AU2008101281B4 - High/low bed - Google Patents

Abstract

A bed is described having a support member for supporting an individual thereon; a base member configured to support the support member above a floor surface; a primary height adjusting mechanism operable to adjust the height of the support member with respect to the base member. A secondary height adjusting mechanism is operable independently to adjust the height of the base member with respect to the floor surface to enable a base of a patient lifting device to fit under the base member, e.g. by a clearance height of at least 150 mm, preferably about 160 mm.

Description

1 HIGH/LOW BED Field of the Invention The present application relates to a bed, and in particular, to a height adjustable high/low bed for use in a hospital or care facility. 5 Background of the Invention Beds used in hospital and care facilities, such as care facilities for the aged and or disabled, are typically adjustable in both height and contour. Such beds typically comprise a patient support that supports a mattress, upon which the patient is received. 10 The height level of the patient support is typically adjustable between accepted limits by way of a variety of drive systems controllable by the patient or a healthcare worker. The patient support is typically divided into a plurality of sections, including a head section, a seat section and a leg section. The various sections are movable with respect to each other by way of one or more controllable drive mechanisms to facilitate angular 15 adjustability that enables the patient supported thereon to assume a variety of positions so as to improve their comfort as well as to facilitate their treatment. In hospitals and nursing homes devoted to providing care for the elderly and/or those individuals suffering from dementia and the like, conventional hospital beds have considerable drawbacks. Often, such individuals have limited movement and control 20 over their movement, and are prone to periods of confusion either due to their condition, or influenced by medication they may be taking. In such instances, it is not uncommon for individuals to fall from their beds and sustain injury, even in instances where their conventional hospital bed is placed in a lowered position. Whilst rails and the like have been proposed to assist in retaining the individual 25 on the bed, the use of rails and other such enclosures has been known to cause injury, and in extreme cases death, when the individual has become entangled in the rails. In order to address such problems, it has been proposed to provide high/low beds for use with individuals prone to falling from their beds. Such high/low beds provide greater vertical adjustability than conventional hospital beds as the height of 30 the bed can be lowered to a level that is substantially at the level of the floor. In this regard, should the individual fall from the bed to the floor, they are unlikely to sustain significant injury due to their close proximity to the floor. These beds overcome the need to provide protective rails about the bed, and hence reduce the possibility of strangulation and limb breakage should the individual become entangled in such rails.

2 As high/low beds require a large degree of vertical movement to move the bed between a position that is substantially located on the floor and a conventional elevated bed position, conventional high/low beds have typically required a dedicated height adjustment mechanism located underneath the bed. Such a mechanism is controllable 5 to raise and/or lower the bed as desired. In this regard, the bed may be lowered at night to reduce the chance of injury should the individual fall out of the bed, and raised during awake periods. A problem with such conventional high/low beds having the height adjusting mechanism located underneath the bed, is that there is minimal clearance underneath 10 the bed to accommodate a patient-lifting device. In this regard, due to various health and safety regulations, most hospital and nursing homes provide a dedicated patient lifting device in the event that an individual falls from a bed or requires lifting from the bed to perform everyday functions. Conventional patient lifting devices employ a cradle-type system to be located around the patient and a hoist to elevate the patient 15 onto the bed. As the patient-lifting device requires at least partial accommodation under the bed during use, the lack of clearance under a conventional high/low bed prevents use of such a device. Where such high/low beds provide a clearance to accommodate a patient-lifting device, the height of the bed in its lowest position is often too high to prevent injury to an individual falling therefrom. 20 To overcome this deficiency in high/low beds, beds commonly referred to as floor beds have been proposed. Such floor beds are also capable of being raised/lowered between an elevated position and a position adjacent the floor, and typically employ screw mechanisms at the head and foot of the bed to elevate/lower the patient support. In this regard, most floor beds comprise columns located at the head 25 and foot of the bed, which accommodate the screw mechanisms for raising and lowering the patient support. Such conventional floor beds are typically visually distinctive and are readily identified as a hospital bed, lacking the aesthetics of a conventional or "home-style" bed. The columns at the head and foot of the bed allow little scope to improve the aesthetics. 30 The above references to and descriptions of prior proposals or products are not intended to be, and are not to be construed as, statements or admissions of common general knowledge in the art.

