Patent Publication Number: US-11020293-B2

Title: Multi-function person handling equipment

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Prov. Appl. Ser. No. 62/369,417, filed on Aug. 1, 2016, which is incorporated by reference herein in its entirety. 
    
    
     TECHNICAL FIELD AND BACKGROUND 
     The present disclosure relates to a person handling equipment for handling a person, for example, when they need to be moved from a supine position to a seated position. 
     A common challenge in the emergency medical service (EMS) industry is to reduce the stress and strain on EMS personnel when handling people who need assistance. For example, a common situation that can subject EMS personnel to undue stress, and possible injury, is when moving a person from one person handling apparatus, such as an emergency cot, to another person handling apparatus, such as a chair. Further, when dealing with injured people, the time it takes to lift someone, for example, onto a backboard, and then transfer them onto a cot to get them into appropriate transport vehicle may be critical. 
     Accordingly, there is a need to reduce the stress and strain on EMS personnel when moving a person from one apparatus to another apparatus. Further, there is a need to reduce the time it takes to lift someone up and then get them into appropriate transport. 
     SUMMARY 
     Accordingly, a person handling apparatus includes a deck that can be reconfigured between a flat configuration for supporting a person in a supine position and a reclined or seated position. 
     In one embodiment, a person handling apparatus includes a deck having a seat section, a leg section, and a back section, with the back section pivotally mounted to the seat section. The leg section has a proximal end pivotally mounted to the seat section and a cantilevered, distal end that is spaced from its proximal end. The seat section, the leg section, and the back section are operable to lie in a common plane to define a supine configuration for the deck to support a person in a supine position and to reconfigure to define a chair configuration for the deck to support a person in a seated position. First and second leg assemblies are pivotally mounted to the back section of the deck to move between (1) first deployed positions wherein the first and second leg assemblies are angled relative to the deck when the deck is in the supine configuration to support the deck in a raised composition and (2) second deployed positions when the deck is supported in the chair configuration. 
     In one aspect, each respective leg assembly includes an actuator to pivot the respective leg assembly. 
     In another aspect, the first and second leg assemblies each include a pair of legs. 
     Optionally, each of the leg assemblies includes a pair of wheels. 
     In yet a further aspect, the first leg assembly is an articulatable leg assembly and is pivotally mounted to the back section at a first pivot connection. The articulatable leg assembly includes a hinge spaced from the first pivot connection wherein the first leg assembly is foldable about the hinge. 
     According to other aspects, the seat section has a seat section length. The first leg assembly has an upper portion above the hinge and a lower portion below the hinge. The hinge is spaced from the first pivot connection approximately equal to the seat section length wherein when the first leg assembly is folded about the hinge, the lower portion of the first leg assembly is positionable to extend alongside the leg section to define the second deployed position when the deck is folded into the chair configuration. Further, the upper portion of the first leg assembly is positionable to extend alongside the seat section. 
     In another aspect, the leg section has a leg section length. The lower portion of the first leg assembly has a lower portion length approximately equal to or greater than the leg section length. In this manner, when the first leg assembly is moved to the second deployed position, the leg section of the deck may be moved to a vertical orientation without interfering with the floor surface. 
     In yet a further aspect, the first leg assembly includes a first pivot connection actuator wherein the first pivot connection actuator pivots the first leg assembly about the first pivot connection. Optionally, the first pivot connection actuator may comprise an electric actuator, a pneumatic actuator, a hydraulic actuator, or a manual mechanical actuator. 
     According to other aspects, the first leg assembly includes a hinge actuator at the hinge to fold the first leg assembly about the hinge. Optionally, the hinge actuator includes a motor and a gear. 
     In another aspect, the second leg assembly is pivotally mounted to the back section by a translatable pivot connection. In a further aspect, the second leg assembly includes a translatable pivot connection actuator. The translatable pivot connection actuator pivots the second leg assembly about the translatable pivot connection. In one embodiment, the translatable pivot connection actuator includes a motor and a gear. 
     In another aspect, the second leg assembly includes a stair climbing track. Optionally, the stair climbing track has a length sufficient to span three steps of a stairway. In yet another aspect, the stair climbing track is a powered stair climbing track. 
     In a further aspect, the stair climbing track is pivotally mounted to the person handling apparatus wherein the stair climbing track can be moved from a deployed position to a stowed position. 
     According to other aspects, the second leg assembly includes a pair of legs with the stair climbing track pivotally mounted between the legs. 
     In another aspect, the translatable pivot connection includes an actuator to move the translatable pivot connection along the back section. In one embodiment, the actuator comprises a linear actuator, such as a screw drive. 
     In yet another aspect, the leg assembly includes one or more wheels. In a further aspect, the one or more wheels of the first leg assembly include caster wheels, with each caster wheel having a swivel axis. In yet a further aspect, the swivel axis is maintained in a vertical orientation regardless of the position of the leg assembly. 
     According to other aspects, the person handling apparatus further includes a back actuator to pivot the back section relative to the seat section. Optionally, the back actuator includes a powered actuator, such as a motor and gear. 
     In yet another aspect, the person handling apparatus further includes a leg actuator to pivot the leg section relative to the seat section. Optionally, the leg actuator includes a powered actuator, such as a motor and gear. 
     In another aspect, the person handling apparatus further includes a foot section mounted to the leg section. 
     In yet another aspect, the person handling apparatus further includes a handle mounted to the back section. 
     In another embodiment, a person handling apparatus includes a deck having a seat section, a leg section, and a back section, with the back section being pivotally mounted to the seat section. The leg section has a proximal end pivotally mounted to the seat section and a cantilevered distal end spaced from the proximal end. The seat section, the leg section, and the back section are operable to align to define a supine configuration for the deck to support a person in a supine position and to pivot to define a chair configuration for the deck to support a person in a seated position. First and second leg assemblies are pivotally mounted to the back section of the deck to move between (1) folded positions wherein the first and second leg assemblies generally lie in a common plane with the deck when the deck is in the supine configuration, (2) first deployed positions wherein the first and second leg assemblies are angled relative to the deck when the deck is in the supine configuration to thereby raise the deck, and (3) second deployed positions wherein the deck is supported in the chair configuration. 
     In one aspect, the person handling apparatus further includes a stair climbing track. Optionally, the stair climbing track has a length sufficient to span three steps of a stairway. 
     In a further aspect, the second leg assembly is pivotally mounted to the back section by a translatable pivot connection. The second leg assembly is moved alongside the back section when moved to the second deployed position. The stair climbing track is pivotally mounted in the second leg assembly wherein the stair climbing track can be moved from a stowed position in the second leg assembly to a deployed position extending from the second leg assembly. 
     In other aspects, the second leg assembly includes a pair of legs with the stair climbing track pivotally mounted between the legs. 
     In another aspect, each leg assembly includes one or more wheels. 
     In a further aspect, the one or more wheels include caster wheels. Each caster wheel has a swivel axis that includes a mechanism to maintain the swivel axis of each caster wheel in a generally vertical direction when in the first deployed position or the second deployed position. 
     According to other aspects, the person handling apparatus further includes an actuator. The actuator pivots (1) the leg section relative to the seat section, (2) the back section relative to the seat section, or (3) one or more of the leg assemblies. 
     In other aspects, the first and second leg assemblies are configured to support the deck at a cot height when the deck is in the supine configuration and the first and second leg assemblies are moved to their first deployed positions, and to support the deck at a chair height when the first and second leg assemblies are moved to their second deployed positions and the deck is in the chair configuration. 
     In another embodiment, a person handling apparatus includes a deck and first and second track assemblies mounted relative to the deck. Each track assembly is mounted independently of the other track assembly so that each track assembly can be independently positioned to engage surfaces having different orientations. 
     In one aspect, at least one of the track assemblies is mounted to the deck by a wheeled leg assembly. Optionally, each track assembly is mounted to the deck by a wheeled leg assembly. 
     For example, one or both wheeled leg assemblies may comprise articulating wheeled leg assemblies. Each wheeled leg assembly has an upper leg portion pivotally mounted to the deck and a wheeled lower leg portion pivotally mounted to its upper leg portion. Each track assembly is then mounted to the lower leg portion of its respective leg assembly. 
     In one aspect, the track assemblies each have a longitudinal extent greater than the longitudinal extent of its respective lower leg portion. 
     In another aspect, each track assembly is fixedly mounted to the lower leg portion of its respective leg assembly and articulates with its lower leg portion. Alternately, each track assembly may be mounted so that it articulates relative to the lower leg portion of its respective leg assembly. 
     In one embodiment, the track assemblies comprise powered track assemblies. 
     In another embodiment, the leg assemblies are pivotally mounted to the deck to move to folded positions wherein the lower leg portions of the leg assemblies generally lie in a common plane with each other and the track assemblies lie in a common plane with each other, both of which lie generally parallel to at least a portion of the deck. Optionally, the leg assemblies are movable to first deployed positions wherein the upper leg portions of each leg assembly are angled at an acute angle relative to the deck to thereby raise the deck to an intermediate position. Further, one or more of the leg assemblies may be movable to second deployed positions wherein the leg assembly is fully extended such that its upper and lower leg portions are aligned along a common longitudinal axis, which forms an obtuse angle with respect to the deck. 
     According to other aspects, the deck includes at least one articulatable section, such as an articulatable back section, and an actuator. The actuator pivots (1) the back section or (2) one or more of the leg assemblies. 
