Patent Publication Number: US-7588532-B2

Title: Lifting apparatus for patient support surface

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a divisional application of U.S. application Ser. No. 10/731,337, filed on Dec. 9, 2003, which in turn is a continuation of U.S. application Ser. No. 09/955,850 filed on Sep. 19, 2001, now U.S. Pat. No. 6,659,935. U.S. application Ser. No. 09/955,850 claims priority under 35 U.S.C. §119(e) to U.S. Provisional Application Ser. No. 60/234,443, filed Sep. 21, 2000, all of which applications are expressly incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     Field of Invention 
     This invention relates to infant incubators and warmers, and more particularly, to the provision of a lifting mechanism for the patient support surface of an incubator and warmer. In this application, the lifting mechanism will be described as used in an incubator, but it will be appreciated that the mechanism will be useful in an incubator, a warmer, or combination incubator and warmer. 
     BRIEF SUMMARY OF THE INVENTION 
     An incubator provides a generally transparent enclosure within which heated air is circulated to minimize the heat loss of an infant. The infant typically lies on a mattress supported by a deck or support surface inside the incubator. Such incubators are typically provided with a large access door to allow for placement or removal of the infant in the incubator, as well as supplemental access ways such as hand ports or small entry doors to permit routine care of the infant while minimizing heat loss from the incubator and the infant. 
     To provide appropriate care to the infant the caregiver may need to move the infant relative to the incubator. Conventional support surfaces are configured to raise and lower relative to the incubator, giving the caregiver a more convenient work environment inside the incubator. Commonly referred to as trendelenberg and reverse-trendelenberg positions, the support surfaces of conventional incubators are often configured to tilt at both the head and foot ends. 
     Conventional incubators include independent lifting mechanisms to raise and lower either end of the support surface. This requires the caregiver to engage a first mechanism to tilt one end, then lower that mechanism and then raise a second mechanism to tilt the other end. For example, the caregiver will either manually turn a first hand crank or knob, or engage a first motor, that engages the first lifting mechanism for lifting one end of the surface. If the caregiver wishes to tilt the other end, he/she will first have to lower the first lifting mechanism. This requires the caregiver to either reverse turn the hand crank or knob, or reverse engage the first motor to lower the raised end. Once the raised end is lowered, the caregiver will then have to either manually turn a second hand crank or knob, or engage a second motor, that engages a second lifting mechanism for lifting the other end of the surface. These several motions made by the caregiver take a substantial amount of time and effort to accomplish, thereby, reducing response time and efficiency in moving the patient when needed. 
     It would be desirable, therefore, to provide an infant support surface for an incubator or warmer that includes a mechanism for raising or lowering or tilting or reverse tilting the support surface, which system requires only a single action or reverse action by the caregiver. For example, it would be desirable for the caregiver to have to turn only one hand crank or knob to tilt one end of the surface, and then simply reverse turn the crank or knob to tilt the other end of the surface. It would be advantageous to provide a motor drive arrangement which can be controlled by operating a switch assembly with one hand. 
     According to an illustrative embodiment of the present disclosure, an infant support for an incubator or a warmer or a combination thereof comprises a support surface for receiving an infant, the support surface having a head end and a foot end, an elevator coupled to each end of the support surface to raise and lower each end, and a drive associated with the elevators. The drive comprises a motor coupled to each elevator and a control for the motors, whereby either end of the support surface may be moved between raised and lowered positions. Each motor is, for example, a stepper motor and is coupled to the associated elevator by a rack and pinion gear unit. A switch is coupled to the control to raise and lower the support surface and tilt the support surface between trendelenberg and reverse-trendelenberg positions. 
     In another illustrative embodiment, the infant support comprises a head end lifting mechanism for the head end, a foot end lifting mechanism for the foot end, and a driver coupled to the head end lifting mechanism and the foot end lifting mechanism. The driver includes a rotatable drive screw, a bracket coupled to the drive screw for movement along the drive screw, and a line, such as a chain or a cable, coupled to the bracket for movement therewith. Each lifting mechanism comprises idlers in the form of sprockets or pulleys, for example. The line extends past the idlers to couple to an elevator of each lifting mechanism. A bias member, such as a spring, is coupled to one of the idlers to take up slack in the chain during raising or lowering or tilting of the support surface between trendelenberg and reverse-trendelenberg positions. 
     A caregiver can raise the head end while the foot end remains lowered by causing the bracket to move away from the head end lifting mechanism. Similarly, a caregiver can raise the foot end while the foot end remains lowered by causing the bracket to move away from the foot end lifting mechanism. 
     In yet another embodiment, the infant support has a support surface, opposing first and second elevators, a driver and first and second drive plate mechanisms. The opposing first and second elevators are movable between raised and lowered positions. The driver is coupled to the support for movement in first and second directions. The first and second drive plate mechanisms are each coupled to the driver. The first drive plate mechanism is configured to move the first elevator to the raised position when the driver is moved in the first direction. The second drive plate mechanism is configured to move the second elevator to the raised position when the driver is moved in the second direction. 
