Patent Publication Number: US-6698041-B2

Title: Patient transfer apparatus

Description:
This application claims the benefit of a U.S. Provisional patent application, Ser. No. 60/193,891, filed on Mar. 31, 2000, and entitled “PATIENT TRANSFER APPARATUS”, and a U.S. Provisional patent Application, Serial No. 60/222,244, filed on Aug. 1, 2000, and also entitled “PATIENT TRANSFER APPARATUS”, both of which being incorporated herein by reference. 
    
    
     BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention generally relates to a patient transfer apparatus, and more particularly relates to a patient transfer apparatus to facilitate transfer of a patient from one support surface, such as a stretcher, to another adjacent support surface, such as a hospital bed or an operating table. 
     Several devices exist for the purpose of transferring less mobile and totally immobile residents or patients from one support surface, such as a stretcher, to another adjacent support surface, such as a hospital bed in a nursing home or a medical facility. One such resident transfer device is disclosed in the U.S. Pat. No. 6,012,183, entitled “Resident Transfer Apparatus”, which is incorporated herein by reference. The therein-disclosed device includes a sheet of material formed as a continuous loop having a low-friction inner surface so that when placed under the resident, two slick surfaces slide against each other reducing the coefficient of friction and making it easier to transfer the resident. The device includes a plurality of spaced-apart handles around the outer surface of the sheet to enable the caregiver to roll the sheet of material over itself toward the second support surface to transfer the resident from the first support surface to the second support surface. 
     Another such device for moving less mobile and totally immobile residents or patients is illustratively disclosed in the U.S. Pat. No. 5,067,189, issued to Weedling et al. and entitled “Air Chamber Type Patient Mover Air Pallet With Multiple Control Features”. The air pallet-type patient mover of Weedling et al. includes a thin flexible bottom sheet for defining an air chamber, with the bottom sheet having pinhole-type perforations through which air escapes under pressure to create an air bearing between the bottom sheet and the underlying support surface to facilitate transfer of patients. 
     According to the present invention, a patient transfer apparatus includes an upper platform, a lower conveyor and an actuator configured to be coupled to the lower conveyor to drive the lower conveyor. The lower conveyor is movable such that movement of the lower conveyor to move the apparatus toward a support on which a patient is resting moves the patient from the support onto the upper platform. 
     In preferred embodiments, a patient transfer apparatus includes an upper conveyor, a lower conveyor, an adjustment mechanism configured to movably support the upper conveyor relative to the lower conveyor, and an actuator configured to be coupled to the lower conveyor to drive the lower conveyor. The upper conveyor is movable to engage the lower conveyor to couple the motion of the lower conveyor to the upper conveyor such that movement of the lower conveyor to move the apparatus toward a first support on which a patient is resting moves the upper conveyor to move the patient onto the upper conveyor. 
     In accordance with another aspect of the illustrative embodiment, a patient transfer apparatus includes an upper conveyor, a lower conveyor, and an adjustment mechanism configured to raise and lower the upper conveyor relative to the lower conveyor between a raised disengaged position in which the upper conveyor is spaced apart from the lower conveyor and a lowered engaged position in which the upper conveyor engages the lower conveyor to couple the motion of the lower conveyor to the upper conveyor such that when the lower conveyor is driven to move under the patient, the upper conveyor is driven to move the patient onto the upper conveyor. 
     According to still another aspect of the illustrative embodiment, an apparatus for transferring a patient from a first support to a second support configured to be positioned alongside the first support includes upper and lower structures to be placed on the second support to extend alongside the patient on the first support. The upper structure includes laterally spaced-apart, elongated upper side members and an endless conveyor web trained about the side members to provide an upper flight and a lower flight. The upper conveyor web is movable about the upper side members to provide a movable support for patient. The lower structure includes laterally spaced-apart, elongated lower side members and an endless conveyor web trained about the lower side members to provide an upper flight and a lower flight. The lower conveyor web is movable about the lower side members to move the apparatus relative to the second support. The upper conveyor web and the lower drive web are configured to be operatively connected such that movement of the lower conveyor web about the lower side members to move the apparatus from the second support to the first support moves the upper conveyor web about the upper side members to move the patient from the first support onto the upper conveyor. 
     In accordance with a further aspect of the illustrative embodiment, a transfer mechanism for moving a patient from a first support to a second support includes an assembly to be placed on the second support between the head and foot ends thereof to be positioned alongside the patient on the first support. The assembly includes an upper conveyor and a lower conveyor and an adjustment mechanism configured to raise and lower the upper conveyor relative to the lower conveyor. Each conveyor includes laterally spaced, longitudinally extending side members and an endless conveyor web trained about the side members. The upper conveyor web is movable to engage the lower conveyor web to couple the motion of the lower conveyor web to the upper conveyor web such that the patient is moved from the first support onto the upper conveyor by the web of the upper conveyor and the assembly is moved from the second support to the first support and under the patient by the web of the lower conveyor. 
     Additional features and advantages of the present invention will become apparent to those skilled in the art upon consideration of the following detailed description of preferred embodiments exemplifying the best mode of carrying out the invention as presently perceived. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The detailed description particularly refers to the accompanying figures in which: 
     FIG. 1 is a perspective view showing a patient located on a first support and a patient transfer apparatus located on a second support positioned alongside the patient on the first support prior to the transfer of the patient from the first support to the second support, 
     FIG. 2 is a perspective view showing the patient transfer apparatus moved to the first support, and under the patient, 
     FIG. 3 is a perspective view showing the patient transfer apparatus with the patient thereon being moved back to the second support; 
     FIG. 4 is a perspective view showing the patient successfully positioned on the second support, 
     FIG. 5 is an exploded perspective view of a first embodiment of the patient transfer apparatus, and showing an upper conveyor assembly, a lower conveyor assembly, a four-bar linkage movably connecting the upper conveyor assembly to the lower conveyor assembly, a lift handle coupled to the four-bar linkage for moving the upper conveyor assembly between a raised disengaged position and a lowered engaged position, a front idler roller assembly coupled to the lower conveyor assembly to facilitate movement of the patient onto the upper conveyor assembly and an actuator configured to be coupled to the lower conveyor assembly to drive the lower conveyor assembly, the upper conveyor assembly including a pair of laterally spaced-apart, elongated upper side rollers, an upper platen assembly extending between the upper side rollers and an endless conveyor web trained about the pair of upper side rollers to provide an upper flight and a lower flight, the lower conveyor assembly also including a pair of laterally spaced-apart, elongated lower side rollers, a lower platen assembly extending between the lower side rollers and an endless drive conveyor web trained about the pair of lower side rollers to provide an upper flight and a lower flight, 
     FIG. 6 is an end view of the patient transfer apparatus of FIG. 5 showing the lift handle moved to a forward position to move the upper conveyor assembly to the lowered engaged position to cause the lower flight of the upper conveyor web to engage the upper flight of the lower drive web, the upper conveyor web being movable about the upper side rollers to provide a movable support for patient, the lower drive web being movable about the lower side rollers to move the apparatus relative to the first and second supports, the upper conveyor assembly being shown located forwardly and downwardly and closer to the front edge of the apparatus, 
     FIG. 7 is an end view similar to FIG. 6, and showing the lift handle moved to a retracted position to lift the upper conveyor assembly to the raised disengaged position to disengage the lower flight of the upper conveyor web from the upper flight of the lower drive web, and further showing the upper conveyor assembly located rearwardly from the lower conveyor assembly past its over-the-center position against a stop bar to hold the upper conveyor assembly in place, 
     FIG. 8 is a partial sectional side view corresponding to FIG. 6 of the patient transfer apparatus, with the lower flight of the upper conveyor web shown in engagement with the upper flight of the lower drive web to transmit the motion of the lower drive web to the upper conveyor web, 
     FIG. 9 is a partial sectional side view corresponding to FIG. 7 of the patient transfer apparatus, showing the upper conveyor assembly in the raised disengaged position with the lower flight of the upper conveyor web spaced apart from the upper flight of the lower drive web, 
     FIG. 10 is a sectional end view of the upper platen assembly positioned between the laterally spaced upper side rollers, 
     FIGS. 11 and 12 are partial sectional side views showing construction of the upper platen assembly, 
     FIG. 13 is a sectional end view similar to FIG. 10 of the lower platen assembly positioned between the lower side rollers, the lower platen assembly being generally a mirror image of the upper platen assembly, 
     FIGS. 14 and 15 are partial sectional side views similar to FIGS. 11 and 12, showing construction of the lower platen assembly, 