     These and other advantages and features of the invention will be more fully understood and appreciated by reference to the description of the current embodiment and the drawings. 
     Before the embodiments of the invention are explained in detail, it is to be understood that the invention 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 invention may be implemented in various other embodiments and of being practiced or being carried out in alternative ways not expressly disclosed herein. Also, 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 invention to any specific order or number of components. Nor should the use of enumeration be construed as excluding from the scope of the invention any additional steps or components that might be combined with or into the enumerated steps or components. 
    
    
     
       DETAILED DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of a person handling apparatus shown in supine configuration in a fully lowered position; 
         FIG. 2  is a side elevation view of the person handling apparatus of  FIG. 1 ; 
         FIG. 3  is a side elevation view of the person handling apparatus of  FIG. 1  shown in the supine configuration in a raised position; 
         FIG. 4  is a perspective view of the person handling apparatus of  FIG. 3 ; 
         FIG. 4A  is an enlarged elevation view of an actuator for maintaining the vertical pivot shaft of the caster wheel assembly in a vertical orientation; 
         FIG. 4B  is a similar view to  FIG. 4A  showing the actuator maintaining the vertical pivot shaft in its vertical orientation when the leg of the person handling apparatus is lowered; 
         FIG. 4C  is an enlarged elevation view of another embodiment of an actuator for maintaining the vertical pivot shaft of the caster wheel assembly in a vertical orientation; 
         FIG. 5  is a similar view to  FIG. 3  illustrating a person handling apparatus in a fully raised position; 
         FIG. 6  is a perspective view of the person handling apparatus of  FIG. 5 ; 
         FIG. 7  is a side elevation view of the person handling apparatus illustrating the person handling apparatus is a supine raised configuration but with the leg assemblies in a more stable configuration; 
         FIG. 8  is a perspective view of the person handling apparatus of  FIG. 7 ; 
         FIG. 8A  is an enlarged perspective view of another embodiment of a translatable pivot connection; 
         FIG. 9  is a side elevation view of the person handling apparatus illustrating the person handling apparatus is a reclined chair configuration; 
         FIG. 10  is a perspective view of the person handling apparatus of  FIG. 9 ; 
         FIG. 11  is a side elevation view of the person handling apparatus illustrating the person handling apparatus is a stair chair configuration; 
         FIG. 12  is a perspective view of the person handling apparatus of  FIG. 11 ; 
         FIG. 13  is a side elevation view of a vertical or near vertical orientation of the person handling apparatus; 
         FIG. 14  is a side elevation view of illustrating the person handling apparatus in a loading configuration; 
         FIG. 15  is a side elevation view of the person handling apparatus being loaded into the rear opening of an emergency vehicle; 
         FIG. 16  is a side elevation view of the person handling apparatus in a second loading configuration; 
         FIG. 17  is a schematic view of another embodiment of a pivot mechanism that can be used at any of the pivot connections; 
         FIG. 18  is an enlarged side elevation view of a second embodiment of a caster assembly that may be used in the person handling apparatus; 
         FIG. 19  is an enlarged front elevation view of the second embodiment of the caster assembly; 
         FIG. 20  is a fragmentary plan view illustrating a caster synchronizing assembly of the caster assembly of  FIG. 18 ; 
         FIG. 21  is a fragmentary plan view illustrating a second embodiment of a caster synchronizing assembly; 
         FIG. 21A  is a fragmentary plan view illustrating a third embodiment of a caster synchronizing assembly; 
         FIG. 22  is a side elevation view of another embodiment of a person handling apparatus with the person handling apparatus shown in a raised configuration; 
         FIG. 22A  is a perspective view of the person handling apparatus of  FIG. 22 ; 
         FIG. 22B  is another perspective view of the person handling apparatus of  FIG. 22 ; 
         FIG. 23  is a side elevation view of the person handling apparatus of  FIG. 22  shown in a raised but tilted configuration; 
         FIG. 24  is a side elevation view of the person handling apparatus of  FIG. 22  shown in an intermediate raised or lowered configuration; 
         FIG. 25  is a side elevation view of the person handling apparatus of  FIG. 22  shown in a fully lowered configuration; 
         FIG. 26  is a side elevation view of the person handling apparatus shown in its raised but tilted configuration with the head-end loading wheel inserted into the rear compartment of an emergency vehicle; 
         FIG. 26A  is a similar view to  FIG. 26  of the person handling apparatus shown with the head-end leg assemblies folding for insertion into the rear compartment of the emergency vehicle; 
         FIG. 27  is a similar view to  FIG. 26  illustrating the person handling apparatus with its head-end leg assemblies and tracks folded for insertion of the person handling apparatus into the emergency vehicle; 
         FIG. 27A  is a similar view to  FIG. 27  illustrating the head-end leg assembly and track fully folded and engaged with the floor of the emergency vehicle and the foot-end leg assembly fully extended to raise the foot-end of the deck to its fully raised height; 
         FIG. 28  is a similar view to  FIG. 27  illustrating the person handling apparatus partially inserted into the rear compartment of an emergency vehicle; 
         FIG. 29  is a similar view to  FIG. 28  illustrating the person handling apparatus fully inserted into the rear compartment of an emergency vehicle; 
         FIG. 30  is a side elevation view of the person handling apparatus positioned in a lowered position, such as its fully lowered position, at the top of a flight of stairs with the foot-end leg assembly and tracks partially unfolded and positioned to engage the steps of the stairs; 
         FIG. 31  a similar view to  FIG. 30  illustrating the head-end leg assembly and track extended over the top step; 
         FIG. 31A  a similar view to  FIG. 31  illustrating the head-end leg assembly and track extended over the top step and the foot-end leg assembly and track engaged with at least one of the steps; 
         FIG. 31B  a similar view to  FIG. 31A  illustrating both leg assemblies and tracks extended and engaged with the steps of the stairs; 
         FIG. 32  a similar view to  FIG. 31  illustrating the head-end leg assembly and track extended to engage the steps of the stairs and the foot-end leg assembly and track partially unfolded ready for engagement with the floor at the bottom of the stairs; 
         FIG. 32A  a similar view to  FIG. 32  illustrating the foot-end leg assembly and track partially unfolded for engagement with the floor at the bottom of the stairs; 
         FIG. 33  a similar view to  FIG. 32  illustrating the head-end track engaging the steps of the stairs with the foot-end leg assembly and track extended so that the leg assembly wheel(s) engage the floor at the bottom of the stairs; and 
         FIG. 34  a similar view to  FIG. 33  illustrating both legs extended with their wheels engaging the floor at the end of the stairs. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , the numeral  20  generally designates a person handling apparatus. As will be more fully described below, person handling apparatus  20  includes a deck that can be reconfigured between a flat or generally planar configuration, for supporting a person in a supine position, and a reclined or seated position so that the person need not be transferred to another apparatus for handling, for example, in an emergency situation. Further, the deck can be raised or lowered as needed, from a low height where the deck is just above a floor surface, for example, in a range of 2 inches to 6 inches, optionally 3 inches to 5 inches, and optionally about 4 inches, to a raised position corresponding to a conventional cot height suitable for loading into an emergency vehicle, or anywhere in between. 
     As best seen in  FIG. 1 , person handling apparatus  20  includes a deck  22  and first and second leg assemblies  24  and  26 . Deck  22  comprises an articulatable deck with a plurality of deck sections, namely a back section  28 , a seat section  30 , and a leg section  32 , with the back section  28  and leg section  32  pivotally mounted to opposed ends  30   a  and  30   b  of seat section  30 . In the illustrated embodiment, deck  22  is formed from deck sections ( 28 ,  30 , and  32 ) that are within the footprint of leg assemblies  24 ,  26  and, therefore, form a “spine deck”, with the leg assemblies  24 ,  26  mounted to the lateral sides  22   a  of the deck  22 . Alternately, deck  22  may comprise an exterior deck, where at least a portion of the legs of the leg assemblies  24 ,  26  are within the footprint of the deck sections. Additionally, while deck  22  itself can be used as a backboard, deck  22  may be configured to couple to a separate backboard, such as described in U.S. Prov. Pat. Appl. entitled EMS BACKBOARD, filed by Stryker Corporation on Aug. 1, 2016, which is hereby incorporated by reference in its entirety. 
     Further, in addition to back section  28 , seat section  30 , and leg section  32 , deck  22  optionally includes a foot section  34 . In one embodiment, foot section  34  is mounted to the cantilevered distal end  32   a  of leg section  32 , whereas the proximal end  32   b  of leg section  32  is pivotally mounted to end  30   b  of seat section  30 . For example, foot section  34  may comprise a plate that is pivotally mounted to the distal end  32   a  of leg section  32  by pivot shafts  34   b  ( FIG. 3 ), which may include a detent mechanism to define certain predefined positions for foot section  34 , such as in the same plane as sections  28 ,  30 , and  32  when in the supine configuration or angled upwardly when deck  22  is in its chair or reclined configurations. 
     Further, deck  22  may optionally include a handle  35 , formed from a loop structure  35   a , which is secured to the distal end of back section  28 . Handle  35  can facilitate the transport of apparatus  20 , especially in emergency situations. Further, handle  35  may be used as a mounting surface for mounting accessories, as well as the control unit described below. 