     In yet another embodiment, the infant support has a support surface lifting apparatus for moving an infant between trendelenberg and reverse trendelenberg positions. The apparatus comprises a support surface, a driver, a pivot member and an actuator. The support surface for supporting the infant is movable relative to the incubator. The pivot member comprises a pair of angularly extending arms pivotally attached to the incubator at the vertex of the arms. The pivot member is also movably coupled to the driver such that each of the arms is engageable with the support surface. The actuator is coupled to the driver to move the arms to engage the support surface for moving each end of the support surface between raised, lowered and level positions. 
     Additional features and advantages of the application will become apparent to those skilled in the art upon consideration of the following descriptions. 
    
    
     
       BRIEF DESCRIPTION OF SEVERAL VIEWS OF THE DRAWINGS 
       The invention will be described in conjunction with the following drawings in which like reference numerals designate like elements and wherein: 
         FIG. 1  is a perspective view of a patient support apparatus; 
         FIG. 2  is a side cross-sectional view of the patient support apparatus of  FIG. 1  along the lines A-A of  FIG. 1  showing the lifting apparatus; 
         FIG. 3  is a cross-sectional view of one of the lifting mechanisms taken along the lines B-B of  FIG. 7  with the lifting bar of the lifting mechanism in the lowered position when a bracket coupled to a chain of the lifting apparatus is positioned at a mid-line; 
         FIG. 4   a  is a cross-sectional view of the lifting mechanism of  FIG. 3  showing its lifting bar in the raised position when the bracket is moved away from the lifting mechanism and the mid-line; 
         FIG. 4   b  corresponds to the situation shown in  FIG. 4   a  and is a cross-sectional view of another lifting mechanism taken along the lines C-C of  FIG. 7  showing its spring in a lowermost position to tack up slack in the chain; 
         FIG. 5  corresponds to the situation shown in  FIG. 3  and is a cross-sectional view of the lifting mechanism of  FIG. 4   b  showing its lifting bar in the lowered position when the bracket is positioned at the mid-line; 
         FIG. 6   a  is a cross-sectional view of the lifting mechanism of  FIG. 5  showing its lifting bar in the raised position when the bracket is moved away from the lifting mechanism and the mid-line; 
         FIG. 6   b  corresponds to the situation shown in  FIG. 6   a  and is a cross-sectional view of the lifting mechanism of  FIG. 3  showing its spring in a lowermost position to tack up slack in the chain; 
         FIG. 7  is a perspective view of the lifting apparatus of  FIG. 2 ; 
         FIG. 8  is a side cross-sectional view of the patient support apparatus of  FIG. 1  along the lines A-A of  FIG. 1  showing another embodiment of the lifting apparatus; 
         FIG. 9  is a perspective detail view of the lifting apparatus of  FIG. 8 ; 
         FIG. 10  is a cross-sectional view of one of the lifting mechanisms along the lines F-F of  FIG. 9  with the lifting bar in the lowered position; 
         FIG. 11  is another cross-sectional view of the lifting mechanism along the lines F-F of  FIG. 9  with the lifting bar in the raised position; 
         FIG. 12  is a cross-sectional view of another lifting mechanism along the lines G-G of  FIG. 9  with the lifting bar in the lowered position; 
         FIG. 13  is another cross-sectional view of the other lifting mechanism along the lines G-G of  FIG. 9  with the lifting bar in the raised position; 
         FIGS. 14   a  through  14   p  are several cross-sectional views of the drive and driven plates of the loss drive mechanism along the lines D-D or E-E of  FIG. 8  showing their different positions relative to each other; 
         FIG. 15  is a side cross-sectional view of the patient support apparatus of  FIG. 1  along the lines A-A of  FIG. 1  showing still another embodiment of the lifting apparatus; 
         FIG. 16  is another side cross-sectional view of the patient support apparatus of  FIG. 1  along the lines A-A of  FIG. 1  showing the lifting apparatus of  FIG. 15  with the support surface in a tilted position; and 
         FIG. 17  is a side view of yet another embodiment of the lifting apparatus. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplification set out herein illustrates the embodiment of the application, in several forms, and such exemplification is not to be construed as limiting the scope of the application in any manner. 
     DETAILED DESCRIPTION OF THE INVENTION 
     An infant-support apparatus  2 , such as an infant warming device or incubator, includes a base  4 , a plurality of castors  6  extending downwardly from base  4 , and in infant supporting portion or patient support  7  supported above base  4  as shown in  FIG. 1 . Patient support  7  includes a pedestal  8  coupled to base  4  for vertical movement, a platform tub  10  supported by pedestal  8 , and a support surface  12  positioned above platform tub  10 . Platform tub  10  is formed to include a handle  11  on each side of canopy support arm  14 . Handles  11  can be grasped by a caregiver to maneuver infant-support apparatus  2  during transport. 
     Infant-support apparatus  2  also includes a canopy support arm  14  comprising a telescoping vertical arm  16  and a horizontal overhead arm  18 . A canopy  20  is coupled to overhead arm  18  and is positioned to lie above platform tub  10 . Canopy  20  includes a pair of canopy halves  22  coupled to overhead arm  18  for pivoting movement between a lowered position (as shown) and a raised position (not shown). Up and down buttons (not shown) can be pressed to extend and retract vertical arm  16  of canopy support arm  14 , thereby raising and lowering overhead arm  18  and canopy  20  with respect to tub  10 . 
