Abstract:
A patient transfer device includes a base assembly movable in forward and lateral directions. A power train is mounted within the base assembly, and is connected to a clamping and strap assembly. A power and switching system is in electrical communication with the power train. A retractor bar carries one or more clamping devices that are releasably attachable to a sheet. The clamping devices include a clamp handle pivotally connected to a clamp base and a clamp arm eccentrically pivotally connected to the clamp handle. The clamping and strap assembly is supported on the base assembly by a vertical adjustment assembly that includes a positioning mechanism for releasably locking the clamping and strap assembly at one of a plurality of vertical positions. An attendant can stand on the base assembly to act as a counterbalance to a patient&#39;s weight.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
   This application claims the benefit of U.S. Provisional Application Ser. No. 60/623,950, filed Nov. 1, 2004. 

   FIELD OF THE INVENTION 
   The invention relates to a patient transfer device, specifically a device for transferring a patient from one patient support apparatus to another. In one of its aspects, the invention relates to a patient transfer device for shifting a patient position on a patient support apparatus. 
   BACKGROUND OF THE INVENTION 
   Patient transfer devices configured to move a patient from one hospital bed to another, or to a transport gurney, are generally known. 
   It would be advantageous to provide a patient transfer device that is portable, does not require attachment to a patient support apparatus, and that is configured to readily convey a patient without the provision of specially configured sheets. 
   SUMMARY OF THE INVENTION 
   A patient transfer device for pull-up, rollover and transfer of a patient disposed on a sheet comprises a base assembly including one or more wheels for movement of the caddy and one or more wheels for lateral positioning of the caddy, the wheels for lateral positioning of the caddy being operably independent of and mutually exclusive of the wheels for movement of the caddy, a power train mounted within the base assembly, and a clamping and strap assembly including one or more straps attachable to the power train. A retractor bar is attachable to the one or more straps and one or more clamping devices are pivotally attached to the retractor bar and releasably attachable to the sheet. The clamping device includes a clamp handle pivotally connected to a clamp base and a clamp arm eccentrically pivotally connected to the clamp handle. The clamping device is pivotal between a clamping position and a non-clamping position. The clamp arm includes a bight portion for engaging a clamping face of the clamping base and a pair of arm portions for pivotally connecting to the clamp handle. A power and switching system is in electrical communication with the power train. 
   A vertical adjustment assembly is operably adjoined between the base assembly and the clamping and strap assembly for adjusting the vertical position of the clamping and strap assembly. The vertical adjustment assembly includes a pair of upstanding rails and a pair of upstanding sleeves slidably receiving the rails, the rails including a plurality of spaced indentations defining a plurality of vertical positions of the clamping and strap assembly. At least one of the sleeves includes a positioning mechanism for releasably locking the clamping and strap assembly at one of the plurality of vertical positions. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The purposes of the invention will be apparent to persons acquainted with apparatus of this general type upon reading the following specification and inspecting the accompanying drawings, in which: 
       FIG. 1  is a perspective view of a patient transfer device according to the invention; 
       FIG. 2  is a bottom perspective view of a base assembly of the patient transfer device of  FIG. 1 ; 
       FIG. 3A  is a side view of the base assembly of  FIG. 2  in a horizontal position; 
       FIG. 3B  is an enlarged detail view according to  FIG. 3A ; 
       FIG. 4A  is a side view of the patient transfer device of  FIGS. 1 through 3 ; 
       FIG. 4B  is an enlarged detail view according to  FIG. 4A ; 
       FIG. 5  is a side view of the patient transfer device of  FIGS. 1 through 4  with a lock lever in a locked position; 