     Referring again to  FIG. 1 , back section  28 , seat section  30 , and leg section  32  are pivotally joined together, as noted, and may be arranged to generally lie in a common plane (supine configuration) so that deck  22  can be used as a cot and support a person in a supine position. Further, back section  28  may be raised to raise the head-end of the deck  22 . Deck sections  28 ,  30 , and  32  may also be reconfigured into a plurality of different configurations, including a reclined configuration, such as shown in  FIGS. 9 and 10 , and a chair configuration, such as shown in  FIGS. 11 and 12 . The term “reclined configuration” refers to when the back section is tilted up from the supine configuration, but not fully up like in the chair configuration. Therefore, it should be understood that the reclined configuration may include the deck raised high enough but with back section raised low enough to allow transfer to or from a flat surface, such as a table. Reclined configuration also may include the deck at or near a chair height and with the back section high enough to allow transfer to or from a chair, including a bed or stretcher in a chair configuration. Further, as will be more fully described below, deck sections  28 ,  30 , and  32  may be reconfigured, essentially, into an infinite number of configurations between the supine configuration and a vertical or near vertical position, such as shown in  FIG. 13 . 
     Leg assemblies  24  and  26  are pivotally mounted to a deck  22  to raise deck  22  between a fully lowered position ( FIGS. 1 and 2 ) and one or more raised positions ( FIGS. 3-12 ) and a vertical or near vertical position ( FIG. 13 ). Further, as will be more full described below, leg assemblies  24  and  26  and deck sections  28 ,  30 ,  32 , and  34  may be configured to provide, in essence, an infinite number of configurations, including a fully lowered supine configuration ( FIGS. 1 and 2 ), raised cot configurations ( FIGS. 3-8 ), reclined configurations (such as illustrated in  FIGS. 9 and 10 ), chair configurations ( FIGS. 11-12 ); vertical or near vertical configurations (such as illustrated in  FIG. 13 ), and various loading configurations (such as shown in  FIGS. 14-16 ). 
     In the illustrated embodiment, each deck section  28 ,  30 , and  32  may be formed from an inverted channel shaped member  40 ,  42 ,  44 , optionally with perforated upper webs  40   a ,  42   a ,  44   a , respectively, to reduce the weight of apparatus  20 , and further perforated, downwardly depending flanges  40   b ,  42   b , and  44   b , with flanges  40   b ,  42   b , and  44   b  together forming the lateral sides of deck  22 . Alternately, as noted below, one or more of the deck sections  28 ,  30 ,  32  or foot section  34 , maybe formed from panels, such as honeycomb or corrugated plastic or metal, such as aluminum, panels. Optionally, leg section  32  may have a split construction to allow one side of the leg section  32  to remain raised, while the other side of leg section  32  to be lowered. For example, this might be suitable in the case of a person that has an injured leg that cannot bend. 
     Leg assemblies  24 ,  26  each include a pair of legs  50 ,  52 , respectively. As noted above, leg assemblies  24  and  26  are mounted to the lateral sides  22   a  of deck  22 . In the illustrated embodiment, legs  50 ,  52  are pivotally mounted to the opposed lateral sides of deck  22  and, more specifically, to flanges  40   b  of back section  28 . 
     As best seen in  FIG. 4 , each leg  50  comprises an articulating leg with a hinge  50   a  that joins the upper leg portion  50   b  of leg  50  with the lower leg portion  50   c  of leg  50 . Further, hinges  50   a  may be formed by a pivot shaft  50   d  that extends between both legs (and is fixed to lower leg portions  50   c  and journaled in upper leg portions  50   b ) to form a common pivot connection or hinge for both legs  50 , so that lower leg portions pivot about hinge  50   a  together and legs  50  move in unison. In the illustrated embodiment, upper leg portions  50   b  are linear and generally parallel, whereas lower leg portions  50   c  have diverging portions  50   e  to provide a wider footprint at the lower end of leg assembly  24 . 
     Optionally, hinge  50   a  includes an actuator  54 . In the illustrated embodiment, hinge  50   a  includes a single actuator; however, it should be understood that more than one actuator may be provided. Suitable actuators include electrical, pneumatic, hydraulic, or manual mechanical actuators. In the illustrated embodiment, the actuator is a motor and rotary gear, which is mounted about the pivot shaft and is driven by its corresponding motor, which is fixedly mounted to upper leg portion  50   b . In this manner, hinge  50   a  may be powered and, further, controlled either locally or remotely, as described below. Furthermore, by using a motor and gear arrangement for the actuator, the angular orientation of lower leg portions  50   c  may be controlled by simply stopping the motor, which means that lower leg portions  50   c  may be positioned, in essence, in an infinite number of positions. 
     Similarly upper leg portions  50   b  may be pivotally mounted to back section  28  by a pivot connection  50   f  formed by a common pivot shaft  50   g , which is journaled in flanges  40   b  of back section  28  and fixedly mounted to the upper ends of legs  50 . Further, leg assembly  24  may include a second actuator  60  to pivot leg assembly  24  about pivot connection  50   f . Similar to actuator  54 , suitable actuators include a motor and rotary gear. In this manner, pivot connection  50   f  may be powered and, further, controlled either locally or remotely. 
     As noted above, leg assembly  26  is also pivotally mounted to deck  22 . In the illustrated embodiment, leg assembly  26  is pivotally and linearly mounted to deck  22  by a translatable pivot connection  61  ( FIGS. 2 and 3 ). Legs  52  are pivotally mounted to a carrier  62  by a pivot shaft  52   g  ( FIGS. 1, 2, and 6 ), which is rigidly coupled to legs  52  at their opposed ends and is journaled in carriers  62  so that legs  52  can pivot relative to carriers  62 . Pivot shaft  52   g  extends through deck  22  in slotted openings  28   a  ( FIG. 3 ) formed in flanges  40   b  on each side of deck  22 . Carriers  62  are mounted for linear movement along on back section  28  on tracks  64 , which are mounted to or formed on back section  28 , to thereby form translatable pivot connection  61 . In this manner, as carriers  62  move along tracks  64 , shaft  52   g  ( FIGS. 4 and 6 ) moves with the respective carrier to move the pivot connection of legs  52  along back section  28 . Carriers  62  may be driven by an actuator mounted to back section  28 , such as a pneumatic actuator, an electric actuator, a hydraulic actuator, or a manual mechanical actuator. Suitable actuators, therefore, include cylinders, such as a pneumatic cylinder, an electric cylinder, or a hydraulic cylinder; an acme screw; a looped chain with corresponding gears; a cog and belt assembly; a four-bar linkage; or a bell crank lever, or by any other mechanism that facilitates translational movement from one point to another point. 
     Legs  52  also include an actuator  66  ( FIG. 6 ) to pivot legs  52  about pivot shaft  52   g  ( FIGS. 4 and 6 ). Similar to the previous described actuators, actuator  66  may include a pneumatic actuator, an electric actuator, a hydraulic actuator, or a manual mechanical actuator. In the illustrated embodiment, actuator  66  comprises a motor and rotary gear. For example, the gear may be mounted about shaft  52   g , and is driven by its corresponding motor, which is mounted to one of the carriers  62 . Alternately, as described below in reference to  FIG. 8A , the translatable pivot connection  161  may include a single movable, slidable carrier  162  that extends across the deck  22  to which both legs  52  are pivotally mounted and which is moved along back section  28  of deck  22  by an actuator  165 . 
     To facilitate transport of person handling apparatus  20 , each lower leg portion  50   c ,  52   b  of legs  50 ,  52  supports a wheel  56 ,  58 . As will be more fully described below, one or more of wheels  56 ,  58  may comprise caster wheels. Further, leg assembly  26  may support a track  70 , such as a driven or powered track, so that apparatus  20  may also be used as a stair chair, as will be more fully described below in reference to  FIGS. 11 and 12 . 
     As noted above, leg section  32  is pivotal relative to seat section  30 , and back section  28  is pivotal relative to seat section  30  so that deck  22  can be configured in a reclined configuration, such as shown in  FIG. 9 , or a chair configuration, such as shown in  FIGS. 11 and 12 . Suitable pivot connections may include conventional pivot mechanisms, such as shown in U.S. Pat. No. 5,537,700, entitled EMERGENCY STRETCHER WITH X-FRAME SUPPORT, commonly owned by Stryker Corporation of Kalamazoo, Mich., which is incorporated herein in its entirety. Further, the pivot mechanisms may include a detent mechanism that locks the orientation of the respective deck sections and a manual release mechanism, such as a button or handle, which releases the detent of the detent mechanism from its locked position so that the angle can be adjusted until the release mechanism is no longer actuated. 
     In the illustrated embodiment, each deck section  28 ,  30 , and  32  is joined with its adjacent deck section by a pivot shaft  80  ( FIG. 3, 6, 12 ) that forms a hinge. Similar to leg assemblies  24  and  26 , each pivot shaft  80  may include an actuator  82  (actuator for pivoting seat section not shown), such as a pneumatic actuator, an electric actuator, a hydraulic actuator, or a manual mechanical actuator, including a motor and gear actuator, such as described above. In the case of motor and gear actuators  84 , the gear may be mounted to the respective pivot shaft and then driven by its corresponding motor, which is mounted to the deck. For example, for suitable gear and motor arrangements, reference is made to U.S. Prov. Pat. Appls. Entitled PATIENT SUPPORT SYSTEMS WITH ROTARY ACTUATORS, Ser. No. 62/356,351, filed on Jun. 29, 2016; PATIENT SUPPORT SYSTEMS WITH ROTARY ACTUATORS COMPRISING NO-BACK DEVICES, Ser. No. 62/356,359, filed on Jun. 29, 2016; ROTARY ACTUATOR HAVING CLUTCH ASSEMBLY FOR USE WITH PATIENT SUPPORT APPARATUS, Ser. No. 62/356,366, filed on Jun. 29, 2016; PATIENT SUPPORT SYSTEMS WITH HOLLOW ROTARY ACTUATORS, Ser. No. 62/356,362, filed on Jun. 29, 2016; and PATIENT SUPPORT SYSTEMS WITH ROTARY ACTUATORS HAVING CYCLOIDAL DRIVES, Ser. No. 62/356,364, filed on Jun. 29, 2016, all filed by and commonly owned by Stryker Corporation of Kalamazoo, Mich., and which are incorporated herein by reference in their entireties. 