     A pair of transparent side guard panels  24  and a pair of transparent end guard panels  26  extend upwardly from platform tub  10 , as shown in  FIG. 1 . Side and end guard panels  24 ,  26  cooperate with canopy halves  22  and overhead arm  18  to provide an isolation chamber. Panels  24  include hinges  28  that are also attached to platform tub  10  allowing a caregiver to pivot panels  24  downwardly away from canopy  20  providing increased access to the infant on support surface  12 . End guard panels  26  also include hinges  32  which also pivot downwardly for further access to the infant on support surface  12 . 
     A pair of access ports  34  are provided on side guard panels  24 . Ports  34  are normally closed by access port covers  36 . Access port covers  36  can be removed to allow access to the infant on support surface  12  while isolated in infant-support apparatus  2 . 
     At least one end guard panel  26  is formed to include at least one pass-through grommet  38 . Wires and tubes (not shown) can be routed into the isolation chamber through pass-through grommets  38 . 
     Infant-support apparatus  2  further includes an “up” pedal  40  that is depressed to raise patient support  7  relative to base  4  and a “down” pedal  42  that is depressed to lower patient support  7  relative to base  4 . A crank handle  46  is shown extending from platform tub  10 . By rotating crank handle  46  in a particular direction surface  12  will tilt or reverse tilt (also known as trendelenberg and reverse trendelenberg), as shown by directional arrows  48 ,  50 ,  52 , and  54 . 
     Other features of infant-support apparatus  2  are discussed in detail in U.S. Pat. No. 6,022,310, titled “Canopy Adjustment Mechanisms for Thermal Support Apparatus,” which is incorporated herein by reference. 
     In the illustrated embodiment, lifting apparatus  56 , shown in  FIG. 2 , is positioned in well  58  of tub  10 . Lifting apparatus  56  comprises a pair of lifting mechanism housings  60 ,  62 , a threaded drive shaft  64 , a chain  66 , and a bracket  68 . Lift bars  70 ,  72  extend from lifting mechanism housings  60 ,  62 , respectively, engaging couplings  74 ,  77  to lift support surface  12  in either direction  48  or  52 . As depicted by broken outlines  78 ,  80 , as each lift bar  70 ,  72 , raises in respective direction  84 ,  86 , support surface  12  and mattress  82  will tilt in respective directions  48 ,  52 . 
     Each lift bar  70 ,  72  includes a rounded head bar  88 ,  90 . (See also  FIG. 7 .) Head bars  88 ,  90  engage couplings  74 ,  77 , respectively. Coupling  74  is formed to include an elongated space to allow head  88  to travel in the space when support surface  12  is raised or lowered. As depicted in  FIG. 2 , a comparison of the position of head  88 , while support surface  12  is in the generally horizontal position, with its position in the broken outline  78 , shows the distance bar  88  moves relative to coupling  74  to compensate for the movement of surface  12 . 
     Coupling  77  receives head bar  90 . Coupling  77  is configured similar to a socket within which head bar  90  pivots, as support surface  12  moves upwardly to position  52 , as depicted by broken outline  80 . It is appreciated that, as lift bar  72  moves upwardly, the longitudinal shifting of surface  12  is compensated for by movement of head bar  88  within coupling  74 , as previously discussed. 
     An actuator assembly  92  is positioned adjacent wall  94  of well  58 . Actuator assembly  92  is configured to bi-directionally rotate drive shaft  64 . Gears (not shown) or some other mechanism can be used to translate motion from the actuator assembly  92  to drive shaft  64 . 
     Such power can be a motor, or as shown in  FIGS. 1 and 7  it can be crank handle  46 . When the caregiver turns handle  46  in one direction  98 , for example, drive shaft  64  will be caused to move in one direction. When turning handle  46  in the opposite direction  100 , drive shaft  64  will be caused to move in the opposite direction. In the illustrated embodiment, the first end  102  of drive shaft  64  is disposed through wall  94  and is coupled with actuator assembly  92 . Similarly, second end  104  of drive shaft  64  is disposed through wall  106  of well  58 . Wall  106  can act as the bearing within which end  104  rotates or can act as a bearing mount for such a bearing. 
     As drive screw  64  is rotated, bracket  68  is caused to move selectively in either direction  108  or  110 . In the illustrated embodiment, drive screw  64  includes threads  111  and screw mount portion  112  has an aperture disposed therethrough having corresponding threads (not shown) to mate with threads  111 . Accordingly, as drive shaft rotates in a longitudinally fixed position, the mating threads of drive shaft  64  and screw mount portion  112  move bracket  68  along the length of drive shaft  64 . A space bar  114  is appended to screw mount portion  112  at one end and nut assembly  116  at the other end. Nut assembly  116  is configured to attach to chain  66 . Nuts  118 ,  120  engage chain  66  and fasten to assembly  116 . Therefore, as assembly  68  travels in either direction  108 ,  110 , chain  66  is caused to move therewith. 
