Patent Publication Number: US-2021177679-A1

Title: Patient support with lift assembly

Description:
This application claims the benefit of U.S. Prov. App. Ser. No. 62/948,540, entitled PATIENT SUPPORT WITH LIFT ASSEMBLY, filed on Dec. 16, 2019 (P-600), which is incorporated by reference in its entirety herein. 
    
    
     BACKGROUND 
     The present disclosure relates to a patient support apparatus with a lift assembly for raising or lowering a patient support apparatus deck relative to a floor surface. More specifically, the present disclosure relates to a patient support apparatus with a lift assembly that can lower the patient support apparatus deck to a very low height while still providing a full range of motion to a height where a caregiver can access the patient. 
     SUMMARY 
     A lift mechanism is described that is compact at a very low height while still providing a long range of travel to raise the patient support apparatus deck to a height that is suitable for caregivers. Further, the lift mechanism is configured so that it can raise or lower one end of the patient support deck to orient the patient in a Trendelenburg or reverse Trendelenburg position. 
     In one form, a patient support apparatus includes a base, a frame supported relative the base, with the frame configured to support a deck for supporting a patient thereon. The patient support apparatus further includes a lift assembly for raising or lowering the frame relative to the base. The lift assembly includes a first leg and a second leg, with the first leg being pivotally coupled to the frame at an upper end thereof and pivotally and slidably coupled to the base at a lower end thereof. The second leg is pivotally at its upper end mounted to the first leg at a medial portion thereof to form an inverted Y-shaped leg assembly when unfolded. The lift assembly further includes an actuator mounted in the leg assembly with a mounting configuration to produce a maximum force F1 when raising the frame occurring after the lift assembly is raised from its lowermost configuration. For example, the maximum force F1 may occur approximately at mid-stroke of the lift assembly. 
     In one embodiment, the actuator is mounted in the leg assembly with a mounting configuration to produce a starting force SF wherein the starting force SF is in a range of 95% to 99% of or 96% to 98% of or about 97% of the maximum force F1. 
     In one aspect, the actuator is mounted with a mounting configuration to produce a minimum force F2 when raising or lowering the frame wherein the minimum force F2 is in a range of 50% to 70% of the maximum force F1 and, optionally, about 60% of the maximum force F1. 
     In another embodiment, a patient support apparatus includes a base, a frame supported relative to the base, which is configured to support a deck for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly is pivotally coupled to the frame at an upper end thereof and pivotally coupled to the base at a lower end thereof. The lift assembly includes a first leg and a second leg, with the second leg being pivotally mounted to the first leg at a medial portion thereof to form an inverted Y-shaped leg assembly when unfolded. An actuator is mounted in the leg assembly with a mounting configuration to produce a maximum force F1 and a minimum force F2 when raising or lowering the frame wherein the minimum force F2 is a range of 55% to 65% of the maximum force F1. For example, the minimum force F2 may occur at a maximum height of the lift assembly. 
     In one aspect, the actuator is mounted in the leg assembly with a mounting configuration to produce a starting force SF wherein the minimum force F2 is in a range of 55% to 65% of the starting force SF. 
     In another embodiment, a patient support apparatus includes a base, a frame supported relative to the base, which is configured to support a deck for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly is pivotally coupled to the frame at an upper end thereof and pivotally coupled to the base at a lower end thereof. The lift assembly includes an actuator and a first leg and a second leg, with the second leg being pivotally mounted to the first leg at a medial portion thereof to form an inverted Y-shaped leg assembly when unfolded. The actuator is mounted in the leg assembly to the first leg on one end by a first connection and at its opposed end by a second sliding pivotal connection to the first leg. 
     In one aspect, the second sliding pivot connection is linked to the second leg wherein when the actuator extends or contracts, the first leg and the second leg are unfolded or folded with respect to each other. 
     In a further aspect, the first leg includes an upper pivot connection to the frame, a lower pivot connection to the base, and further comprises a drive link coupled on one end to the actuator and coupled at its opposed end to the first leg by a sliding link pivot connection. The drive link is eccentrically coupled to the second leg. 
     In one aspect, the sliding link pivot connection between the drive link and the first leg comprises a non-linear sliding pivot connection. 
     In another aspect, the sliding link pivot connection between the drive link and the first leg extends below the lower pivot connection of the first leg when the lift assembly is in its lowermost position. 
     In yet another embodiment, a patient support apparatus includes a base, a frame supported relative to the base, which is configured to support a deck for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly is pivotally coupled to the frame at an upper end thereof and pivotally coupled to the base at a lower end thereof. The lift assembly includes an actuator and a first leg and a second leg, with the second leg being pivotally mounted to the first leg at a medial portion thereof to form an inverted Y-shaped leg assembly when unfolded. The second leg has a crank arm. The lift assembly further includes a drive link having first and second ends, with the first end of the drive link pivotally coupled to actuator and the second end of the drive link coupled to the crank arm and configured to move in a nonlinear path to thereby to push or pull on the crank arm from a range of angles and thereby unfold or fold the first leg and the second leg with respect to each other to contract or extend the lift assembly. 
     In one aspect, the first leg includes an upper pivot connection to the frame, a lower pivot connection to the base, and the driving link is slidingly coupled to the first leg by a sliding pivot connection and eccentrically coupled the crank arm. 
     In another aspect, the sliding pivot connection comprises a non-linear sliding pivot connection. 
     According to yet another embodiment, a patient support apparatus includes a base, a frame supported relative to the base, which is configured to support a deck for supporting a patient thereon, a head end actuator, and a foot end actuator. The patient support further includes a lift assembly for raising or lowering the frame relative to the base, which includes a head end leg assembly and a foot end leg assembly. Each of the leg assemblies has a pair of legs, with each pair of legs including a first leg and a second leg forming an inverted Y-shaped configuration when raising the frame and being folded generally flat when lowering the frame. The first legs are pivotally mounted at their upper ends to the frame and pivotally mounted at their lower ends to the base. Each pair of legs has a folding pivot axis, and each of the head end and foot end actuators has a first connection to its respective first leg and a sliding lower pivot connection to its respective first leg, wherein the first and second legs of each leg assembly are linked such that extension and contraction of their respective actuators will unfold or fold the leg assemblies to raise or lower the frame. 
     In one aspect, each of the first legs is linked to its respective second leg by a drive link, which are eccentrically mounted to their respective second legs. 
     In a further aspect, one end of each of the drive links is coupled to its respective first leg by a sliding pivot connection with an arcuate path. 
     In another aspect, the sliding pivot connections of the actuators to the first legs have linear paths. 
