Patent Publication Number: US-6341393-B1

Title: Patient transfer and repositioning system

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This is a continuation-in-part of U.S. patent application Ser. No. 09/057,139, filed Apr. 8, 1998, which is a continuation-in-part of U.S. patent application Ser. No. 08/713,412, filed Sep. 13, 1996 now U.S. Pat. No. 5,890,238, which is a continuation-in-part of U.S. patent application Ser. No. 08/527,519, filed Sep. 13, 1995 and now U.S. Pat. No. 5,737,781, all hereby incorporated by reference. U.S. patent application Ser. No. 09/057,139 claimed the benefit of U.S. Provisional Patent Application No. 60/043,208, filed Apr. 8, 1997. This Application claims the benefit of U.S. Provisional Application No. 60/084,519, filed May 7, 1998 and U.S. Provisional Patent Application Nos. 60/092,286 and 60/092,287, both filed Jul. 10, 1998, all hereby incorporated by reference. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to systems which assist in moving, transporting, repositioning, and rolling over patients who are partly or completely incapacitated. The invention more particularly relates to systems which give a single health care worker the capability to move a patient from one bed to another bed, between a bed and a cart or gurney, between a sitting and a standing position, or from a slumped position in a chair or bed to a more elevated position. 
     BACKGROUND OF THE INVENTION 
     Health care workers at hospitals, nursing homes, and home care programs face the challenge of moving partly or completely incapacitated patients. A typical patient weighs between 45 and 90 kilograms, although many others weigh more. Consequently, at least two to four health care workers are usually needed to move the patient. These activities often create unacceptable risks of injury, almost without regard to the number of health care workers used in the patient transfer. The risks are particularly high when a sufficient number of workers is not available to assist in a patient transfer. For example, injuries to workers&#39; backs account for approximately 50% of worker&#39;s compensation costs for work place injuries in the health care industry in the United States. Thus, back injuries to health care workers are a particularly vexing problem. 
     Patient transfers can be placed in several broad categories. A first category includes the horizontal transfer of a patient from one flat surface to another. A second category involves upright transfers where a patient is moved from a horizontal position to an upright or sitting position in a wheelchair, chair or commode, and the return of the patient to the horizontal position from an upright or sitting position. A third category of transfer relates to the positioning or movement of patients in order to change their position in a bed or chair, for example pulling the patient up in the bed or rolling the patient from side to side. Although many attempts have been made to devise improved systems for patient transfer, almost all of these transfers continue to be manually performed. 
     Current healthcare guidelines typically recommend that four health care workers participate in a patient transfer. Two workers are at the bed side and two workers are at the cart side. Each worker grabs an edge of a draw sheet, which is positioned under the patient. The patient is then transferred between the bed and the cart through a combination of lifting, pulling, and pushing. An elongated plastic sheet is often placed beneath the patient to reduce friction or drag. Since a health care worker has to bend over at the waist to accomplish these patient transfers, the stresses encountered are magnified well beyond what would otherwise be expected for a maximum recommended lift of approximately fifty pounds. Normally this recommended maximum lift is measured with the lift at or near the worker&#39;s center of mass. Extremes in a health care worker&#39;s height, either taller or shorter than average, or any weakness in either the arms or legs further exaggerate these risks. 
     Many hospitals have swing-type mechanical lift devices to assist in certain patient transfers. However, these devices are not widely used because they are often cumbersome and time-consuming to set up and operate. Depending on the lift required, the devices may also be inappropriate. 
     The upright transfer and positioning categories provide similar difficulties, especially if the patient is unable to cooperate. For example, weak and elderly patients reclining in a semi-erect position tend to slide down. These patients must be returned to a position more toward the head of the bed. To do so, two health care workers usually grasp the patient by the upper arms to hoist the patient toward the head of the bed after the bed has been lowered to a more horizontal position. This manual transfer often causes strain on the workers&#39; upper and lower backs and possible contact bruises on the patient. Similar difficulties occur with upright transfers. 
     Given these formidable difficulties, there have been other attempts to mechanize the patient transfer process. For example, U.S. Pat. No. 2,665,432 (Butler), describes a cart with a manual crank connected to an extensive pull unit. The pull unit has a large number of straps which connect at an edge by hooks to a transfer sheet. Rotation of the crank winds the pull unit onto a roller. The size of the pull unit presents many difficulties including it attachment at many locations to the sheet and the awkwardness of winding it on the roller. The pull unit must be placed under the patient just prior to transfer, since it would not normally be kept there. Also, no means are provided for transferring the patient off the cart. 
     U.S. Pat. No. 2,827,642 (Huff) describes a similar system mounted to the head of a bed and designed to move a patient from the foot toward the head of the bed. The &#39;642 Patent does not describe the process of moving a patient laterally from one horizontal surface to another. 
     U.S. Pat. No. 4,970,738 (Cole) discloses another patient transfer system which employs a manual crank and self-locking gear system. This system has an advantage over the system described in the &#39;432 patent in that the transfer is reversible. Rotating the crank drives a belt system, which is attached to a semi-rigid transfer apron. The apron is thereby transferred horizontally while supporting a patient. This system has the disadvantage that the apron must be first positioned under the patient before the patient can be transported from a bed onto a cart. Another disadvantage is that the transfer support alone does not provide sufficient support for the patient or the transfer system. Because of the complexity of its design, considerable operator interaction would be required for the transfer support to be mounted to a cart and then operated to transfer a patient. 
     U.S. Pat. No. 2,733,452 (Tanney) describes a transfer system that uses a motorized pulley to transfer a patient on a metal-reinforced transfer sheet. The transfer sheet has metal grommets in its corners for attachment to cables. A motor is used to wind the cables onto reels thereby resulting in the transfer of the sheet and the patient thereon. However, the patient must first be moved onto the transfer sheet before being moved from a bed to the cart. Moreover, this invention fails to provide support beneath a patient being transferred. 
     U.S. Pat. Nos. 4,747,170 and 4,868,938 (both to Knouse) reveal a motorized winch-type transfer system. This transfer system has apparent advantages over the transfer system of the &#39;452 patent, which include a more secure transfer sheet gripping mechanism and the use of a transfer sheet which does not need grommets or other similar devices. Though more secure, the gripping system is difficult and awkward to use. 
     U.S. Pat. No. 5,038,424 (Carter et al.) teaches a system for reciprocally transferring a patient between a bed and a cart. This system employs a pliable transfer web wound about two detachable, cylindrical rollers and a drive motor mounted on the bed and the cart. In use, the bed and cart are positioned side-by-side and the web is placed beneath the patient. The roller adjacent the cart or bed onto which the patient is to be transferred is detached. While unwinding a sufficient length of transfer web wound thereon, the roller is extended to the opposite side of the bed or cart onto which the patient is to be transferred, and there connected to the drive motor. The drive motor is then activated, thereby rewinding the transfer web onto the roller and transporting the patient disposed thereon. Thus, while enabling reciprocal transfer, the system of the &#39;424 patent is time consuming and awkward to set up. Moreover, as in the previous inventions discussed hereinabove, the patient is not supported adequately while being transferred. 
     While considerable effort has gone into developing horizontal patient transfer systems, all of the systems previously developed have significant drawbacks. These drawbacks primarily relate to the significant difficulties encountered in set-up and operation. 
     The patents described hereinabove primarily relate to systems for transferring patients from one horizontal surface to another horizontal surface. By partial contrast, U.S. Pat. Nos. 4,700,415 and 4,837,873 (both to DiMatteo et al.) teach a system for transferring patients between a reclined wheelchair and a bed. The bed is equipped with a sheet wound about a right side roller and a left side roller. The sheet is positioned beneath a patient reclining thereupon. The right and left side rollers are positioned laterally on each side of the bed, usually slightly below the plane of the patient. Two corner rollers are situated above the right side and left side rollers. The two corner rollers are approximately level with the top surface of the bed. The reclined wheelchair is equipped with two articulated rollers. Extending between these articulated rollers is a sheet, the sheet including three bands. The lateral edges of the sheet may be joined or separate. If the lateral edges are to be joined, the sheet spans above and below the wheelchair upper surface. If the lateral edges are free, the sheet spans the wheelchair upper surface with its ends wound about the two rollers. The separate transfer systems for the bed and wheelchair must be powered such that both sheets rotate with equal velocities. In use, the patient reclining upon the bed is conveyed laterally by the bed transfer system. Upon encountering the wheelchair transfer system, the patient is thereupon further conveyed onto the wheelchair. The wheelchair may then be further adjusted, allowing the patient to assume a sitting position. 
     The system of DiMatteo allows for transfer to or from a reclining wheelchair and for adjusting the wheelchair between sitting and reclining positions. However, its shortfalls include the complexity of its design, the need to retrofit beds with the rollers and sheet provided, and the possibility of pinching the patient or catching clothing in the gaps between the bands. 