     A cross-sectional view of lifting mechanism housing  60  is shown in  FIGS. 3 and 4  depicting lifting bar  70  in the lowered position. A cross-sectional view of lifting mechanism housing  62  is shown in  FIGS. 5 and 6  depicting lifting bar  72  in the lowered position. Housings  60 ,  62  are similar to one another so that like reference numerals refer to like parts and the description of housing  60  applies also to the description of housing  62 , except as otherwise noted. 
     Housing  60  comprises an end wall  120  and an opposed longitudinally extending, spaced-apart beam  122  defining a channel  124  through which bar  70  extends. A flange  126  extends from surface  128  of bar  70  which attaches to a portion of chain  66 . 
     A first sprocket or bearing wheel  130  is positioned on wall  132  of housing  60  between the end  134  of beam  122  and top wall  136 . Chain  66  engages sprocket or bearing wheel and extends around idler sprocket or idler pulley wheel  138  and a second sprocket or bearing wheel  140  near chain opening  142  where chain  66  exist housing  60 . Sprocket or pulley wheel  138  is operatively coupled to spring  144  at end  146  which is attached to wall  132  at attachment  148 . A pin  150  extends through sprocket or pulley wheel  138  and slot  152 . (See also  FIGS. 2 and 7 .) The remainder of the casing of housing  60  includes angled wall  154  adjacent opening  142  and lower wall  156  all extending from wall  132 . Base  158  includes a stepped portion  160  which engages notched portion  162  of bar  70  while in the lowered position, as shown in  FIG. 3 . 
     A first sprocket or bearing wheel  130  is positioned on wall  132  of housing  60  between the end  134  of beam  122  and top wall  136 . Chain  66  engages sprocket or bearing wheel and extends around sprocket or pulley wheel  138  and a second sprocket or bearing wheel  140  near chain opening  142  where chain  66  exits housing  60 . Sprocket or pulley wheel  138  is operatively coupled to spring  144  at end  146  which is attached to wall  132  at attachment  148 . A pin  150  extends through sprocket or pulley wheel  138  and slot  152 . (See also  FIGS. 2 and 7 .) The remainder of the casing of housing  60  includes angled wall  154  adjacent opening  142  and lower wall  156  all extending from wall  132 . Base  158  includes a stepped portion  160  which engages notched portion  162  of bar  70  while in the lowered position, as shown in  FIG. 3 . 
     Housing  60  further includes covers  232  and  234 , as illustrated, for example, in  FIG. 7 . Covers  232 ,  234  are coupled to one another along interface  151 . Cover  232  is formed to include slot  152  and wall  132 . Pin  150  extends through slots  152  which defines the slide path along which the sprocket or pulley wheel  138  moves. 
     Rounded head bars  88 ,  90  are longitudinally extending cylinders, as illustrated, for example, in  FIG. 7 . They mate with couplings  74 ,  77 , as previously discussed. 
     Support surface  12  is level or horizontal in its lowered position when bracket  68  is positioned along amid-line  170 . When bracket  68  is positioned at mid-line  170 , idlers  138  and pins  150  are positioned at their upper most positions, thereby stretching springs  144 , and support surface  12  is positioned in its horizontal lowered position, as illustrated, for example, in  FIGS. 2 ,  3 , and  5 . 
     Bracket  68  moves longitudinally along drive screw  64  in either direction  108  or  110  upon rotation of drive screw  64 . When bracket  68  is positioned between mid-line  170  and housing  62 , lifting arm  70  is elevated while lifting arm  72  is positioned in its lowered position, as illustrated, for example, in  FIGS. 4   a  and  4   b . In this configuration, support surface  12  is tilted in one of the trendelenberg position and the reverse-trendelenberg position. Similarly, when bracket  68  is positioned between mid-line  170  and housing,  60 , lifting arm  72  is elevated while lifting arm  70  is positioned in its lowered position so that support surface  12  is tilted in the other of the trendelenberg position and the reverse-trendelenberg position, as illustrated, for example, in  FIGS. 6   a  and  6   b.    
     Chain  66  moves with bracket  68  to cause lifting arms  70 ,  72  to raise and lower. Movement of bracket  68  away from mid-line  170  toward housing  62  in direction  110  causes chain  66  to move past idlers  130 ,  138 ,  140  of housing  60  to pull upwardly on flange  126  of housing  60  and thereby raise lifting arm  70  to tilt support surface  12 , as illustrated, for example, in  FIG. 4   a . At the same time, slack is produced in the portion of chain  66  positioned in housing  62 . This slack allows spring  144  of housing  62  to pull idler  138  and pin  150  of housing  62  downwardly along slot  152  of housing  62  to take up that slack, as illustrated, for example, in  FIG. 4   b . Lifting arm  70  is lowered by moving bracket  68  back toward mid-line  170  away from housing  62 . 