       FIG. 6  is a side view of the patient transfer device of  FIGS. 1 to 4  with a lock lever in the unlocked position; 
       FIG. 7  is a perspective view of the patient transfer device of  FIGS. 1 through 6  with a rail assembly in the extended position; 
       FIG. 8  is an enlarged detail view according to  FIG. 7 ; 
       FIG. 9  is a reverse perspective view of the patient transfer device of  FIGS. 1 through 8 ; 
       FIG. 10  is a perspective view of the patient transfer device of  FIGS. 1 through 9  with the stand off tubes extended; 
       FIG. 11  is a front view of the patient transfer device of  FIGS. 1 through 10  with the sheet clamping assemblies extended; 
       FIG. 12  is a front view of the patient transfer device of  FIGS. 1 through 11  with the sheet clamping assemblies in the stowed position; 
       FIG. 13  is a perspective view of the patient transfer device of  FIGS. 1 through 12 ; 
       FIG. 14  is an enlarged view of a sheet clamping assembly of the patient transfer device of  FIGS. 1 through 13 ; 
       FIG. 15  is a bottom perspective view of the sheet clamping assembly of  FIG. 14 ; 
       FIG. 16  is an exploded perspective view of the sheet clamping assembly of  FIGS. 14 and 15 ; 
       FIG. 17  is a partial cutaway perspective view of the sheet clamping assembly of  FIGS. 14 through 16 ; 
       FIG. 18  is a perspective view of a sheet clamping assembly according to  FIGS. 1 through 17 ; 
       FIG. 19  is an enlarged detail view of a pivot assembly according to  FIGS. 1 through 18 ; 
       FIG. 20  is an enlarged perspective view of a pivot assembly according to  FIG. 19  in a disengaging condition; 
       FIG. 21  is a side view of a sheet clamping assembly according to  FIGS. 1 through 20 ; 
       FIG. 22  is a side view of the sheet clamping assembly according to  FIG. 21  in a disengaged condition; 
       FIG. 23  is a side view of the sheet clamping assembly of  FIGS. 21-22  in an open position; 
       FIG. 24  is a perspective view of the sheet clamping assembly according to  FIG. 22 ; 
       FIG. 25  is a perspective view of the clamping assembly according to  FIG. 23 ; 
       FIG. 26  is a side view of the clamping assembly according to  FIGS. 21 through 25  in an open position with a sheet inserted in the clamping assembly; 
       FIG. 27  is a side view of the sheet clamping assembly according to  FIGS. 21 through 26  with a sheet inserted in the clamping assembly in a partially closed condition; 
       FIG. 28  is the sheet clamping assembly according to  FIGS. 21 through 27  with a sheet inserted in the clamping assembly and in a closed condition; 
       FIG. 29  is a side view of the sheet clamping assembly according to  FIGS. 21 through 28  with an alternative sheet inserted in the clamping assembly; 
       FIG. 30  is a perspective view of the patient transfer device of  FIGS. 1 through 29  with the retractor assembly in an extended position; 
       FIG. 31  is a perspective view of the patient transfer device according to  FIG. 30 ; 
       FIG. 32A  is a perspective view of the patient transfer device of  FIGS. 30 and 31  with the retractor assembly in the retracted position; 
       FIG. 32B  is an enlarged detail view according to  FIG. 32A ; 
       FIG. 33  is a perspective view of the patient transfer device according to a further embodiment of the invention; 
       FIG. 34  is a perspective view of a cable assembly housing for the further embodiment of  FIG. 33 ; 
       FIG. 35  is a partial cutaway perspective view of the cable housing of  FIG. 34 ; 
       FIG. 36  is a side view of the patient transfer device in a use position adjacent a patient bed and receiving bed; 
       FIG. 37  is a side view of the patient transfer device adjacent the patient bed and receiving bed with the sheet clamping assembly extended; 
       FIG. 38  is a perspective view according to  FIG. 37 ; 
       FIG. 39  is a side view according to  FIG. 37  with the sheet clamping assembly in the open position; 
       FIG. 40  is a side view according to  FIGS. 37 through 39  with the sheet clamping assembly closed; 
       FIG. 41  is a side view of the patient transfer device according to  FIGS. 36 through 40  with an attendant preparing to move a patient; 
       FIG. 42  is a side view of the patient transfer device according to  FIGS. 36 through 41  in a retracting condition; 