     According to another aspect, the head end leg assembly is independent from the foot end leg assembly. 
     In yet another embodiment, the lifting leg of the head end leg assembly is pivotally mounted at a head end pivot connection at or near the head end of the frame, and the lifting leg of the foot end leg assembly is pivotally mounted at a foot end pivot connection at or near the foot end of the frame. 
     In a further aspect, the head end and foot end pivot connections are offset below the frame. 
     In another embodiment, a patient support apparatus includes a base, a support frame supported relative to the base, which is configured to support a deck for supporting a patient thereon, and a lift assembly. The lift assembly includes a head end leg assembly and a foot end leg assembly. Each of the leg assemblies has an actuator and forms an independent assembly that can be mounted between the base and the support frame as an assembled unit simply inserting the pivot connections between the leg assembly and the base and coupling the pivot connections between the leg assembly and the support frame. 
     For example, in one aspect, the head end leg assembly and the foot end leg assembly each have an inverted Y-shaped configuration when the lift assembly moves the support frame to a raised position. 
     In yet further aspects, at least one of the leg assemblies includes first and second lifting legs. Optionally, the first lifting leg comprises an inverted U-shaped frame. Similarly, the second lifting leg may comprise a second inverted U-shaped frame. In another embodiment, one or both lifting legs may be L-shaped. 
     In another embodiment, the second lifting leg forms a stop for the first lifting leg when the lift assembly is folded to it lowermost configuration. 
     According to yet another embodiment, a patient support apparatus includes a base, a frame supported relative to the base, with the frame configured to support a cushion for supporting a patient thereon, and a lift assembly for raising or lowering the frame relative to the base. The lift assembly includes a first lifting leg and a second lifting leg. A linear actuator is mounted to the first lifting leg on one end and mounted to the first lifting leg at another end for linear movement relative to the first leg. The second lifting leg is linked to the actuator in a manner to cause the second lifting leg to pivot about the first lifting leg when the linear actuator is extended or contracted. 
     In yet another aspect, the second lifting leg includes a crank arm that is coupled to the actuator by a link so that extension or retraction of the actuator induces rotation of the second lifting leg. 
     These and other objects, advantages, and features of the disclosure will be more fully understood and appreciated by reference to the description of the current embodiment and the drawings. 
     Before the embodiments of the disclosure are explained in detail, it is to be understood that the disclosure is not limited to the details of operation or to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The disclosure may be implemented in various other embodiments and is capable of being practiced or being carried out in alternative ways not expressly disclosed herein. In addition, it is to be understood that the phraseology and terminology used herein are for the purpose of description and should not be regarded as limiting. The use of “including” and “comprising” and variations thereof is meant to encompass the items listed thereafter and equivalents thereof as well as additional items and equivalents thereof. Further, enumeration may be used in the description of various embodiments. Unless otherwise expressly stated, the use of enumeration should not be construed as limiting the disclosure to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the disclosure any additional steps or components that might be combined with or into the enumerated steps or components. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of a patient support apparatus; 
         FIG. 1A  is a perspective view of the patient support apparatus of  FIG. 1  with the deck, headboard, and footboard removed to show the mounting arrangement of the lift assembly; 
         FIG. 1B  is a side elevation view of the patient support apparatus of  FIG. 1  with the deck, headboard, and footboard removed to show the mounting arrangement of the lift assembly; 
         FIG. 1C  is a plan view of the patient support apparatus of  FIG. 1  with the deck, headboard, and footboard removed to show the mounting arrangement of the lift assembly in its fully lowered position; 
         FIG. 2  is a perspective view of the patient support apparatus of  FIG. 1  with the deck, frame, headboard, and footboard removed to show the lift assembly in a full height position; 
         FIG. 2A  is an enlarged view of the foot end leg assembly of the lift assembly of  FIG. 2 ; 
         FIG. 3  is another perspective view of the patient support apparatus similar to  FIG. 2  illustrating the lift assembly in a mid-height position; 
         FIG. 3A  is an enlarged view of the foot end leg assembly of the lift assembly of  FIG. 3 ; 
         FIG. 4  is another perspective view of the patient support apparatus similar to  FIG. 2  illustrating the lift assembly in a lowermost position; 
         FIG. 4A  is an enlarged view of the foot end leg assembly of the lift assembly of  FIG. 4 ; 
         FIG. 5  is another perspective view of the patient support apparatus similar to  FIG. 2  illustrating the lift assembly in a Trendelenburg position; 
         FIG. 6  is a side elevation view of the patient support apparatus with the deck, frame, headboard, and footboard removed to show the lift assembly in its full height configuration; 
         FIG. 6A  is an enlarged view of the foot end leg assembly of the lift assembly of  FIG. 6 ; 
         FIG. 7  is a side elevation view similar to  FIG. 6  with the lift assembly in its mid-height position; 
         FIG. 7A  is an enlarged view of the foot end leg assembly of the lift assembly of  FIG. 7 ; 
         FIG. 8  is a side elevation view similar to  FIG. 6  with the lift assembly in its lowermost position; 
         FIG. 8A  is an enlarged view of the foot end leg assembly of the lift assembly of  FIG. 8 ; 
         FIG. 9  is a side elevation view similar to  FIG. 6  with the lift assembly in its Trendelenburg position; 
         FIG. 9A  is an enlarged perspective view of the lift assembly; 
         FIG. 9B  is an enlarged perspective view of the lift assembly; 
         FIG. 9C  is an enlarged perspective view of the lift assembly with actuator removed; 
         FIG. 9D  is an enlarged perspective view of the lift assembly with actuator removed; 
         FIG. 9E  is an enlarged perspective view of the lift assembly with actuator removed; 
         FIG. 9F  is an enlarged perspective view of the lift assembly with actuator removed; 
         FIG. 9G  is an enlarged perspective view of the lift assembly with actuator removed; 
         FIG. 9H  are graphs of the force and force margin versus stroke of the actuator; 
         FIG. 10  is an enlarged fragmentary outside elevation view of the mounting arrangement of one of the leg assemblies of the lift assembly to the base of the patient support apparatus; 
         FIG. 10A  is an enlarged cut-away of the base frame member illustrating a slide block of the lifting assembly; 
         FIG. 10B  is an enlarged perspective view of the slide block of  FIG. 10A ; 
         FIG. 10C  is an enlarged elevation view of a mounting block; 
         FIG. 11  is an enlarged fragmentary inside elevation view of the mounting arrangement of one of the leg assemblies to the base of the patient support apparatus; 
         FIG. 12  is an enlarged perspective view of one of the leg assemblies and actuator of the lift assembly; 
         FIG. 12A  is an enlarged perspective view of one of the lifting legs of the lift assembly; 
         FIG. 12B  is a second enlarged perspective view of the lifting leg of  FIG. 12A ; 
         FIG. 12C  is a perspective view of the other lifting leg of the lift assembly; 
         FIG. 12D  is an enlarged perspective view of one of the links of the lift assembly; 
         FIG. 12E  is an enlarged perspective view of another link of the lift assembly; and 
         FIG. 12F  is an enlarged perspective view of an exemplary pivot connection of the lift assembly. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Referring to  FIG. 1 , the numeral  10  generally designates a patient support apparatus. In the illustrated embodiment, patient support apparatus  10  is configured as a bed, such as a hospital bed, with head and foot boards  10   a,    10   b,  side rails (not shown), and an articulating deck  16 . However, it should be understood the patient support apparatus  10  may take on other forms, including a stretcher, a cot, or the like. In general, patient support apparatus  10  is used whenever a patient is to be supported and it is desirable to raise and lower the patient relative to a floor surface or other supporting surface. As will be more fully described below, patient support apparatus  10  includes a lift assembly for raising and lowering the patient support apparatus surface, such as a mattress or other cushioning device, which supports a patient thereon, between a fully raised position and a lowermost position, while still leaving clearance sufficient to allow a base of an over bed table or a patient lift to be extended under the patient support apparatus. 