     U.S. Pat. No. 3,597,774 (Warren) describes a harness and winch mechanism for raising a patient reclining upon a bed. The winch is mounted to a post attached to the head of the bed and is operated by a hand crank. The harness loops under the patient&#39;s armpits such that excessive stress may be applied thereto during operation of the device. 
     SUMMARY OF THE INVENTION 
     The invention includes devices for transferring patients which greatly simplify, and provide enhanced versatility over, any known device. The adoption of these transfer devices will likely reduce the wide incidence of back injuries in health care workers. A first system for the horizontal transfer of patients is adapted to use existing transfer sheets and an appropriately modified cart. The sheet is readily attached to a clamping device close to the patient. The clamping device has a releasable catch which holds the sheet. One or more straps are attached to the clamping device, and the other ends of the straps are attached to reels that are part of a winch. Activation of the winch winds the straps onto the reels. In a highly portable embodiment of this transfer device, the entire apparatus may weight only about 8-15 kilograms, and may be readily attachable and removable to bed and cart rails. 
     A long narrow rectangular cushion can be placed between the bed and cart when using the portable transfer device. The cushion is, optionally, the length of the bed, and may be partially coated with a low friction surface. The cushion may have fasteners for attachment to a bed or cart, or it may also be configured to hang from the side of the bed or cart by the fasteners when not in use. The cushion is particularly convenient when used with a portable transfer device of the invention because no other modifications to the bed or cart may be needed. 
     Other embodiments of horizontal transfer devices facilitate the transfer of the patient by providing some lift to the patient as well as horizontal motion. The vertical and horizontal transfer mechanisms may both be operably attached to a single bed or cart frame. One embodiment of a horizontal transfer mechanism within the invention has a transfer element that moves within tracks. Another embodiment of a horizontal transfer system of the invention moves the patient on a modularized cushion. In other embodiments, lift is added by use of a harness which provides significant advantage in distributing the weight of the patient without the need to lift the patient to place a portion of the harness under the patient. The harness has a support that goes across the patient&#39;s upper body. Another portion of the harness goes under the patient&#39;s arms. The harness has a fastener that attaches a lift mechanism near the back of the patient&#39;s head. 
     An improved patient transfer system is capable of transferring a patient using only a single attendant. The transfer system includes patient transfer means for transferring the patient, a transfer sheet, a retaining member assembly operably coupled to the patient transfer means and a contact element assembly. 
     The improved transfer system may also include a highly portable transfer unit. The portable transfer unit may be totally self-contained or may be installable on a bed or cart and connectable to a separate clamp. The portable transfer unit may utilize a plurality of detachable spools, as well as means for sensing the proximity of a patient being transferred and means for discontinuing the transfer in response to the sensing. 
     The improved transfer system may still further include a transfer bridge support means for supporting a patient being transported when the patient spans the bed or cart. The transfer bridge support means may be foldable and may include a stabilizer, a cross sectional camber and a leading edge camber to further prevent the transfer bridge support means from being displaced during patient transfer, and improved slip-resistant features. 
     A system for enabling a person to singly and ergonomically transfer a patient disposed on a sheet as provided. The system may include a caddy. The caddy may include means for enabling the person to transport the caddy from a first location to a second location, a power train, a hook and web assembly attachable to the power train, a power and switching system in electrical communication with the power train, and means for adjusting a vertical position of the hook and web assembly. The transport means may be operably disposed proximate the caddy. The system may further include means for gradually accelerating and decelerating a transfer force exerted by the power train. The power train may include a motor and a plurality of spools in mechanical communication with the motor. The plurality of spools may further be in mechanical and magnetic communication with the motor. The power train may still further include a plurality of magnetic clutch assemblies and a plurality of slip plates. Each magnetic clutch assembly may be in mechanical communication with the motor and each slip plate may be in magnetic communication with one of the magnetic clutch assemblies. Each spool may be in mechanical communication with one of the slip plates. 
     The hook and web assembly may include a plurality of webs and a plurality of transfer hooks, each web being connectable to one of the spools and each transfer hook being connectable to one of the webs. The power and switching system may further include means for automatically discontinuing a transfer. The system may provide a transfer rod, the transfer rod accommodating the transfer hook when at least a portion of the transfer sheet is wrapped around the transfer hook. The transfer rod may include a plurality of joinable sections, the sections may be elastically connected. 
     The system may further include a transfer bridge. The transfer bridge may further include a low-friction surface and a plurality of sections, foldable into a generally facing relationship. 
     There is also provided a movable caddy for enabling a single person to ergonomically turn a patient disposed on a sheet in cooperation with sheet-gripping means or to transfer the patient from a first horizontal surface to a second horizontal surface in cooperation with the sheet-gripping means. The caddy may include a base assembly, the base assembly including means enabling a single person to transport the caddy from a first site to a second site, a vertical adjustable head assembly, the vertical adjustable head assembly including a power train, the power train including a motor, a plurality of magnetic clutches, a plurality of slip plates, and a plurality of spools. Each magnetic clutch may be in mechanical communication with the motor. Each slip plate may be in magnetic communication with one of the magnetic clutches. Each spool may be in mechanical communication with one of the slip plates. The magnetic clutches and the slip plates may cooperate to exert a gradually accelerable transfer force. The system may further include a hook and web assembly with a plurality of webs and means for gripping the sheet. A first end of each web may be windably attachable to one of the spools. The sheet-gripping means may be attachable to a second end of each of the belts. The sheet-gripping means may grip a portion of the sheet, thereby transmitting the transfer force to the gripped sheet. The sheet-gripping means may include a plurality of transfer hooks and a transfer rod. Each transfer hook may be attachable to a second end of each belt and each transfer hook may cooperate with a transfer rod to grip the sheet. 
     There is also provided a transfer rod for cooperatively gripping and exerting a transfer force on a sheet. A portion of the sheet may be partially enwrapped around the transfer rod, the transfer rod exerting the transfer force in cooperation with the plurality of transfer hooks. The transfer rod may include means for mating with the transfer hooks. 
     There is also provided a transfer bridge. The transfer bridge may include a first inboard member, a plurality of outboard members, means for interfolding the inboard and outboard members, and means for reducing friction arising from contact between a sheet and the transfer bridge. An outboard member may extend from a lateral edge of the first inboard member. The transfer bridge may include a second inboard member and an outboard member may extend from each inboard member. 
     There is provided a substantially pliable underlayment for transferring, repositioning, or rolling a patient disposed thereon, the underlayment including a substantially smooth mantle proportioned to accommodate at least a central portion of the patient&#39;s body, an attaching structure operably adjacent the mantle, and a reinforcing structure for imparting a resistance to distortion of the mantle in response to a force exerted on the attaching structure. 