3 It is an object of the present invention to provide a high/low bed that can locate a patient close to the floor so as to reduce the likelihood of injury in the event of the patient falling from the bed. A further objecL is to provide a high/low bed that can enable use of a patient 5 lifting device with that bed. A preferred object is to provide a bed that can be aesthetically pleasing and which can be relatively simply adapted for use with conventional patient lifting devices and other such equipment, as required. Summary of the Invention 10 According to a first aspect, the present invention provides a bed comprising a support member for supporting an individual thereon; a base member configured to support the support member above a floor surface; a primary height adjusting mechanism selectively operable to adjust the height of the support member with respect to the base member, the primary height adjusting mechanism providing a connection 15 between the base member and the support member, and a secondary height adjusting mechanism selectively operable to adjust the height of the base member with respect to the floor surface between a lowered position in which the base member is adjacent the floor and a clearance providing position sufficient to accommodate a base of a patient lifting device under the base member, wherein the secondary height adjusting 20 mechanism includes a plurality of legs selectively extendable from an underside of the base member and further includes a pair of shafts rotatably mounted to the base member with each of the shafts having a plurality of said legs mounted thereto, the secondary height adjusting mechanism being selectively operable to rotate the shafts so that each of said legs mounted to the shafts is moveable between a retracted position 25 wherein each leg is lifted and an extended position wherein each leg is in contact with the floor surface, and wherein, when the legs are in their extended positions, the base member is supported above the floor surface by the plurality of legs so as to define the said clearance providing position of the base member_ Preferably, the secondary height adjusting mechanism is selectively operable 30 independently of the primary height adjusting mechanism.

4 The base member may comprise a generally rectangular base frame member. Also, the support member may comprise a generally rectangular support frame member and preferably the base frame member. is arranged to support the support frame member thereon when the bed is in a lowered position. Preferably, when the bed is in the 5 lowered position, the primary height adjusting mechanism and the secondary height adjusting mechanism are contained within the base frame member. In one possible embodiment, the secondary height adjusting mechanism comprises a plurality of legs extendible from an underside of the base member. Preferably, the secondary height adjusting mechanism is operable such that each leg is 10 movable between a retracted position wherein each leg is lifted from the floor surface and an extended position wherein each leg is in contact with the floor surface. When the legs of the secondary height adjusting mechanism are in their extended positions, the base member is preferably supported above the floor surface by the plurality of legs, such that the height of the base member above the floor surface is at least 150mm 15 and is sufficient to accommodate a base of a patient lifting device. Preferably the base member when in its clearance providing position is at least 150mm above the floor surface, and most preferably the clearance is about 160mm. In one embodiment, the support member comprises a substantially rectangular frame member having one or more platforms provided thereon, upon which the 20 individual is received. The support member may be divided into a plurality of sections, including a head section, a seat section and a leg section. One or more drive mechanisms may be provided within the support member to facilitate angular adjustability between adjacent sections of the support member. The, or each, drive mechanism may be substantially fully housed within the frame member of the support 25 member. In another embodiment, the base member comprises a substantially rectangular frame member configured to be received on the surface. The frane member may comprise one or more wheels or castors extending from an underside thereof such that the base member is movable about the surface. 30 The frame member of the base member may be configured to support the frame member of the support member thereon when the bed is in a lowered position. In this 5 position, the primary height adjusting mechanism and the secondary height adjusting mechanism may be contained within the frame member of the base member. The primary height adjusting mechanism may provide connection between the frame member of the base member and the frame member of the support member. The 5 primary height adjusting mechanism may include one or more link arms in combination with one or more actuators to facilitate vertical movement of the frame member of the support member with respect to the frame member of the base member. The secondary height adjusting mechanism comprises a pair of shafts rotatably mounted to the frame member of the base member preferably at opposing ends thereof, 10 Each shaft may have a plurality of the legs mounted thereto and may be rotated by an actuator device. The actuator device may be a linear actuator having a reciprocating piston contained therein. In one fonn, extension of the piston from the linear actuator may cause each shaft to rotate thereby facilitating movement of the legs from the first position to the second position. 15 6 When used in this specification and claims, the terms "comprises" and "comprising" and variations thereof mean that the specified features, steps or integers are included. The terms are not to be interpreted to exclude the presence of other features, steps or components. 5 Brief Description of the Drawings By way of example only, the invention is now described with reference to the accompanying drawings: FIG. 1 is a side view of a high/low bed in accordance with an embodiment of the present invention; 10 FIG. 2 is a side view of the high/low bed of FIG. 1 in a lowered position; FIG. 3 is a side view of the high/low bed of FIGS. 1 and 2 in an intermediate raised position in accordance with an embodiment of the present invention; FIG. 4 is a top view of an auxiliary height adjustment mechanism in accordance with an embodiment of the present invention, representative of the high/low bed being 15 in the lowered position of FIG. 2; FIG. 5 is a top view of an auxiliary height adjustment mechanism in accordance with an embodiment of the present invention, representative of the high/low bed being in the intermediate raised position of FIG. 3; FIG. 6 is a cross sectional side view of the high/low bed of FIGS. 1 - 3 showing 20 an embodiment of the height adjustment mechanism of the present invention; FIG. 7 is a side view of the high/low bed with the height adjustment mechanism of FIG. 6 in a lowered position; FIG. 8 is a side view of an embodiment of the high/low bed of the present invention with the frame members of the base and the patient support in a lowered 25 position; FIG. 9 is a cross-sectional side view of the height adjustment mechanism in accordance with an embodiment of the present invention in a first lifting stage; FIG. 10 is a cross-sectional side view of the height adjustment mechanism of FIG. 9 in a final or second lifting stage; 30 FIG. 11 is a side view of an embodiment of the actuator and lever arm of the height adjustment mechanism of FIG. 9 during a first or initial lifting stage; and FIG. 12 is a side view of an embodiment of the actuator and lever arm of the height adjustment mechanism of FIG. 9 during a second lifting stage.