     As best seen in  FIG. 2 , patient support apparatus  10  includes a base  12 , a support frame  14  for supporting deck  16  ( FIG. 1 ), and a lift assembly  18  for raising or lowering support frame  14  (and deck  16 , see  FIG. 1 ) relative to base  12 . It should be understood that frame  14  may also support a load frame beneath deck  16 , which is used for mounting sensors, such as load cells, to measure the weight of a patient supported on the deck. However, the load frame may be eliminated and. Instead, load cells may be placed in frame  14  due to the reduction of forces, especially the reduction of torque on the frame  14 , which is achieved the arrangement of the lift assembly components described more fully below. 
     As best seen in  FIG. 2 , base  12  is a wheeled base with a plurality of caster wheels  15  to facilitate movement of the bed across a floor surface. In the illustrated embodiment, again referring to  FIG. 1 , deck  16  includes a plurality of articulating deck sections  16   a,    16   b,    16   c,    16   d , and  16   e.  It should be understood, however, that the number of deck sections may vary. Each deck section may be articulated by an actuator (not shown) to raise or lower the deck sections, for example, to orient the deck sections in a flat configuration or in a chair configuration (and various other configurations in between). The construction of any of base  12 , support frame  14 , the headboard  10   a,  footboard  10   b,  and/or the side rails may take on any known designs, such as, for example, those disclosed in U.S. Pat. No. 7,690,059 issued to Lemire et al., and entitled HOSPITAL BED, commonly assigned to Stryker Corp., the complete disclosure of which is incorporated herein by reference herein in its entirety; or U.S. Pat. No. 8,689,376 entitled PATIENT HANDLING DEVICE INCLUDING LOCAL STATUS INDICATION, ONE-TOUCH FOWLER ANGLE ADJUSTMENT, AND POWER-ON ALARM CONFIGURATION, also commonly assigned to Stryker Corp., the complete disclosure of which is also hereby incorporated by reference herein in its entirety. The construction of any of base  12 , support frame  14 , the headboard  10   a,  footboard  10   b,  and/or the side rails may also take on forms different from what is disclosed in the aforementioned patent and patent publication. 
     As will be more fully described below, lift assembly  18  is configured so that actuators with a shorter stroke and consistent force margin (“applied force less actuator capacity”) may be used while still being able to lower the deck to a low height position, such as 11 inches off the floor, and to a full height position, such as in a range of 26 to 34 inches off the floor. In other words, the same energy may be applied by better optimizing the force curve. In this manner, lower maximum loads may be applied to the components, such as the weldments forming the leg assemblies. Additionally, this may reduce costs and allow use of a lighter actuator. 
     Optionally, the actuator may be mounted to reduce, if not eliminate, any side loading on to the lifting legs by providing sufficient play in the actuator mounting arrangement, but no so much play that will induce lateral loads at its rod mounting location. Further, as noted above, the actuators are not mounted to the frame and, instead, are fully contained and mounted in the leg assemblies, as described below, which reduces forces on the frame so that load cells may be mounted to the frame to measure patient weight, as well as movement and patient biometrics. 
     Additionally, when lift assembly  18  is moved to its lowermost configuration, such as shown in  FIGS. 4 and 8 , the lift assembly  18  may be substantially contained within base  12  without interfering with the central space S under the base, which may be needed, for example, for mounting a drive wheel and controls for the wheel drive system (such as the ZOOM system sold by Stryker). As such, for example, when lowered, patient support apparatus  10  may be configured so that the central space S under the base is clear at least over a length  51  of about  18  inches. In this manner, patient support apparatus  10  can provide a very low height patient support apparatus, which can reduce the chance of a patient fall, but without eliminating the available space under the base. 
     Referring again to  FIG. 2 , lift assembly  18  includes a head end lift assembly  18   a  and a foot end lift assembly  18   b,  which may be substantially mirror images of each other and mounted adjacent the respective head and foot ends of the frame  14 . For ease of description, many of the following details are made in reference to the head end lift assembly  18   a,  with the understanding that the same details apply to the illustrated foot end lift assembly  18   b,  which is shown as a mirror image and numbered with the same numbers as the head end lift assembly. However, it should be understood that the head end and foot end lift assemblies may have different configurations. 
     As best seen in  FIG. 1A , frame  14  includes a pair of longitudinal frame members  14   a  and a pair of transverse frame members  14   b,  which connect longitudinal frame members  14   a  to form the frame. Referring to  FIGS. 2, 2A, 3, 3A, 4 and 4A , head end lift assembly  18   a  includes a first lifting leg  20  and a second lifting leg  22 , which are pivotally joined by pivot connections  30  (best seen in  FIG. 3A ) to form a folding leg assembly  21 . Pivot connections  30  are formed by pins  30   a  ( FIG. 9F ) that pivotally join first lifting leg  20  with second lifting leg  22  via openings  30   b,    30   c  (see  FIG. 12A and 12C ) formed in the respective legs  20 ,  22 . 