       FIG. 43  is a side view of the patient transfer device according to  FIGS. 36 through 42  with standoff tubes extended; 
       FIG. 44  is a perspective view of a patient transfer device according to  FIGS. 1 through 43  being positioned adjacent a head end of a patient bed; 
       FIG. 45  is a side view of the patient transfer device of  FIGS. 1 through 44  adjacent the head end of a patient bed; 
       FIG. 46  is a side view of the patient transfer device of  FIGS. 1 through 45  between a patient bed and an adjacent wall; 
       FIG. 47  is a side view of the patient transfer device of  FIG. 46  with the retractor assembly extended; 
       FIGS. 48  is a perspective view according to  FIG. 47 ; 
       FIG. 49  is a plan view of the patient transfer device of  FIGS. 44 through 47  with the retractor assembly extended to a patient on a patient bed; and 
       FIG. 50  is a side view of the patient transfer device of  FIGS. 44 through 48  in the retracting condition. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “up”, “down”, “right” and “left” will designate directions in the drawings to which reference is made. The words “in” and “out” will refer to directions toward and away from, respectively, the geometric center of the device and designated parts thereof. Such terminology will include derivatives and words of similar import. 
   Referring to  FIG. 1 , a patient transfer device  10  according to the invention is illustrated. The patient transfer device  10  comprises a base assembly  15 , a rail assembly  20 , and a retractor assembly  25 . 
   The base assembly  15  comprises a base housing  30  supported on a base deck  35 . The base assembly further comprises transport wheels  40  and lateral positioning wheels  45 . The base deck  35  includes a pair of extending toes  50  under which are mounted a pair of anti-slip rubber toenails  55 . 
   The rail assembly  20  includes a pair of vertical rail sleeves  60  received on a pair of vertical rails  65  connected to the base housing  30 . Each vertical rail sleeve  60  includes a resilient bumper strip  67  on a front face  70  thereof. A standoff assembly comprises a pair of standoff tubes  75 ,  80  pivotally mounted to an inner face  85 ,  90  of the vertical rail sleeves  60 . A sill  95 ,  100  is provided at an upper end of each vertical rail sleeve  60  for supporting the retractor assembly  25 . Adjacent to each sill  95 ,  100 , a retractor strap aperture  105 ,  110  (see  FIG. 30 ) and an associated safety shut off switch  115 ,  120  are provided. The upper ends of the vertical rail sleeves  60  are connected by a handle  125  incorporating a retractor activation switch  130 . A vertical adjustment lock lever  135  is further pivotally connected between the upper ends of the vertical rail sleeves  60 . 
   The retractor assembly  25  includes a retractor bar  140  having a head relief portion  145  and a pair of sheet clamping assemblies  150 ,  155  attached to each end  160 ,  165  by a respective pivot assembly  170 ,  175 . 
   Referring now to  FIG. 2 , the base assembly  15  includes the pair of transport wheels  40 . The transport wheels  40  are rotatably mounted on the base assembly  15  on a fixed axle  180  arranged transversely on the base assembly  15 . The transport wheels  40  are thereby configured to provide fore and aft movement of the patient transfer device  10 . The base assembly  15  is further provided with the lateral positioning wheels  45  mounted to an underside  185  of the base deck  35 . The lateral positioning wheels  45  are each rotatably mounted on one of a plurality of parallel fixed axles  190  arranged on base deck  35  and configured to provide transverse movement of the patient transfer device  10 . It is further contemplated that the lateral positioning wheels  45  can be swivel-mounted to the underside  185  of base deck  35 , thereby being configured to provide positioning movement of the patient transfer device in all directions. 
   Referring now to  FIGS. 3A and 3B , the patient transfer device  10  is shown with the base deck  35  parallel to a floor surface. In the horizontal position of the base deck  35 , the lateral positioning wheels  45  are in contact with the floor surface to enable lateral movement of the patient transfer device  10 . As best seen from  FIG. 3B , the transport wheel  40  is not in contact with the floor surface with the patient transfer device  10  in the horizontal orientation. 