7 Detailed Description of an Exemplary Embodiment of the Invention Referring to the accompanying drawings, the high/low bed 10 of the present invention comprises a base 12 in the form of a substantially rectangular frame member 13, in combination with a patient support 16, also in the form of a substantially 5 rectangular frame member 15. As is shown in FIG. 1, the patient support 16 is height adjustable with respect to the base 12 by way of a height adjustment mechanism 14. In this regard, the bed 10 can be adjusted between a conventional raised position (FIG. 1) and a lowered position adjacent the floor (FIG. 2) so as to reduce the possibility of injury to a patient falling from the bed 10. 10 The frame member 15 of the patient support 16 supports a plurality of platforms or slats (not shown) that support a mattress 15a or the like upon which a patient is received. Whilst not shown, the frame member 15 of the patient support 16 may also house one or more drive mechanisms to facilitate contour control of the mattress 15a, as is known in the art. It will be appreciated that the various components that facilitate 15 contour control of the mattress 15a will be contained within the frame member 15 of the patient support 16. The frame member 13 of the base 12 is supported above a floor surface 5 by way of castors 11, or the like, that enable the bed 10 to be moved, as desired. The castors II are disposed on the underside of the four corners of the frame member 13 20 and are configured such that the underside of the frame member 13 is located substantially on or adjacent the floor surface 5. The height adjustment mechanism 14 provides connection between the frame member 13 of the base 12 and the frame member 15 of the patient support 16. When the bed 10 is in a lowered position, as shown in FIG. 2, the height adjustment 25 mechanism 14 is contained within the frame member 13 of the base 12. In such a position the frame member 15 is supported on the frame member 13 of the base 12, thereby ensuring a compact bed 10 that minimises the height of the mattress 15a above the floor 5. As is shown in FIG. 2, when the bed 10 is in the lowered position, it is suitable 30 for supporting a patient in a relatively safe manner. In the event of a patient inadvertently falling off the bed 10, they will merely roll onto the floor with minimal likelihood of causing an injury to themselves. Should the patient require assistance to return to the bed 10, the patient is lifted on to the mattress 15a, typically by way of a patient-lifting device. 35 A patient lifting device is a hoist-type device that safely and securely lifts a patient onto a bed 10, or similar elevated surface. The patient lifting device typically 8 comprises a harness that is fitted about the patient and a mechanical hoist arrangement that lifts the patient onto the bed. Such devices typically comprise a base portion that extends therefrom to stabilise the device during use. The base portion is typically provided with wheels such that the base portion can be rolled under the bed 10 to lift 5 the patient onto the bed 10, if desired. As will be appreciated in FIG. 2, as the bed 10 is configured to be located as close to the floor 5 as possible, there is insufficient clearance 'A' below the bed 10 to accommodate a base of a patient-lifting device. In the embodiment as shown, clearance 'A' is typically in the region of between 0 - 50 mm, preferably around 40 mm. 10 It is accepted that in order to accommodate a patient-lifting device, a minimum clearance of 150mm is required under the bed 10. To provide this clearance whilst also ensuring that that bed 10 is located as close to the floor as possible, the bed 10 of the present invention employs an auxiliary height adjustment mechanism 18. The auxiliary height adjustment mechanism 18 comprises at least four legs 17 15 located adjacent the underside of the four corners of the frame member 13. Each of the legs 17 are actuated to raise the bed 10 from the lowered position (FIG. 2) to an intermediate position (FIG. 3) having a clearance 'B' sufficient to accommodate a patient-lifting device. The size of clearance 'B' is typically dictated by the devices with which the bed is to be used. In a preferred embodiment, the clearance 'B' is 20 around 160mm to accommodate a patient-lifting having a base height of around 150 mm. It will be appreciated that In this regard, should a patient require lifting from the floor 5 to the bed 10 through the use of a patient lifting device, the bed 10 can be lifted to the intermediate position by merely actuating the legs 17 into position as is shown in FIG. 3. 25 In the embodiment as shown, legs 17 have wheels 19 provided at the end thereof such that when actuated, the legs 17 roll into position with reduced friction. The wheels 19 are omnidirectional such that when actuated the bed 10 can be moved in a back and forth position. It will be appreciated that the legs 17 need not have wheels attached thereto to achieve their auxiliary lifting function and other arrangements are 30 also envisaged. Referring to FIGS. 4 and 5, the manner in which the auxiliary height adjustment mechanism 18 functions is shown. A pair of legs 17 are mounted to opposing ends of a pair of shafts 20. The shafts 20 are mounted at opposing ends of the underside of the frame 13 by way of brackets 21, which enable the shafts 20 to rotate as desired. When 35 the auxiliary height adjustment mechanism 18 is not actuated, the legs extend substantially horizontally with respect to the frame 13 as shown in FIGS. 2 and 4.