     First lifting leg  20  is pivotally mounted at its upper end to support frame  14  at pivot connections  24  ( FIG. 1A ) formed by a pair of pins that are pivotally mounted to frame  14  such as by pivot blocks  14   d,  which are mounted to transverse frame members  14   b  of frame  14  via brackets  14   c.  Optionally, pivot connections  24  may be formed by a single pivot rod  24   a  (shown in phantom in  FIG. 2A ) that extends transversely beneath upper transverse frame member  44  (described below) and into the upper ends of leg  20  to extend through pivot blocks  14   d,  which as described below nest in the upper end of legs  20  when the lift assembly is lowered folded. Optionally, rod  26   a  may be supported by intermediate brackets  24   b  ( FIG. 2A ) mounted to the underside of frame member  44 . 
     Lifting leg  20  is pivotally mounted at its lower end to base  12  at sliding pivot connections  26 , such as by the pivot blocks  60  (described more fully below). Second lifting leg  22  is pivotally mounted at its lower end to base  12  at pivot connections  28  and pivotally mounted adjacent its upper end to the medial portion of lifting leg  20  by pivot connections  30 . In this manner, when legs  20  and  22  are unfolded about pivot connections  30  they form an inverted Y shaped frame and when folded are generally arranged in flattened configuration (see  FIG. 4 ). Further, as will be more fully described below, when folded, the legs  20  and  22  may be arranged in base  12  so that the deck  16  may be lowered to a height H of less than  12  inches off the surface on which the base is supported. Optionally, also more fully described below, when folded, second lifting leg  22  may provide a bearing surface, for example, in the form of a stop  22   a  (see  FIG. 1 ), for lifting leg  20  so that the load of the frame and deck may be directly transmitted to the base  12  via pivot connections  26  and  28 . 
     As will be more fully described below, lift assembly  18   a  (as well as lift assembly  18   b ) includes an actuator  36 , in the form of a linear actuator, such as a pneumatic, electric or hydraulic actuator. As will be more fully described below, upper end (fixed base  36   d,  e.g.  FIGS. 2A and 3 ) of head end actuator  36  is mounted to the upper end of first lifting leg  20 , for example by a pivot connection  37   a  and bracket  37   b,  and, further, mounted at its opposed end via sliding pivot connection  37   c,  also to first lifting leg  20 . In this manner, when extensible rod  36   a  extends, it is extended along an axis  36   b  that is fixed relative to first lifting leg  20  (further details are provided below). In other words, the actuator does not pivot relative to the first lifting leg  20  and, instead, optionally extends generally parallel to lifting leg  20  (e.g. at least the upper linear portion of leg  20 , see below for further details on the optional construction of first lifting leg  20 ). 
     In order to translate the linear motion of the actuator  36  into pivotal motion of second lifting leg  22  (and hence lifting motion of lift assembly  18   a ), lifting leg  22  is coupled to the actuator via a link and crank arm arrangement. Further, as will be more fully described below, the link and crank arrangement may be configured to tailor the force curve of the lift assembly to closely match the allowable force of the actuator. 
     For example, in one embodiment, the actuator and link and crank arm arrangements in the lift assembly are configured to produce a maximum force F1 to occur when raising the frame  14  after the lift assembly  18  has been raised from its lowermost configuration. Referring to  FIG. 9H , the maximum force F1 may occur approximately at mid-stroke of the lift assembly. Further, the actuator, link and crank arms are mounted in the leg assembly  21  with a mounting configuration to produce a starting force SF wherein the starting force SF is in a range of 95% to 99% of, 96% to 98% of, or about 97% of the maximum force F1 (see  FIG. 9H ). As a result, the actuator may have a shorter stroke size than normally would otherwise be used, and moreover, may have a consistent force margin, with the force margin varying from about 1500 Newtons to about 3000 Newtons (see  FIG. 9H ). 
     Further, in so doing, the speed of the lifting of the deck is more uniform throughout its range of motion, which is more comforting to a patient supported thereon. For example, the speed of the actuator over its full range of motion may be more consistent and may range from about 0.7 to 1.3 dist/time. It should be understood that the speed will vary due to the weight of the patient supported thereon and the capacity of the selected actuator. 
     In the illustrated embodiment, and referring to  FIGS. 9A-9G , second lifting leg  22  is coupled to actuator  36  via a pair of crank arms  32  and via links  38 ,  40 . Each crank arm  32  is fixed mounted at its upper end to second lifting arm  22  and pivotally coupled by a pivot connection  32   a  at its lower end to a respective link  40 . In turn, each link  40  is pivotally coupled to link  38  via a pivot connection  40   a.  Additionally, link  38  is pinned at its opposed end to actuator  36  via a transverse pin  36   c  mounted in the distal end of rod  36   a  of actuator  36 . Therefore, the distal end of link  38  is extended along axis  36   b  as rod  36   a  extends or retracts along axis  36   b.  Additionally, pin  36   c  and the distal end of link  38  move in a linear path P 1 , described more fully below. Optionally, the distal end of link  38  may have a slotted opening  38   a  formed therein for receiving pin  36   c  to help offload forces on the actuator at the low height, as more fully described below in reference to stop  22   a.    
     As best seen in  FIGS. 9A-9C , link  38  extends rearwardly from pin  36   c  toward the fixed based  36   d  of actuator  36 . Further, link  38  forms an acute angle with respect to rod  36   a  through its full range of motion, described below, while it distal end moves along path P 1 . The opposed, proximal end of link  38  (at pivot connection  40   a ) is guided along a non-linear path P 2  (see  FIG. 9E-9G and 1A ) that at least initially diverges away from the linear path P 1  of pin  36   c , or in other words away from axis  36   b.  As noted above the rod  36   a  of actuator extends along an axis  36   b  that is fixed and generally parallel to at least the linear portion of lifting leg  20 . As such, when rod  36   a  is extended, link  38  will become a tension driver link that pulls pin  40   a ′ of pivot connection  40   a  along path P 2 , which in turn pushes on links  40 . Links  40  in turn push on crank arms  32 , which apply a moment to second lift legs  22  to cause them to rotate counter clockwise (as view in  FIG. 9A , e.g.) about pivot connections  30  and unfold leg assembly  21  until pin  40   a ′ of pivot connection  40   a  reaches the end of path P 2 . In reverse, as would be understood, when rod  36   a  is retracted, link  38  will become a compression driver link that pushes pin  40   a ′ along path P 2  (toward fixed based  36   d  of actuator  36 ), which in turn pulls on links  40 . Links  40  then in turn pull on crank arms  32 , which apply a moment to second lift legs  22  to cause them to rotate clockwise (as view in  FIG. 9E ) about pivot connections  30  and fold leg assembly  21  until pin connection  40   a  reaches the other end of path P 2 . As would be understood, the path P 2  may extend beyond the path of the pivot connection  40   a  so that the end of the path of the pivot connection  40   a  is defined by the actuator  36  rather than a hard stop on either end of path P 2 . 