     FIG. 16 is a partially broken away and partially exploded perspective view of a second embodiment of the patient transfer apparatus similar to the first embodiment shown in FIGS. 1-15, the FIG. 16 patient transfer apparatus including an upper conveyor assembly, a lower conveyor assembly, a four-bar linkage movably connecting the upper conveyor assembly to the lower conveyor assembly, a lift handle coupled to the four-bar linkage for moving the upper conveyor assembly between a raised disengaged position and a lowered engaged position, a front idler roller assembly coupled to the lower conveyor assembly to facilitate movement of the patient onto the upper conveyor assembly and an actuator configured to be coupled to the lower conveyor assembly to drive the lower conveyor assembly, the upper conveyor assembly including a pair of laterally spaced-apart, elongated upper side rollers, an upper platen assembly extending between the upper side rollers and an endless conveyor web trained about the pair of upper side rollers, the lower conveyor assembly including a plurality of laterally spaced-apart, elongated rollers and an endless drive web trained about the plurality of rollers, 
     FIG. 17 is a sectional view along line  17 — 17  in FIG. 16, diagrammatically showing the construction of a roller clutch-type actuator configured to be coupled to the drive roller of the lower conveyor assembly of FIG. 16, 
     FIG. 18 is a partially broken away and partially exploded perspective view of a third embodiment of the patient transfer apparatus similar to the first and second embodiments shown in FIGS. 1-15 and  16 - 17  respectively, the FIG. 18 patient transfer apparatus including an upper conveyor assembly, a lower conveyor assembly, a four-bar linkage movably connecting the upper conveyor assembly to the lower conveyor assembly, a lift handle coupled to the four-bar linkage for moving the upper conveyor assembly between a raised disengaged position when the lift handle is moved to a retracted position and a lowered engaged position when the lift handle is moved to a forward position, an actuator configured to be coupled to the lower conveyor assembly to drive the lower conveyor assembly and a pair of brake pads coupled to the lift handle and configured to engage the upper conveyor assembly when the lift handle is moved to the retracted position, the upper and lower conveyor assemblies each including a pair of longitudinally spaced-apart, laterally-extending end rails, a plurality of laterally spaced-apart elongated rollers extending between the end rails, a pair of laterally spaced-apart elongated spacer rods extending between the end rails and positioned inside the second front and the second last rollers, and an endless conveyor web trained about the plurality of rollers to provide an upper flight and a lower flight, the brake pads being configured to engage the upper conveyor web when the lift handle is retracted to lock the upper conveyor web in place, 
     FIG. 19 is an end view of the patient transfer apparatus of FIG. 18 similar to FIG. 6, and showing the lift handle moved to a forward position to move the upper conveyor assembly to the lowered engaged position to cause the lower flight of the upper conveyor web to engage the upper flight of the lower drive conveyor web, the upper conveyor web being movable about the upper rollers to provide a movable support for patient, the lower drive conveyor web being movable about the lower rollers to move the apparatus relative to the first and second supports, the upper conveyor assembly being shown located forwardly and downwardly and closer to the front edge of the patient transfer apparatus, 
     FIG. 20 is an end view similar to FIG. 19, and showing the lift handle moved to a retracted position to lift the upper conveyor assembly to the raised disengaged position to disengage the lower flight of the upper conveyor web from the upper flight of the lower drive conveyor web, and showing the upper conveyor assembly located rearwardly and upwardly from the lower conveyor assembly and resting against a stop bar, and further showing the brake pads pressed against the upper conveyor web to lock it in place, 
     FIG. 21 is a sectional end view of the upper conveyor assembly showing an end rail adjacent to the head end of the patient transfer apparatus, a plurality of laterally spaced-apart elongated rollers, a pair of laterally spaced-apart elongated spacer bars mounted inside the second front and second last rollers, and an endless conveyor web trained about the plurality of rollers to provide an upper flight and a lower flight, 
     FIG. 22 is a sectional end view similar to FIG. 21 of the lower conveyor assembly, and showing an end rail adjacent to the head end of the patient transfer apparatus, a plurality of laterally spaced-apart elongated rollers, a pair of laterally spaced-apart elongated spacer bars mounted inside the second front and second last rollers, and an endless conveyor web trained about the plurality of rollers to provide an upper flight and a lower flight, and further showing the lower conveyor web looped around the second last roller located next to the rear drive roller to increase the wrap of the lower conveyor web around the rear drive roller, 
     FIG. 23 is a partial sectional end view showing the head end of the upper front roller rotatably coupled to the upper end rail near the head end of the patient transfer apparatus by a flanged radial bearing, the attachment of the foot end of the upper front roller to the upper end rail near the foot end of the patient transfer apparatus being similar, 
     FIG. 24 is a partial sectional end view similar to FIG. 23, and showing the attachment of the head end of the upper second front roller and the enclosed spacer rod to the upper end rail near the head end of the patient transfer apparatus, and showing the head end of the upper second front roller rotatably coupled to the upper end rail near the head end of the patient transfer apparatus by a flanged radial bearing, the attachment of the foot end of the upper second front roller and the enclosed spacer rod to the upper end rail near the foot end of the patient transfer apparatus being similar, 
     FIG. 25 is a partial sectional end view similar to FIGS. 23 and 24, and showing the head end of the upper third front roller rotatably coupled to the upper end rail near the head end of the patient transfer apparatus by a flanged radial bearing, the attachment of the foot end of the upper third front roller to the upper end rail near the foot end of the patient transfer apparatus being similar, 
     FIG. 26 is a partial sectional end view similar to FIGS. 23-25, and showing the attachment of the rear drive roller of the lower conveyor assembly to the lower end rails, and showing the head end of the rear drive roller rotatably coupled to the lower end rail near the head end of the patient transfer apparatus by a flanged radial bearing, and further showing the foot end of the rear drive roller coupled to a drive shaft extending through the end rail near the foot end of the patient transfer apparatus and supported by a needle bearing, the free end of the drive shaft carrying a roller clutch configured to be coupled to the actuator for driving the rear drive roller, 
     FIG. 27 is a perspective view showing the actuator coupled to the roller clutch mounted on the drive shaft for driving the rear drive roller of the lower conveyor assembly, 
     FIG. 28 is a partially broken away perspective view showing the upper and lower end rails adjacent to the head end of the patient transfer apparatus and a link having its ends pivotally coupled to the upper and lower end rails near the front side thereof, and further showing the upper and lower end rails having cutouts forming a protective enclosure for the link, 
     FIG. 29 is a perspective view showing the upper conveyor web trained about the upper rear roller, the lower conveyor web trained about the lower drive roller, the lift handle of the four-bar linkage moved to the forward position, and the brake pad coupled to the lift handle spaced apart from the upper conveyor web, 
     FIG. 30 is a perspective view similar to FIG. 29, and showing the lift handle of the four-bar linkage moved to the retracted position, and the brake pad pressed against the upper conveyor web to lock it in place, 
     FIG. 31 is a sectional view showing the attachment of the brake pad to the lift handle, and 
     FIG. 32 is a perspective view showing the upper conveyor web trained about the upper rear roller, and the lift handle moved to the retracted position and resting against a stop pin coupled to the upper end rail near the head end and adjacent to the rear side of the patient transfer apparatus. 
    
    
     DETAILED DESCRIPTION OF THE DRAWINGS 
     FIGS. 1-15 show a first embodiment  20  of the patient transfer apparatus to assist in the transfer of a patient “P” from a first patient support  21 , such as a stretcher, to a second patient support  23 , such as a hospital bed, or an operating table. As shown in FIG. 5, the patient transfer apparatus  20  includes an upper conveyor assembly  22 , a lower conveyor assembly  24 , a four-bar linkage adjustment mechanism  26  movably connecting the upper conveyor assembly  22  to the lower conveyor assembly  24 , a lift handle  28  coupled to the four-bar linkage  26  for moving the upper conveyor assembly  22  between a lowered engaged position shown in FIGS. 1,  2  and  6  where the upper patient conveyor web  150  engages the lower drive conveyor web  250  to couple the motion of the lower conveyor web  250  to the upper conveyor web  150  and a raised disengaged position shown in FIGS. 3,  4  and  7  where the upper conveyor web  150  is spaced from the lower conveyor web  250 , a drive shaft  30  configured to be coupled to a driver actuator  300  to drive the lower conveyor assembly  24 , and a front idler roller assembly  32  located adjacent to the front edge of the apparatus  20  to facilitate movement of the patient onto the upper conveyor assembly  22 . As used in this description, the terms “upper” and “top” are used interchangeably, and the terms “lower” and “bottom” are used interchangeably. 
     The patient transfer apparatus  20  is generally rectangular in configuration having a length dimension  50  and a width dimension  52 . The patient transfer apparatus  20  is dimensioned to comfortably support a patient during the transfer of the patient to and from a patient support—such as a hospital bed. Illustratively, the length dimension  50  of the patient transfer apparatus  20  is about 30 inches (76 centimeters), and the width dimension  52  is about 14 inches (36 centimeters). The height of the patient transfer apparatus  20  is about 2½ inches ( 6 centimeters). The height of the patient transfer apparatus  20  including the lift handle 28 is about 9 inches (23 centimeters). 
     As shown in FIGS. 5-7, the patient transfer apparatus  20  includes an elongated front side  42 , an elongated rear side  44 , a first head end  46  and a second foot end  48 . As used in this description, the phrase “front side  42 ” will be used to denote the side of any referred-to object that is positioned to lie nearest the front side  42  of the patient transfer apparatus  20 , and the phrase “rear side  44 ” will be used to denote the side of any referred-to object that is positioned to lie nearest the rear side  44  of the patient transfer apparatus  20 . Likewise, the phrase “first end  46 ” will be used to denote the end of any referred-to object that is positioned to lie nearest the first end  46  of the patient transfer apparatus  20 , and the phrase “second end  48 ” will be used to denote the end of any referred-to object that is positioned to lie nearest the second end  48  of the patient transfer apparatus  20 . 