9 When the auxiliary height adjustment mechanism 18 is actuated, the legs extend vertically from the frame 13 to contact the floor 5 and elevate the underside of the frame 13 from the floor 5, in the manner to be described below. An actuator 22, such as a LINAKTM linear actuator, is mounted at an end of the 5 frame 13. A reciprocating piston 23 of the actuator 22 is connected at a distal end thereof to an end of a pivot plate 24. The pivot plate 24 is mounted to the frame 13 by way of a bolt 25 or the like, which forms a point about which the plate 24 pivots upon reciprocating motion of the piston 23. A first connecting rod 26 forms a connection between one of the shafts 20 and 10 an end of the pivot plate 24, and a second connecting rod 26 forms a connection between the other shaft 20 and the pivot plate 24. Both the first and second connecting rods 26, 28 are flexibly attached to the pivot plate 24 at a common end of the plate 24 by way of a pin, bolt or the like. The opposing ends of the first and second connecting rods 26, 28 are fixedly connected to arms 27 formed on the periphery of the shafts 20. 15 In this arrangement, upon activation of the actuator 22 by way of an appropriate controller, such as a control pad or the like, the reciprocating piston 23 of the actuator 22 is caused to extend from the actuator, from the retracted position (FIG. 4). As the reciprocating piston 23 extends, it applies a pushing force to the pivot plate 24, causing the plate 24 to rotate about pivot point 25. Continual pushing motion of the piston 23 20 against the plate 24 results in the plate 24 applying a pushing force to first connecting rod 26 and a corresponding pulling force to second connecting rod 28. The pushing force of first connecting rod 26 to shaft 20 results in the shaft rotating such that legs 17 rotate from the frame 13 into contact with the floor 5. Similarly, the corresponding pulling force of second connecting rod 28 to shaft 20 results in the shaft rotating such 25 that legs 17 rotate from the frame 13 into contact with the floor 5. This causes the underside of the base 12 of the bed 10 to be raised from the floor surface 5 in the manner as shown in FIGS. 3 and 5. It will be appreciated that further activation of the actuator 22 will result in the piston 23 being retracted back into the actuator 22. This causes a reversal of forces 30 against the shafts 20 by way of connecting rods 26, 28, such that the shafts will rotate back into the position as shown in FIGS. 2 and 4. In this position, the bed 10 is returned to its lowest configuration, such that the underside of the frame 13 is at or adjacent the level of the floor 5. The provision of the auxiliary height adjustment mechanism 18 with the bed 10 35 enables the bed 10 to be readily and simply adapted for use with conventional patient lifting devices and other such equipment, as required. This can be achieved without the 10 need to alter the vertical relationship between the base 12 and the patient support 16, which may be set to specific patient requirements. Such an arrangement also ensures that the bed 10, in its lowered position, is as close to the floor as possible, as there is no need to accommodate a conventional patient lifting devices and other such equipment 5 in such a position. To accommodate such a device the bed 10 is merely raised to the intermediate position (FIG. 3) to achieve the lifting, after which the bed can be simply returned to its lowered position (FIG. 2). Referring to FIG. 6 and 7, one embodiment of the height adjustment mechanism 14 of FIG. 1 is shown in detail. As previously discussed, the height adjustment 10 mechanism 14 links the frame member 13 of the base 12 and the frame member 15 of the patient support 16 such that the bed 10 can be moved between a lowered position (FIG. 7) and an elevated position (FIG. 6). As previously discussed, each component of the height adjustment mechanism 14 is configured such that it is contained within the frame member 13 of the base 12 when the bed 10 is in the lowered position. 15 Referring to FIG. 6, the height adjustment mechanism 14 comprises two substantially identical link arrangements 30a, 30b linked together by a connecting rod 31. The link arrangements 30a, 30b are positioned along each side of the bed 10, however, for reasons of clarity, only two link arrangements 30a, 30b are shown. It will be appreciated that the bed 10 typically requires four link arrangements to perform the 20 height adjusting function. In the embodiment as shown, each link arrangement 30a, 30b is mounted to a shaft member 32a, 32b that extends across the frame member 13. The connecting rod 31 extends between two arms 33a, 33b. The arms 33a, 33b are each securely mounted on a respective shaft member 32a, 32b such that rotational movement applied to shaft 25 member 32a is also applied to shaft member 32b. A linear actuator 34 having a reciprocating piston 34a is pivotally mounted to frame member 13 at pivot point 34b. The linear actuator 34 is operable to apply either a pushing or pulling force to a lever arm 35 as the piston 34a moves in a reciprocal motion. The lever arm 35 is mounted on shaft member 32a such that the force applied 30 thereto by the piston 34a is converted into rotational motion of the shaft member 32a. Primary link arms 36a and 36b are also securely mounted at a proximal end to shaft 32a, 32b respectively, and are pivotally mounted at a distal end to secondary link arms 37a, 37b respectively at pivot point 36c. The secondary link arms 37a, 37b are pivotally connected to the frame member 15 of the patient support 16 at a first end by 35 way of lugs 38 extending from the underside of the frame member 15. A second end of 11 the secondary link arms 37a, 37b is pivotally connected to the frame member 13 of the base 12 by way of intermediate link members 39a, 39b, respectively. As will be appreciated from FIGS. 8 - 12, the height adjustment mechanism 14 of the present invention comprises a two stage lifting action. 