     To retain the rod  36   a  of actuator  36  along its fixed linear path, first lifting arm  20  includes a track  42  extending therefrom along axis  36   b,  which guides the rod  36   a  of actuator  36  when extending or retracting. In the illustrated embodiment, track  42  is formed form a pair of opposed plates  48 , such as stamped plates, with elongated slots  48   a  for guiding pin  36   c  of rod  36  along its linear path P 1  along axis  36   c.  Optionally, as more fully described below, plates  48  may be configured to provide a bearing surface  48   b  along edges of slots  48   a  for pin  36   c  to reduce slop and play and provide a tighter assembly. For example, bearing surfaces  48   b  may be provided by lips formed in plates  48  along at least the lower edge of slot  48   a,  but which may extend around the full perimeter of the slot to reinforce the plate at the slot location. 
     In the illustrated embodiment, referring to  FIG. 9A , first lifting leg  20  is formed from an inverted U-shape frame with a transverse upper frame member  44  and two depending frame members  46 , which are joined together such by as welding. Actuator  36  is mounted to lifting leg  20  between frame members  46  with its upper end mounted to transverse frame member  44  by a pivot connection  37   a.  Pivot connection  37   a  may be formed by a bracket  37   b , such a pair of plate brackets attached, such as by welding, to transverse frame member  44 . 
     Tracks  42  (which as noted guide the extension of rod end  36   a  along axis  36   b ) extend from transverse upper frame member  44  and are supported and rigidly mounted (e.g. by welds) at one end to transverse frame member  44  (see  FIGS. 9A and 2A ). Tracks  42  are also supported and mounted to a second transverse frame member  50 . Transverse frame member  50  is spaced from transverse frame member  44  and rigidly mounted, for example by welding, between frame members  46  and provides rigidity to frame members  46 , in addition to providing support to tracks  42 . 
     In the illustrated embodiment, second lifting leg  22  may also be formed from an inverted U-shaped frame with an upper transverse member  56  and two depending frame members  58 , which are joined together, for example by welding. Depending frame members  58  straddle frame members  46  of first lifting leg  20  and are each pivotally joined thereto by pivot connections  30 . Transverse frame member  56  supports and provides a mount for crank arms  32 , which are rigidly attached to transverse frame member  56 , for example, by welding, and which straddle tracks  42 . 
     As best seen in  FIGS. 9A-9G , each plate  48  that forms tracks  42  is supported and mounted to transverse member  44  and to transverse member  50 , for example, by welding. In the illustrated embodiment, transverse member  50  passes through openings  48   c  formed in plates  48  and is welded to the plates  48  about openings  48   c,  which are commensurate in size to the transverse member  50 . Similarly, the upper end of plates  48  have notches  48   d  ( FIG. 12B ) formed therein sized to receive transverse member  44  therein so that transverse member  44  can be welded to the respective plates  48  around the respective notches. Optionally, the ends of plates  48  may extend to form bracket  37   b.    
     Path P 2  may also be formed by a pair of slots  48   e  to guide pivot connections  40   a . Slots  48   e  may also be formed in plates  48  and also include bearing surfaces  48   f  for the pin  40   a ′ of pivot connections  40   a  to thereby reduce slack and hence increase the tightness of the movement of the lift assembly. Similar to bearing surfaces  48   b,  bearing surfaces  48   f  may be provided by a lip or lips formed in plate  48  along at least the lower edge of slot  48   e,  but which may extend around the full perimeter of the slot  48   e  to reinforce the plate  48  at the slot location. 
     As best seen in  FIG. 9E , the lips that form bearing surfaces  48   b  and  48   f  may extend in opposed directions from each other—that is bearing surfaces  48   b  are formed on a lip(s) that extend from the inner side of plates  48 , while bearing surfaces  48   f  are formed on a lip(s) that extend from the outer side of plates  48 . 
     To guide pivot connection  40   a  and link  38 , and hence crank arm  32 , in the desired path, each slot  48   e  may be non-linear. Each slot  48   e  includes a first curved portion that is located approximately at the distal end of the slot  48   e  closest to the end of the rod  36 . The first curved portion forms the portion of the path P 2  that initially diverges away from path P 1  (and hence away from axis  36   b ). The second portion of slot  48   e  may be linear but is angled upwardly toward axis  36   b  and extends from the first curved portion toward to the proximal end of the slot  48   e  (end closest to the fixed body  36   c  of actuator  36 ). 
     In this manner, when rod  36   a  is fully extended and leg assembly  21  is fully raised, and then actuator  36  is retracted, links  38 , now acting as compression links, will push pivot connections  40   a  along the first curved portion of path P 2 , which will pull links  40  and cause links  40  to increase their angle with respective to crank arms  32  while pulling on crank arms  32 . This increase in angle increases as the pivot connections  40   a  move along the curved portion due to the diverging angle of path P 2  from path P 1 , which increases their leverage on crank arms  32 . As the rod  36   a  continues to retract, pivot connections  40   a  will continue to move along path P 2  where links  40  and crank arms  32  increase their angular separation. This increase in angular separation increases the leverage of links  40  to pull on crank arms  32  until the legs are fully folded and in their lower most positions where links  40  can exert their maximum leverage. At the lowermost position, this is normally where the greatest torque is required due to the greatest separation of pivot connections  26 ,  28 . However, with the present configuration, at this point, the force needed by the actuator  36  to move second leg  22  is not the maximum and, instead, is less than the maximum force due to the increased leverage of links  40  when in their orientation that corresponds to the lower most position of lift assembly  18   a.  Thus, the shape of the path P 2  is such that the greatest leverage occurs where the greatest force is normally needed to lift the leg assembly, which as noted is typically when leg assembly  21  in its lowest height where the pivot connections  26 ,  28  of the first and second legs  20 ,  22  are furthest apart. But here due to the increased leverage by links  40  on crank arms  32 , as noted, the force require is not the maximum force. Instead, the maximum force is required when leg assembly  21  is raised about halfway where the pivot connections  26 ,  28  of the first and second legs are still significantly separated but links  40  have a reduced leverage on crank arms  32 . 