     In one embodiment, the motor is mounted to the neighboring deck, where the pivot shaft is rotatably mounted. In another embodiment, the shaft and gear are fixed to the second neighboring deck, with the motor mounted to the first neighboring deck to drive the second neighboring deck by driving the gear and shaft mounted to the second neighboring deck. As would be understood, various mounting arrangements of the pivot shaft, gear, and motor may be used to effect the relative pivoting of one deck section to another. In this manner each of the articulating components (deck sections or leg assemblies) of person handling apparatus  20  may be driven and, further, in the case of electrically controlled actuators may be controlled by a control unit described below. 
     Referring to  FIG. 11 , optionally upper leg portion  50   b  has a length that is approximately equal to the length of seat section  30 . Similarly, lower leg portion  50   c  is approximately equal to or longer than the length of leg section  32  of deck  22 . In this manner, when deck  22  is folded into a chair configuration (where leg section  32  is folded relative to seat section  30  and is angled downwardly toward a floor or ground surface), leg  50  may also be folded about its hinge  50   a  so that upper leg portion  50   b  and lower leg portion  50   c  can extend alongside seat section  30  and leg section  32 , respectively, and provide support for the seat section  30  and leg section  32 . Further, leg section  32 , with or without foot section  34 , may be pivoted to a position that is orthogonal to the floor or ground surface without running interference with the floor or ground surface (assuming if there is a foot section that it is folded up). Alternately, the foot section  34  may have a fixed orientation or may be adjusted so that it remains in the same orientation relative to the floor surface. For example, the foot section  34  may also include an actuator that maintains the orientation of the foot section  34  regardless of the orientation of the leg section  32 , including for example, parallel to the floor surface. 
     As noted above, leg assembly  26  may include a track  70  so that apparatus  20  may be used as a stair chair when deck  22  is reconfigured into its chair configuration, such as shown in  FIGS. 11 and 12 . As best seen in  FIG. 8 , legs  52  of leg assembly  26  support a transverse shaft or rod  86 , which is secured at both ends in legs  52  and, further, extends through legs  52  to provide a mount for wheels  58 . In addition, rod  86  supports track  70 . Track  70  is formed by a looped belt  90 , which is mounted about a pair of spaced apart pulleys  92 , which are mounted between a pair of frame members  94 , such as plates, which form a track assembly. For reference of a suitable track or looped belt, reference is made to U.S. Pat. No. 9,004,204, entitled MOTORIZED SLED FOR STAIR CHAIRS, commonly owned by Stryker Corporation of Kalamazoo, Mich., which is incorporated herein by reference in its entirety. 
     Frame members  94  are pivotally mounted at their lower ends to shaft or rod  86  to allow track  70  to be moved from a stowed position, such as shown in  FIG. 10 , to a deployed position, such as shown in  FIGS. 11 and 12 . The position of track  70  is controlled by a control arm  98 , which is pivotally mounted at one end to one or both frame members  94  and movably mounted at its opposed end by a translatable pivot connection to one or both of the legs  52  of leg assembly  26 . Furthermore, track  70  may be driven or powered by an actuator, such as a motor, housed between frame members  94 . 
     The length of track  70  optionally spans at least  3  steps of a standard staircase, which provides enhanced stability to apparatus  20  when used as a stair chair. This length can be achieved in part by the translatable pivotal connection  61  of leg assembly  26 . Translatable pivotal connection  61  allows the length of legs  52  to be increased over a conventional stair chair. By increasing the length of legs  52 , legs  52  can support a longer track than a conventional stair chair leg. By decreasing the angle between leg assembly  26  and deck  22 , the overall vertical height of the legs can be reduced so that legs  52  can still provide the correct height (as noted below) when used as a chair, even with their increased lengths. 
     As noted above, leg assemblies  24  and  26  and deck sections  28 ,  30 ,  32 , and  34  may be configured to provide, in essence, infinite positions. For example, as noted, in reference to  FIG. 13 , deck  22  may be arranged in a generally planar arrangement but moved into a vertical or near vertical orientation. In vertical or near vertical configuration, the person supported by person handling apparatus  20  is secured to the deck  22  by one or more straps and possibly a harness, depending on the condition of the person. Deck  22  is moved into this configuration by folding leg  50  so that lower leg portions  50   c  are folded toward deck  22  (as seen in  FIG. 13 ) and by pivoting legs  52  toward the foot-end of deck  22 , beyond the hinge  50   a  of legs  50 , but still angled further away from deck  22  than at least the lower leg portions  50   c  of legs  50 . In this manner, wheels  56  are located between wheels  58  and deck  22 . In this configuration, deck  22  may be used as a vertical backboard, but then be transitioned into another configuration by pivoting the legs back to one of the other configurations noted above, or somewhere in between. 
     In another configuration, as noted, person handling apparatus  20  may be configured in a cot configuration and, further, in a cot loading configuration, for loading into the back opening of an emergency vehicle, such as an ambulance. As best seen in  FIGS. 14-16 , leg assemblies  24  and  26  may be positioned to facilitate loading of person handling apparatus  20  into the back opening of an emergency vehicle. In the illustrated embodiment in  FIGS. 14-15 , when deck  22  is arranged in its cot configuration, and has been moved toward the back opening of an emergency vehicle so that at least a portion of the head-end of deck  22  can be supported on the deck of the emergency vehicle, legs  50 ,  52  can be pivoted to facilitate loading. Once deck  22  is at least partially inserted into or supported by the deck of the emergency vehicle, an attendant can support the foot-end of the person handling apparatus  20  while legs  50  and  52  are pivoted toward the foot-end of the deck  22  so that they fold under the deck  22 . This can be controlled by a user interface, or controlled remotely, for example, by a hand-held user interface as noted below. Further, track  70  may be driven to engage the deck of the emergency vehicle once inserted into the opening of the emergency vehicle, which also can be controlled by a user interface, or controlled remotely, to facilitate moving the person handling apparatus  20  into the emergency vehicle. Optionally, the track  70  may be used to assist in loading the cot into the emergency vehicle and, therefore, may be deployed to engage the outer edge, including the bumper, of the vehicle opening to in effect pull the cot into the emergency vehicle compartment. 
     Alternately, as shown in  FIG. 15 , legs  52  can be pivoted toward the head-end of the deck  22  prior to inserting the head-end of the deck  22  into the opening of the emergency vehicle so that track  70  can be used to pull person handling apparatus  20  into the emergency vehicle at the very outset. Depending on the configuration, the loading of apparatus  20  may require two attendants to hold and guide the head-end of the deck  22  until the track  70  has been inserted into the opening of the emergency vehicle a sufficient distance to support the head-end of the deck  22 . In this configuration, legs  50  may remain engaged with the floor and be used to assist in guiding person support apparatus  20  into the emergency vehicle until the seat section  30  is inserted into the emergency vehicle or until person handling apparatus  20  is otherwise sufficiently inserted into the emergency. At that time, legs  50  can be folded toward the foot-end of the deck so that the person handling apparatus  20  can be fully inserted into the vehicle. Alternately, the head-end of the deck may be lengthened beyond the end of track  70  so that when the head-end of the cot is supported by the emergency vehicle, leg  52  can be folded so that it is out of the way and allow a single attendant to push the cot into the ambulance and/or optionally use the track to assist. 
     In one embodiment, the head-end of the cot may be retractable between an extended position (where the cot extends beyond track  70 ) and a retracted position to maintain the length of the deck in a more compact configuration when needed. 
     Referring to  FIGS. 1, 3 and 4 , wheels  56  or wheels  58  may each comprise a conventional wheel that rotates about a pivot shaft (i.e. which rolls about a horizontal axis but does not swivel) or a caster wheel assembly (which rolls about a horizontal axis and swivels about a vertical axis). In the illustrated embodiment, and as best seen in  FIG. 1 , each wheel  56  comprise a caster wheel assembly  110  and includes a caster wheel  110   a  that is rotatably mounted to a yoke  112 , which in turn is mounted to the distal end of one of the legs  50  of leg assembly  24 . Each caster wheel assemblies  110  also includes an actuator  114  that maintains the vertical pivot shaft or pin  112   a  of the yoke  112  in a generally vertical orientation regardless of the angle of lower leg portions  50   c  of legs  50 . In this manner, the swivel axis of each caster wheel assembly is maintained in a vertical orientation regardless of the position of the leg assembly. For example, suitable actuators include manual or powered actuators, such as gears and belts (such as shown in  FIG. 4A ); a four-bar linkage (such as shown in  FIG. 4C ); motors; solenoids; cylinders, including pneumatic, hydraulic, or electric cylinders; or magnets, namely electromagnets that be turned on or off to control the motion of the wheel. Optionally, any of the other casters wheel assemblies (e.g. such as wheels  58 ) provided on apparatus  20  may incorporate an actuator to maintain the caster wheel in a vertical orientation. Alternately, the vertical pivot mechanism (e.g. the vertical pivot shaft  112   a  and yoke  112 ) may also be actuated by another part of patient support apparatus, such as a pin on the deck to move (e.g. lock or unlock) the vertical pivot axis mechanism. For further details of a caster wheel assembly and mechanism to move the wheel of the caster wheel between an operative position and a non-operative position, reference is made to U.S. Prov. Pat. Appl. Ser. No. 62/369,423, filed Aug. 1, 2016, entitled PERSON SUPPORT APPARATUS SYSTEM, and U.S. Ser. No. 15/664,831 filed Jul. 31, 2017 entitled PERSON SUPPORT APPARATUS SYSTEM, by Applicant Stryker Corporation which are incorporated by reference herein in their entireties. 