5 As depicted in FIG. 8, when the bed is in the lowered position, frame member 15 is positioned on frame member 13 such that the actuator 34 and the link arrangements 30a, 30b are contained within the frame member 13. As shown in FIG. 11, in this retracted position, the actuator 34 and the corresponding lever arm 35 are in a substantially horizontal relationship. Due to this substantially horizontal orientation 10 of the actuator 34 and the lever arm 35, a significant amount of work is required by the actuator 34 to apply a pushing force against the lever arm 35 during the initial lifting stage. In this regard, upon a control to activate the actuator 34, the piston 34a is caused to extend therefrom, applying a pushing force against the lever arm 35. The shaft 32a 15 is then caused to rotate under this pushing force, causing the primary link arm 36a to also rotate into a vertical position, thereby causing the frame member 15 to be raised from the frame member 13, as is shown in FIG. 9. During this initial or first lifting stage, it is the action of the primary link arms 36a, 36b, which extend from the shafts 32a, 32b to the pivot point 36c, that lifts the 20 frame member 15. This relatively short leverage distance of the primary link arms 36a, 36b provides maximum compensation for the relatively large amount of inertia required by the actuator 34 to initiate the lifting action, as discussed above. As the secondary link arm 37a is substantially horizontal with respect to the underside of the frame member 15, it performs a minimum function during this first or initial lifting stage. 25 The second lifting stage occurs at the instance when the secondary link arms 37a, 37b pivots beyond horizontal and transfers the lifting force to the frame member 15 (FIG. 10). This lifting force is applied to the frame member 15 at the region where the secondary link arms 37a, 37b pivotally link with the lugs 38 of the frame member 15. In this regard, as the primary link arms 36a, 36b rotate into a vertical position, the 30 intermediate link member 39a, 39b come into effect to constrain further movement of the ends of the secondary link arms 37a, 37b. This causes the secondary link arms 37a, 37b to move into a vertical orientation about pivot point 36c. As such, the leverage distance of the height adjustment mechanism 14 during the second lifting stage is greater that the leverage distance in the first or initial lifting stage. Namely, the 35 leverage distance in the second lifting stage comprises the length of the primary link 12 arms 36a, 36b and the length of the secondary link arms 37a, 37b, between the pivot point 36c and the lug 38. At this second stage of the lifting process, the angle of orientation between the actuator 34 and the lever arm 35 has changed significantly, as is shown in FIG. 12. In 5 this regard, the lever arm 35 and the piston 34a are orientated closer to right angles ensuring a greater transfer of force between the actuator 34 and the lever arm 35. Therefore whilst the leverage distance of the height adjustment mechanism 14 is greater during the second stage of the lifting process, there is increased efficiency in the lifting force and output of the actuator 34 to cater for such a change. 10 Due to the arrangement of the link arrangements 30a, 30b, further rotation of the shaft 32a results in the primary link arm 36a bringing the secondary link arms 37a into a more vertical position, thereby raising the frame member 15 of the patient support 16 to its maximum elevation with respect to the frame member 13 of the base 12. In this position the actuator 34 ceases operation thereby locking the bed 10 in position. Other 15 locking means may be used in replace of, or in addition to, this actuator 34, as will be appreciated by those skilled in the art. To return the bed 10 to its lowered position the actuator 34 is caused to operate to retract the piston 34a, as will be appreciated by those skilled in the art. It will be appreciated that the height adjustment mechanism 14 of the present 20 invention provides an efficient means for lifting a high/low bed between a low position and an elevated position whilst ensuring that the mechanism 14 can be compactly retained within the base of the bed 10. By providing such a two stage lifting process the output load of the actuator 34 can be maximised, particularly during the early lifting phase, where resisting forces are at their greatest. Such a height adjustment mechanism 25 14 of the present invention is also simply concealed within the frame member 13 of the base 12 thereby reducing the need for unsightly lifting columns at the head and foot of the bed 10, allowing for beds having a more 'home-style' design. It will be appreciated by persons skilled in the art that numerous variations and/or modifications may be made to the invention as shown in the specific 30 embodiments without departing from the spirit or scope of the invention as broadly described. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.