     Stated another way, when leg assembly  21  is fully lowered (see  FIGS. 9G and 8A ), and pivot connections  40   a  are at the proximal end of path P 2 , links  40  are substantially perpendicular to crank arms  32  and, therefore, as noted have the greatest leverage. In addition, as noted, due to the increased leverage, the amount of force is less than the maximum force needed during raising or lowering leg assembly  21 . As rod  36  is extended, however, the force needed by the actuator increases as the leg assembly is moved from its lower most position to its medial position where pivot connection  40   a  reaches its furthest distance from path P 1  (or axis  36   b ), which corresponds to where link  40  forms an acute angle and therefore is angled closer to crank arm  32 . In this orientation, link  40  has less leverage than when in the lower most position. As the rod continues to extend, however, the pivot connections  26 ,  28  of the first and second legs are moved closer together to reduce the amount of torque needed for continued unfolding of the first and second legs  20 ,  22  so that the reduced leverage of link  40  as it approaches the distal end of path P 2  coincides with a reduce amount of torque needed to move second leg  22  closer to the fully raised height of leg assembly  21 . As a result, and referring to  FIG. 9H , the force margins of the actuator are reduced. 
     Although described as sliding pivot connections, pivot connections  40   a  may be formed from a single pin or rod  40   a ′ that extends between links  40  and plates  48 . 
     Optionally, to provide additional support to tracks  42 , crank arms  32  may be pivotally coupled to tracks  42  by a pin or rod  58   a  that passes through apertured flanges  48   g  ( FIG. 9B and 12A ) extending upwardly from plates  48 . 
     In the illustrated embodiment, in order to increase the rigidity and torsional resistance of lifting legs  20 ,  22 , each frame member that forms the respective lifting leg may be formed from one or more closed cross-section members, such as formed from a metal, such as steel. Alternately, each lifting leg  20 ,  22  may be formed from a solid member, such as steel bar or plate. Similarly, transverse frame members  50  and  56  may also be formed from tubular members and extended into one or more transverse openings formed in the respective legs  20 ,  22  and welded thereto around one or both openings to thereby form a rigid frame. 
     For example, depending members  46  and  58  may be formed from closed tubular members or solid plates. The closed tubular members may be formed from structural channel members or two stamped plates that are joined together, such as by welding. For example, each plate may be stamped into a channel shaped cross-section, which are then joined together in a facing relationship (open sides facing each other, like a clam shell arrangement). Optionally, the two plates may be slightly nested to allow the flanges of one channel shaped member to be inserted into the open face of the other channel-shaped plate and then welded in place with spot welds or continuous welds along their length. Alternately, the plates may be sized so their flanges abut each other and are also welded together, for example, by spot welding or continuous welds along their lengths. 
     In addition to increasing the strength and torsional resistance of the lifting legs, their construction allows the shape of the legs to be tailored. For example, rather than having to have longer pins  26   b  on pivot connections  26  to span the space between leg  20  and base ( 12 ), as seen in  FIG. 9A , the lower portions of leg  20  (e.g. depending members  46 ) may be formed so that they are offset or angled outwardly. For example, starting below pivot connections  30 , the lower portions of leg  20  (e.g. depending members  46 ) may be formed so that they are offset or angled outwardly so that the mounts  26   a  for pivot connections  26  on leg  20  are offset outwardly and can be aligned in the same plane as the mounts  28   a  for pivot connections  28 . In this manner, pivot connections  26  and  28  may be mounted in the same channel (channel  12   c  of frame members  12   a ). Consequently, a single tube weldment may be used to form base  12 . 
     Transverse member  44 , on the other hand, may be formed from an open sectioned member, such as a channel shaped member, including a channel formed from a stamped plate or a structural channel member. 
     Track  42 , as noted, may be formed from plates, which may be reinforced with braces  48   h  ( FIG. 9A ). Similarly, links  38 ,  40  and crank arms  32  may also be formed from plates and when needed provided with embossments or bosses around their mounting openings to increase their strength. For example referring to  FIG. 12E , each link  40  may be formed from an elongated rectangular plate with an embossment  40   b  to reinforce the plate. Similar, crank arms  32  ( FIG. 12C ) may be formed from a generally triangular shaped pate and include embossments  32   b,  which reinforce the crank arms. 
     Referring to  FIG. 12B , links  38  may be formed from two plates  38   b  joined at their (e.g. lower) edges by a transverse plate  38   c,  which may be welded to or formed with plates  38   b  to form an U-shaped link assembly. Openings  38   a  to may be reinforced by bosses or lips  38   a ′ that encircle openings  38   a  and which also form bearing surfaces for pin  36   c  of actuator  36 . As noted above, openings  38   a  may also be elongated to allow off-loading from the actuator  36 , for example, when lift assembly  18   a  is fully lowered. 
     Further, as shown in the illustrated embodiment, the cross-section for the components of the lift assembly may vary along their length to provide increased strength where needed, but reduced in cross-section where the loads on the lift assembly are reduced to thereby provide a more compact and reduced weight light assembly. Further, by varying the cross-sections, the components of the lift assembly may provide a better nesting arrangement when folded. In the illustrated embodiment, frame members  46  are formed with three different cross-sections at three different elevations, which allow the lifting leg  20  to avoid interference with other components of the bed, including leg  22 , as it swings though its full range of motion. 
     For example, referring to  FIG. 9A , the upper end of leg  20 , for example, depending frame members  46  may have the largest cross-section given that the forces to raise or lower the frame  14  are greatest at the upper end of leg  20 . Further, with the increased cross-section, a portion of the frame members  46  may have an open section at their upper ends to provide for cable routing through lift assembly and, further, to provide better nesting. As best understood from  FIG. 1A , when lift assembly is fully folded and frame  14  is lowered, the mounting brackets  14   c  and mounting blocks  14   d  may extend into and nest in the open sections of the upper portion of frame members  46 , which again assists in reducing the overall height of the deck when the lift assembly is in its lower most configuration. 
     As noted above, the lower ends of lifting legs  20 ,  22  are mounted to base  12  by pivot connections  26 ,  28 . As seen in  FIG. 9 , pivot connections  26  may be formed by a sliding block  60  rotationally mounted to each of the lower ends of the lifting legs  20  by pins  26   b . Blocks  60  are guided in channels  12   c  formed in base frame members  12   a  ( FIGS. 2 and 4 ) between upper and lower flanges  12   b.  Similarly pivot connections  28  may be formed by blocks  64  rotationally mounted to each of the lower ends of the lifting legs  20  by pins  28   b.  Blocks  64  are located and fixed in channels  12   c  by fasteners  65 , which extend through openings in upper flange  12   c  of frame members  12   a.    