     For example, referring to  FIGS. 4A and 4B , as noted above, in one embodiment actuator  114  comprises a gear and belt assembly  120 . Gear and belt assembly  120  includes a first gear  122  rotatably mounted about a shaft  122   a , which is fixedly mounted to the upper end of lower leg portion  50   c  of the respective leg  50  at its pivot axis, and a second gear  124  fixedly mounted about a shaft  124   a , which is journaled to the lower end of lower leg portion  50   c  and fixedly mounted to vertical pivot shaft  112   a . Gear and belt assembly  120  further includes a chain or cogged belt  120   a  that extends around the gears so that rotation of the lower leg portion  50   c  about its pivot axis will cause first gear  122  to rotate and thereby pull on chain or cogged belt  120   a  inducing rotating of second gear  124 , which in turn rotates vertical pivot shaft  112   a  to maintain the vertical pivot shaft  112   a  vertical. As would be understood, the size of the gears may be varied to control the rate of rotation of the vertical pivot shaft  112   a  to thereby maintain the vertical pivot shaft  112   a  vertical. 
     In another embodiment, actuator  114  comprises a four-bar linkage assembly  130 , with a pair of parallel arms  132  that are pinned at their upper ends to lower leg portion  50   c  of a respective leg  50 . Lower ends of arms  132  are pinned to a cross-bar  134  to thereby form a four-bar linkage with the lower leg portion  50   c . Vertical pivot shaft  112   a  is coupled cross-bar  134  so that as lower leg portion  50   c  is raised, the weight of the caster wheel assembly  110  on cross-bar  134  will pull on cross-bar  134  causing four-bar linkage assembly  130  to expand with cross-bar  134  remaining generally parallel to the floor surface. Thus, vertical pivot shaft  112   a  will remain vertical. When lower leg portion  50   c  is lowered, the caster wheel assembly will push up on cross-bar  134  causing four-bar linkage assembly  130  to fold with cross-bar  134  remaining generally parallel to the floor surface. Again, vertical pivot shaft  112   a  will remain vertical. 
     As noted above, deck  22  includes multiple articulatable deck sections  28 ,  30 ,  32 , and  34 . Optionally, in another embodiment, each deck section may be formed from a frame with a web or skin that extends over the frame to form a patient support surface on each deck. For example, the frame or the web or skin may be metal or plastic or a combination of both. Optionally, one or more deck sections may be formed form a panel with a honeycomb or corrugated construction, for example, honeycomb or corrugated aluminum, which can reduce the weight of the deck sections and/or increase the stiffness and, further, capacity of the deck sections. 
     To provide comfort to a person seated or lying on deck  22 , each section  28 ,  30  and  32  (and foot section  34 ) may be coated or have a pad, including a foam pad, a gel pad or a combination of both, and/or a fabric cover, such as a stretch fabric, which is applied over the channel members (or panels) forming the respective deck sections. Suitable gel materials for forming the gel pad or cushioning material may be formed by blending an A-B-A triblock copolymer with a plasticizer oil, such as mineral oil. The “A” component in the A-B-A triblock copolymer is a crystalline polymer like polystyrene and the “B” component is an elastomer polymer like poly(ethylene-propylene) to form a SEPS polymer, a poly (ethylene-butadiene) to form a SEBS polymer, or hydrogenated poly(isoprene+butadiene) to form a SEEPS polymer. For examples of suitable gels for covering or being applied to any of the deck sections, or for covering or being applied to the side rails reference is made to U.S. Pat. Nos. 3,485,787; 3,676,387; 3,827,999; 4,259,540; 4,351,913; 4,369,284; 4,618,213; 5,262,468; 5,508,334; 5,239,723; 5,475,890; 5,334,646; 5,336,708; 4,432,607; 4,492,428; 4,497,538; 4,509,821; 4,709,982; 4,716,183; 4,798,853; 4,942,270; 5,149,736; 5,331,036; 5,881,409; 5,994,450; 5,749,111; 6,026,527; 6,197,099; 6,843,873; 6,865,759; 7,060,213; 6,413,458; 7,730,566; 7,823,233; 7,827,636; 7,823,234; and 7,964,664, which are all incorporated herein by reference in their entireties. 
     Other formulations of gel materials may also be used in addition to those identified in these patents. As one example, the gel material may be formulated with a weight ratio of oil to polymer of approximately 3.1 to 1. The polymer may be Kraton 1830 available from Kraton Polymers, which has a place of business in Houston, Tex., or it may be another suitable polymer. The oil may be mineral oil, or another suitable oil. One or more stabilizers may also be added. Additional ingredients—such as, but not limited to—dye may also be added. In another example, the gelatinous elastomeric material may be formulated with a weight ratio of oil to copolymers of approximately 2.6 to 1. The copolymers may be Septon 4055 and 4044 which are available from Kuraray America, Inc., which has a place of business in Houston, Tex., or it may be other copolymers. If Septon 4055 and 4044 are used, the weight ratio may be approximately 2.3 to 1 of Septon 4055 to Septon 4044. The oil may be mineral oil, and one or more stabilizers may also be used. Additional ingredients—such as, but not limited to—dye may also be added. In addition to these two examples, as well as those disclosed in the aforementioned patents, still other formulations may be used. 
     As noted above, translatable pivot connection  161  ( FIG. 8A ) may be formed from a single movable, slidable carrier  162  that extends across the deck  22  and through slotted openings  28   a  formed in the flanges of back section  28  on each side of deck  22 . Legs  52  are each pivotally mounted to carrier  162  by respective pivot shafts  152   g , which are driven to rotate about their longitudinal axes by one or more actuators  166  (only one shown). In this manner, one actuator may be used to drive both legs or to drive one leg. For example, the actuator or each actuator  166  may comprise a motor and gear, with the gear mounted to the shaft  152   g  and the motor mounted to the carrier. 
     Carrier  162  is mounted for linear movement along slotted openings  28   a  in back section  28  to thereby form translatable pivot connection  161 . In this manner, as carrier  162  moves along back section  28 , shafts  152   g  move with the respective carrier to move the pivot connection of legs  52  along back section  28 . Carrier  162  may be driven by an actuator  165  mounted to back section  28 , such as pneumatic actuator, electric actuator, hydraulic actuator, or a manual mechanical actuator. In the illustrated embodiment, actuator  165  comprises an acme screw and motor. Motor  152  may be mounted to the back section  28  adjacent the end of the screw supported on the carrier  162 . Alternately, motor  152  may be mounted to the frame. Other suitable actuators, therefore, include cylinders, such as a pneumatic cylinder, an electric cylinder, or a hydraulic cylinder; a looped chain with corresponding gears; a cog and belt assembly; a 4-bar linkage; or a bell crank lever, or by any other mechanism that facilitates translational movement from one point to another point. 
     As noted above, person handling apparatus  20  optionally includes one or more powered components—all of which may be controlled locally, for example, by way of a user interface, or controlled remotely, for example, by a hand-held user interface or from an interface in an emergency vehicle. In one embodiment, person handling apparatus  20  includes a control unit  100  ( FIG. 10 , shown mounted to handle  35 ) with one or more user input devices, such as buttons, or a touch screen, to enable a user to control the various powered components, including the referenced actuators, such as the motors, or other control circuitry for operating any hydraulic or pneumatic components that may be used. As noted, the control unit  100  may be mounted to person handling apparatus  20  or comprise a hand-held device to allow remote communication with an onboard processor, for example located under the seat section or in the back section, to control of the various powered components. 
     In one embodiment, the remote control unit uses the communication systems described in U.S. patent application Ser. No. 14/211,613, filed on Mar. 14, 2014, by Applicants Michael Joseph Hayes et al., entitled PATIENT SUPPORT APPARATUS WITH REMOTE COMMUNICATIONS (STR03 P-414B), which is incorporated by reference herein in its entirety. 
     Accordingly, the person handling apparatus  20  described herein can facilitate handling of a patient while reducing the strain or stress on a caregiver. Further, when powered actuators are used to pivot the various pivot connections, person handling apparatus  20  can be reconfigured into an infinite number of operative (where it can support a person and be used to transport a person) configurations, including the illustrated cot configuration, recliner chair configuration, or stair chair configuration. Additionally, because the person handling apparatus is a single integrated apparatus, there is no need to disassemble and reassemble or change equipment. As a result, the use of the person handling apparatuses described herein can reduce the amount of time spent handling a person and getting them into the correct configuration for transport. 