     There is also provided a method of transferring or repositioning a patient disposed on a substantially pliable underlayment, the method comprising the steps of providing the substantially pliable underlayment, the underlayment including a substantially smooth and pliable mantle, an attaching structure operably adjacent the mantle, and a reinforcing structure for imparting a resistance to distortion of the mantle in response to a force exerted on the attaching structure; attaching a connecting member to the attaching structure; and exerting the force on the connecting member, the force being sufficient to displace the patient. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view of a bed with an adjacent cart adapted with a first embodiment of a horizontal patient transfer system; 
     FIG. 2 is a front, schematic view of a cart adapted with the first embodiment of a horizontal patient transfer system with side rails in a lowered storage position; 
     FIG. 3 is a front, schematic view of a cart adapted with the first embodiment of a horizontal patient transfer system with side rails in a raised patient transport position; 
     FIG. 4 is a front, schematic view of a cart adapted with the first embodiment of a horizontal patient transfer system with one side rail in a raised position and a second side rail in a bridge position used during patient transfer; 
     FIG. 5 is a front fragmentary view of one embodiment of hinges supporting a side rail; 
     FIG. 6 is an exploded view of a side rail of the first embodiment of a horizontal transfer system; 
     FIG. 7 is a cut away view of a second drive system within the side rail; 
     FIG. 8 is a perspective view of a first embodiment of a clamping device useful with a first embodiment of the horizontal transfer system in an orientation to be clamped to a transfer sheet folded over a rod; 
     FIG. 9 is an end view of a first embodiment of the clamping device; 
     FIG. 10 is a perspective view of a second embodiment of the clamping device; 
     FIG. 11 is an end view of the second embodiment of the clamping device; 
     FIG. 12 is a perspective view of a third embodiment of the clamping device; 
     FIG. 13 is an end view of the third embodiment of the clamping device; 
     FIG. 14 is a perspective view of the attachment of a portable horizontal transfer device for the transfer of a patient from one horizontal surface to another; 
     FIG. 15 is a perspective view of the portable horizontal transfer device; 
     FIG. 16 is an exploded view of the portable horizontal transfer device; 
     FIG. 17 is a perspective view of a portable cushion attached to a horizontal surface to provide a smooth continuous surface for the transfer of a patient with the portable horizontal transfer system, with the cushion in a lowered, stored position shown in phantom lines; 
     FIG. 18 is a perspective view of a further embodiment of a horizontal transfer system; 
     FIG. 19 is a partial, cut away perspective view of the further embodiment of the horizontal transfer system showing the drive system for horizontal extensions; 
     FIG. 20 is a perspective view of the further embodiment of the horizontal transfer system with a patient elevated over a cart to indicate the ranges of motion obtainable by the transfer system; 
     FIG. 21 is a perspective view of the further embodiment of the horizontal transfer system with an alternative design for the horizontal drive; 
     FIG. 22 is a fragmentary perspective view of a sheet clamp indicating its motion relative to a lifting support and its attachment to a transfer sheet; 
     FIG. 23 is a perspective view of a bed equipped with the further embodiment of the horizontal transfer device with the bed in a raised position; 
     FIG. 24 is a partial perspective view of one end of the embodiment of FIG. 21 with an arrow showing the disengagement of a removable panel; 
     FIG. 25 is a partial perspective view of one end of the embodiment of FIG. 21 with a removable panel attached as a shelf; 
     FIG. 26 is a perspective view of a portion of the foot board bed or cart adapted with the further embodiment of the horizontal transfer system indicating a location for the attachment of a control unit; 
     FIG. 27 is a top view of a transfer sheet designed for use with the further embodiment of the horizontal transfer system; 
     FIG. 28 is a perspective view of the transfer sheet of FIG. 27 shown in its folded position; 
     FIG. 29 is perspective view of an alternative embodiment of the horizontal transfer system; 
     FIG. 30 is a perspective view of a portion of the alternative embodiment of FIG. 29 showing extendable horizontal supports; 
     FIG. 31 is a perspective view of the alternative embodiment of FIG. 29 being used to assist a patient to sit up; 
     FIG. 32 is a perspective view as in FIG. 31 indicating the rotation of a lifting element; 
     FIG. 33 is a perspective view of a transfer system with a horizontal transfer mechanism; 
     FIG. 34 is a cut away side view of one embodiment of a docking mechanism; 
     FIG. 35 is a cut away side view of a second embodiment of a docking mechanism; 
     FIG. 36 is a perspective view of the transfer system of FIG. 33 with a transfer element bridging between a bed and a cart; 
     FIG. 37 is a perspective view of a transfer bridge used with the transfer system of FIG. 33; 
     FIG. 38 is a perspective view of the transfer bridge of FIG. 37 with the bridge in the bridging position; 
     FIG. 39 is a side view of the transfer bridge in the bridging position with lever and rods removed; 
     FIG. 40 is a side view of the transfer bridge in the raised position with lever and rods removed; 
     FIG. 41 is a perspective view of a split transfer bridge; 
     FIG. 42 is a perspective view of a mattress transfer system; 
     FIG. 43 is a perspective view of a docking mechanism used with the mattress transfer system of FIG. 42; 
     FIG. 44 is a perspective view of a gripping mechanism of the mattress transfer system in pushing position; 
     FIG. 45 is a perspective view of a gripping mechanism of the mattress transfer system in pulling position; 
     FIG. 46 is an exposed, top perspective view of a mattress and fixed cushion of the mattress transfer system indicating the location of structures within and below the mattress and cushion; 
     FIG. 47 is a perspective view of a mattress transfer system used with a position changing cart and a folding mattress; 
     FIG. 48 is a perspective view of the mattress transfer system and position changing cart depicting the cart in a folded position; 
     FIG. 49 is a side view of the position changing cart in the chair orientation; 
     FIG. 50 is a perspective view of a lobster claw type of bed jacket being placed on one side of a person; 
     FIG. 51 is a perspective view of the bed jacket in place around a person; 
     FIG. 52 is a perspective view of the bed jacket secured around a person and hooked to a hoisting mechanism; 
     FIG. 53 is a perspective view of a motorized bed jacket attached to a stand above a wheel chair; 
     FIG. 54 is a front view of a padded vest; 
     FIG. 55 is a perspective view of the padded vest around a person and attached to a tether where hidden portions of the vest are depicted with phantom line; 
     FIG. 56 is a perspective view of a motorized bed jacket being attached to a mount above a headboard; 
     FIG. 57 is a top perspective view of the motorized bed jacket; 
     FIG. 58 is a partial cut away view of the drive system of the motorized bed jacket; 
     FIG. 59 is a perspective view of a bed jacket attached to three hoisting mechanism on a ceiling using a three way control cylinder; 
     FIG. 60 is a side perspective view of the three way control cylinder; 
     FIG. 61 is a schematic view of the internal components of the three way control unit; 
     FIG. 62 is a top right perspective view of another clamp embodiment of the present invention; 
     FIG. 63 is a side plan view of the clamp of FIG. 62, in an open position; 
     FIG. 64 is a side plan view of the clamp of FIG. 62 in a closed, locked position; 
     FIG. 65 is a top perspective view of another clamp embodiment of the present invention, the clamp disassembled and depicted in an exploded view; 
     FIG. 66 is a top perspective view of the clamp of FIG. 65 assembled; 
     FIG. 67 is a top plan view of another clamp of the present invention; 
     FIG. 68 is a side plan view of the clamp embodiment of FIG. 67; 
     FIG. 69 is another embodiment of the transfer system of the present invention, whereby a patient may be bidirectionally transferred without the necessity of reinstalling this embodiment on another bed or cart; 
     FIG. 70 is a side plan view of the embodiment of FIG. 69, wherein a patient is being transferred away from the bed on which the embodiment is installed; 
     FIG. 71 is a side plan view of the embodiment of FIG. 69, wherein a patient is being transferred onto the bed or cart onto which the embodiment is installed; 
     FIG. 72 is a top, side perspective view of a remote control usable for any of the embodiments described herein; 
     FIG. 73 is a top, side view of a remote control, which may be used for any of the embodiments described herein; 
     FIG. 74 is a top, side perspective view of a portable transfer device and clamp installed onto a hospital bed; 
     FIG. 75 is a top, side perspective view of an embodiment of the portable transfer device, wherein a spool or reel may be detachably installed onto a drive shaft; 
     FIG. 76 is a side plan view of any of the portable transfer devices of the present invention depicting a reel for winding a retraction belt, wherein an automatic cutoff device is operationally installed; 
     FIG. 77 is another embodiment of a portable transfer device installed onto a bed, and wherein one of the clamps of the present invention is connected thereto by means of belts; 
     FIG. 78 is a side view of any of the portable transfer devices of the present invention, depicting a mounting bracket and quick release pin; 
     FIG. 79 is a top perspective view of another portable transfer device of the present invention; 
     FIG. 80 is a top perspective view of a detachable remote control for any of the portable transfer devices of the present invention; 
     FIG. 81 is a fragmentary top perspective view of a portable transfer device of the present invention, depicting a clip for securing the jaws therein; 
     FIG. 82 is a fragmentary top perspective view of a portable transfer device of the present invention, depicting a lock-down device for securing the jaws thereto; 
     FIG. 83 is a top plan view of a portable transfer device of the present invention, depicting the downwardly opening jaw portion of the clamp thereto; 
     FIG. 84 is a side plan view of a portable transfer device of the present invention, depicting an upwardly opening jaw portion thereof; 
     FIG. 85 is a top plan view of a motor and winch system, suitable for any of the transfer devices of the present invention; 
     FIG. 86 is an exploded view of the motor and winch assembly of FIG. 85; 
     FIG. 87 is a top front perspective view of a transfer bridge spanning a gap between a bed with a patient reclining thereon and a transfer cart; 