     The upper conveyor assembly  22  includes a pair of laterally spaced-apart, longitudinally-extending idler side member rollers  102 ,  104 , each having its opposite ends rotatably coupled to a pair of longitudinally spaced-apart, laterally-extending end rails  106 ,  108 . Flanged radial bearings  110  at opposite ends of the end rails  106 ,  108  rotatably support the idler rollers  102 ,  104 . Although flanged radial bearings  110  are used for rotatably supporting the idler rollers  102 ,  104  in the illustrated embodiment, it is within the scope of the invention as presently perceived to use any suitable means, such as ball bearings, bushings, and so on, for rotatably supporting the guide rollers  102 ,  104 . Also, it is within the scope of the invention as presently perceived to replace the pair of rotatably-mounted idler rollers  102 ,  104  with a pair of nonrotatably-mounted cylindrical members of appropriate low friction material, each cylinder having its opposite ends fixed to the respective end of the laterally-extending end rails  106 ,  108 . Alternatively, it is within the scope of the invention as presently perceived to replace one of the rotatably-mounted idler rollers  102 ,  104  with such a cylinder. 
     As shown in FIGS. 5 and 10, a platen support structure assembly  120  is received in the space  118  between the idler rollers  102 ,  104 . The platen assembly  120  includes a generally rectangular top plate or panel  122 . A pair of longitudinally-extending bars or supports  132 ,  134  are secured to the underside of the panel  122  along opposite sides  42 ,  44  thereof by a plurality of screws  124 . As shown in FIGS. 5,  11  and  12 , the end rails  106 ,  108  are each provided with laterally-extending blocks  136 ,  138  which are received in the space  140  formed between the longitudinally-extending supports  132 ,  134  of the platen assembly  120  at the respective opposite ends  46 ,  48  thereof. The blocks  136 ,  138  are secured to the underside of the top panel  122  along opposite ends  46 ,  48  thereof by a plurality of screws  126 . The longitudinally-extending supports  132 ,  134  and the laterally-extending blocks  136 ,  138  form a picture frame-like structure for supporting the rectangular top panel  122 . The outer side edges  142 ,  144  of the platen assembly  120  are adjacent to the respective longitudinally-extending idler rollers  102 ,  104 , but are spaced therefrom so as not to interfere with rotation of the idler rollers  102 ,  104 . An endless upper conveyor web  150  is trained about the front and rear idler rollers  102 ,  104  to provide an upper run or flight  150 ′ and a lower run or flight  150  ″ as shown in FIGS. 5-9. 
     The lower conveyor assembly  24  is generally a mirror image of the upper conveyor assembly  22 . Referring to FIGS. 5-7, the lower conveyor assembly  24  includes a longitudinally-extending idler roller  202  and a laterally spaced-apart, longitudinally-extending drive roller  204 . The opposite ends of the longitudinally-extending rollers  202 ,  204  are rotatably coupled to a pair of longitudinally spaced-apart, laterally-extending end rails  206 ,  208 . Flanged roller bearings  210  at opposite ends of the end rails  206 ,  208  rotatably support the guide rollers  202 ,  204 . Although flanged radial bearings  210  are used for rotatably supporting the rollers  202 ,  204  in the particular embodiment described herein, it is within the scope of the invention as presently perceived to use any suitable means, such as ball bearings, bushings and so on, for rotatably supporting the guide rollers  202 ,  204 . Also, it is within the scope of the invention as presently perceived to replace the rotatably-mounted idler roller  202  located adjacent to the front side  42  of the patient transfer apparatus  20  with a nonrotatably-mounted cylinder of, for example, appropriate low friction material. 
     As shown in FIGS. 5 and 13, a platen assembly  220  is received in the space  218  between the guide rollers  202 ,  204 . The platen assembly  220  includes a generally rectangular bottom plate or panel  222 . A pair of longitudinally-extending bars or supports  232 ,  234  are secured to the topside of the bottom panel  222  along opposite sides  42 ,  44  thereof by a plurality of screws  224 . As shown in FIGS. 5,  14  and  15 , the end rails  206 ,  208  are each fitted with laterally-extending blocks  236 ,  238  which are received in the space  240  formed between the longitudinally-extending supports  232 ,  234  of the platen assembly  220 . The blocks  236 ,  238  are secured to the topside of the bottom panel  122  along opposite ends  46 ,  48  thereof by a plurality of screws  226 . The longitudinally-extending supports  232 ,  234  and the laterally-extending blocks  236 ,  238  form a picture frame-like structure for supporting the rectangular bottom panel  222 . The outer side edges  242 ,  244  of the platen assembly  220  are adjacent to the respective longitudinally-extending guide rollers  202 ,  204 , but are spaced therefrom so as not to interfere with rotation of the rollers  202 ,  204 . 
     As shown in FIGS. 5-9, an endless conveyor web  250  is trained about the front idler roller  202  and the rear drive roller  204  to provide an upper run or flight  250 ′and a lower run or flight  250 ″. An actuator  300  is configured to be coupled to the rear drive roller  204  near the foot end  48  of the patient transfer apparatus  20  to drive the lower conveyor  250 . As shown in FIGS. 8 and 9, the rear drive roller  204  includes a drive shaft  30  extending through the lower end rail  208  adjacent to the foot end  48  of the patient transfer apparatus  20 . The drive shaft  30  has a hexagonal head portion  36  to facilitate the use of a mechanical socket wrench (or a lever with a ratchet mechanism) to turn the rear drive roller  204  to, in turn, drive the lower conveyor web  250 . The rear drive roller  204  may be bead blasted or overcoated with suitable material to give its outer surface a textured finish to enhance its grip on the lower conveyor web  250 . Likewise, other rollers  102 ,  104 ,  202  may be bead blasted or overcoated with a suitable coating to give their outer surfaces a textured finish. 
     Although a mechanical device such as a socket wrench or a lever is used in the illustrated embodiment for driving the lower conveyor web  250 , it will however be appreciated that other types of actuators may well be used to drive the conveyor web  250  without exceeding the scope of the invention as presently perceived. Various types of mechanical, electromechanical, hydraulic, and pneumatic actuators or drives may be used to drive the rear drive roller  204 . As a result, the term “actuator” in the specification and in the claims is intended to cover all types of mechanical, electromechanical, hydraulic, and pneumatic drives, including manual cranking mechanisms of all types and including combinations of the above elements for rotating the rear drive roller  204 . 
     As shown in FIGS. 5-7, the four-bar linkage  26  movably connects the upper conveyor assembly  22  to the lower conveyor assembly  24 . The lift handle  28  is coupled to the four-bar linkage  26  for moving the upper conveyor assembly  22  between a raised disengaged position shown in FIGS. 7,  9  and a lowered engaged position shown in FIGS. 6,  8 . The four bar linkage  26  includes a pair of swing arms or links  306 ,  308  adjacent to the front side  42  of the patient transfer apparatus  20 . The links  306 ,  308  have their respective ends  306 ′,  306 ″ and  308 ′,  308 ″ pivotally coupled to the upper and lower conveyor assemblies  22 ,  24 . The top end  306 ′ of the first link  306  is pivotally coupled to the top end rail  106  adjacent to the head end  46  by a pivot pin  316 ′. The bottom end  306 ″ of the first link  306  is pivotally coupled to the bottom end rail  206  by a pivot pin  316 ″. Likewise, the top end  308 ′ of the second link  308  is pivotally coupled to the top end rail  108  adjacent to the foot end  48  by a pivot pin  318 ′. The bottom end  308 ″ of the second link  308  is pivotally coupled to the bottom end rail  208  adjacent to the foot end  48  by a pivot pin  318 ″. The links  306 ,  308  are mounted on the inside of the top and bottom end rails  106 ,  206  and  108 ,  208  adjacent to the front side  42  of the patient transfer apparatus  20 . The top and bottom blocks  136 ,  236  adjacent to the first end  46  of the patient transfer apparatus  20  are provided with respective cutouts  326 ′,  326 ″ to accommodate swinging motion of the first link  306 . Similarly, the top and bottom blocks  138 ,  238  adjacent to the second end  48  of the patient transfer apparatus  20  are provided with respective cutouts  328 ′,  328 ″ to accommodate swinging motion of the second link  308 . 
     The four bar linkage  26  further includes a pair of handle brackets  336 ,  338  adjacent to the rear side  44  of the patient transfer apparatus  20 . The handle brackets  336 ,  338  have their respective ends  336 ′,  336 ″ and  338 ′,  338 ′ pivotally coupled to the upper and lower conveyor assemblies  22 ,  24 . The top end  336 ′ of the first handle bracket  336  is pivotally coupled to the top end rail  106  by a pivot pin  346 ′. The bottom end  336 ″ of the first handle bracket  336  is pivotally coupled to the bottom end rail  206  by a pivot pin  346 ″. Likewise, the top end  338 ′ of the second handle bracket  338  is pivotally coupled to the top end rail  108  by a pivot pin  348 ′. The bottom end  338 ″ of the second handle bracket  338  is pivotally coupled to the bottom end rail  208  by a pivot pin  348 ″. As shown in FIGS. 6-9, the handle brackets  336 ,  338  are mounted on the outside of the top and bottom end rails  106 ,  206  and  108 ,  208  adjacent to the rear side  44  of the patient transfer apparatus  20 . The lift handle  28  includes a middle portion  54  and end portions  56 ,  58 . The end portions  56 ,  58  of the lift handle  28  are secured to the respective handle brackets  336 ,  338  by means of screws  56 ′,  58 ′. The handle bracket  338  near the foot end  48  includes a slot  358  through which the drive shaft  30  extends beyond the end rail  208  near the rear side  44  of the patient transfer apparatus  20 . The slot  358  is sufficiently large to allow free turning of the drive shaft  30  without interference from the handle bracket  338 . 