     To make the lift assembly more compact, blocks  60  and  64  may be mounted to pins  26   b,    28   b  without the use fasteners or spring clips and, instead, retained on pins  26   b  and  28   b  using a tab and slot arrangement with blocks  60  and  64 , respectively, described below in reference to  FIGS. 10, 10A, 10B, and 10C . Further, in order to avoid blocks  60 ,  64  being rotated off pins  26   b,    28   b,  each block has a tabbed connection for mounting the pins  26   b,    28   b  to the block. Each pin  26   b,    28   b  has one or more tabs that have to align with corresponding notches provided in the block mounting opening  60   b,    64   b  in order to mount the blocks or remove the blocks from the pins. Additionally, referring to  FIGS. 3 and 10 , each of the mounting blocks are square or rectangular in shape so that they can be retained between the upper and lower flanges  12   b  of frame members  12   a  and do not rotate, though pins  26   b  and  28   b  are free to rotate in the blocks. The tabs on the pins (and corresponding notches) are arranged so that they do not align during normal movement of the lift mechanism and, therefore, retain the respective blocks on the pins ( 26   b    28   b ) during normal operation. 
     As best seen in  FIGS. 10A and 10B , blocks  60  have rectangular body  60   a  with a central transverse opening  60   b,  which includes one or more notches  60   c.  In the illustrated embodiment, opening  60   b  includes a pair of opposed notches. Similarly, pin  26   b  has one or more tabs  26   c  for aligning with the notch or notches. When so aligned, pins  26   b  may be inserted into the opening  60   b  in the block  60  and, thereafter, the block  60  rotated about the pin to thereby retain the pin on the block. The block is then inserted into the frame member  12   a  (via cutouts or notches  12   e  described below) and captured between the upper and lower flanges. Optionally, upper and low flanges may include downwardly and upwardly extending lips  12   b ′ ( FIGS. 10 and 10A ), respectively, to further help retain blocks  60  and  64  in channels  12   c.    
     As best seen in  FIG. 10C , blocks  64  similarly have a rectangular body  64   a  with a central transverse opening  64   b,  which includes one or more notches  64   c.  In the illustrated embodiment, opening  64   b  includes a pair of opposed notches  64   c.  Similarly, pin  28   b  has one or more tabs  28   c  for aligning with the notch or notches. When so aligned, pins  28   b  may be inserted into the opening  64   b  in the block  64  and, thereafter, the block  64  rotated about the pin to thereby retain the pin on the block. The block is then inserted into the frame member  12   a  (via cutouts or notches  12   e  described below) and captured between the upper and lower flanges  12   b.  To secure block  64  in a fixed location, block  64  includes transverse openings through body  64   a  and offset portions  64   d  that are curved and align with the transverse openings for receiving fasteners  65  through body  64   a  and thereby fix the location of the pivot connection  28  along frame members  12   a  of base  12 . 
     Referring to  FIGS. 3 and 10 , blocks  60  and  64  are inserted in channels  12   c  of frame members  12  via notches  12   e  formed in the upper flanges  12   b  of frame members  12 . Notches  12   e  are located offset from pivot connections  28 , which when installed are fixed along the longitudinal axis of frame members  12   a  via fasteners  65 , and out of the normal travel of the sliding pivot connections  26 . Once inserted therein, blocks  60 ,  64  are moved to their in use locations and then retained therein by the upper and lower flanges  12   b  and optional lips  12   b ′ of frame members  12   a.  Thus, base  12  has install locations for the pivot connections offset from their use locations. 
     In addition to the overall construction, this installation arrangement and mounting configuration allows for lift assembly  18   a  (and  18   b ) to be installed as a unit (with the actuator and lines (e.g. power and/or hydraulic lines and/or pneumatic lines) already assembled in the unit), simply requiring the lift assembly to be inserted into the base and connected at their upper ends to mounting blocks  14   d  without the need for additional brackets and fasteners for installation. 
     Further, referring again to  FIGS. 1C and 4 , when frame  14  is in its lowermost position, frame members  14   a  of frame  14  may rest on base  12 , namely on between base members  12   a.  Additionally, lifting legs  20 ,  22  and crank arms  32  are arranged so that they fold into the space defined between base members  12   a,  with the majority, if not all of, legs  20  and actuator  36  lying at or below the upper flange of base members  12   a  ( FIG. 8 ). Further, as noted, pivot connections  26  and  28  are aligned along the respective base frame members  12   a  and lie in the same plane, with pivot connections  30  aligned at or just below the upper flange of the respective frame members  12   a.    
     In this manner, when lift assembly  18  is in its lowermost configuration, many of the components of the lift assembly (lifting legs, crank arms) are lowered into the space defined between or slightly below base frame members  12   a,  but leave there between space S, as described above. Additionally, when lift assembly  18  is in its lowermost configuration, the distance from the top of the deck to the floor may be less than 14″, less than 13″, and optionally less than 12″. Further, the space below base members  12   a  is sufficient to allow a base of an overbed table or lift assembly to extend under base. For example, the distance from the underside of the base members  12   a  to the floor is at least 4″, at least 5″ or between about 5″-6″. 
     As noted about, second lifting legs  22  have one or more stops  22   a  to provide a stop for the upper portion of leg  20  when leg assembly  21  is fully folded. Stops  22   a  are mounted and arranged to extend inwardly of legs  22  so that they provide bearing surfaces for depending frame members  46  of first lifting leg  20  when it is fully folded. 
     In the illustrated embodiment, stops  22   a  are formed by L-shaped brackets  22   b  mounted, such as by welding, to the inner side  22   c  of lifting legs  22 . Brackets  22   b  extend inwardly from inwardly facing side  22   d  of leg  22  to contact downwardly facing side of leg  20  when leg  20  is folded. Brackets  22   b  may have a rubber bumper or rubber bumpers  22   c  ( FIG. 11 ) mounted thereto to reduce noise and absorb some vibration. Because the stop is located adjacent pivot connection  28 , when folded, the weight of the deck and frame pass essentially directly through legs  22  to base  12 . 
     Referring to  FIG. 9A , as described above, actuator  36  may be mounted to reduce side loading on the lift assembly components. For example, pin  36   c  of actuator  36  may be mounted in slot  48   a  of plate  48  between links  38  and between a pair of bushings  37   e  ( FIG. 9D ). Optionally, gaps or spaces are provided between bushings  37   e,  for example plastic bushings, and rod  36   a  (or between the bushings and links  48 ) to provide sufficient play to avoid binding but also play that is sufficiently small to avoid inducing side loading (e.g. to avoid actuator from angling relative to path P 1 ) on lift assembly, and more specifically on track  42 . For example, the gaps on each side may fall in a range of ½ to 1/1000 th  inch. Further, to help retaining pin in slots  48   a,  each opposed end of the pin  36   c  may be guided by a rectangular bushing  37   f  that is taller than the height of the slots  48   a  so that they ride on the outside of plates  48 . Optionally, springs may be provided in lieu of, or in addition to bushings  37   e,  to help maintain the alignment of the rod  36   a  along path P 1 . 