     FIG. 88 is a bottom plan view of an alternate embodiment of the transfer bridge of FIG. 87; 
     FIG. 89 is a fragmentary side view of the transfer bridge of FIG. 87 or FIG. 88, depicting the hinge thereon; 
     FIG. 90 is a top front perspective of the bridge of FIG. 87 being folded and prepared for either transport or storage; 
     FIG. 91 is an exploded view of a clamp of the present invention; 
     FIG. 92 is a top perspective view of the assembled clamp of FIG. 91; 
     FIG. 93 is a side perspective view of a portable transfer unit; 
     FIG. 94 is a side plan view of the portable transfer unit of FIG. 93; 
     FIG. 95 depicts an attendant carrying a portable transfer unit; 
     FIG. 96 is an elevated left perspective view of the patient transfer system of the present invention; 
     FIG. 97 is an elevated left perspective view thereof; 
     FIG. 98 is an exploded view of the top frame of the present invention; 
     FIG. 99 is an exploded view of the base assembly thereof; 
     FIG. 100 is a left elevated perspective view of the remote switch of the patient transfer system of FIG. 96; 
     FIG. 101 is an exploded view depicting the components of the switch of FIG. 100; 
     FIG. 102 is an elevated perspective view of a transfer rod of the present invention; 
     FIG. 103 is an exploded view of the transfer rod of FIG. 102; 
     FIG. 104 is a fragmentary elevated perspective view depicting how the elastic cord is secured to the cord plate of the transfer rod of FIG. 102; 
     FIG. 105 is a top plan view of the transport rod of FIG. 102 being disassembled for storage or transport; 
     FIG. 106 is a top plan view of the transfer rod of FIG. 105 partially disassembled; 
     FIG. 107 is a side plan view of the transfer rod of FIG. 102 disassembled and ready for storage; 
     FIG. 108 is an elevated perspective view of the transfer bridge of the present invention; 
     FIG. 109 is a cross section taken along lines  109 — 109  of FIG. 108; 
     FIG. 110 is a side plan view depicting the transfer bridge of FIG. 108 being folded for storage or transport; 
     FIG. 111 is a side plan view of the transfer bridge of FIG. 108 being completely folded and ready for storage or transport; 
     FIG. 112 is a side plan view of the patient transfer system of FIG. 96 depicting the transfer rod and the transfer bridge in storage positions; 
     FIG. 113 is a side plan view of the patient transfer system of FIG. 96 depicting vertical adjustment of the head assembly; 
     FIG. 114 is a fragmentary elevated perspective view of the head assembly of the lateral patient transfer system with the upper shield removed; 
     FIG. 115 is a fragmentary side view of the head assembly of the lateral patient transfer system depicting a patient transfer in progress; 
     FIG. 116 is a fragmentary side plan view of the patient transfer system depicting completion of a patient transfer event; 
     FIG. 117 is a fragmentary elevated perspective view of the webbing attached to the drum of the head assembly and extending through a slot therefor in the top frame and upper shield and further depicting an interlock switch in place thereto; 
     FIG. 118 is a top plan view of a webbing attached to the drum of the transfer system of FIG. 96; 
     FIG. 119 is a fragmentary elevated perspective view of the transfer hook, joint connector, and webbing of the present invention; 
     FIG. 120 is a side plan view of the hook, joint connector, and webbing of FIG. 119; 
     FIG. 121 is a fragmentary elevated right perspective view of the base assembly of the present invention depicting attachment of the cable to the peddle and actuator assembly thereof; 
     FIGS. 122-132 sequentially depict a patient transfer event by an attendant using the patient transfer system of the present invention; 
     FIG. 133 is a fragmentary elevated left perspective view of a transfer hook emplaced over an enwrapped transfer bar of the present invention; 
     FIG. 134 is a diagram of the electrical and switching system of the present invention; 
     FIG. 135 is an elevated perspective view of another embodiment of the patient transfer system of FIG. 96, with extended bumpers; 
     FIG. 136 is a top plan view of a pair of sheet grippers alternately used with the patient transfer system of FIGS. 96 and 135; 
     FIG. 137 is an elevated left perspective view of an alternate embodiment of the patient transfer system of FIG. 96; 
     FIG. 138 is an elevated rear perspective view of another alternate embodiment of the patient transfer system of FIG. 96; 
     FIG. 139 is a fragmentary perspective view of a stabilizing weight being positioned on a bumper of the transfer caddy of FIG. 96; 
     FIG. 140 is a fragmentary elevated perspective view of the transfer caddy of FIG. 139 with the weight in place; 
     FIG. 141 is a side view of the transfer caddy of FIG. 140; 
     FIG. 142 is a bottom plan view of another embodiment of a stabilizing weigh to be installed on the transfer caddy of FIG. 96; 
     FIG. 143 is a front exploded view depicting placement of the weight of FIG. 142; 
     FIG. 144 is a side view depicting the weight of FIG. 142 installed on the transfer caddy of FIG. 96; 
     FIG. 145 is a top plan view of a first embodiment of a transfer sheet cooperating with a plurality of attaching members to form pockets; 
     FIG. 146 is a top plan view of a second embodiment of the sheet of FIG. 145; 
     FIG. 147 is a top plan view of a third embodiment of the sheet of FIG. 145; 
     FIG. 148 is a fragmentary perspective view of the sheet of FIG. 145 with a repositioning bar being inserted therein; 
     FIG. 149 is a fragmentary perspective view of the sheet of FIG. 145 with a repositioning bar in place; 
     FIG. 150 is fragmentary perspective view of the sheet of FIG. 145 with a repositioning bar inserted and with a transfer hook being attached thereto; 
     FIG. 151 is a fragmentary perspective view of a first embodiment of another sheet of this invention; 
     FIG. 152 is a fragmentary perspective view of a second embodiment of the sheet of FIG. 151; 
     FIG. 153 is a fragmentary perspective view of a third embodiment of the sheet of FIG. 151; 
     FIG. 154 is a fragmentary perspective view of a fourth embodiment of the sheet of FIG. 151; 
     FIG. 155 is a fragmentary perspective view of a transfer hook being connected to the sheet of FIG. 154; 
     FIG. 156 is a top plan view of a transfer and repositioning sheet of this invention; 
     FIG. 157 is a sectional view of the sheet of FIG. 156 taken along line  157 — 157 ; 
     FIG. 158 is a top plan view of a drawsheet layer of the sheet of FIG. 156; 
     FIG. 159 is a sectional view of an alternate embodiment of the sheet of FIG. 156; 
     FIG. 160 is a fragmentary perspective view of another embodiment of a transfer and repositioning sheet of this invention; 
     FIG. 161 is a top plan view of the sheet of FIG.  160 ; 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The invention includes improved devices and methods for moving and repositioning patients and other individuals who lack full mobility. Patients must be moved in a variety of ways in health care facilities such as hospitals, nursing homes and other residences. For example, patients may need to be transferred horizontally between a bed and a cart, they may need to be repositioned in a bed or chair, or they may need to assume a prone, sitting or standing position. The unifying feature of the various embodiments of this invention is enabling empowering a single health care worker to move a patient in a substantially low risk manner to either the patient or the healthcare worker. The embodiments of this invention further allow a patient transfer event to require between about 20 seconds and 28 seconds and preferably about 24 seconds. 
     A feature of the horizontal transfer systems of the present invention includes a support beneath the patient and a mechanical or electromechanical system for applying a horizontal force to the support to effect the transfer. The designs of the various embodiments incorporate varying features to achieve this utility. In order to reduce cost, the simplest systems are designed to be adapted for use with beds, carts and transfer sheets now commonly in use in health care facilities. Other embodiments optimize the particular characteristics of the design with less regard to adaptation to existing equipment. In all cases, each design focuses toward the goal of a safe and efficient ergonomic patient transfer event by a single health care worker. Each design also focuses toward greatly reducing the number of healthcare workers required for each transfer event. 
     This is a continuation-in-part of U.S. patent application Ser. No. 08/713,412, filed Sep. 13, 1996, which is a continuation-in-part of U.S. patent application Ser. No. 08/527,519, now U.S. Pat. No. 5,737,781. The embodiments of the present invention described hereinbelow are also disclosed in U.S. Provisional Application Ser. No. 60/023,572, filed Aug. 19, 1996, in U.S. Provisional Application Ser. No. 60/025,084, filed Aug. 30, 1996, and U.S. Provisional Application No. 60/043,208, filed Apr. 8, 1997, the entire contents of each being hereby incorporated by reference. 
     Referring to FIG. 1, the first exemplary embodiment of horizontal transfer system  100  includes standard patient cart  102  retrofitted with horizontal transfer mechanism  104 . Cart  102  will generally have base  106  with four wheels  108 . Wheels  108  preferably have lock levers  110  for applying brakes to prevent rotation of wheels  108 . Base  106  may have a top surface  112  that usually, but not necessarily, will have a flat portion  114 . 
     Cart  102  includes support portion  116 . Support portion  116  is attached to base  106  by one or more upright supports  118 . The exemplary embodiment represented in FIG. 1 has two upright supports  118 . Some designs may have wheels  108  attached directly to upright supports  118 , thereby eliminating the need for base  106 . Support portion  116  will preferably include cushioned bumpers  120 . Cart  102  may have the capability of raising and lowering support portion  116  relative to base  106 , as well as other features. Support portion  116  provides support structure  122  for supporting cushion (or mattress)  124  for holding patient  126 . 
     Exemplary horizontal transfer mechanism  104  includes two side rails  128 . Referring to FIG. 5, side rails  128  are mounted to cart  102  by hinges  130 ,  131 . Side rails  128  and hinges  130 ,  131  are preferably adapted from existing side rails and hinges on cart  102 . Hinges  130 ,  131  can adjust to place side rails  128  in either an elevated pull position or a lowered storage position as depicted in FIG.  2 . Preferably, hinges  130 ,  131  are used to place side rails  128  in a horizontal bridge position to provide support and a smooth surface for transferring the patient (FIG.  4 ). The different positions are schematically depicted in FIGS. 2-4. Alternative designs for the side rail may allow for the side rail to slide straight down to a lowered position, although other variations are within the spirit and scope of this invention. 