     The lift handle  28  is movable between a forward position shown in FIGS. 6 and 8, and a retracted position shown in FIGS. 7 and 9. The four-bar linkage  26  is configured such that the upper conveyor assembly  22  is spaced upwardly from the lower conveyor assembly  24 , and located rearwardly therefrom, when the lift handle  28  is moved to the retracted position as shown in FIG.  7 . On the other hand, when the lift handle  28  is moved to the forward position, the upper conveyor assembly  22  is lowered to engage the lower conveyor assembly  24 , and located forwardly therefrom closer to the front side  42  of the patient transfer apparatus  20  as shown in FIG.  6 . Furthermore, the four-bar linkage  26  is configured such that the upper conveyor assembly  22  is positioned rearwardly, slightly to the left of over-the-center position with respect to the lower conveyor assembly  24  as shown in FIG. 7 to hold the upper conveyor assembly  22  in place against a stop bar (not shown). The front idler roller assembly  32  is rotatably coupled to the bottom end rails  206 ,  208 , and is located forwardly and downwardly with respect to the upper conveyor assembly  22  to facilitate movement of the patient onto the upper conveyor assembly  22  as shown in FIG.  6 . The front idler roller assembly  32  is optional, and may be eliminated. Although a four-bar linkage  26  is used for lifting and lowering the upper conveyor assembly  22  relative to the lower conveyor assembly  24 , it will be understood that any suitable mechanism may well be used for adjustably moving the upper conveyor assembly  22  relative to the lower conveyor assembly  24 . 
     Illustratively, the dimensions and materials used in the particular embodiment described above are as follows: The rear idler roller  104  and the rear drive roller  204  are both about 1 inch (2.54 centimeters) in diameter, and are made from stainless steel. The front idler rollers  102 ,  202  are both about ⅝ inches (1.59 centimeters) in diameter, and are made from aluminum. The end rails  106 ,  108 ,  206 ,  208 , the longitudinal supports  132 ,  134 ,  232 ,  234 , the end blocks  136 ,  138 ,  236 ,  238 , the links  306 ,  308 , the handle brackets  336 ,  338 , the lift handle  28  are all made from aluminum. The top and bottom panels  122 ,  222  are made from a carbon fiber composite. The upper and lower conveyors  150 ,  250  are both made from Lectrolite Duotone material. 
     The operation of the patient transfer device  20  will now be explained with reference to FIGS. 1-4. To transfer a patient from a first support  21 , for example a stretcher, to a second support  23 , for example a hospital bed, the first support  21  with the patient resting thereon is positioned next to the second support  23  to which the patient is to be transferred. The patient transfer device  20  is placed on the second support  23  between the head and foot ends thereof alongside the patient on the first support  21  as shown in FIG. 1, and the lift handle  28  is pushed forward as shown in FIGS. 6 and 8 to lower the upper conveyor assembly  22  onto the lower conveyor assembly  24 . When the upper conveyor assembly  22  is lowered, the lower run  150 ″ of the upper patient conveyor  150  engages the upper run  250 ′ of the lower drive conveyor  250  as shown in FIGS. 6 and 8 to transmit the motion of the lower drive conveyor  250  to the upper patient conveyor  150 . An actuator or wrench  300  is then used to turn the lower flight  250 ″ of the lower drive conveyor  250  in a first direction  262  shown in FIG.  6 . Motion of the lower flight  250 ″ in the first direction  262  causes the patient transfer apparatus  20  to move toward the first support  21 , and causes the upper flight  150 ′ of the upper patient conveyor  150  to also move in the first direction  262 . Motion of the upper flight  150 ′ in the first direction  262  moves the patient onto the upper conveyor assembly  22 . As a result, the patient transfer apparatus  20  moves onto the first support  21 , with the patient supported on the upper conveyor assembly  22  as shown in FIG.  2 . The front idler roller assembly  32 , being situated forwardly and downwardly relative to the upper conveyor assembly  22 , facilitates movement of the patient from the first support  21  onto the upper patient conveyor  150 . 
     To move the patient to the second support  23 , the lift handle  28  is retracted or pulled backward as shown in FIGS. 3,  7  and  9  to lift the upper conveyor assembly  22  with the patient resting thereon above the lower conveyor assembly  24 . The actuator  300  is then used to turn the lower flight  250 ″ of the lower drive conveyor  250  in a second direction  264  shown in FIG. 6 to cause the patient transfer apparatus  20  to move toward the second support  23 . The upper patient conveyor  150 , being disengaged from the lower drive conveyor  250 , does not turn. As a result, the patient transfer apparatus  20  with the patient resting thereon moves to the second support  23  as shown in FIG.  4 . 
     To remove the patient transfer apparatus  20  from under the patient and to deposit the patient onto the second support  23 , the lift handle  28  is again pushed forward to engage the upper patient conveyor  150  with the lower drive conveyor  250  as shown in FIGS. 6,  8 . The actuator  300  is then used to turn the lower flight  250 ″ of the lower drive conveyor  250  in the second direction  264 . Motion of the lower flight  250 ″ in the second direction  264  causes the upper flight  150 ′ of the upper patient conveyor  150  to also turn in the second direction  264 . As a result, the patient is transferred to the second support  23 , and the patient transfer apparatus  20  is moved out from under the patient. A third support, such as a gurney, may be positioned alongside the second support  23  on the side of the second support  23  opposite from the first support  21  to support the weight of the patient transfer apparatus  20  as it comes out from under the patient. The procedure for removing the patient transfer apparatus  20  from under the patient is generally opposite of the procedure for inserting the patient transfer apparatus  20  under the patient. 
     FIG. 16 is a partially broken away and partially exploded perspective view of a second embodiment  420  of the patient transfer apparatus similar to the first embodiment  20  of the patient transfer apparatus shown in FIGS. 1-15. Identical components in the two embodiments are identified by identical numerals. For example, the upper conveyor assembly in both embodiments is identified by numeral  22 , the four-bar linkage in both embodiments is identified by numeral  26 , and so on. On the other hand, functionally similar components in the two embodiments are identified by similar numerals. For example, the lower conveyor assembly in the second embodiment is identified by numeral  424  while the lower conveyor assembly in the first embodiment is identified by numeral  24 . Likewise, the actuator in the second embodiment is identified by numeral  4300  while the actuator in the first embodiment is identified by numeral  300 , and so on. The two embodiments are generally identical with the exception of the lower conveyor assembly and the actuator for driving the lower conveyor assembly. Generally speaking, the lower conveyor assembly  24  in the first embodiment includes a pair of laterally spaced-apart, elongated side rollers  202 ,  204 . The lower conveyor assembly  424  in the second embodiment, however, includes a set of five laterally spaced-apart, elongated rollers as explained below. 
     The second embodiment  420  of the patient transfer apparatus includes the upper conveyor assembly  22 , the lower conveyor assembly  424 , the four-bar linkage  26  movably connecting the upper conveyor assembly  22  to the lower conveyor assembly  424 , the lift handle  28  coupled to the four-bar linkage  26  for moving the upper conveyor assembly  22  between a raised disengaged position and a lowered engaged position, the front idler roller assembly  32  to facilitate movement of the patient onto the upper conveyor assembly  22 , and the actuator  4300  configured to be coupled to the lower conveyor assembly  424  to drive the lower conveyor assembly  424 . As previously indicated, the front idler roller assembly  32  is optional, and may be eliminated. 
     Referring to FIG. 16, the lower conveyor assembly  424  in the second embodiment includes a longitudinally-extending front idler roller  4202 , a laterally spaced-apart, longitudinally-extending rear drive roller  4204 , and a set of three longitudinally-extending intermediate idler rollers  4202 ′,  4202 ″,  4202 ′″ located between the front idler roller  4202  and the rear drive roller  4204 . The opposite ends of the longitudinally-extending rollers  4202 ,  4202 ′,  4202 ″,  4202 ′″,  4204  are rotatably coupled to a pair of longitudinally spaced-apart, laterally-extending end rails  4206 ,  4208 . Flanged radial bearings  4210  coupled to the end rails  4206 ,  4208  rotatably support the longitudinally-extending rollers  4202 ,  4202 ′,  4202 ″,  4202 ′″,  4204 . Unlike the first embodiment  24 , the second embodiment  424  of the lower conveyor assembly does not include a platen assembly between the front idler roller  4202  and the rear drive roller  4204 . Instead, a pair of longitudinally-extending spacer bars  4232 ,  4234  are employed to provide rigidity to the lower conveyor assembly  424 . The spacer bars  4232 ,  4234  are located adjacent to the front idler roller  4202  and the rear drive roller  4204  respectively, and have their opposite ends secured to the end rails  4206 ,  4208 . Although flanged radial bearings  4210  are used for rotatably supporting the rollers  4202 ,  4202 ′,  4202 ″,  4202 ′″,  4204 , it is within the scope of the invention as presently perceived to use any suitable means, such as ball bearings, bushings and so on. 