     Similarly, movement of bracket  68  away from mid-line  170  toward housing  60  in direction  108  causes chain  66  to move past idlers  130 ,  138 ,  140  of housing  62  to pull upwardly on flange  126  of housing  62  and thereby raise lifting arm  72  to tilt support surface  12 , as illustrated, for example, in  FIG. 6   a . At the same time, slack is produced in the portion of chain  66  positioned in housing  60 . This slack allows spring  144  of housing  60  to pull idler  138  and pin  150  of housing  60  downwardly along slot  152  of housing  60  to take up that slack, as illustrated, for example, in  FIG. 6   b . Lifting arm  72  is lowered by moving bracket  68  back toward mid-line  170  away from housing  60 . 
     An advantage of lifting apparatus  56  is that a single actuation means can be used to tilt support surface  12  in either direction  48  or  50 , as illustrated, for example, in  FIG. 2 . Lifting apparatus  56  includes hand crank  46  which is rotatable in directions  98 ,  100 , as illustrated, for example, in  FIG. 7 . A gear box  226  of actuator assembly  92  is operatively coupled to both crank  46  and drive shaft  64 . Gear box  226  translates turning crank  64  in direction  98  or  100  into rotational movement of drive shaft  64  in direction  228  or  230  for movement of bracket  68  in direction  108  or  110 . 
     Another embodiment of the lifting apparatus, indicated by reference numeral  250 , is shown in  FIGS. 8 through 12 . Similar to the previous embodiment, lifting apparatus  250  includes a support surface  12 , lifting mechanism housings  260 ,  262 , and lifting bars  70 ,  72 . Lift bars  70 ,  72  extend from lifting mechanism housings  260 ,  262 , respectively, engaging couplings  74 ,  77 , to lift support surface  12  in either direction  48  or  52 , also similar to the previous embodiment. As depicted by hatched lines  78 ,  80 , in  FIG. 8 , as either of the lift bars raise in directions  84  or  86 , the support surface  12  and mattress  82  will be tilted in directions  48  or  52 . 
     As described in the previous embodiment, each lift bar  70 ,  72 , includes a rounded head for bars  88 ,  90 . (See also  FIG. 9 .) Bars  88 ,  90 , engage couplings  74 ,  77 , respectively. Coupling  74  is formed to include an elongated space to allow bar  88  to travel in the space when support surface  12  is raised or lowered as previously discussed. Opposite coupling  74 , coupling  77  receives bar  90 , also previously discussed in the apparatus  56 . Coupling  77  is configured similar to a socket within which bar  90  pivots as support surface  12  moves upwardly  52 , as depicted by broken lines  80 . It is shown in  FIG. 8  that as lift bar  72  moves upwardly, the increased length at which the support surface moves is compensated for by movement of bar  88  within coupling  74 . 
     Lifting apparatus  250  also comprises a loss-motion drive mechanism  254  that includes a motor  256 , a belt drive system  258 , a first drive shaft  264 , first and second loss-motion drive plate assemblies  266 ,  268 , and second and third drive shafts  270 ,  272 . A base panel  274  is positioned between housing mechanisms  260 ,  262 , to support the loss-motion drive mechanism  254 . Motor  256  is a conventional bi-directional motor attached to bracket  276  which is attached to the lower surface  278  of panel  274 . A drive shaft  280  extends from motor  256  and a first belt spool or wheel  282 . A belt  284  is coupled to first belt spool or wheel  282  and extends through an opening  286  of base panel  274  coupling to a larger second belt spool or wheel  288 , as shown in  FIG. 9 . Accordingly, as motor  256  rotates, first spool or wheel  282  is caused to rotate translating motion to second belt spool or wheel  288  through belt  284 . First drive shaft  264  is caused to rotate in either direction  290 ,  292 , depending on the rotation of motor  256 . To support drive shaft  264  while it is rotating, it is disposed through support blocks  303 ,  304 , that is appended to surface  308  of panel  274 . The first end  294  of drive shaft  264  is coaxially attached to drive plate  296  of second loss-motion drive plate assembly  268 . Second end  300  of drive shaft  264  is coaxially attached to drive plate  302  of the first loss-motion drive plate assembly  266 . Each drive plate  302 ,  296  is engageable with a driven plate  306 ,  308  forming lost-motion assemblies  266 ,  268 . Second and third drive shafts  270 ,  272  attach to driven plates  306 ,  308  at ends  310 ,  312 , respectively. To support shafts  270 ,  272 , they are disposed through support blocks  314 ,  316 , that are appended to surface  308  of panel  274  in similar fashion to support blocks  303 ,  304 , previously discussed. 
     Opposite ends  310 ,  312 , of shafts  270 ,  272 , extend in and are rotationally coupled to housing mechanisms  260 ,  262 , respectively. As shown in  FIGS. 10-13 , housings  160 ,  162 , comprise lifting bar  70 ,  72 , that move between a lowered position, as shown in  FIGS. 10 and 12 , and a raised position shown in  FIGS. 11 and 13 . In the illustrated embodiment, second drive shaft  270  extends through aperture  320  of cover  322  operatively coupling to a first sprocket or wheel  324 . Second drive shaft  270  serves as the axle for sprocket or wheel  324 . (See  FIG. 9 .) Second and third sprockets or wheels  326 ,  328 , are spaced apart and rotationally attached to wall  330 . A belt or chain  332  encircles the three sprockets or wheels  324 ,  326 ,  328 . Moving one of the sprockets or wheels will cause chain  332  to move. Accordingly, as drive shaft  270  causes sprocket or wheel  324  to move or rotate, chain  332  moves in the direction of rotation of sprocket or wheel  324 , indicated by either reference numerals  334 ,  336 . (See, for example,  FIG. 10 .) 