     Referring to FIG. 6, each exemplary side rail  128  includes handle  132 , control panel  134  and a plurality of openings  136  for a power assembly, such as winch  138 . Other openings may be used for access to the winch unit. Control panel  134  has a plurality of switches  140  to control the operation of winch  138 . The particular design of side rail  128  and control panel  134  may be varied without effecting their function. 
     Referring to FIG. 6, a convenient structure for side rail  128  includes frame  142 , winch  138 , front cover  144  and back cover  146 . Frame  142  further includes extensions  148  attached to frame substructure  150  at frame hinge  152 . Frame substructure  150  may include winch mounting portion  154 . Frame substructure  150  may be made from metal, a rigid polymer or a composite material, although other materials exhibiting the proper strength, weight, and cost characteristics may be suitable. Back cover  146  may define open portions  156  and handle  132 . In this example, extensions  148  are disposed through open portion  156 . Moreover, the sizes and configurations of open portions  156  admit frame hinges  152 . Open portions  152  are further dimensioned to admit coincident movement when side rail  128  is raised or lowered by pivoting side rail  128  on hinges  152 . Outer surface  147  of back cover  146  (FIG. 5) is a transfer surface which may include a low friction material to assist with the transfer process and reduce the risk of injury. Front cover  144  includes a mated part of handle  132 . Front cover  144  further defines openings  136  and control panel opening  158 . 
     Winch  138  is coupled to control panel  134  by wires  160 . A conventional manual winch may also be used without excess difficulty, but less conveniently. Drive system  143  may include at least one motor  162 . Both drive system  143  and motor  162  may be configured in a variety of conventional designs. Motor  162  may directly rotate drive shaft  164  as depicted in FIG.  6 . In the embodiment of FIG. 7, motor  162  rotates first drive shaft  165 , thereby rotating first gear  166 . First gear  166  engages second gear  168 . Second gear  168  is connected to second drive shaft  170 . Second gear  168  may have a larger diameter than first gear  166 , thereby causing a reduced rate of rotation of second drive shaft  170  relative to first draft shaft  165 . 
     Two belts  172  each with a clip  174  are attached to second drive shaft  170  at positions coincident openings  136 . Belts  172  preferably wind on spools  175 . Spools  175  help ensure that belts  172  wind and unwind straight. Belts  172  are preferably made from very strong synthetic fabric such as the material used in seat belts for automobiles. Winch  138  may be powered by a battery pack  176 . Winch  138  and battery pack  176  are electrically connected by power cord  178 . Alternatively, winch  138  may be powered by alternating current using another power cord (not shown). Cart  102 , or any other embodiment of the present invention, may also include aligning and docking mechanisms. Aligning mechanisms may further include powering and steering means, whereby at least two wheels  108  of cart  102  are powered and steered by operation of control switches  140 . Docking mechanisms may include clamps and electromagnets. These clamps and electromagnets may also be operated by control switches  140 . These clamps and electromagnets may secure cart  102  to the horizontal surface onto which the patient is to be transferred. 
     In addition to control switches  140 , hand-held remote control units communicating with the control mechanism of cart  102  by electric or electromagnetic means are within the scope of the present invention. Voice actuated controls are also within the scope of the present invention, thereby enabling the patient, as well as an attendant, to begin and discontinue a transfer event. 
     Cart  102 , or any other embodiment of the present invention, may further include means for sensing an asynchronous operation of the transfer mechanisms. Such means include sensing the individual belt torque or drag experienced when belts  172  are being retracted and a comparison of these sensings. A difference between sensings exceeding a predetermined value or a sensing ratio greater than or less than a predetermined ratio range would result in an alarm being actuated or an automatic discontinuance of transfer. 
     Cart  102  of FIG. 1 is designed for use with standard patient draw sheet  190 . Standard patient draw sheet  190  is sufficiently wide that it can be folded over patient  126  if desired. Typically draw sheet  190  is not long enough that it extends under the head or feet of the patient. Rather than using several persons to move the patient disposed on draw sheet  190 , horizontal transfer mechanism  104  performs a comparable function. Clips  174  are designed to attach directly to draw sheet  190 . However, a worker may also use another clamping device to provide a more even pull over more of the length of sheet  190  and thus provide a smoother transfer motion to the patient. For particularly tall patients, draw sheet  190  may be wrapped around patient  126  for added support. Both ends of draw sheet  190  are then attached to the clamping device. 
     Three embodiments of exemplary clamping device  194  are presented in FIGS. 8-13. The first embodiment of clamping device  194  is shown in FIGS. 8 and 9. Clamping device  194  may be used to attach draw sheet  190  to winch  138 . Clamping device  194  may employ rod  192  in doing so. A cross section of clamp  196  includes U-shaped portion  196 , which forms cavity  198 . Cavity  198 , in turn, is covered by spring loaded gate  200 . Rod  192  can enter cavity  198  when pushed against gate  200 . Force from rod  192  against gate  200  from inside cavity  198  tends to force gate  200  closed, thereby further preventing withdrawal of rod  192 . Gate  200  includes upward extension  202 . Forward force on upward extension  202  opens gate  200  for the withdrawal of rod  192  from cavity  198 . Clips  174  are conveniently attached to clamping device  194  at J-shaped flanges  204 . Rod  192  can be optionally tethered to the clamping device  194  at one or more positions. Rod  192  may also be clipped to clamping device  194  for storage. 
     In the second and third embodiments, clamping device  194  includes upper portion  206  and lower portion  208  attached at hinge  210 , thereby defining cavity  212 . The front of cavity  212  is closed by L-shaped, hinged closure  214 . The two embodiments to device  194  differ in their design for J-shaped flanges  216 ,  218  for attaching clips  174 . In these embodiments, sheet  190  is directly placed into cavity  212  without the need to wrap sheet  190  around rod  192 . However, rod  192  could still be used if desired. Sheet  190  is held in place by L-shaped hinge closure  214 . A thin rigid tucking device (not shown) of any convenient length may be used if desired to assist with tucking sheet  190  into clamp  194 . 
     Clearly, a variety of other designs for clamping device  194  are possible within the general concepts presented. In each of these embodiments, any portion of sheet  190  may be attached, not just the edge of sheet  190 . This is an important feature because clamping device  194  should preferably be placed as near as possible to the patient so that transfer mechanism  104  can fully transfer the patient from the first horizontal surface to the second. 
     In operation, cart  102  is wheeled to a patient&#39;s bed  220 , as depicted in FIG. 1, or onto another cart. Side rail  128  facing bed  220  is placed in the bridge position with low friction surface  147  directed upward. Draw sheet  190  is attached to a clamping device. Belts  172  are unwound from drive shafts  164  or  170  until they reach rod  192  at the edge of bed  220 . Belts  172  are unwound either by activating motor  162  to unwind them or by using a clutch (not shown) to allow belts  172  to be freely withdrawn from the drive shaft. Clips  174  on the ends of belts  172  are attached to exemplary clamping device  194 . Clamping device  194  is then engaged by rod  192  and sheet  190 . Other embodiments of clamping device  194  may be used with or without rod  192 . 
     After the appropriate switch mechanism  140  is actuated, winch  138  begins winding belts  172  onto drive shafts  164  (FIG. 6) or spool  175  (FIG.  7 ). Motor  162  may be designed to apply a slow, steady and constant force to move patient  126  without jerking. Motor  162  may further advantageously provide variable speeds of movement consistent with gradual starts and stops and safe transfer throughout the length of travel. Draw sheet  190  helps to distribute transfer forces over significant areas of the patient&#39;s body. When patient  126  is on cart cushion  124 , motor  162  is turned off or otherwise disengaged. At this point, belts  172  are disconnected from clamping device  194 . Sheet  190  is then removed from clamping device  194 . 
     To transfer a patient from a cart to a bed, the bed should be equipped with a winch such as winch  138  present on cart  102 . This bed-based transfer device may include the side rails of a conventional bed. These side rails typically slide vertically rather than folding under the bed. Winch  138  could easily be adapted on one or both sides of the bed, and may be retrofitted to a bed in a comparable fashion as with cart  102 , based on the above description. 
     Alternatively, a portable winch unit readily carried by a single health care provider may be used to replace winch  138  on bed  220 , or cart  102 . Exemplary portable winch unit  250  is shown in FIGS. 14-16. Portable winch unit  250  includes housing  252 , clamping device  254  and winch  256 . Clamping device  254  may hold and grip transfer sheet  190  in a similar manner as clamping device  194 . Clamping device  254  also serves as a frame or a portion of a frame for the portable winch unit  250 . Housing  252  preferably includes top portion  258  and bottom portion  260 . Top portion  258  and bottom portion  260  may be heavy plastic shells surrounding clamping device  254  and winch  256 . 