     An endless lower conveyor web  4250  is trained about the plurality of lower rollers  4202 ,  4202 ′,  4202 ″,  4202 ′″,  4204  to provide an upper run or flight  4250 ′ and a lower run or flight  4250 ″. The rear drive roller  204  includes a drive shaft  430  which protrudes through the end rail  4208  adjacent to the foot end  48  of the patient transfer apparatus  420 . The actuator  4300  is coupled to the protruding portion of the drive shaft  430  to rotate the rear drive roller  4204  to, in turn, drive the lower conveyor web  4250 . The actuator  4300  includes a unidirectional roller clutch to transmit rotation of the actuator  4300  in clockwise locking direction  4302  to the drive shaft  430 . Rotation of the actuator  4300  in anticlockwise overrunning direction  4304 , however, is not transmitted to the drive shaft  430 . 
     Referring to FIGS. 16 and 17, the actuator  4300  includes a roller clutch  4310  mounted on the drive shaft  430 . A C-clip or a nut may be mounted on the drive shaft  430  adjacent to its free end to hold the roller clutch  4310  on the drive shaft  430 . A split collar  4312  includes a central opening  4314  for receiving the roller clutch  4310 . A swing arm  4316  has a threaded portion  4318  at one end which is screwed into a threaded opening  4320  in the split collar  4312 . A knob  4322  is coupled to the distal end of the swing arm  4316 . Rotation of the knob  4322  in clockwise direction  4306  pulls the two halves of the split collar  4312  together to, in turn, lock the swing arm  4316  to the roller clutch  4310 . Rotation of the knob  4322  in the opposite anticlockwise direction  4308  separates the two halves of the split collar  4312  to, in turn, release the swing arm  4316  from the roller clutch  4310 . Suitable releasable fastening means—such as a velcro fastener or a clip (not shown) may be used to attach the swing arm  4316  to a frame member, such as the lift handle  28  or the end rail  4208  to prevent the swing arm  4316  from flopping around when not in use. 
     The roller clutch  4310  includes a plurality of spring-loaded needle rollers  4324  (for example, 9) disposed between toothed ramp portions  4326  formed on the inner surface of the roller clutch  410  and the outer surface of the drive shaft  430 . Rotation of the swing arm  4316  in the locking direction  4302  wedges the rollers  4322  against the outer surface of the drive shaft  430  to lock the roller clutch  4310  to the drive shaft  430  to, in turn, transmit the motion of the swing arm  4316  to the drive shaft  430 . Only 3 rollers are shown in the schematic representation in FIG.  17 . 
     Illustratively, the dimensions and materials used in this particular embodiment are as follows: The front idler roller  102  is about ⅝ inches (1.59 centimeters) in diameter, and is made from aluminum. The rear idler roller  104  is about 1 inch (2.54 centimeters) in diameter, and is made from stainless steel. The front idler roller  4202  and the second idler roller  4202 ′ are each about ⅝ inches (1.59 centimeters) in diameter, and are made from aluminum. The third idler roller  4202 ″ is about ¾ inches (1.90 centimeters) in diameter, and is made from aluminum. The fourth idler roller  4202 ′″ is about 1 inch (2.54 centimeters) in diameter, and is made from aluminum. The rear drive roller  4204  is both about 1 inch (2.54 centimeters) in diameter, and is made from stainless steel. Other parts are illustratively made from aluminum. 
     The operation of the patient transfer device  420  will now be explained with reference to FIGS. 1-4. To transfer a patient from a first support  21 , for example a stretcher, to a second support  23 , for example a hospital bed, the first support  21  with the patient resting thereon is positioned next to the second support  23  to which the patient is to be transferred. The patient transfer device  420  is placed on the second support  23  between the head and foot ends thereof alongside the patient on the first support  21  as shown in FIG. 1, and the lift handle  28  is pushed forward to lower the upper conveyor assembly  22  onto the lower conveyor assembly  424  to, in turn, engage the upper patient conveyor  150  with the lower drive conveyor  4250 . The knob  4322  is turned to lock the swing arm  4316  to the roller clutch  4310 . The swing arm  4316  is then moved forward (i.e., toward the patient) and backward (i.e., away from the patient) to turn the lower drive conveyor  4250  to, in turn, move the patient transfer apparatus  420  toward the patient on the first support  21 , and to move the patient onto the upper conveyor assembly  22 . The front idler roller assembly  32 , situated forwardly and downwardly relative to the upper conveyor assembly  22 , facilitates movement of the patient from the first support  21  onto the upper conveyor assembly  22 . 
     To move the patient to the second support  23 , the lift handle  28  is retracted to lift the upper conveyor assembly  22  above the lower conveyor assembly  424 , and to disengage the upper conveyor assembly  22  from the lower conveyor assembly  424  as shown in FIG.  3 . The knob  4322  is then turned to loosen the split collar  4312  to, in turn, free the roller clutch  4310 . The lift handle  28  is then used to roll the patient transfer apparatus  420  with the patient resting thereon onto the second support  23 . The use of flanged radial bearings  4210  for rotatably supporting the bottom rollers  4202 ,  4202 ′,  4202 ″,  4202 ′″,  4204  makes it easy to roll the patient transfer apparatus  420 . 
     To deposit the patient onto the second support  23  and remove the patient transfer apparatus  420  from under the patient, the lift handle  28  is pushed forward. The lift handle  28  is then used to retract the patient transfer apparatus  420  to allow the patient to gently slide onto the second support  23 . 
     The drive roller  4204  may be bead blasted or overcoated with a suitable coating  4205  to give its outer surface a textured finish to enhance its grip on the lower conveyor  4250 . Likewise, other rollers  102 ,  104 ,  4202 ,  4202 ′,  4202 ″,  4202 ′″ may be bead blasted or overcoated with a suitable coating to give their outer surfaces a textured finish. Although a mechanical device such as a roller clutch-type actuator is used in the illustrated embodiment to drive the lower conveyor  4250 , it will however be appreciated that other types of actuators may well be used to drive the lower conveyor  4250  without exceeding the scope of the invention as presently perceived. 
     FIGS. 18-32 show a third embodiment  520  of the patient transfer apparatus similar to the first embodiment  20  shown in FIGS. 1-15 and the second embodiment  420  shown in FIGS. 16 and 17. Referring to FIGS. 18-22, the patient transfer apparatus  520  includes an upper conveyor assembly  522 , a lower conveyor assembly  524 , a four-bar linkage adjustment mechanism  526  movably connecting the upper conveyor assembly  522  to the lower conveyor assembly  524 , a lift handle  528  coupled to the four-bar linkage  526  for moving the upper conveyor assembly  522  between a lowered engaged position shown in FIG. 19 where the upper conveyor assembly  522  engages the lower conveyor assembly  524  when the lift handle  528  is moved to a forward position, and a raised disengaged position shown in FIG. 20 where the upper conveyor assembly  522  is spaced upwardly and rearwardly from the lower conveyor assembly  524  when the lift handle  528  is moved to a retracted position, a drive shaft  530  configured to be coupled to an actuator  5300  to drive the lower conveyor assembly  524 , a pair of brake pads  534 ,  536  coupled to respective lift handle brackets  5334 ,  5336  and configured to be pressed against the upper conveyor assembly  522  to lock the upper conveyor assembly  522  when the lift handle  528  is moved to the retracted position, and a stop pin  532  against which the handle bracket  5334  near the head end  514  rests when the lift handle  528  is moved to the retracted position. When the lift handle  528  is moved to the forward position shown in FIG. 19, the upper conveyor assembly  522  engages the lower conveyor assembly  524  to couple the motion of the lower conveyor assembly  524  to the upper conveyor assembly  522 . Although a four-bar linkage  526  is used for lifting and lowering the upper conveyor assembly  522  relative to the lower conveyor assembly  524 , it will be understood that any suitable mechanical, electrical, hydraulic or pneumatic device may well be used for lifting and lowering the upper conveyor assembly  522 . The overall dimensions of the patient transfer apparatus  520  are about the same as the first embodiment  20  or the second embodiment  420 —the length about 30 inches (76 centimeters), and the width about 14 inches (36 centimeters), the height about 2½ inches (6 centimeters) without the lift handle  528 , and about 9 inches (23 centimeters) with the handle  528 . 
     The patient transfer apparatus  520  includes an elongated front side  510 , an elongated rear side  512 , a head end  514  and a foot end  516 . As used in this description, the phrase “front side  510 ” will be used to denote the side of any referred to object that is positioned to lie nearest the front side  510  of the patient transfer apparatus  520 , and the phrase “rear side  512 ” will be used to denote the side of any referred-to object that is positioned to lie nearest the rear side  512  of the patient transfer apparatus  520 . Likewise, the phrase “head end  514 ” will be used to denote the end of any referred-to object that is positioned to lie nearest the head end  514  of the patient transfer apparatus  520 , and the phrase “foot end  516 ” will be used to denote the end of any referred-to object that is positioned to lie nearest the foot end  516  of the patient transfer apparatus  520 . 