Claims (5)

1. A bed comprising: a support member for supporting an individual thereon; a base member configured to support the support member above a floor surface; 5 a primary height adjusting mechanism selectively operable to adjust the height of the support member with respect to the base member, the primary height adjusting mechanism providing a connection between the base member and the support member, and a secondary height adjusting mechanism selectively operable to adjust the height 10 of the base member with respect to the floor surface between a lowered position in which the base member is adjacent the floor and a clearance providing position sufficient to accommodate a base of a patient lifting device under the base member, wherein the secondary height adjusting mechanism includes a plurality of legs selectively extendable from an underside of the base member and further includes a 15 pair of shafts rotatably mounted to the base member with each of the shafts having a plurality of said legs mounted thereto, the secondary height adjusting mechanism being selectively operable to rotate the shafts so that each of said legs mounted to the shafts is moveable between a retracted position wherein each leg is lifted and an extended position wherein each leg is in contact with the floor surface, and wherein, when the 20 legs are in their extended positions, the base member is supported above the floor surface by the plurality of legs so as to define said clearance providing position of the base member.

2. A bed according to claim I wherein the base member when in its said clearance 25 providing position is at least 150mm above the floor surface to accommodate a base of a patient lifting device.

3. A bed according to claim I or 2 wherein the secondary height adjusting mechanism includes a selectively operable actuator device arranged to rotate the shafts 30 so as to move the legs between their retracted and extended positions. 14

4. A bed according to claim 3 wherein the actuator device is a linear actuator having a reciprocating drive rod drivingly coupled to a drive crank associated with at least one of the shafts.

5 5. A bed according to any one of the proceeding claims wherein the base member comprises a generally rectangular base frame member, the support member comprises a generally rectangular support frame member, and wherein the base frame member is arranged to support the support frame member thereon when the bed is in a lowered position, and wherein, when the bed is in the lowered position, the primary height 10 adjusting mechanism and the secondary height adjusting mechanism are contained within the base frame member.