   Referring now to  FIGS. 4A and 4B , the patient transfer device  10  is titled rearwardly, raising the base deck  35  away from the floor surface. As best shown in  FIG. 4B , as the patient transfer device  10  is tilted rearwardly, the transport wheels  40  are configured to contact the floor surface and raise the lateral positioning wheels  45  off of the floor surface to facilitate transport of the patient transfer device  10  on the transport wheels  40 . 
   The base housing  30  encloses a power supply and a motor and gear assembly operably connected to the retractor assembly  25  through the vertical rails  65 . The motor assembly is activated by the retractor activation switch  130  mounted on the handle  125 . 
   Referring to  FIGS. 5 and 6 , the vertical adjustment lock lever  135  is pivotally mounted to the vertical rail sleeves  60 , and is rotatable from a locked position shown in  FIG. 5  to an unlocked position shown in  FIG. 6 . The vertical adjustment lock lever  135  is positioned adjacent the handle  125  and is configured so that an operator grasping the handle  125  will not inadvertently activate the lock lever  135 . However, an operator grasping the handle  125  can reach the lock lever  135  for intentional operation. 
   Referring now to  FIGS. 7-8 , the rail sleeves  60  are slidably mounted on the vertical rails  65 . With the lock lever  135  in the unlocked position, the rail sleeves  60  are released to slide vertically on the vertical rails  65 . As shown in the detail of  FIG. 7B , the vertical rails  65  include a plurality of pockets  200  on a front face  205  of the vertical rail  65 . A ball-ramp locking mechanism (not shown), as is well known in the art, is operably connected to the locking lever  135 , the pockets  200  in the vertical rail  65  being configured to receive a ball bearing of the ball-ramp locking mechanism when the locking lever is released to the locked position. The vertical rail sleeves  60  are thereby configured for locking in one of a plurality of vertical height positions corresponding to the pockets  200  found on the front face  205  of the vertical rails  65 . 
   Referring now to  FIGS. 9-10 , the standoff assembly, comprising the standoff tubes  75 ,  80 , is shown pivotally mounted to the inner faces  85 ,  90  of the vertical rail sleeves  60 . The standoff tubes  75 ,  80  each include a bight portion  210 ,  215 . The standoff tube  75  further includes an upper leg  220  and a lower leg  225 . The standoff tube  80  includes an upper leg  230  and a lower leg  235 . The upper leg  220  of the standoff tube  75  is pivotally mounted to a hinge bracket  240  mounted to the inner face  85  of vertical rail sleeve  60 . The lower arm  225  of the standoff tube  75  is pivotally mounted to a spring-loaded plunger lock mechanism  245  attached to the inner face  85  of the vertical rail sleeve  60 . In like fashion, the upper leg portion  230  of the standoff tube  80  is pivotally mounted to a hinge bracket  250  attached to the inner face  90  of the vertical rail sleeve  60 . The lower leg portion  235  of the standoff tube  80  is further pivotally connected to a spring-loaded plunger lock mechanism  255  mounted on the inner face  90  of the vertical rail sleeve  60 . As shown in  FIG. 10 , a vertical plunger knob  260 ,  265  is configured to be lifted to release the spring-loaded plunger lock mechanism  245 ,  255 , thereby releasing the standoff tubes  75 ,  80  to rotate from their nested position between the vertical rail sleeves  60  to a forwardly extending deployed position. It should be noted that, while the standoff assembly is illustrated as comprising standoff tubes  75 ,  80 , it is further anticipated that the standoff assembly can comprise panels pivotally attached to the vertical rail sleeves  60 . 
