Claim 5 in which the portions of the base frame adapted to allow passage of a wheeled chassis over them comprise members with a curved or chamfered upper surface.

7. Bed lifting apparatus as claimed in Claim 6 in which the portions of the base frame adapted to allow passage of a wheeled chassis over them comprise sections formed with a substantially D-shaped cross-section.

8. Bed lifting apparatus as claimed in any of Claims 3 to 7 in which in both pairs of crossed arms, a first arm is attached to the base frame in a sliding pivoted relationship and to the upper frame in a stationary pivoted relationship, and a second arm is attached to the base frame in a stationary pivoted relationship and to the upper frame in a sliding pivoted relationship.

S

9. Bed lifting apparatus as claimed in any of the preceding Claims in which the upper frame carries a skirt which contacts the ground when the upper frame is at its lowest point :. in relation to the base frame and the base frame is on the ground.

S 5.

10. Bed lifting apparatus as claimed in Claim 9 in which the upper frame is provided * with wheels, which wheels are adapted to move between a stowed position in which they * do not contact the ground when the upper frame at its lowest point in relation to the base frame and the base frame is on the ground, and an unfurled position in which they contact the ground at a point when the upper frame is higher than its lowest point in relation to the base frame and the base frame is on the ground.

11. Bed lifting apparatus as claimed in Claim 10 in which the wheels are carried on arms which are pivoted to the upper frame, in which in the stowed position the arms are substantially parallel with the upper frame, and in which in the unfurled position the arms are substantially perpendicular to the upper frame.

12. Bed lifting apparatus as claimed in any of the preceding Claims in which the lifting means is mechanically operated by a motor.

13. Bed lifting apparatus as claimed in Claim 12 in which gas struts are provided on the upper frame, which are compressed when the upper frame at its lowest point in relation to the base frame and the base frame is on the ground, and which provide lift during the initial stages of raising the upper frame from the base frame when the base frame is on the ground.

14. Bed lifting apparatus as claimed in Claim 1, or Claim 4 when dependent on Claim 1, in which the portion of the base frame extending between the first ends of the first and / or second pair of crossed arms comprises a raised section adapted to allow passage of a wheeled chassis under it when the upper frame is in a raised position.

15. Bed lifting apparatus as claimed in Claim 1, or Claim 4 when dependent on Claim 1, in which the portion of the base frame extending between the first ends of the first and / or second pair of crossed arms comprises a receding section shaped to allow passage of a wheeled chassis towards it when the upper frame is in a raised position. a,. * a *.s'

: . 16. Bed lifting apparatus substantially as described herein and as shown in the accompanying drawings. S.,.' t * S. dS * * I

I I