     Winch  256  includes motor  262 . In operation motor  262  rotates a drive shaft (not shown) on which reel  263  is mounted. Belt  264  winds around reel  263 . Belt  264  is comparable to belts  172  in embodiment  100 . Handle  266  attaches to a free end of belt  264 . Handle  266 , in turn, attaches to clamp  268 . Clamp  268  attaches to the edge of a bed or cart. Clamp  268  may be designed to fold out of the way when not in use. Belt  264  passes out of housing  252  through opening  270 . The operation of winch  256  may be controlled through circuit board  272 . Circuit board  272  may electrically connect to motor  262  by means of wire  274 . Circuit board  272  may be electrically connected to port  276 . 
     Control unit  278  with switches  280  may be electrically connected to port  276  by way of tether  282 . The operator may operate winch  256  using control unit  278 . Alternatively, control switches  280  may be present within housing  252 , as shown in FIG.  15 . However, this may be less desirable because the operator would need to lean over the bed or cart while the patient was being transferred. Control unit  278  may also have a wireless connection with circuit board  272  using a transmitter/receiver (not shown). Winch  256  may be powered by a standard wall outlet using cord  284 . Retractable cord assembly  286  may be used to retract cord  284  when cord  284  is not in use. Retractable cord assembly  286  may also be used to prevent excess cord from being in the way during a patient transfer. Alternatively, a battery, preferably rechargeable, may be used to power winch  256 . 
     As shown in FIG. 14, a patient may be transferred from a first bed/cart  288  to a second bed/cart  290 . Draw sheet  190  may be disposed under the patient in a similar manner as described above with respect to embodiment  100 . FIG. 17 depicts portable cushion  292 . Cushion  292  may be placed between the first bed/cart  288  and the second bed/cart  290  to provide a relatively smooth continuous surface for transferring the patient. Mating portions of a hook and loop fastener are present on a surface of portable cushion  292  and the bed or cart. Thus, portable cushion  292  may be attached to the bed or cart when not in use. Portable cushion  292  may also be used with other transfer devices or as an aid during a manual transfer. A top surface of cushion  292  may include a very low friction material. The very low friction material may be plastic. 
     Portable winch unit  250  may be attached to draw sheet  190  by means of clamping device  254 , (FIGS. 15,  16 ). The design of clamping device  254  may be similar to the clamping devices in FIGS. 8-13 or a comparable design based on similar concepts. Draw sheet  190  may be wrapped about rod  192  (FIG. 8) for attachment to clamping device  254 . Referring to FIG. 14, belt  264  is withdrawn from housing  252  so that handle  266  can be attached to clamp  268 . Clamp  268  is rigidly attached to second bed/cart  290  on its side opposite the side near first bed/cart  288 . Clamp  268  can be optionally reversibly detachable or lowerable to a storage position. The operator uses control unit  278  to activate motor  262 . As motor  262  retracts belt  264 , portable winch unit  250  and the patient are drawn toward clamp  268  which result in the patient being moved onto second bed/cart  290 . 
     Referring to FIG. 14, the transfer devices of the present invention, especially the clamps, are designed to be centered at the patient&#39;s center of gravity when the patient is in a supine position. A patient&#39;s center of gravity is usually about midway between the patient&#39;s navel and buttocks, represented as lines N and B, respectively. Thus, to move the patient smoothly and evenly, the clamp center of gravity (represented by arrow C) should be aligned about midway between lines N and B on the patient. 
     Exemplary horizontal transfer system  300  includes an especially designed transfer sheet  302  and transfer unit  304 , as shown in FIG.  18 . Transfer unit  304  can move a patient in either of two directions. Thus, horizontal transfer system  300  has the advantage that only the cart or bed, but not both, must be equipped with transfer unit  304 . Therefore, the cart or bed not adapted by transfer unit  304  may be conventional in design. 
     Transfer unit  304  includes head frame  306  and foot frame  308 . Head frame  306  and foot frame  308  are in mechanical communication with drive system  310  (FIG.  19 ). Head frame  306  replaces or attaches to the head board of the bed or cart. Foot frame  308  replaces or is attached to the foot board of the bed or cart. Head frame  306  and foot frame  308  include at least one vertical support  312 . A bottom portion of vertical support  312  may include wheel  314 . Wheels  314  are oriented to roll in a direction defined by the width of the bed/cart. Wheels  314  may be attached to vertical support  312  in such a manner that wheels  314  are shifted up and out of contact with the floor. Thus, the bed or cart may then be moved more easily because wheels  314  are retracted away from the floor. Vertical supports  312  may have a removable brace (not shown) extending therebetween. When in use, the removable braces serve to enable vertical supports  312  to become more rigid by compensating for forces created by the weight of the patient during transport. 
     Referring to FIGS. 19-21, head frame  306  and foot frame  308  each include at least one expandable horizontal support  316  and lifting support  324 . Each horizontal support  316  extends from vertical supports  312 . Horizontal supports  316  include fixed portions  318  and telescoping portions  322 . Fixed portions  318  are attached to the head board, foot board, head board portion  320 , or foot board portion  320 . Fixed portions  318  may extend at least across the width of the bed or cart. Telescoping portions  322  are attached to each vertical support  312  and slidably engage a corresponding fixed portion  318 . In certain embodiments, telescoping portion  322  will slide into a corresponding fixed portion  318 , although other types of slidable engagement are possible. 
     Lifting support  324  slidably attaches to fixed portion  318  such that lifting support  324  moves with vertical support  312  and telescoping portions  322 . Each lifting support  324  includes gripping portion  328  and two lifting portions  330 . Gripping portion  328  may define opening  332 . Sheet clamp  325  will be discussed in more detail hereinbelow. However, first ends of cables  327  may extend from sheet clamp  325  through opening  332 . Second ends of cables  327  may be secured to gripping portion  328 . Thus, raising lifting support  324  will also raise clamp  325 . Referring to FIG. 23, cables  327  permit sheet clamps  325  to remain attached to transfer sheet  302  while mattress support  329  goes through a range of motion. In one configuration, first lifting portion  330  engages vertical support  312  at slot  336 . Second lifting portion  330  engages moving support  338  which is attached to telescoping portion  322 . 
     Exemplary lifting support  324  is capable of a range of vertical motion. The range of vertical motion enabled by lifting support  324  will typically be between 6″ and 12″. This range of vertical motion provides sufficient clearance for a horizontal transfer from a first bed/cart to a second bed/cart. Thus, retrofitted bed/cart  326  with attached transfer unit  304  can transfer patients from or to retrofitted bed/cart  326 . Lifting support  324  also enables workers to change linen more conveniently. However, transfer sheet  302  needs to be changed separately. 
     Referring to FIG. 19, drive system  310  includes horizontal drive system  340  and vertical drive system  342 . Drive system  310  is operated from control panel  344  (FIGS.  18 - 20 ). Control panel  344  may be located on vertical supports  312 . Alternatively, portable controller  345  (FIG. 23) is patched into head frame  306  or foot frame  308  through connector  348 . Other embodiments for controlling drive system  310  are possible. Drive  342  enables vertical motion of lifting support  324 . Drive  342  may be adapted to operate by motorized worm drive  343  or by other motor or hydraulic systems. 
     Two embodiments are shown for horizontal drive system  340  in FIGS. 19 and 21, respectively. The first embodiment includes motor  350 . Motor  350  is secured to the frame of bed/cart frame  352 . Motor  350  turns drive shafts  352 ,  354 . Drive shafts  352 ,  354  connect to transmission  356 . Transmission  356 , in turn, is in mechanical communication with telescoping portion  322 . Thus, actuating motor  350  results in extending or retracting telescoping portion  322  within fixed portion  318 . 
     The second embodiment of drive system  340  includes motor  358  mounted on either head frame  306  or foot frame  308 . Motor  358  rotates worm drive  360 . Worm drive  360  is mounted horizontally alongside motor  358 . Worm drive  360  transfers motion from motor  358  to telescoping portion  322 . Optional removable panel  362  can be removed, as shown in FIG. 24, and mounted on foot frame  308 . When mounted on foot frame  308 , panel  362  may be used as a shelf, as a cardiopulmonary resuscitation (CPR) board, or to support additional equipment as shown in FIG.  25 . 