     The upper conveyor assembly  522  includes a longitudinally-extending front roller  5102 , a laterally spaced-apart, longitudinally-extending rear last roller  5112 , and a set of four longitudinally-extending intermediate rollers  5104 ,  5106 ,  5108 ,  5110  located between the front and rear rollers  5102 ,  5112 . The rollers  5102 ,  5104 ,  5106 ,  5108 ,  5110 ,  5112  are all idler rollers, and are referred to herein as the front roller, second front roller, third front roller, third last or third rear roller, second last or second rear roller and the last or rear roller. The opposite ends of the longitudinally-extending rollers  5102 ,  5104 ,  5106 ,  5108 ,  5110 ,  5112  are rotatably coupled to a pair of longitudinally spaced-apart, laterally-extending end rails  5114 ,  5116 . As shown in FIGS. 23-25, flanged radial bearings  5120 ,  5160 ,  5170  coupled to the end rails  5114 ,  5116  rotatably support the longitudinally-extending rollers  5102 ,  5104 ,  5106 ,  5108 ,  5110 ,  5112 . The front roller  5102  is preferably made smaller than the rest of the rollers  5104 ,  5106 ,  5108 ,  5110 ,  5112  to facilitate lifting of the patient onto the upper conveyor assembly  522  as the patient transfer apparatus  520  is driven under the patient. Illustratively, the upper end rails  5114 ,  5116  are made from aluminum. The upper end rails  5114 ,  5116  are each 0.75 inches tall (1.91 centimeters) and about 0.375 inches wide (0.95 centimeters). Although flanged radial bearings  5120 ,  5160 ,  5170  are used for rotatably supporting the rollers  5102 ,  5104 ,  5106 ,  5108 ,  5110 ,  5112  in the embodiment described, it is within the scope of the invention as presently perceived to use any suitable means, such as ball bearings, roller bearings, bushings, etc. 
     Unlike the first embodiment  22 , the upper conveyor assembly  522  does not include a platen assembly between the front and rear rollers  5102 ,  5112 . Instead, a pair of longitudinally-extending spacer rods  5132 ,  5134  are employed to provide rigidity to the upper conveyor assembly  522 . As illustrated in FIG. 24, the spacer rods  5132 ,  5134  are mounted inside the second front and the second last rollers  5104 ,  5110  respectively, and have their opposite ends secured to the end rails  5114 ,  5116  by flat head screws  5144 , one on each side. The end rails  5114 ,  5116  have countersunk holes  5140  so that the outer surfaces of the flat head screws  5144  are flush with the outer surfaces of the end rails  5114 ,  5116 . Illustratively, the flat head screws  5144  are made from stainless steel. The front and rear spacer rods  5132 ,  5134  are both made from aluminum, and have a diameter of 0.3125 inches (0.79 centimeters). 
     FIG. 23 shows the attachment of the front roller  5102  to the end rail  5114  near the head end  514 . The attachment of the front roller  5102  to the other end rail  5116  near the foot end  516  is similar. The outer ring of the flanged radial bearing  5120  is formed to include a seat  5122  for fixedly receiving an end portion of the front roller  5102  as shown. The inner ring of the radial bearing  5120  is fixedly secured to the inside wall of the end rail  5114  by means of a cap screw  5124 . The inside wall of the end rail  5114  includes a tapped blind hole  5126  into which the threaded portion of the cap screw  5124  is threaded. Illustratively, the upper front roller  5102  is made from thin walled stainless steel tubing about 0.0625 inches in thickness (0.16 centimeters) and about 0.625 inches in diameter (1.59 centimeters). The cap screw  5124  is made from stainless steel, is 0.25 inches in diameter (0.635 centimeters), and has 20 threads per inch (2.54 centimeters). The flanged radial bearing  5120  is marketed by NMB Bearing Corporation, Model No. SSRIF814HA1. 
     FIG. 24 shows the attachment of the second front roller  5104  and the enclosed spacer rod  5132  to the end rail  5114  near the head end  514 . The attachment of the second front roller  5104  and the enclosed spacer rod  5132  to the other end rail  5116  near the foot end  516  is similar. The end rail  5114  has a countersunk through hole  5140 , and the spacer rod  5132  has a blind tapped hole  5142  for receiving a flat head screw  5144 . The flat head screw  5144  is passed through the opening  5140  in the end rail  5114 , and screwed into the blind tapped hole  5142  in the spacer rod  5132  to firmly secure the spacer rod  5132  to the end rail  5114 . The countersunk through hole  5140  allows the outer surface of the flat head screw  5144  to be flush with the outer surface of the end rail  5114 . A flanged radial bearing  5160  is slid over the spacer rod  5132 . The inner ring of the radial bearing  5160  is fixed to the spacer rod  5132 . The outer ring of the radial bearing  5160  is formed to include a seat  5162  for fixedly receiving an end portion of the second front roller  5104 . The second last roller  5110  and the enclosed spacer rod  5134  are attached to the end rails  5114 ,  5116  in similar fashion. Illustratively, the rollers  5104 ,  5110  are made from thin walled aluminum tubing about 0.0625 inches in thickness (0.16 centimeters), and about 1 inch in diameter (2.54 centimeters). The flat head screw  5144  is made from stainless steel, is 0.19 inches in diameter (0.48 centimeters), and has 24 threads per inch (2.54 centimeters). The front and rear spacer rods 5132, 5134 are both made from aluminum, and have a diameter of 0.3125 inches (0.79 centimeters). The flanged radial bearing  5160  is marketed by General Bearing Corporation, Model No. 31623-01. 
     FIG. 25 shows the attachment of the third front roller  5106  to the end rail  5114  near the head end  514 . The attachment of the third front roller  5106  to the other end rail  5116  near the foot end  516  is similar. The outer ring of the flanged radial bearing  5170  is formed to include a seat  5172  for fixedly receiving an end portion of the third front roller  5106  as shown. The inner ring of the radial bearing  5170  is fixedly secured to the inside wall of the end rail  5114  by means of a cap screw  5174 . The inside wall of the end rail  5114  includes a tapped blind hole  5176  into which the threaded portion of the cap screw  5174  is threaded. The third last roller  5108  and the last roller  5112  are attached to the upper end rails  5114 ,  5116  in similar fashion. Illustratively, the rollers  5106 ,  5108 ,  5112  are all made from thin walled aluminum tubing about 0.0625 inches in thickness (0.16 centimeters) and about 1 inch in diameter (2.54 centimeters). The cap screw  5174  is made from stainless steel, is 0.25 inches in diameter (0.635 centimeters), and has 20 threads per inch (2.54 centimeters). An endless upper conveyor web  5150  is trained about the plurality of upper rollers  5102 , 5104 , 5106 , 5108 , 5110 , 5112  to provide an upper run or flight  5150 ′ and a lower run or flight  5150 ′ as shown in FIGS. 19-22. The flanged radial bearing  5170  is marketed by General Bearing Corporation, Model No. 31622-01. 
     The lower conveyor assembly  524  includes a longitudinally-extending front roller  5202 , a laterally spaced-apart, longitudinally-extending rear drive roller  5212 , and a set of four longitudinally-extending intermediate rollers  5204 ,  5206 ,  5208 ,  5210  located between the front and rear rollers  5202 ,  5212 . The rollers  5202 ,  5204 ,  5206 ,  5208 ,  5210 ,  5212  are referred to herein as the front roller, second front roller, third front roller, third last or third rear roller, second last or second rear roller and the last or rear roller  5212 . All the rollers are all idler rollers with the exception of the last roller  5212 , which is a drive roller. A drive shaft  530  secured to the rear drive roller  5212  near foot end  516  is configured to be coupled to the actuator  5300  for driving the patient transfer apparatus  520 . The rear drive roller  5212  is made larger than the rest of the rollers  5202 ,  5204 ,  5206 ,  5208 ,  5210  to increase the traction between the drive roller  5212  and the lower conveyor web  5250 . The opposite ends of the longitudinally-extending rollers  5202 ,  5204 ,  5206 ,  5208 ,  5210 ,  5212  are rotatably coupled to a pair of longitudinally spaced-apart, laterally-extending end rails  5214 ,  5216 . Flanged radial bearings  5260 ,  5270 ,  5280  coupled to the end rails  5214 ,  5216  rotatably support the longitudinally-extending rollers  5202 ,  5204 ,  5206 ,  5208 ,  5210 ,  5212 , with one exception. A needle bearing  5290  is used to support the foot end  516  of the rear drive roller  5212  coupled to the drive shaft  530 . Illustratively, the end rails  5214 ,  5216  are made from aluminum. The end rails  5214 ,  5216  are each about 1.375 inches tall in the back (3.49 centimeters), about 0.625 inches tall in the front (1.59 centimeters), and about 0.375 inches wide (0.95 centimeters). Although flanged radial bearings  5260 ,  5270 ,  5280  are used for rotatably supporting the rollers  5202 ,  5204 ,  5206 ,  5208 ,  5210 ,  5212 , it is within the scope of the invention as presently perceived to use any suitable means, such as ball bearings, roller bearings, bushings, etc. 