   The sheet clamping assemblies  150 ,  155  are pivotally mounted to the retractor bar  140  by the pivot assemblies  170 ,  175 , and are configured to pivot from an operational position shown in  FIG. 11  to a stored position shown in  FIG. 12 . The stored position, wherein the sheet clamping assemblies  150 ,  155  depend from the retractor bar  140 , presents a narrower profile of the patient transfer device  10  than the operational position, for ease in transport and storage. The following description of the sheet clamping assembly  155  and associated pivot assembly  175  are equally applicable to the sheet clamping assembly  150  and the pivot assembly  170 . 
   Referring to  FIGS. 13-16 , the sheet clamping assembly  155  is pivotally mounted to the end  165  of the retractor bar  140  by the pivot assembly  175 . The pivot assembly  175  comprises a pivot arm  270  attached to the end  165  of the retractor bar  140 , a pivot screw  275  with a pivot nut  280 , a pivot base  285 , a rubber bushing  290 , a retainer washer and screw  295 ,  300  and a pivot cap  305 . 
   The pivot arm  270  includes a cylindrical body  310  including a partial circumferential through slot  315  having a detent portion  320 . The cylindrical body  310  terminates in a shoulder  325  surrounding an internally threaded stud  330  extending from the end of the cylindrical body  310 . The pivot base  285  is comprised of a cylindrical sleeve  335  and a tangentially extending flange  340 . The flange  340  includes a hexagonal recess  345  (see  FIG. 15 ) for receiving a head  350  of the pivot screw  275 . The hexagonal recess surrounds an aperture  355  passing through the cylindrical sleeve  335 . The pivot base is thereby configured to receive the pivot screw through the aperture  355  and through the cylindrical sleeve, with the head  350  of the pivot screw  275  received in the recess  345 . The flange  340  further includes a pair of apertures  360 ,  365  for receiving a pair of screws  370 ,  375  adapted to mount the sheet clamping assembly  155  to the pivot base  285 . 
   The pivot cap  305  is a partial cylindrical sleeve adapted for sliding over the cylindrical sleeve  335  of the pivot base  285 , and includes an aperture  380  configured to align with the aperture  355  of the pivot base  285 . 
   The pivot assembly  175  is assembled in the following manner: the cylindrical sleeve  335  of the pivot base  285  is slidably received on the cylindrical body  310  of the pivot arm  270 . The rubber bushing  290  is then slidably received on the stud  330  against the shoulder  325  of the cylindrical body  310 . The rubber bushing is then retained on the stud  330  by the retainer washer and screw  295 ,  300 . The pivot cap  305  is then slid over the cylindrical sleeve  335  of the pivot base  285 , enclosing the rubber bushing  290  and the retainer washer and screw  295 ,  300 , until the aperture  380  aligns with the aperture  355 . The apertures  355 ,  380  are aligned with a portion of the slot  315 , and the pivot screw  275  is inserted through the aperture  355 , through the slots  315  and out through the aperture  380 . The pivot screw  275  is secured in place by the pivot nut  280 . The sheet clamping assembly  155  is secured to the flange  340  of the pivot base  285  by the screws  370 ,  375 . 
   As shown in  FIG. 17 , the cylindrical sleeve  335  of the pivot base  285  is urged by the rubber bushing  290  such that the pivot screw  275  is urged into the detent portion  320  of the slot  315 . With the pivot screw  275  in the detent portion  320  of the slot  315 , the sheet clamping assembly  155  is retained in the operational position of  FIG. 11 . 
   Referring to  FIGS. 18-20 , as a downward force is applied to the sheet clamping assembly  155 , the pivot screw  275  is forced out of the detent portion  320  of the slot  315  against the bias of the rubber bushing  290  acting on cylindrical sleeve  335  of pivot base  285  (see  FIG. 20 ). The sheet clamping assembly  155  can then be lowered to the stored position of  FIG. 12  as the pivot screw  275  traverses the circumferential slot  315 . 