     An appropriate transfer sheet  302  for use in this embodiment of horizontal transfer unit  300  is depicted in FIGS. 27 and 28. Transfer sheet  302  includes wings  380 . Hook and loop or comparable fasteners  382  may be present on the edges of wings  380 . Wings  380  may be folded over the patient and closed with fasteners  382 . The shape of wings  380  may be selected as desired. The top and bottom of transfer sheet  302  may include reinforced attachment portions  384 . Reinforced holes, grommets  334 , or other improved attachment means are optionally present within reinforced portions  384 . Sheet  302  may be attached to sheet clamps  325 . Alternatively, sheet  302  may be attached to the clamps shown in FIGS. 8-13. The presence of grommets on sheet  302  may be a disadvantage when sheet  302  is being laundered. Attachment portions  384  will generally extend to or just beyond the end of the mattress  386 . Other designs are possible for sheet  302 , for example an embodiment which does not fold over the patient. 
     As depicted in FIGS. 19 and 20, vertical supports  312  and telescoping portion  322  are initially placed in a retracted position if the patient is being moved from retrofitted bed/cart  326 . Vertical supports  312  and telescoping portion  322  are initially placed in their extended position if the patient is being moved from a separate bed/cart  331  to retrofitted bed/cart  326 . Transfer sheet  302  is optionally folded over the patient, and fasteners  382  are secured together. Attachment portions  384  are placed into opening  332  and sheet clamps  325  engage reinforced holes  334 . At this point, vertical drive system  342 , originally in its lower point, is engaged to extend to its upper point, thereby raising the patient into a suspended position. 
     Horizontal transfer system  300  is engaged accordingly to move the patient from an original location to the transfer location. If the patient was originally disposed on retrofitted bed/cart  326 , vertical supports  312  and telescoping portion  322  are moved to extended positions. If the patient was not originally located on the retrofitted bed/cart  326 , vertical supports  312  and telescoping portion  322  are moved to retracted positions. Once the horizontal transfer is complete, vertical drive system  342  is lowered and transfer sheet  302  is disengaged therefrom. 
     Another embodiment of a patient transfer device  400  is shown in FIG.  29 . Head portion  402  and foot portion  404  may be similar in construction to head frame  304  and foot frame  306 , respectively. However, head portion  402  and foot portion  404  lack lifting supports  324  attached to telescoping portion  320 . Head portion  402  and foot portion  404  instead include top supports  406 . Top supports  406  support upper transverse support  408 . Upper transverse support  408  provides support to counterforces resulting from the weight of the patient during a transfer. 
     Upper transverse support  408  may include transverse tracks  410  on both sides thereof. Transverse tracks  410  support lifting elements  412 . Lifting elements  412  include track wheels  414 . Track wheels  414  rotate within tracks  410 , thereby enabling lifting elements  412  to transverse thereon. Lifting elements  412  may include winches (not shown) to retract cords  416 . Cords  416  may have fasteners  418  at their ends for attaching to reinforced holes or grommets  420  at the corners of draw sheet  422 . Retracting cords  416  raise draw sheet  422 , on which the patient is secured therewithin. 
     As shown in FIG. 30, extendable horizontal supports  424  may include wheels  428 . Horizontal supports  424  enable lateral motion of vertical supports  426 , along with upper transverse support  408  and lifting elements  412 . As with system  300 , device  400  can transfer a patient from a retrofitted bed/cart to a second bed/cart or from a second bed/cart to the retrofitted bed/cart. 
     An exemplary single lifting element  412  is depicted in FIGS. 31,  32 . Element  412  may be used with lift jacket  430 . Lift jacket  430  fits around the torso of a patient and includes loops  432 . Fasteners  418  attach to loops  432 . When thusly attached to lift jacket  430 , cords  416  may be retracted, thereby lifting the patient&#39;s torso off the bed and into a bent position at the patient&#39;s waist. Lifting element  412  may then be translated and rotated as shown in FIGS. 31 and 32, thereby placing the patient in a seated position at the side of the bed. The patient&#39;s back is supported in this position. In this way horizontal transfer device  400  serves a second purpose in assisting a patient from a supine to a sitting position. 
     Exemplary transfer system  500  is depicted in FIG.  33 . Transfer system  500  is designed for retrofitting both bed  502  and cart  504 . Transfer system  500  includes horizontal transfer mechanism  508  and transfer bridge  510  (FIGS.  37 - 41 ). Horizontal transfer mechanism  508  includes docking mechanism  506 . FIGS. 34 and 35 depict two representative embodiments of docking mechanism  506 . Bed  502  of the first embodiment includes foot board  518 . An opening  516  is defined in the side of foot board  518 . The first embodiment of transfer system  500  includes spring loaded clamp  512 . Clamp  512  includes arms  514 , each arm  514  with an angled front edge  524 . Arms  514  protrude from opening  516  at side of foot board  518  of bed  502 . Spring loaded clamp  512  engages cavity  520 , which opens into transfer bar  522 . When angled front edge  524  of arms  514  engage cavity  520 , arms  514  resiliently deflect towards each other until tips  526  clear flanges  528 . When tips  526  clear flanges  528 , arms  514  return outwardly as tips  526  engage flanges  528 . Arms  514  pivot on docking support  530  within bed foot board  518 . Head boards (not shown) of bed  502  and cart  504  have a comparable docking mechanism. When clamp  512  is protruding from opening  516 , arms  514  may be disengaged by being pressed together. 
     The second embodiment of the docking mechanism  506  is depicted in FIG.  35 . In this second embodiment, gear  538  is supported by a docking support  540 . Gear  538  protrudes from opening  542  in the side of bed foot board  544 . Protruding gear  538  engages teeth  548 , which are disposed on top surface  550  of cavity  552  within transfer bar  522 . Gear  538  may flex slightly on its support  540  to engage teeth  548 . Cavity  552  within transfer bar  522  may not have flanges at its opening. Gear  538  is disengaged by pressing downwardly on docking support  540  when docking support  540  is protruding from opening  542 . The head boards (not shown) of bed  502  and cart  504  may have a comparable docking mechanism. 
     The two embodiments of docking mechanisms  506  are described in a particular configuration with respect to the cart and the bed. This configuration may be reversed with the bed containing protruding gear  532  or clamp  512 . In either configuration, the protruding gear or clamp may be retracted by worm gear drive  532  during a docking. 
     Horizontal transfer mechanism  508  is shown in FIG.  36 . Transfer mechanism  508  includes transfer element  556  and drive system  558 . Transfer element  556  includes gripping mechanism  560  and transfer bar  522 . Gripping mechanism  560  grips transfer sheets such as transfer sheet  302 . Gripping mechanism  560  is attached to transfer bar  522  by a plurality of support bars  564 . Gripping mechanism  560  may be similar to sheet clamp  325 . Transfer bar  522  slides within cart channel  566  and bed channel  568 . Cart channel  566  and bed channel  568  respectively define slots  570 ,  572 . Support bars  564  extend through slots  570 ,  572  within cart channel  566  and bed channel  568 , respectively. Docking supports  530  or  540  may be moved laterally by drive system  558  which may comprise worm gear drive  532  (FIGS. 34,  35 ). Worm gear drive  532  includes motor  534  and worm  536 . Rotating worm  536  laterally moves docking supports  530  or  540 . The motion of the docking supports  530  or  540  moves transfer bar  522  within channels  566  and  568  (FIG.  28 ). Worm gear drive  532  can move the transfer bar  522  in either direction, thereby effecting a patient transfer in either direction. 
     Transfer bridge  510  is mounted on the side of cart  504  (FIGS. 37,  41 ). Transfer bridge  510  includes bridge  574 , lever  576  and mounting portions  578 . Bridge  574  is preferably molded from a low friction material such as, for example, polypropylene, to facilitate passage of the transfer sheet. It is recognized that other low friction materials may also be suitable. Mounting portions  578  are attached to the side of cart  504  by rods  580 . Mounting portions  578  include hinge  582  which supports bridge  574 . Lever  576  passes through mounting portions  578 . Rotating lever  576  changes the configuration of hinges  582 , thereby moving bridge  510  between a stored position and a bridge position, as shown in FIGS. 37-40. In the bridge position, bridge  574  fills in the gaps between bed  502  and cart  504 . In the storage position, bridge  574  may function as a side rail for cart  504 . FIG. 41 depicts a different embodiment of transfer bridge  510 , including split transfer bridge portions  584 . These embodiments of the transfer bridge may be adapted for use with other transfer systems including the conventional manual transfer system. 
     To transfer a patient between bed  502  and cart  504 , transfer sheet  302  is attached to gripping mechanisms  560  proximate the patient&#39;s head and foot, in a similar manner to the attachment of transfer sheet  302  in the embodiment of FIG.  18 . Referring to FIG. 36, cart  504  and bed  502  are positioned to align channels  566  and  568 . Referring to FIG. 38, transfer bridge  510  is placed in its transfer position to fill the gap between bed  502  and cart  504 . As shown in FIG. 36, drive system  558  is engaged to move transfer element  556  from bed  502  or cart  504  where the patient was located to the bed  502  or cart  504  to which the patient is being transferred. Once the patient is transferred, cart  504  and bed  502  are undocked, and transfer sheet  302  is disconnected from gripping mechanisms  560 . 