     A link  340  is attached to both chain  332  and lifting bar  70 . As chain  332  moves in a direction  238 , lifting bar  70  is caused to elevate in direction  84 . Elevating bar  70  thereby causes support surface  12  to tilt to position  48 , as depicted by hatched lines  78 . (See  FIG. 8 .) Conversely, as chain  332  moves in direction  342 , as shown in  FIG. 11 , bar  70  lowers in the direction opposite to direction  84 . 
     Third drive shaft  272  extends through an aperture (not specifically shown) of cover  322  of mechanism housing  162  (not specifically shown). Shaft  272  is operatively coupled to a first sprocket or wheel  321 . Shaft  272  serves as the axle for sprocket or wheel  321 , as previously described with housing mechanism  260 . (See  FIGS. 12 and 13 .) Second and third sprockets or wheels  325 ,  329  are spaced apart and rotationally attached to wall  331 . A belt or chain  323  encircles the three sprockets or wheels  321 ,  325 ,  329 . Moving one of the sprockets or wheels causes chain  323  to move. Accordingly, as drive shaft  272  causes sprocket or wheel  321  to rotate, chain  323  moves in the direction of rotation of sprocket or wheel  324 , indicated by either reference numeral  334 ,  336 . 
     A link  341  is attached to both chain  323  and lifting bar  72 . As chain  323  moves in a direction  237 , lifting bar  72  is caused to elevate in direction  86 . Elevating bar  72  thereby causes support surface  12  to tilt to position  52 , as depicted by hatched lines  80 . (See  FIG. 8 .) Conversely, as chain  323  moves in direction  348 , as shown in  FIG. 13 , bar  72  lowers in the direction opposite to direction  86 . 
     Lifting bars  70 ,  72 , move by the selective motion of first and second loss-motion drive plate assemblies  266 ,  268 . Depending on the direction motor  256  is moving, belt drive system  258  translates the rotation to drive shaft  264  rotating shaft  264  in either direction  290  or  292 . As shaft  264  rotates, both drive plates  296 ,  302  rotate. As both drive plates rotate, however, only one will cause a lifting bar to move. The opposed lifting bar will either lower or remain stationary depending on its position relative to the other bar. Each drive plate  296 ,  302 , is a cylindrical body having a tooth  350 ,  351 , extending from an end,  352 ,  353 , respectively. (See  FIGS. 9 and 14 .) Each driven plate  306 ,  308 , is a cup-like structure having an end  312 ,  314 , with a cylindrical wall  354 ,  356  appended thereto, respectively. Each cylindrical wall  354 ,  356  is sized to receive one drive plate  296 ,  302 , as shown in  FIGS. 9 and 14 . Each driven plate end  312 ,  314  also includes a tooth  358 ,  360  that cooperates with tooth  350 ,  351  of the drive plates, respectively, to move second and third drive shafts  270 ,  272 . 
     The progressive cooperation between the two loss-motion drive plate assemblies  266 ,  268  is shown in  FIG. 14 . As previously discussed, the principal of the two loss motion plate assemblies is that as one drive plate moves in one direction, its corresponding driven plate is caused to move, thus, causing the drive shaft to move, thereby moving the chain, and ultimately causing lift bar to raise and tilt the end of the deck. Concurrently, the other drive plate moves as well, yet it does not cause its corresponding driven plate to move, thereby not causing its lift bar to raise. It is appreciated, however, that when the other driven plate moves in an opposite direction its lifting bar is caused to raise while the one drive plate, while it too moves, does not cause its lifting bar to raise. For example, in  FIG. 14   a , drive plate  302  is shown with tooth  350 . When moved in direction  290 ,  FIG. 14   b  shows the interaction between tooth  350  of drive plate  302  and tooth  358  of driven plate  306 . As drive plate  302  rotates in direction  290 , its first surface  362  engages the first surface  364  of tooth  358  of driven plate  306 , causing driven plate  306  to rotate in direction  290 , as shown in  FIGS. 14   c  and  14   d . Continued rotation of mechanism  306 , as shown in  FIGS. 14   e  and  14   f , rotates drive shaft  270 , which, as previously discussed, is extended through first sprocket or wheel  324 , causing sprocket or wheel  324  to rotate. As shown in  FIG. 10 , the rotation of shaft  290  will cause sprocket or wheel  324  to rotate in direction  334 , thereby moving chain in direction  338  and ultimately raising lifting bar  70  in direction  84 . 