   The sheet clamping assembly  155  is illustrated in greater detail in  FIGS. 21 through 29 . The sheet clamping assembly  155  includes a clamp handle  390 , a compression assembly  395 , a clamp base  400  and a cam guide  405 . The clamp handle  390  includes a grip portion  410  and two depending lever arms  415 . The clamp base  400  includes a base flange  420  and a pair of upstanding side flanges  425 ,  430  having apertures  435 ,  440 . The clamping base  400  further includes a clamping receiver  445  having a concave front face  450 . The receiver  445  is formed of a high durometer rubber material, and is supported by the base flange  420  and side flanges  425 ,  430 . 
   The compression assembly  395  includes a pair of clamping arms  455 ,  460  joined by a clamping carriage  465  carrying a clamping bar  470 . 
   As shown in  FIG. 21 , the clamping bar  470  is received in the concave front face  450  of the receiver  445 , and is in a locked position with the clamp handle  390  rotated forward (or counterclockwise). In order to release the clamping bar  470  from the receiver  445 , the clamping handle  390  is rotated clockwise about a pair of fasteners  475 ,  480  received in the apertures  435 ,  440  of the side flanges  425 ,  430 . The clamping bar  395  is eccentrically pivotally mounted to the lever arms  415  of the clamp handle  390  such that as the clamp handle  390  is rotated clockwise, the compression assembly  395  is displaced forwardly so that the clamping bar  470  disengages the receiver  445  as shown in  FIGS. 22-23 . The compression assembly  395  can then be rotated clockwise in order to clear the front face  450  of the receiver  445  as shown in  FIGS. 24-25 . 
   Referring to  FIGS. 26-29 , a sheet  500  can then be laid over the receiver  445 . The compression assembly  395  is then rotated counterclockwise back over the receiver  445 , and as the clamp handle  390  is rotated counterclockwise, the clamping bar  470  is drawn into the concave front face  450  of the receiver  445  to trap the sheet  500  therebetween.  FIG. 29  illustrates that a sheet  505  that is thicker in cross-section then the sheet  500  can also be retained by the clamping assembly  155  without modification, due to the resilient nature of the receiver  445 . 
   The cam assembly  405  is geometrically configured to cooperate with the clamping arms  455 ,  460  so that the compression assembly  395  rotates counterclockwise with the clamp handle  390  in a one-handed motion. 
   Referring now to  FIG. 30 , the retractor assembly  25  is further shown to comprise a pair of retractor straps  510 ,  515  mounted to the retractor bar  140  by a pair of retractor strap mounts  520 ,  525  respectively. The retractor straps  510 ,  515  extend from the retractor bar  140  and into the retractor strap apertures  105 ,  110  adjacent the safety shut off switches  115 ,  120  on the rail sleeves  60 . The retractor straps  510 ,  515  then pass through the vertical side rails  65  into the base housing  30 , where they are engaged by the motor and gear assembly. At the motor and gear assembly, the retractor straps  510 ,  515  are attached to two spring-loaded recoil drums and an electronic clutch. The electronic clutch allows the straps  510 ,  515  to be withdrawn from the patient transfer device  10  so that the retractor bar  140  can be extended. The spring-loaded recoil drums collect the retractor straps  510 ,  515  without tangling as the retractor bar  140  is returned toward the patient transfer device  10  when it is not under load. When in use, with the retractor assembly  25  extended and attached to a sheet  500  by the sheet clamping assemblies  150 ,  155 , the motor and gear assembly can be activated by the retractor activation switch  130  to draw the straps  510 ,  515  and the retractor bar  140  toward the patient transfer device  10  (see  FIG. 31 ). 
   Referring to  FIGS. 32A and 32B , as the retractor bar  140  reaches the sill  95 ,  100 , the retractor strap mount  525  contacts the safety shut-off switch  120 . The safety shut-off switch  120  activates a safety feature of the motor and gear assembly, wherein the motor is stopped and briefly reversed in order to release any load on the straps  510 ,  515 , and to release any object that might have been trapped as the retractor bar  140  traveled toward the patient transfer device  10 . 