     Unlike the first embodiment  24 , the lower conveyor assembly  524  does not include a platen assembly between the front and rear rollers  5202 ,  5212 . Instead, a pair of longitudinally-extending spacer rods  5232 ,  5234  are employed in the third embodiment  520  to provide rigidity to the lower conveyor assembly  524  as shown in FIGS. 18-22. As described below, the spacer rods  5232 ,  5234  are mounted inside the second front and the second last rollers  5204 ,  5210  respectively, and have their opposite ends secured to the end rails  5214 ,  5216  by flat head screws  5244 . The end rails  5214 ,  5216  have countersunk holes  5240  so that the outer surfaces of the flat head screws  5244  are flush with the outer surfaces of the end rails  5214 ,  5216  in the manner shown in FIG.  24 . Illustratively, the flat head screws  5244  are made from stainless steel. The spacer rods  5232 ,  5234  are both made from aluminum. The spacer rods  5232 ,  5234  have a diameter of 0.3125 inches (0.79 centimeters). Illustratively, the rear drive roller  5212  is made from thin walled aluminum tubing about 0.0625 inches in thickness (0.16 centimeters), and about 1.75 inches in diameter (4.45 centimeters). The remaining rollers  5202 ,  5204 ,  5106 ,  5108 ,  5110  are all made from thin walled aluminum tubing about 0.0625 inches in thickness (0.16 centimeters), and about 1 inch in diameter (2.54 centimeters). As previously indicated, the rear drive roller  5212  is made larger than the rest of the rollers  5202 ,  5204 ,  5206 ,  5208 ,  5210  to increase the traction between the drive roller  5212  and the lower conveyor web  5250 . 
     The lower rollers  5202 ,  5206 ,  5208  are rotatably coupled to the lower end rails  5214 ,  5216  by the flanged radial bearings  5270  in the same way the upper rollers  5106 ,  5108   5112  are rotatably coupled to the upper end rails  5114 ,  5116  by the flanged radial bearings  5170  as shown in FIG.  25 . The lower rollers  5204 ,  5210  and the enclosed spacer rods  5232 ,  5234  are rotatably coupled to the lower end rails  5214 ,  5216  by the flanged radial bearings  5260  in the same way the upper rollers  5104 ,  5110  and the enclosed spacer rods  5132 ,  5134  are rotatably coupled to the upper end rails  5114 ,  5116  by the flanged radial bearings  5160  as shown in FIG.  24 . 
     FIG. 26 shows the attachment of the rear drive roller  5212  to the end rails  5214 ,  5216 . The head end  514  of the rear drive roller  5212  is rotatably coupled to the end rail  5214  by a flanged radial bearing  5280  in the same way the upper rollers  5106 ,  5108   5112  are rotatably coupled to the upper end rails  5114 ,  5116  by the flanged radial bearings  5170  as indicated in FIG.  25 . The outer ring of the flanged radial bearing  5280  is formed to include a seat  5282  for fixedly receiving a spacer sleeve  5288  attached to an end portion of the roller  5212  as shown. The inner ring of the radial bearing  5280  is fixedly secured to the inside wall of the end rail  5214  by means of a cap screw  5284 . The inside wall of the end rail  5214  includes a tapped blind hole  5286  into which the threaded portion of the cap screw  5284  is screwed. Illustratively, the cap screw  5284  is made from stainless steel, is 0.375 inches in diameter (0.953 centimeters), and has  16  threads per inch (2.54 centimeters). The flanged radial bearing  5280  is marketed by General Bearing Corporation, Model No. 31861-00. 
     The foot end  516  of the rear drive roller  5212  is coupled to the drive shaft  530  by means of a spacer sleeve  5292  as shown in FIG.  26 . The drive shaft  530  is rotatably coupled to the end rail  5216  by a needle bearing  5290 . The outer ring of the needle bearing  5290  is fixedly secured to the end rail  5216  as shown in FIG.  26 . The inner ring of the needle bearing  5290  is fixedly secured to the drive shaft  530 . Illustratively, the needle bearing  5290  is marketed by INA Bearing Corporation, Model No. HK2018RS. 
     An endless lower drive conveyor web  5250  is trained about the plurality of lower rollers  5202 ,  5204 ,  5206 ,  5208 ,  5210 ,  5212  to provide an upper run or flight  5250 ′ and a lower run or flight  5250 ″. As shown in FIGS. 19,  20  and  22 , the lower conveyor web  5250  is looped around the second last roller  5210  adjacent to the rear drive roller  5212  to increase the wrap of the lower conveyor web  5250  about the rear drive roller  5212  so that the lower conveyor web  5250  does not slip as the rear drive roller  5212  is turned by the actuator  5300 . Illustratively, the rollers  5202 ,  5204 ,  5206 ,  5108 ,  5210 ,  5212  are all made from thin walled aluminum tubing about 0.0625 inches (0.16 centimeters) in thickness. The rear drive roller  5212  is about 1.75 inches (4.45 centimeters) in diameter, and the rest of the rollers  5202 ,  5204 ,  5206 ,  5208  and  5210  are about 1 inch in diameter (2.5 centimeters). 
     The drive shaft  530  coupled to the rear drive roller  5212  extends through the end rail  5216  adjacent to the foot end  516  as shown in FIGS. 26 and 27. The actuator  5300  is configured to be coupled to the drive shaft  530  to rotate the drive roller  5212 . Rotation of the drive roller  5212  is, in turn, transmitted to the lower conveyor web  5250 . The actuator  5300  includes first and second elongated arm portions  602 ,  604  and an intermediate portion  606  in the form of a split collar. The split collar  606  includes a central opening  608  for receiving a roller clutch  5310  similar to the roller clutch  4310  used in the second embodiment  420  shown in FIG.  17 . The roller clutch  5310  is mounted on the drive shaft  530  to transmit rotation of the actuator  5300  only in clockwise locking direction  620 . Rotation of the actuator  5300  in anticlockwise overrunning direction  622 , however, is not transmitted to the drive shaft  530 . The inner ring of the roller clutch  5310  is fixedly secured to the drive shaft  530 . The outer ring of the roller clutch  5310  received in the central opening  608  of the split collar  606  is releasably securable to the actuator  5300 . The actuator  5300  and the roller clutch  5310  are held in place on the drive shaft  530  by a large diameter washer  610  secured to the free end of the drive shaft  530  by a screw  612 . 
     The actuator  5300  includes a pair of handles  614 ,  616  coupled to the respective elongated arm portions  602  and  604 . When the handles  614  and  616  are squeezed together, the two halves of the split collar  606  are pulled together to, in turn, lock the actuator  5300  to the outer ring of the roller clutch  5310 . When the handles  614  and  616  are released, the two halves of the split collar  606  are again separated to free the outer ring of the roller clutch  5310 . Suitable releasable fastening means—such as a hook and loop device (for example, a fastener sold under the trademark “Velcro”) or a clip (not shown) may be used to attach the actuator  5300  to a frame member, such as the lift handle  528  or the end rail  5216  to prevent the actuator  5300  from flopping around when not in use. Illustratively, the roller clutch  5310  is marketed by NA Bearing Corporation, Model No. HF2016. 
     Referring to FIG. 18, the four-bar linkage  526  movably connects the upper conveyor assembly  522  to the lower conveyor assembly  524 . The lift handle  528  is coupled to the four-bar linkage  526  for moving the upper conveyor assembly  522  between a lowered engaged position shown in FIG. 19 when the lift handle  528  is moved to the forward position, and a raised disengaged position shown in FIG. 20 when the lift handle is moved to the retracted position. The four bar linkage  526  includes a pair of swing arms or links  5314 ,  5316  adjacent to the front side  510  of the patient transfer apparatus  520 . The links  5314 ,  5316  have their respective upper and lower ends  5314 ′,  5314 ″ and  5316 ′,  5316 ″ pivotally coupled to the upper and lower conveyor assemblies  522 ,  524 . 
     The upper end  5314 ′ of the first link  5314  is pivotally coupled to the upper end rail  5114  adjacent to the front side  510  near the head end  514  by a pivot pin  5324 ′ as shown in FIGS. 18,  28 . The upper end  5314 ′ of the first link  5314  is configured to form an open-ended slot for receiving the pivot pin  5324 ′. The open-ended construction of the slot facilitates assembly of the upper conveyor assembly  522  with the lower conveyor assembly  524 . The open-ended construction of the slot also permits removal of the upper conveyor web  5150  from the upper conveyor rollers  5102 - 5112  for cleaning, repair, or replacement. The lower end  5314 ″ of the first link  5314  is pivotally coupled to the lower end rail  5214  adjacent to the front side  510  near the head end  514  by a pivot pin  5324 ″. 
     Likewise, the upper end  5316 ′ of the second link  5316  is pivotally coupled to the upper end rail  5116  adjacent to the front side  510  near the foot end  516  by a pivot pin  5326 ′. The upper end  5316 ′ of the second link  5316  is configured to form an open-ended slot for receiving the pivot pin  5326 ′. As previously described, the open-ended construction of the slot simplifies assembly of the upper conveyor assembly  522  with the lower conveyor assembly  524 . The open-ended construction of the slot also permits removal of the upper conveyor web  5150  from the upper conveyor rollers  5102 - 5112  for cleaning, repair, or replacement. The lower end  5316 ″ of the second link  5316  is pivotally coupled to the lower end rail  5216  adjacent to the front side  510  near the foot end  516  by a pivot pin  5326 ″. 