     As drive shaft  264  is rotating in direction  290 , so too is drive plate  296 . As shown in  FIG. 14   g , teeth  351  and  360  do not engage to cause third drive shaft  272  to raise lifting bar  72 . Rather, lifting bar  72  either remains at rest or lowers while lifting bar  70  raises in direction  84 . Support surface  12  will thereby be moved to a tilted position  48 . In the illustrated embodiment, as drive plate  296  continues to move in direction  290 , as shown in  FIG. 14   h , tooth  360  may contact tooth  351 , as shown in  FIG. 14   i , but that contact, will not cause lifting bar  72  to raise. Contrarily, the movement causes a slow rate of descent of bar  72 . 
     As drive shaft  264  rotates in opposite direction  292 , so too do both drive plates  296 ,  302 . As shown in  FIG. 14   j , drive plate  296  is shown with tooth  351 . When Moved in direction  292 ,  FIG. 14   k  shows the engagement between tooth  351  of plate  296  and tooth  360  of driven plate  308 . As drive plate  296  rotates in direction  292 , its first surface  368  engages the first surface  370  of tooth  360  of driven plate  308 , causing driven plate  308  to rotate in direction  292 . (See  FIGS. 14   k  and  n .) Continued rotation of mechanism  268  rotates drive shaft  272  which, as previously discussed, is extended through first sprocket or wheel  321 , causing sprocket or wheel  321  to rotate. As shown in  FIG. 12 , the rotation of shaft  272  causes sprocket or wheel  321  to rotate in direction  336 , thereby moving chain in direction  237  and ultimately raise lifting bar  72  in direction  86 . 
     As shown in  FIGS. 14   o  and  p , teeth  350  and  358  do not engage each other as drive shaft  264  rotates in direction  292  to raise bar  70 . Lifting bar  70  either remains at rest or lowers while lifting bar  72  raises in direction  86 . Support surface  12  will thereby be positioned in a tilted position  52 . In the illustrated embodiment, as drive late  296  continues to move in direction  292 , as shown in  FIG. 14   n , tooth  350  of plate  302  may contact tooth  358  of plate  306 , as shown in  FIGS. 14   p  and  14   o , but that contact will not cause lifting bar  70  to raise. Contrarily, the movement causes a slowing of the rate of descent of bar  70 , if surface  12  is previously in the tilted position  48 , or maintains bar  70  in the lowered position. 
     Accordingly, as motor  256  rotates in one direction, one end of support surface  12  will rise. As one loss-motion assembly causes one side to rise the other loss-motion assembly will allow the opposite side of support surface  12  to descend or remain in the lowered position. 
     As shown in  FIG. 9 , panel  274  includes 2 openings  380 ,  381 , through which housing mechanisms extend. Reinforcing brackets  382 ,  384  surround the periphery of  380 ,  381  to secure housing mechanisms to base panel  274 . In the illustrated embodiment, bottom  386  of housing mechanism  260  is attached to a sub flooring  388 , providing rigidity to apparatus  254 . 
     It is appreciated that any bidirectional motor can be used to rotate shaft  264 . It is contemplated that a caregiver, by the use of a single hand motion, actuates the motor (see e.g., motor  256 ) to cause surface  12  to move to tilted position  48 . It is further contemplated that it will require the caregiver only a second hand action to actuate the motor to move surface  12  to either a level position or tilted position  80 . 
     A still further embodiment of the lifting apparatus, indicated by reference numeral  400 , is shown in  FIGS. 15 and 16 . Lifting apparatus  400  includes a support surface  402  upon which a mattress  404  rests, and a pair of support walls  406 ,  408 , defining a cavity  410  within which lifting mechanism  412  is positioned. Support surface  402  is a panel with an underside  411  that is longitudinally extending over a portion of both lateral surfaces  413 ,  414 . Accordingly, when support surface  402  is lowered in a non-tilted position, underside  411  rests upon both surfaces  413 ,  414 , at head and foot ends  416 ,  418 , respectively. 
     Cavity  410  is defined by a base  420  and upwardly extending walls  422 ,  424 . Surfaces  413 ,  414  extend laterally from the uppermost extent of walls  422 ,  424  at corners  426 ,  428 , respectively. Within cavity  410  is positioned lifting mechanism  412 . A triangularly shaped pivot bracket  430  having a pivot aperture  432  is attached to surface  434  of base  420 . Pivotally attached to bracket  430  is a lifting-arm assembly  436 . 
     Lifting-arm assembly  436  comprises perpendicularly oriented first and second arms  438 ,  440 . The vertex  442  of the arms  438 ,  440  includes a pin  444  disposed therethrough and through bracket  430 , thus, allowing arms  438 ,  440  to pivot bracket  430 . A center arm  446  is coupled to vertex  442 . Arm  446  includes a slot  448  longitudinally extending from uppermost portion  450 . A threaded drive shaft  452  extends from wall  422  to wall  424 . A pocket  454  is disposed within wall  422 . Pocket  454  is sized to receive a bearing surface  456 , through which first end  458  of drive shaft  452  extends and within which drive shaft  452  rotates. Opposite first end  458 , second end  460  is coupled to a bi-directional actuator  462 . Drive shaft  452  extends through an aperture  464  allowing rotation within aperture  464 . 