   Now referring to  FIGS. 33-35 , an alternative retractor assembly  535  utilizes a pair of retractor cables  540 ,  545  for connecting the retractor bar  140  to the patient transfer device  10 . Referring to FIGS.  34 - 35  the cable  545  is contained within a housing  550 , and coiled on a drum  555  within the housing  550 , the drum  555  having a helical groove  560 . The drum  555  is rotatably mounted in the housing  550  by a pair of spindles  565 ,  570  extending through lateral walls  575 ,  580  of the housing  550 . The cable  545  exits the housing through an aperture  585  in a tangential fan-shaped portion  590  of the housing  550 . The drum  555  is driven by a bi-directional power source (not shown) configured to extend or retract the cable  545  from the housing  550 . 
   Operation of the Patient Transfer Device 
   The patient transfer device  10  is operated in the following manner. A receiving bed  600  is moved adjacent a patient bed  610 , and the patient transfer device  10  is positioned centered on the side of the receiving bed  600  opposite the patient bed  610 , as shown in  FIGS. 36-37 . The surface of the receiving bed  600  should be lower than that of the patient bed  610 . If not properly centered on the beds  600 ,  610 , the patient transfer device can be moved laterally on the lateral positioning wheels  45  so that it is centered on the receiving bed  600 . 
   The retractor assembly  25  is then extended across the receiving bed  600  to the patient bed  610 . The sheet clamping assemblies  150 ,  155  are attached to the near side of a sheet  500  underneath the patient on the patient bed  610 . 
   Prior to initiating retraction, the attendant places one foot on a foot counterbalance pad  615  formed in the base deck  35  of the patient transfer device  10 . The weight of the attendant aids in counterbalancing the weight of the patient pulling on the upper end of the patient transfer device  10 . 
   The patient transfer device  10  is activated by depressing the retractor activation switch  130  to draw the retractor assembly  25  back toward the patient transfer device  10 . The anti-slip rubber toenails  55  grip the floor surface to prevent sliding of the base assembly  15  outwardly as the patient is drawn to the receiving bed  600 . 
   In some cases, such as where there is an excess amount of sheet between the retractor bar  140  and the patient, or the receiving bed  600  is narrow, the patient transfer device must be held away from the receiving bed  600 . The standoff tubes  75 ,  80  operate to provide additional maneuvering room or retraction room to move the patient on to the receiving bed  600 , as shown in  FIG. 43 . If the attendant discovers the need for additional reach during the patient transfer, the patient transfer device  10  can be stopped and drawn away from the receiving bed  600 , and the standoff tubes  75 ,  80  can be deployed. The attendant can then resume the transfer. 
   In another operating mode, the patient transfer device  10  can be laterally positioned between the bed  600 ,  610  and a wall surface using the lateral positioning wheels  45 . This situation is particularly encountered in a boosting mode, wherein the patient transfer device  10  is used to boost a patient who has slid downwardly on the bed towards the foot of the bed. 
   Referring to  FIGS. 44-49 , the patient transfer device  10  is laterally positioned between a wall and the head of the patient bed  610 . The retractor assembly is extended toward a patient&#39;s head with the patient&#39;s head being received in the head relief portion  145  of the retractor bar  140 . The patient can then be boosted towards the head of the bed. Due to the limited clearance, the attendant cannot exert any force on the foot counter balance pad  615  of the base deck  35 , but a backside of the patient transfer device  10  is forced against the wall behind the patient&#39;s bed and the wall serves as the counterbalance for the anti-slip rubber toenails  55  of the base assembly  15 . The patient bed  610  must be prevented from shifting, such as by application of its wheel brakes, to prevent the action of the patient transfer device  10  from pushing the bed  610  away from the wall. 
   While the invention has been described in the specification and illustrated in the drawings with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment illustrated by the drawings and described in the specification as the best mode presently contemplated for carrying out this invention, but that the invention will include any embodiments falling within the scope of the appended claims.