     The link  5314  is mounted in cutouts  5304 ′,  5304 ″ provided in the upper and lower end rails  5114  and  5214  adjacent to the front side  510  near the head end  514 . Likewise, the link  5316  is mounted in cutouts  5306 ′,  5306 ″ provided in the upper and lower end rails  5116  and  5216  adjacent to the front side  510  near the foot end  516 . The cutouts  5304 ′,  5304 ″ in the upper and lower end rails  5114 ,  5214  adjacent to the head end  514  and the cutouts  5306 ′,  5306 ″ in the upper and lower end rails  5116 ,  5216  adjacent to the foot end  516  are sufficiently wide to accommodate swinging motion of the first and second links  5314 ,  5316  in response to movement of the lift handle  528  between the forward and retracted positions shown in FIGS. 19,  20 . Enclosure of links  5314 ,  5316  in the respective cutouts  5304 ′,  5304 ″ and  5306 ′,  5306 ″ provide a degree of protection to the caregiver and the patient from accidental injury. The cutouts  5304 ′,  5304 ″ in the upper and lower end rails  5114 ,  5214  adjacent to the head end  514  and the cutouts  5306 ′,  5306 ″ in the upper and lower end rails  5116 ,  5216  adjacent to the foot end  516  may be either through openings extending between the top and bottom walls of the end rails  5114 ,  5116  and  5214 ,  5216  as shown or, in the alternative, blind holes in communication with the bottom walls of the top end rails  5114 ,  5116  and in communication with the top walls of the bottom end rails  5214 ,  5216 . Illustratively, the links  5314 ,  5316  are both made from stainless steel, about 2.25 inches in length (5.72 centimeters), and about 0.125 inches in thickness (0.32 centimeters). The spacing between the pivot pins  5324 ′,  5324 ″ and  5326 ′,  5326 ″ is about 1.60 inches (4.07 centimeters). The cutouts  5304 ′,  5304 ″ and  5306 ′,  5306 ″ are each 2 inches long (5.08 centimeters), and 0.25 inches wide (0.635 centimeters). 
     The four bar linkage  526  further includes a pair of lift handle brackets  5334 ,  5336  adjacent to the rear side  512  of the patient transfer apparatus  520  as shown in FIG.  18 . The handle brackets  5334 ,  5336  have their respective upper and lower ends  5334 ′,  5334 ″ and  5336 ′,  5336 ″ pivotally coupled to the upper and lower conveyor assemblies  522 ,  524 . The upper end  5334 ′ of the first handle bracket  5334  is pivotally coupled to the upper end rail  5114  adjacent to the head end  514  near the rear side  512  by a pivot pin  5344 ′. The lower end  5334 ″ of the first handle bracket  5334  is pivotally coupled to the lower end rail  5214  adjacent to the head end  514  near the rear side  512  by a pivot pin  5344 ″. Likewise, the upper end  5336 ′ of the second handle bracket  5336  is pivotally coupled to the upper end rail  5116  adjacent to the foot end  516  near the rear side  512  by a pivot pin  5346 ′. The lower end  5336 ″ of the second handle bracket  5336  is pivotally coupled to the lower end rail  5216  adjacent to the foot end  516  near the rear side  512  by a pivot pin  5346 ″. As shown in FIGS. 18-20, the handle brackets  5334 ,  5336  are mounted on the outside of the upper and lower end rails  5114 ,  5214  and  5116 ,  5216  adjacent to the rear side  512  of the patient transfer apparatus  520 . Illustratively, the handle brackets  5334 ,  5336  are both made from aluminum, and about 0.25 inches thick (0.635 centimeters). The spacing between the pivot pins  5344 ′,  5344 ″ and  5346 ′,  5346 ″ is about 1.60 inches (4.07 centimeters). 
     The lift handle  528  includes a middle portion  572  and end portions  574 ,  576  as shown in FIG.  18 . The end portions  574 ,  576  of the lift handle  528  are secured to the respective handle brackets  5334 ,  5336  by means of flat head screws  584 ,  586 . The handle brackets  5334 ,  5336  are provided with countersunk holes  594 ,  596  so that the outer surfaces of the screws  584 ,  586  are flush with the outer surfaces of the handle brackets  5334 ,  5336 . 
     The brake pads  534  and  536  in the form of rubber brake sleeves are secured to the handle brackets  5334  and  5336  adjacent to the head end  514  and foot end  516  respectively. As shown in FIGS. 29-31, the brake pad  534  includes a post  544  secured to the inner wall of the handle bracket  5334  near the head end  514  by a flat head screw  554 . The handle bracket  5334  is provided with a countersunk hole  564  so that the outer surface of the screw  554  is flush with the outer surface of the handle bracket  5334 . Likewise, the second brake pad  536  includes a post  546  secured to the inner wall of the handle bracket  5336  near the foot end  516  by a flat head screw  556 . The brake pads  534  and  536  are spaced apart from the upper conveyor web  5150  when the lift handle  528  is moved to the forward position as shown in FIG.  29 . On the other hand, the brake pads  534  and  536  are pressed against the upper conveyor web  5150  as shown in FIG. 30 to prevent inadvertent rolling of the upper conveyor web  5150  during transfer of the patient from one surface to another. 
     When the lift handle  528  is moved to the forward position, the upper conveyor assembly  522  is lowered to engage the lower conveyor assembly  524 , and located forwardly therefrom closer to the front side  510  of the patient transfer apparatus  20  as shown in FIG.  19 . On the other hand, the four-bar linkage  526  is configured such that the upper conveyor assembly  522  is spaced upwardly from the lower conveyor assembly  524 , and located rearwardly therefrom, when the lift handle  528  is moved to the retracted position as shown in FIG.  20 . The handle bracket  5334  rests against a stop pin  532  coupled to the upper end rail  5114  adjacent to the head end  514  near the rear side  512  of the patient transfer apparatus  520  when the lift handle  528  is moved to the retracted position as shown in FIG.  32 . Detachable pinch prevention guards (not shown) may be coupled to the upper end rails  5114 ,  5116  to cover the gaps between the upper and lower end rails  5114 ,  5214  and  5116 ,  5216 . 
     The operation of the patient transfer device  520  will now be explained. with reference to FIGS. 1-4. To transfer a patient from a first support  21 , such as a stretcher, to a second support  23 , such as a hospital bed, the first support  21  with the patient resting thereon is positioned next to the second support  23  to which the patient is to be transferred. The patient transfer device  520  is placed on the second support  23  between the head and foot ends thereof alongside the patient on the first support  21  as shown in FIG. 1, and the lift handle  528  is pushed forward to lower the upper conveyor assembly  522  onto the lower conveyor assembly  524  to, in turn, engage the upper patient conveyor  5150  with the lower drive conveyor  5250 . The handles  614 ,  616  of the actuator  5300  are squeezed together to lock the actuator  5300  to the roller clutch  5310 . The actuator  5300  is then moved forward (i.e., toward the patient) and backward (i.e., away from the patient) to turn the lower drive conveyor  5250  to, in turn, move the patient transfer apparatus  520  toward the patient on the first support  21 , and to move the patient onto the upper conveyor assembly  522 . The material of the upper conveyor web  5150  is sufficiently thick to prevent “hammocking” of the upper conveyor web  5150  between the upper conveyor rollers  5102 - 5112 . 
     The inner wall of the lower arm portion  604  of the actuator  5300  includes a pin (not shown) that is configured to engage a stop  533  on the outer wall of the handle bracket  5336  near the foot end  516  of the patient transfer apparatus  520  during clockwise rotation of the actuator  5300  in the direction  620  in FIG.  27 . Thus, the stop  533  prevents the actuator  5300  from moving downwardly into contact with the patient supports  21  and  23 . 
     To move the patient to the second support  23 , the lift handle  528  is retracted as shown in FIG. 3 to lift the upper conveyor assembly  522  above the lower conveyor assembly  524 , to disengage the upper conveyor assembly  522  from the lower conveyor assembly  524 , and to press the brake pads  534 ,  536  against the upper conveyor web  5150  to lock it in place. The handles  614  and  616  are then released to loosen the split collar  606  to, in turn, free the roller clutch  5310 . The lift handle  528  is then used to roll the patient transfer apparatus  520  with the patient resting thereon onto the second support  23 . The use of bearings  5260 ,  5270 ,  5280  and  5290  facilitate rotation of the bottom rollers  5202 - 5212  when the patient transfer apparatus  520  is rolled to the second support  23 . 
     To deposit the patient onto the second support  23  and remove the patient transfer apparatus  520  from under the patient, the lift handle  528  is pushed forward. The lift handle  528  is then used to tilt the patient transfer apparatus  520  forward to allow the patient to gently slide onto the second support  23 . 
     Although the invention has been described in detail, variations and modifications exist within the scope and spirit of the invention as described and defined in the following claims.