     A bracket  466  having threaded mount portion  468  and a laterally extending pin  470  is disposed on drive shaft  452 . As actuator  462  causes drive shaft  452  to rotate in either direction  472 ,  474 , threaded mount portion  468  moves longitudinally along shaft  452  in directions  476   478 . (Compare  FIGS. 15 , and  16 .) Pin  470  extends through slot  448 . As shown in  FIG. 15 , when shaft  452  is rotated in direction  474 , bracket  466  moves in direction  476 . This movement causes lifting arm assembly  436  to pivot about pin  444  in direction  480 . A hub or wheel  482  is rotatably attached to arm  440  at its uppermost extent. As arm  440  continues to pivot in direction  480 , the engagement between underside  411  of surface  402  and wheel  482  causes surface to lift as depicted by hatched lines of mattress  484 , surface  486  and lifting arm assembly  488 . It is shown in  FIG. 15  that movement of bracket  466  in direction  476  moves pin  470  and, thus, center arm  446  in the same direction to cause this effect. 
     Conversely, as depicted in  FIG. 16 , as shaft  452  is rotated in direction  472 , bracket  466  is caused to move in direction  478  which, in turn, causes pin  470  and center arm  466  to move in direction  478 . The movement of center arm  446  causes assembly  436  to pivot in direction  490 . A hub or wheel  492  is rotatably attached to arm  438  at its uppermost extent, similar to wheel  482 , previously discussed. As arm  438  continues to pivot in direction  490 , the engagement between underside  411  of surface  402  and wheel  492  causes surface  402  to lift, as depicted in  FIG. 16 . 
     It is contemplated that the movement between the tilted positions is accomplished by a switch (not shown) in contact with actuator  462 . In operation, the caregiver using a single motion or action can activate the switch once to move surface  402  to a tilted position, and then a second action to move surface  402  back to a level position or the reverse tilted position. These two motions or actions simplify the caregiver&#39;s task of moving the surface. In addition, it is further contemplated that the switch can be replaced by a single hand crank (not shown) that can be used to move surface  402  between the tilted, level, and reverse tilted positions. 
     A yet further embodiment of the lifting apparatus, indicated by reference numeral  600  is shown in  FIG. 17 . It is contemplated that apparatus  600  is configured to be usable in any of the cavities or below any of the support surfaces described in any of the previous embodiments. Apparatus  600  includes a support surface  602  having an underside  604  with couplings  606 ,  608  similar to couplings  74 ,  77  shown in  FIGS. 2 and 8 , previously described. Elevators  610  and  612  extend upwardly and engage couplings  606 ,  608  at heads  618 ,  620 . It is contemplated that the elevators  610 ,  612  can be attached to racks  622 ,  623  with corresponding gears  625 ,  627 , as shown in  FIG. 17 . 
     In the illustrated embodiment, stepper motors  614 ,  616  are of conventional types that, in response to a signal sent from a controller  624 , move in one direction one unit. For example, controller  624  sending a signal to stepper motor  614  moves elevator  610  upwardly one unit in direction  626  thereby tilting end  628  of surface  602 . Conversely, a signal can be sent to motor  616  to cause elevator  612  to move upward one unit in direction  626  thereby lifting end  630 . It is appreciated that controller  624  can be configured such that, as a signal is sent to raise one of the stepper motors  614 ,  616 , another signal is sent to lower the other stepper motor. 
     A double-throw switch  632  in contact with controller  624  allows a user to determine the desired position of surface  602 . For example, if the user presses first portion  634  of switch  632 , controller  624  will send a signal to stepper motor  614  raising elevator  610  thereby raising and tilting surface  602 . It is appreciated that switch  632  and controller  624  can be configured such that elevator  610  will raise with a single press-and-release of portion  634 . Conversely, switch  632  and controller  624  can be configured such that elevator  610  will raise as portion  634  is pressed-and-held. This type of switch will allow the caregiver to hold portion  634  until surface  602  is raised to a desired level. Releasing portion  634  will stop elevator  610  at that level. 
     In similar fashion, if the user presses second portion  636  of the switch  632 , controller  624  will send a signal to stepper motor  616  raising elevator  612  thereby raising and tilting surface  602 . It is appreciated that controller  624  can be configured such that as either end  628  or  630  raises, the opposite end will lower if previously in the raised position. It is further appreciated that switch  632  and controller  624  can be configured such that elevator  612  will raise with a single press-and-release of portion  634 . Conversely, switch  632  and controller  624  can be configured such that elevator  612  will raise as portion  634  is pressed-and-held. This type of switch will allow the caregiver to hold portion  636  until surface  602  is raised to a desired level. Releasing portion  636  will stop elevator  612  at that level. 
       FIG. 17  shows surface  602  can be raised or lowered from its solid line horizontal position to a raised horizontal (broken line) position or a lowered horizontal (broken line) position. The controller  624  and switch  632  can be configured and operated to raise or lower the surface  602  as well as to tilt the surface  602  between trendelenberg and reverse trendelenberg positions. 
     Although the present application has been described with reference to particular means, materials and embodiments, from the foregoing description, one skilled in the art can easily ascertain the essential characteristics of the present application and various changes and modifications may be made to adapt the various uses and characteristics without departing from the spirit and scope of the present application, as described by the claims which follow.