     Although described as having powered pivot connections, it should be understood that one or more of the pivot connections may be manual and, further, may include detent mechanisms to define discrete positions for respective pivoting components. For example, clutch packs or manually lockable joints may be used at any of the above noted pivot connections so that no gearing is required. 
     As best seen in  FIG. 17 , a manually lockable joint  180  may include a coupler  182  that is fixed to one of the components, such as component A, and rotatably mounted to the other component, such as component B. Component A may represent one of the deck sections or leg sections, and component B may represent another deck section or a leg or leg section. 
     Mounted to the ends of each of the respective components A, B is a disc  184 ,  186  with ridges or teeth on their inwardly facing side so that when the two discs  184 ,  186  are meshed together, they rotatably couple the two components together. One of the discs, for example disc  184 , is fixedly coupled to its respective component B, while the other disc  186  is mounted to linearly translate along its respective component A so that disc  186  can move toward or away from disc  184 . Manually lockable joint  180  also includes a manual actuator  188 , which is supported by coupler  182 . Manual actuator  188  may include a lobed cam  190  and a handle or toggle arm (not shown) that is coupled to the cam and selectively rotates cam  190  between a locking position and an unlocking position. The handle is accessible from coupler  182  and, as noted, operable to rotate cam  190 . As the handle or toggle arm is rotated or twisted, cam  190  pushes on the movable disc  186  toward disc  184  to urge the two discs  184 ,  186  together and thereby lock the pivot connection. When the handle or toggle arm is rotated or twisted in the opposite direction, cam  190  no longer pushes disc  186  toward disc  184 . To separate the discs, disc  186  may include a spring, for example, to urge disc  186  away from disc  184  so that when no longer pushed by cam  190 , the two discs are separated so that one or both components may be pivoted. Alternately, the lobed cam may be replaced with a toggle body that is engaged with disc  186  to pull or push disc  186  toward or away from disc  184 . 
     Referring to  FIGS. 18 and 19 , the numeral  256  generally designates a second embodiment of a suitable caster assembly that may be mounted to legs  50  and used in lieu of the caster wheel assemblies described above in reference to person handling apparatus  20 . As will be more fully explained below, each caster assembly  256  comprises a self-positioning caster assembly that will keep its swivel axis of rotation generally the same (e.g. vertical or nearly vertical) regardless of the position of the leg or the surface on which person handling apparatus  20  is transported or supported. 
     As best seen in  FIG. 18 , each caster wheel assembly  256  includes first and second caster wheels  256   a  and  256   b . Each caster wheel  256   a  and  256   b  is rotatably mounted to a respective yoke  212   a ,  212   b  about an axis of rotation  256   c ,  256   d , respectively, which axes are generally horizontal and form the rolling axes of the caster assembly  256 . Yokes  212   a ,  212   b  in turn are commonly rotationally mounted to a bracket  260  by shafts or pins  212   c ,  212   d  about generally vertical axes  212   e ,  212   f , respectively, which form the swivel axes of the caster wheels. The terms “vertical” and “horizontal” as used herein are used in reference to the orientation shown in  FIG. 18  and in use may be offset from true vertical and horizontal when the support surface is angled, as would be understood. 
     Bracket  260  is then pivotally mounted, optionally at a medial portion thereof, to the end, or near the end, of a respective leg  50  by a pivot connection  260   a . Pivot connection  260   a  has an axis of rotation  260   b  that is parallel to the axis of rotation  256   c ,  256   d  of each caster wheel  256   a ,  256   b . In this manner, caster wheel assembly  256  is decoupled from its respective leg  50  about axis of rotation  260   b . In other words, any moment forces generated by caster wheel assembly  256  about axis of rotation  260   b  will result in the caster wheel assembly  256  rotating about axis  260   b  but not impact the orientation of leg  50 . Similarly, if leg  50  changes its orientation, moment forces from such a change in leg orientation are decoupled from the caster wheel assembly  256  and therefore will not impact the orientation of caster wheel assembly  256 . 
     As a result, when caster wheels  256   a ,  256   b  encounter a change in the ground surface, e.g. a change in slope, they will generate (under the force of gravity) a moment about axis  260   b  that induces bracket  260  to pivot about its pivot axis  260   b  so that caster wheels  256   a ,  256   b  can follow the change in ground surface. As such, caster wheel assemblies  256  are self-positioning and can adjust to different terrains and are able to maintain their swivel axes generally vertical or orthogonal to the support surface on which the person handling apparatus is supported. Additionally, the orientation of caster wheel assemblies  256  is not impacted by a change in orientation of the legs  50 . In this manner, the swivel axes of each caster wheel assembly  256  is maintained (e.g. in a vertical orientation or orthogonal to the support surface on which the person handling apparatus is supported) regardless of the surface terrain or the position of the leg. 
     To form a compact caster assembly, caster wheels  256   a ,  256   b  are mounted to bracket  260  so that their contact points with a support surface form a foot print of about 3.5 square inches. Stated another way, their outer wheel perimeters  256   e ,  256   f  are spaced from each other at a close distance when they are oriented in the same direction. For example, when caster wheels  256   a ,  256   b  are oriented in the same direction, their outer wheel perimeters  256   e ,  256   f  are spaced at a close distance X in a range of about 0.266 to 0.243 inches (about 6.35 mm), or in a range of about 0.391 to 0.359 inches (about 9.52 mm), or in a range of about 0.516 to 0.484 inches (about 12.7 mm). Further, wheels  256   a ,  256   b  are maintained in the same orientation (with respect to each other) about their swivel axes  212   e ,  212   f , otherwise the wheels could interfere with each other. 
     To maintain the wheels in the same orientation (with respect to each other) about their swivel axes  212   e ,  212   f  and enable the compact configuration (without generating interference between the two caster wheels), each caster wheel assembly  256  also includes a caster synchronizing assembly  264 . As best seen in  FIGS. 18 and 20 , each caster synchronizing assembly  264  includes a first force transmitting coupler  266  mounted to yoke  212   a  and a second force transmitting coupler  268  mounted to yoke  212   b . For example, first force transmitting coupler  266  may be mounted to yoke  212   a  on a shoulder of yoke  212   a  about pin or shaft  212   c , and second force transmitting coupler  268  may be mounted to yoke  212   b  on a shoulder of yoke  212   b  about pin or shaft  212   d . Further, first force transmitting coupler  266  is coupled to second force transmitting coupler  268  by a third force transmitting couple  270 , which transmits rotation force from one of the force transmitting coupler to the other force transmitting coupler and thereby synchronize the rotation of each caster wheel about their respective swivel axes. 
     In the illustrated embodiment, first force transmitting coupler  266  comprises a gear mounted to yoke  212   a , and second force transmitting coupler  268  comprises a gear mounted to yoke  212   b . The types of gears may include spur gears, bevel gears, helical gears, worm gears or the like. Similarly, third force transmitting coupler  270  may comprise a gear that transmits the forces between the two gears (of the first and second force transmitting couplers), and its type depends on the type of gears provided for first force transmitting coupler  266  and second force transmitting coupler  268 . Third force transmitting coupler  270  is positioned between the two gears to transmit the forces there between and is mounted to bracket for support. In this manner, as one caster wheel  256   a  or  256   b  is pushed or guided about its swivel axis, caster synchronizing assembly  264  will rotate the other caster wheel about its swivel axis to synchronize the caster wheels and maintain the caster wheels in the same orientation with respect to each other. 
     Referring to  FIG. 21 , alternately, a second embodiment of a caster synchronizing assembly  364  may include chain  370  for the third force transmitting coupler. Chain  370  extends around and transmits the forces between first and second force transmitting couplers  266 ,  268  to thereby synchronize the swivel movement of the caster wheels. 
     In a third embodiment of a caster synchronizing assembly  464  ( FIG. 21A ), first and second force transmitting couplers  466 ,  468  may comprise pulleys (mounted about pins  212   c ,  212   d ), and a third force transmitting coupler  470  may comprise a belt that extends around and transmits the forces between first and second force transmitting couplers  466 ,  468  to thereby synchronize the swivel movement of the caster wheels. 
     In the second and third embodiment, the third force transmitting coupler is supported by the first and second force transmitting couplers and need not be mounted to the bracket of the respectively caster wheel assemblies. 
     Optionally, any of caster assemblies described above may incorporate a default position mechanism. For example, a suitable default position mechanism may include a magnet (or magnets) that is located such that when the caster assemblies are lifted from the supporting surface (e.g. such as a floor), the magnets will pull on the caster wheels so they are returned to designated default or home position (i.e. where the magnets hold them). 
     In yet another embodiment, any of the above caster assemblies may incorporate a steer lock mechanism to lock the caster wheels in a desired orientation about their respective swivel axes. For example, each caster assembly  254  may incorporate a lever that is mounted to its bracket  260 , for example, that is operable to engage one of force transmitting couplers of the caster synchronizing assembly  264 ,  364 , or  464 . 
     Referring to  FIGS. 22-34 , the numeral  510  generally designates another embodiment of a person handling apparatus. As will be more fully described below, person handling apparatus  510  includes a deck  522  and two pairs (e.g. first and second pairs) of track assemblies  570 ,  572 , which are mounted relative to the deck independently of each other so that at least one pair of the track assemblies can be independently positioned to engage the same surface or can be independently positioned to engage different surfaces, including surface with different orientations. For example, when person handling apparatus  510  is used to transport a person down a set of stairs, such as shown in  FIGS. 30-34 , one pair of track assemblies may engage the floor at the top of the stairs, while the other pair of track assemblies may be positioned to engage the steps of the stairs (and, therefore, have a different orientation than the tracks of the head-end leg assemblies, for example). Similarly, while one pair of track assemblies is moved to a deployed position to engage a surface (such as the floor of an emergency vehicle ( FIG. 28 ) or stairs ( FIGS. 32-33 )), the other pair of track assemblies may be moved to a folded, stowed or non-deployed position (for example as shown in  FIGS. 28 and 33 ). 