     Referring to  FIGS. 1A and 3 , optionally one or more of the lift assembly components may include protective and/or aesthetic covers, formed, for example, from plastic. For example, covers C 1  and C 2  may be provided to cover and optionally protect the head end and foot ends of the base  12 . Similarly, at least the rods of the actuators and track may be covered by a cover C 3 . Covers C 4  may also be provided to extend over legs  22 . However, it should be understood with the closed construction of many of the lift assembly components, covers need not be provided for the leg assemblies of the lift assembly. 
     Although not specifically described in each instance, it should be understood that the structural load bearing members of the lift assembly may all be formed from metal, including steel, and further may be stamped, molded, cast or forged members, and assembled by welding. Other members, such as the mounting blocks or covers, may be formed from plastic or other low friction materials, which may be molded. 
     Optionally, at least some, if not all, of the pivot connections may incorporate a retainer  70  ( FIG. 12F ) that renders the pivot connection tamper resistant, and optionally non-serviceable. It also makes the lift assembly connections easy to inspect. Although detailed in reference to pivot connection  40   a  of link  40 , it should be understood that the same or similar details apply to the other pivot connections. 
     As best seen in  FIG. 12F , the end of the pin  40   a ′ of the pivot connection ( 40   a ) projects though the opening provided in link  40 . Optionally, the opening may be reinforced by a raised boss  40   c.  Mounted on pin  40   a ′ about opening is retainer  70 . Retainer  70  is mounted to the distal end of pin  40   a ′ via a standard pop rivet  72 , which extends though retainer  70  and though a transverse opening provided in the distal end of pin  40   a′.    
     In the illustrated embodiment, retainer  70  includes a cylindrical body  70   a  with a closed end  70   b,  which rests against the distal end of pin  40   a ′. The cylindrical wall  70   c  of body  70   a  is bifurcated to ease installation on the end of pin  40   a ′ so that it can be manually mounted on the distal end of pin  40   a ′, though a tool can be used as well. Optionally, body  70   a  includes a flanged end  70   d  that forms an annular bearing surface  70   e,  which can provide some thrust load when for example, when pin  40   a ′ pulls inwardly as view in  FIG. 12F  and engages washer W. Thus, retainer  70  provides an easy to inspect connection, which is tamper resistant and, further, may be non-serviceable, to ensure the correct assembly at the original manufacturing facility. 
     As would be understood, because the head end and foot end lifting assemblies are independent, they can be independently moved to raise or lower the head or foot ends of the support frame to move the deck in a Trendelenburg or reverse Trendelenburg position (see  FIGS. 1A, and 5 ). Additionally, the speeds of each actuator can be independently controlled. For example, suitable actuators include Linak actuators, such as model number LA  40 , or Ilcon actuators. For example, the actuators may include sensors or magnets to measure the speed of the actuator so that, as noted, the actuation and speed of each actuator may be independently controlled. 
     Referring to  FIG. 9H , in one embodiment of a standard hospital bed, the force of the actuators may range from about 5300-5400 N when in the lowermost position, up to about 5700-5800 N when about midway between the lowermost position, and then back down to about 3200-3300 N when in the uppermost position. As would be understood normally the greatest force is needed when the lift assembly is in its most compact, lowermost position; however, with the current arrangement of links and crank arms, which maximizes the moment arm when the leg assembly is in its lowest most position, the initial starting force (SF), as noted above, is less than the maximum force F1. As the lifting legs raise up relative to the base, the leverage provided by the crank arms decreases until the lift assembly has reached the midway region, approximately 19-24 inches off the floor, thus increasing the required force. As the lift assembly continues to rise , the leverage provided by the crank arms furthers reduces but at a reducing rate, as shown in  FIG. 9H , until the lift assembly is in its uppermost configuration. 
     With the above configuration, when lift assembly  18  is in its lowermost position, the distance from the top of the litter deck (shown in phantom in  FIG. 30 ) to the floor may be less than 14″, less than 13″, and optionally less than 12″, and the space beneath base frame members  12   a  is unobstructed to allow a base of an overbed table or lift assembly to extend under base. For example, the distance from the underside of the base frame members  12   a  to the floor is at least 4″, at least 5″ or between about 5″-6″ and provides a minimum clearance of about 2 to 3 inches or about 2.4 inches below the lowermost member of the patient support. Further, when lift assembly is in its raised position, the lifting legs move outwardly toward the ends of the frame to thereby leave a space sufficient to allow a fluoroscope device to extend between the frame and the base. 
     Though not described in each instance, it should be understood that the structural components of the frame, the deck, and the lift assembly may be formed from metal structural members, such as steel, that are either welded (as noted in some cases) or fastened together, e.g. by bolts, rivets, pins, or screws or the like, or simply mechanically interlocked (as noted above in reference to some of the brackets). Further, features on one embodiment may be combined with features of another embodiment or embodiments. Additionally, it should be understood that the actuators may be controlled to extend or contract independently, for example, so that they can raise or lower one end of the patient support apparatus to orient the patient support apparatus deck in a Trendelenburg or reverse Trendelenburg position. 
     Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are used to assist in describing the disclosure based on the orientation of the embodiments shown in the illustrations. The use of directional terms should not be interpreted to limit the disclosure to packages of any specific orientation(s). 
     Various alterations and changes can be made to the above-described embodiments without departing from the spirit and broader aspects of the disclosure as defined in the appended claims, which are to be interpreted in accordance with the principles of patent law including the doctrine of equivalents. This disclosure is presented for illustrative purposes and should not be interpreted as an exhaustive description of all embodiments of the disclosure or to limit the scope of the claims to the specific elements illustrated or described in connection with these embodiments. For example, and without limitation, any individual element(s) of the described disclosure may be replaced by alternative elements that provide substantially similar functionality or otherwise provide adequate operation. This includes, for example, presently known alternative elements, such as those that might be currently known to one skilled in the art, and alternative elements that may be developed in the future, such as those that one skilled in the art might, upon development, recognize as an alternative. Further, the disclosed embodiments include a plurality of features that are described in concert and that might cooperatively provide a collection of benefits. The present disclosure is not limited to only those embodiments that include all of these features or that provide all of the stated benefits, except to the extent otherwise expressly set forth in the issued claims. Any reference to claim elements in the singular, for example, using the articles “a,” “an,” “the” or “said,” is not to be construed as limiting the element to the singular.