     Referring again to  FIG. 22 , as noted above, person handling apparatus  510  includes deck  522 . Deck  522  may comprise a cot deck or a stretcher deck with one or more articulatable sections, such as an articulatable back section  540 , which is pivotally mounted to a seat section  542 , or a deck such as described above with multiple deck sections (for example, back, seat and leg sections). For further details of the overall structure of suitable decks or for further details of other features that may be incorporated into the person handling apparatus  510 , reference is made to U.S. Pat. Nos. 5,537,700; 6,125,485; 6,276,010; 6,735,794; 7,100,224; 7,398,571; 7,478,855; 7,887,113; 8,439,416; and WO 2004/064698, for example, all commonly assigned to Stryker Corporation of Kalamazoo, Mich., which are incorporated by reference in their entireties herein. 
     Further, for each articulatable section, person handling apparatus  510  may include one or more actuators, such as an air cylinder or hydraulic cylinder to at least reduce the force necessary to raise or slow the lowering of the articulatable section. For ease of description, deck  522  will described in the context of a cot deck with an articulating back section, though it should be understood that the features described below can be used with other types of decks as noted and described above. 
     As best seen in  FIGS. 22-24 , each pair of track assemblies  570 ,  572  is mounted to head-end and foot-end wheeled leg assemblies  524 ,  526 , respectively. In addition to supporting track assemblies  570 ,  572 , each wheeled leg assembly  524 ,  526  supports or includes a pair of wheels  525 , such as standard cot wheels, for a total of four wheels. 
     In the illustrated embodiment, each pair of track assemblies  570 ,  572  may be mounted to its corresponding wheeled leg assembly  524 ,  526  in a fixed orientation, such as parallel and offset from the longitudinal axes  524   a ,  526   a  ( FIG. 22 ) of its respective wheeled leg assembly and offset from the wheels&#39; axes of rotation  525   a . Further, each pair of track assemblies  570 ,  572  may be mounted offset sufficiently so that when the lower leg portions (described below) of their respective wheeled leg assemblies  524 ,  526  are rotated, track assemblies  570 ,  572  may engage the ground at the same time as the wheels  525  (as best seen in  FIG. 25 ). For ease of reference, the continued description will be made in reference to each track assembly, with the understanding that the description can apply to both track assemblies in the respective pair of track assemblies. 
     Wheeled leg assemblies  524 ,  526  are each pivotally mounted to deck  522  and are movable such that deck  522  can be moved between a fully lowered position, such as shown in  FIG. 25 , and a raised position, such as shown in  FIG. 22 , as well as intermediate raised or lowered positions, such as shown in  FIG. 24 . Additionally, each leg assembly may be independently moved so that deck can be tilted, for example, moved to a raised and tilted position, such as shown in  FIG. 23 . As will be more fully understood in reference to  FIG. 26 , a tilted position for the deck  522  may be suitable to assist loading the person handling apparatus  510  into the rear opening of an emergency vehicle. 
     In the illustrated embodiment, each wheeled leg assembly  524 ,  526  comprises a pair of legs  528 ,  530 ,  532 ,  534  ( FIG. 22A  and  FIG. 22B ), each with a wheeled lower leg portion  550   a  and an upper leg portion  550   b . For example, each leg assembly  524 ,  526  may be formed from an inverted U-shaped frame with downwardly depending portions of the U-shaped frame forming the legs or formed from H-shaped frames, such as shown in  FIGS. 22A and 22B , such as shown in reference to the previous embodiments, with the side frame members of the H-shaped frames forming the legs. Each wheeled lower leg portion  550   a  is pivotally mounted at or near the lower end of its respective upper leg portion  550   b  by a lower pivot connection  550   c . Similarly, each upper leg portion  550   b  is pivotally mounted to the deck  522  by an upper pivot connection  550   d . For example, the movement of each of the wheeled lower leg portions  550   a  about their upper leg portions  550   b  or of each upper leg portion  550   b  about their pivot connections  550   d  to deck  522  may be controlled by a mechanical connection that has defined positions (e.g. a connection that has spring biased detent mechanisms to define discrete locked positions requiring only a manual force to move the leg portions between their respective locked positions or with a manually operable release) or an actuator, such as a rotary actuator, including the rotary motors described above and in the referenced patents. It should be understood that both or one of the wheeled leg assemblies may comprise articulating wheeled leg assemblies, as noted above. 
     Referring again to  FIG. 25 , each track assembly  570 ,  572  has a track  570   a ,  572   a  with a longitudinal extent LT. Optionally, LT may be greater than the longitudinal extent LL that of its respective lower leg portion  550   a . As described above, tracks  570   a ,  572   a  can be moved independently to engage surfaces with different orientations, such as the landing or floor at the top of a flight of stairs while also engaging and spanning two or three or more steps to enhance the stability of the person handling apparatus when descending or ascending stairs. Further with the split or bifurcated track arrangement, the center of gravity of the person handling apparatus may always extend through one of the tracks. Again this increases the stability and flexibility of the person handling apparatus when it is used to transport a person down or up a flight of stairs or in or out of an emergency vehicle. 
     In one embodiment, the track assembly or track assemblies are fixedly mounted to their respective lower leg portion and articulate with the lower leg portion. Alternately, the track assemblies may be mounted so that they articulate relative to the lower leg portions. For example, each track assembly  570 ,  572  may be pinned at one thereof, for example, at their lower ends, to their respective wheeled lower leg portion  550   b  and then coupled by a link (for example see link  98  shown in  FIG. 12  and described above) to lower leg portion  550   b  to allow the track assemblies to pivot relative to their respective wheeled lower leg portion  550   b . Further, the links may be configured to provide multiple discrete positions for the track assemblies. 
     In one embodiment, the track assemblies are mounted between the legs of the leg assemblies so that only a single track assembly is mounted to each leg assembly. 
     Optionally, one or each track assembly may be powered. As best understood from the various figures, especially  FIG. 22 , each track  570   a ,  572   a  is formed by a looped belt  570   b ,  572   b , which are each mounted about a pair of spaced apart pulleys  570   c ,  570   d . Each set of pulleys  570   c ,  570   d  may be mounted to a support, such as a plate, which together with the looped belt forms the track assembly. Optionally, the looped belts may be driven, as noted, by a driver, such as a motor, which can be controlled and powered by an onboard control and power supply. The motor may be mounted between the pulleys on, for example, the support that extends between and supports the two pulleys, or the motor may be integrated into one of the pulleys. Controls for the motor or motors that drive tracks  570   a ,  570   b , as well as the rotary actuators that fold, unfold and/or pivot the legs of the leg assemblies  524 ,  526  described above, may be mounted on apparatus  510 , for example, at the side or foot-end of deck, including on the handles  510   a  ( FIG. 22 ) at the foot-end of apparatus  510 . However it should be understood that the controls may be mounted at any location on apparatus  510  or even at a remote location, for example, a hand-held control device. The controls may be push button or switches, for example, or a touch screen with icons, for controlling the functions of the various electrically powered devices mounted on apparatus  510 . For a more detailed description of suitable track assemblies, tracks, drivers, or looped belts, reference is made to U.S. Pat. No. 9,004,204, entitled MOTORIZED SLED FOR STAIR CHAIRS, U.S. Pat. Appl. 62/439,379 filed Dec. 27, 2016 entitled VARIABLE SPEED PATIENT TRANSFER DEVICE; 62/441,026 filed Dec. 30, 2016 entitled PATIENT TRANSFER APPARATUS and 62/440,167 filed Dec. 29, 2016 entitled PATIENT TRANSFER APPARATUS WITH INTEGRATED TRACKS, all commonly owned by Stryker Corporation of Kalamazoo, Mich., which are incorporated herein by reference in their entireties. For more details of suitable cots and components that may be included or mounted to the apparatus, reference is made to U.S. Pat. Nos. 5,537,700; 6,125,485; 6,276,010; 6,735,794; 7,100,224; 7,398,571; 7,478,855; 7,887,113; 8,439,416; and WO 2004/064698, for example, all commonly assigned to Stryker Corporation of Kalamazoo, Mich., which are incorporated by reference in their entireties herein. 
     In the illustrated embodiment, wheeled leg assemblies  524 ,  526  are pivotally mounted to the deck to move between folded, stowed positions and deployed positions. In the folded, stowed positions, the lower leg portions  550   a  generally lie in a common plane and the upper leg portions are folded under the deck  522  to lower the deck to its fully lowered or lowermost position. In the fully lowered position, the tracks or track assemblies lie in a common plane parallel to at least a portion of the deck (e.g. the seat portion) as best seen in  FIG. 25 . In this configuration, the tracks may be used to engage the floor and, further, can be used to drive the apparatus across a floor surface, as described below. 
     In one of the deployed positions, the upper leg portions and lower leg portions of each leg of the leg assemblies are aligned along a common axis ( 524   a ,  526   a ) and optionally angled at acute angle with respect to deck  22 . Optionally, the leg assemblies  524 ,  526  may be moved or pivoted so that they are orthogonal to the deck  22  to maximize the height of the deck  22  of the apparatus  510  and move the deck  22  to a fully raised position. 
     In another configuration, shown in  FIG. 23 , one pair of legs, such as the head-end legs  528 ,  530  (as shown in  FIG. 22 ) are moved and extended (i.e. the upper leg portions and lower leg portions of the head-end leg are aligned along a common axis ( 524   a )) to the same or similar deployed position as shown in  FIG. 22 . The foot-end legs  532 ,  534  instead are folded about their lower pivot connection  550   c  so that their upper leg portions  550   b  each form an acute angle B relative to deck  522  and their lower leg portions  550   a  (and their respective tracks or track assemblies) are angled at an acute angle C (or obtuse angle D) relative to the deck  522  to thereby tilt the deck, which can ease loading of person handling apparatus into the rear opening of an emergency vehicle, such as shown in  FIG. 26 . 
     In yet another deployed position, such as shown in  FIG. 24 , each leg assembly is moved to an intermediate deployed position where each leg  528 ,  530 ,  532 ,  534  is folded. For example, each leg  528 ,  530 ,  532 ,  534  may be folded so that their upper leg portions  550   b  each form an acute angle E relative to deck  522  and their lower leg portions  550   a  (and their respective tracks or track assemblies) are pivoted relative to their upper leg portions and are angled to form an acute angle F (or obtuse angle G) relative to the deck  522  to thereby raise or lower the deck to an intermediate height (i.e., a height between its raised position (e.g.  FIG. 22 ) and fully lowered position ( FIG. 25 )). It should be understood that the angular orientation shown in  FIGS. 22, 23 , and  24  are exemplary and that the leg assemblies may be moved to other intermediate deployed positions. Further, as shown in  FIGS. 23, 24, and 26 , each leg assembly may be moved to a different deployed position than the other leg assembly. 
     In this manner, first and second pairs of track assemblies  570 ,  572  of person handling apparatus  510  are mounted relative to the deck independently of each other pair of track assemblies. Consequently, at least one pair of track assemblies can be independently positioned to engage a surface while the leg assembly supporting the other track assembly can support the other end of the person handling apparatus or so that each pair of track assemblies can be independently positioned to engage surfaces having different orientations. As described, when person handling apparatus  510  is used to transport a person down a flight or set of stairs, such as shown in  FIGS. 30-34 , one (e.g. the head-end) track assembly  570  (or pair of track assemblies) may engage the floor at the top of the stairs, while the other (e.g. foot-end) track assembly (or pair of track assemblies) may be positioned to engage the steps of the stairs. Similarly, while one pair of track assemblies is deployed to engage a surface (such as the floor of an emergency vehicle ( FIG. 28 ) or stairs ( FIGS. 32-33 )) the other pair of track assemblies may be moved to a folded, stowed or non-deployed position, and instead support the deck on the wheel of its leg assembly. 
     The independent control of the leg assemblies allows the person handling apparatus  510  to be reconfigured into a variety of different configurations. As illustrated in  FIG. 26 , tilting the deck  522  upwardly at the head-end may better position apparatus  510  for insertion into an emergency vehicle, for example, when the emergency vehicle has a higher compartment. Once the head-end deck wheels  527  are supported on the floor of the compartment, the head-end leg assembly  524  and track assemblies  570  can be folded ( FIG. 27 ) so that tracks  570   a  of the head-end leg assembly may be powered to assist in pulling person handling apparatus  510  into the emergency vehicle while still being supported by the foot-end leg assembly  526 . Further, referring again to  FIG. 27 , the foot-end leg assembly  526  may be extended and pivoted to raise the foot-end of deck  522  so that deck  522  can remain substantially level or horizontal when being loaded into the emergency vehicle. Optionally, depending on the height of the emergency vehicle, the foot-end leg assembly  526  may be fully extended and pivoted where it is generally perpendicular to the deck  522 , such as shown in  FIG. 27A , to raise the foot-end of deck  522  so that deck  522  is in its fully raised position so that it can remain substantially level or horizontal when being loaded into the emergency vehicle the deck  522 . Alternately, when the height of the emergency vehicle compartment permits, the deck  522  not need not be tilted—and instead may remain horizontal and inserted from the raised position, such as shown in  FIG. 27 , and in some cases from an intermediate raised position where both the leg assemblies are folded. 
     Once person handling apparatus  510  is sufficiently inserted into the emergency vehicle, for example, when the deck wheels  527  are on the emergency vehicle compartment floor and the center of gravity is within the compartment of the emergency vehicle (for example as shown in  FIG. 28 ), then an operator while supporting the foot-end of the apparatus  10  can fold the foot-end leg assemblies  526  so that their track assemblies  572  may also engage the floor of the emergency vehicle and used to assist track assemblies  570  in pulling person handling apparatus  510  into the emergency vehicle ( FIG. 29 ). 
     As noted above, this flexible split or bifurcated track configuration also allows the track assemblies of person handling apparatus  510  to be independently positioned to engage different surfaces with different orientations. With reference to  FIGS. 30-34 , when person handling apparatus  510  is moved to the top of a flight of stairs, apparatus  510  can be first lowered down to its lowermost position where both track assemblies  570 ,  572  engage the floor at the floor at the top of the stairs. 
     Once lowered, the foot-end of the deck  522  can be moved (e.g. by driving tracks  570   a ,  572   a ) to extend over the top step, and thereafter the foot-end leg assembly  526  can be unfolded so that its track assemblies  572  can be oriented or positioned to engage and straddle two or more steps ( FIG. 30 ). In this orientation, the center of gravity still remains on top of the stairs, and optionally still passes through the head-end track assemblies  570 . 
     When the deck  522  of the person handling apparatus  510  and the head-end track assemblies  570  are moved to beyond the top step ( FIG. 31 ), the head-end leg assembly  526  can thereafter be unfolded ( FIG. 31A ) to allow track assembly  572  to engage the steps of the stairs. In this configuration, the center of gravity still remains on top of the stairs, and optionally remains passing though head-end track assemblies  570 . Also, during the transition, the foot-end track assemblies may momentarily disengage from the steps ( FIG. 31 ). However, as the person handling apparatus  510  extends over the top step ( FIG. 31A ), the foot-end track assemblies  572  can be further unfolded and/or tilted to re-engage or maintain engagement with the steps until the head-end track assemblies straddle two or more steps, such as shown in  FIG. 31B . Optionally, at this time the center of gravity may still remain extending through the head-end track assemblies. As the person handling apparatus  510  continues to descend, and as shown in  FIGS. 32 and 32A , the foot-end leg assemblies  526  may be gradually fully unfolded so that their track assemblies  572  disengage from the steps, and instead their wheels can engage the floor at the bottom of the stairs ( FIG. 32A ). For a shorter set of stairs, only one of the track assemblies  570  or  572  may be engaged with the steps. 
     As best understood from  FIGS. 33 and 34 , in either situation, once the head-end track assembly  570  is near to the last step and its wheels can engage the floor, head-end wheeled leg assembly  524  will be unfolded so that once again both pairs of wheels are engaged with the floor. In one embodiment, both pairs of leg assemblies  524 ,  526  are moved to their extended positions when apparatus  510  approaches the end of the stairs. However, it should be understood that one or both leg assemblies  524  or  526  may remain in an intermediate deployed position (e.g. leg assemblies  524 ,  526  are folded) when transitioning from the stairs to the floor or ground level (or vice versa). It should be understood that when used to transport or load a patient into an emergency vehicle, apparatus  510  can be operated with the leg assemblies  524 ,  526  in all of the different configurations and any combination thereof. 
     It should be understood the folding and unfolding of the leg assemblies  524 ,  526 , as described above, may be achieved as described above by actuators, such as motors, and controlled by a user using an onboard controller, such the controls described above. Further, apparatus  510  may include one or more sensors that sense the presence or absence of a load on the wheels or proximity to stairs or an emergency vehicle, such as described in copending application entitled PATIENT SUPPORT, U.S. patent Ser. No. 14/998,028, filed on Jul. 7, 2014 (STR03E P-433), which is incorporated by reference in its entirety herein, and generate input signals to the onboard controller, with the controller controlling and driving the various actuators, such as motors, based on the input signals from the sensor or sensors to move the leg assemblies and track assemblies as described to suit the sensed conditions. Further, the controller may be configured to override an input signal from a user based control at the apparatus when the user based signals conflict with the condition or condition sensed by the sensors. 
     Additionally, although some specific examples of actuators have been noted herein, such motors, electric cylinders, pneumatic cylinders, mechanical, actuators, and hydraulic cylinders, the actuators may be any type of pneumatic, electric, hydraulic or mechanical actuator and may or may not have a gear or motor. 
     Directional terms, such as “vertical,” “horizontal,” “top,” “bottom,” “upper,” “lower,” “inner,” “inwardly,” “outer” and “outwardly,” are used to assist in describing the invention based on the orientation of the embodiments shown in the illustrations. The use of directional terms should not be interpreted to limit the invention to any specific orientation(s). 
     The above description is that of current embodiments of the invention. Various alterations and changes can be made without departing from the spirit and broader aspects of the invention 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 invention 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 invention 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 invention 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. Any reference to claim elements as “at least one of X, Y and Z” is meant to include any one of X, Y or Z individually, and any combination of X, Y and Z, for example, X, Y, Z; X, Y; X, Z; and Y, Z.