     The above transfer systems rely on supporting the patient on some type of sheet during the transfer. However, present methods often rely on health care personnel to provide the necessary transfer forces, usually by pulling a transfer sheet. However, supporting the patient on a sheet may be inappropriate for patients with certain injuries. Hence, it may be safer to transfer the entire mattress or cushion, as described below. 
     FIG. 42 depicts exemplary bed  600 . Bed  600  includes exemplary mattress transfer system  602 . Bed  600  supports modular mattress  604  and fixed cushion  606 . Modular mattress  604  includes wing  608  made of padded fabric in this example. Wing  608  wraps around fixed cushion  606  to form a smooth surface without gaps, as shown in the insert to FIG.  42 . Wing  608  tucks under modular mattress  604  when not in use. Referring to FIG. 43, bed  600  connects to cart  610  by way of docking mechanism  612  when mattress  604  is to be transferred. Docking mechanism  612  includes one or more apertures  614  for accepting projections  616 . FIG. 43 displays apertures  614  on bed  600  and projections  616  on cart  610 . However, the opposite arrangement would work similarly. It is possible to provide a locking mechanism (not shown) to lock projections  616  within apertures  614 . The locking mechanism would prevent relative motion of bed  600  and cart  610  during transfer of modular mattress  604 . However, the same effect may be accomplished by locking the wheels of cart  610 . 
     In one embodiment, mattress transfer system  602  includes transverse bar  618 , a plurality of lateral bars  620  and at least one lateral drive bar  622 . Transverse bar  618  is connected to the plurality of lateral bars  620  and to at least one lateral drive bar  622 . Lateral bars  620  slide along lateral tracks  624 . Lateral drive bar  620  engages lateral drive track  626 . Lateral bars  620  and lateral drive bars  622  allow transverse bar  618  to extend just past the edge of bed  600 . Transverse bar  618  has a plurality of gripping mechanisms  628 . Each gripping mechanism  628  may assume a pushing position (FIG. 44) and a pulling position (FIG. 45) for respectively pulling and pushing modular mattress  604 . 
     Referring to FIGS. 42 and 46, gripping mechanisms  628  grip handles  630  near the edge of modular mattress  604 . Mattress transfer system  602  is controlled from control panel  632  mounted on foot board  634 , as shown in FIG.  42 . Actuating mattress transfer system  602  moves transverse bar  618  either toward or away from cart  610  by moving lateral drive bar  622  accordingly. Of course, a variety of designs are possible for the mattress transfer system  602  besides the embodiment described. 
     Referring again to FIG. 46, modular mattress  604  may include channel system  636  to accommodate transfer system  602 . Channel system  636  includes transverse void  638  and longitudinal channels  640 . Transverse void  638  accommodates transverse bar  618 . Longitudinal channels  640  accommodate lateral tracks  624  and lateral drive track  626 . Handles  630  are located along an upper surface of transverse void  638 . To the extent necessary, channels  642  may be present within fixed cushion  606 . 
     In order to transfer modular mattress  604 , cart  610  is first docked with bed  600  using docking mechanism  612 . If modular mattress  604  is being moved to cart  610 , the patient is centered on modular mattress  604 , and gripping mechanisms  628  are set from control panel  632  into a pushing position. Mattress transfer system  602  is then operated to move transverse bar  618  toward cart  610 . When modular mattress  604  is located on cart  610 , docking mechanism  612  is disengaged. 
     If modular mattress  604  is being moved from cart  610  to bed  600 , cart  610  and bed  600  are docked appropriately. Then, transverse bar  618  is placed into an extended position within transverse void  638 . Gripping mechanisms  628  are placed in their pulling position. Mattress transfer mechanism  602  is operated to move transverse bar  618  away from cart  610 . When modular mattress  604  is in position on bed  600 , mattress transfer system  602  is stopped and docking mechanism  612  is disengaged. 
     Bed  600  with mattress transfer system  602  may be adapted to cooperate with exemplary position changing cart  650  when used with folding mattress  652 , as shown in FIGS. 47-49. Position changing cart  650  includes base  654  and a plurality of, preferably two, arms  656 . Base  654  has a plurality of locking wheels  658  to provide a relatively broad base of support for cart  650 . Base  654  should have sufficient weight and a relatively low center of mass such that cart  650  is stable. Top  660  of base  654  provides support for the center of folding mattress  652  when mattress  652  is positioned on cart  650 . 
     Arms  656  may include support portion  662  and lever portion  664 . Support portions  662  extend laterally toward bed  600  from the far edge of cart  650 . Lever portions  664  are rigidly attached to support portions  662  at one end and are attached to hinge mechanism  666  at base  654 . Support portions  662  support folding mattress  652  when mattress  652  is positioned on cart  650 . A folding drive (not shown) within base  654  is operated from control panel  668  at the side of base  654 . The folding drive operates to rotate hinge mechanisms  666  to change folding mattress  652  from a prone configuration to a seated configuration, or visa versa, as depicted in FIGS.  47 , 49 . 
     When going from a supine to a seated configuration, lever portion  664  at the head of mattress  652  rotates upwardly and lever portion  664  at the foot of bed  400  rotates downwardly. Folding mattress  652  may include creases  670  to accommodate changes in configuration. Movement of folding mattress  652  on and off position changing cart  650  is analogous to moving modular mattress  604  on and off cart  610 . 
     The next devices are designed to hoist, or pull up, a patient disposed on a bed or a chair. These devices are configured with at least one lifting device and at least one winch system. Exemplary embodiment  700  illustrates a hoist system. Hoist system  700  includes “lobster claw-shaped” bed jacket  702 , as shown in FIGS. 50-52. Bed jacket  702  has two “claw” portions  704  joined at joint  706 . Claw portions  704  are made of fabric enclosing a padding in one embodiment. Exemplary joint  706  includes folds in the fabric which enable a greater flexibility therein. No portion of bed jacket  702  fits under the mid-torso of a patient. Hence, it is relatively easy to place bed jacket  702  on the patient. Lifting forces generated when bed jacket  702  is used are distributed across the patient&#39;s chest and the patient&#39;s neck is supported by claw portions  704 . 
     Claw portions  704  may display edges  708  at their ends opposite joint  706 . Edges  708  may be joined by hook and loop fastener  710 , with clips (not shown), as well as other suitable fasteners. However, edges  708  do not necessarily have to be joined before the patient is moved by bed jacket  702 . In use, joint  706  is placed across the patient&#39;s chest and claw portions  704  are placed under the patient&#39;s arms. Edges  708  may be joined behind the patient&#39;s neck, if desired. If edges  708  are not joined, they will nonetheless be held together by loops  714 . Loops  714 , in turn, are attached to a hoist cable as described below. 
     Bed jacket  702  may be used with at least two embodiments of the winch system described herein. A first embodiment, winch system  712 , is depicted in FIG.  52 . In this embodiment, bed jacket  702  includes loop  714  for attaching tether  716 . Tether  716  winds on external winch  718 . External winch  718  may be attached to head board  720 , located on support  722 . Support  722  may be in an elevated position above a bed or wheel chair  724  (FIG. 53) or mounted to a ceiling (FIG.  52 ). External winch  718  may be operated manually with a hand crank (not shown) or with a motor (not shown). If present, the motor may be controlled by a control panel. 
     As shown in FIGS. 54,  55 , external winch  712  may also be used with padded vest  762 . Exemplary padded vest  762  offers many of the same advantages as lobster claw bed jacket  702 . Padded vest  762  includes foam portion  764  and straps  766 . Foam portion  764  fits across the patient&#39;s chest. Two adjustable straps  766  extend from foam portion  764 . One strap  766  includes head support  768  attached thereto. The free end of head support  768  may be attached with hook and loop fastener  770  or a comparable fastener to the other strap  766 . Rings  772  may be attached to the ends of straps  766 . Rings  772  attach vest  762  to tether  716 . Tether  716  is wound about winch  718 . 
     FIGS. 53,  56 - 58  depict exemplary winch system  726 . Winch system  726  includes bed jacket  730 . Winch mechanism  728  is disposed within bed jacket  730 . Winch mechanism  728  is preferably motorized. Winch mechanism  728  is embedded in one of claws  732  of bed jacket  730 . However, winch mechanism  728  may be imbedded in other designs of bed jackets as well. Exemplary winch mechanism  728  includes motor  734 . Motor  734  rotates drive shaft  736 . Spool  738  is mounted on drive shaft  736 . A first end of tether  740  is attached to spool  738 . Ring  742  is attached to the second end of tether  740 . 
     Claw  732  may also include controls such as release switch  744 , recoil switch  746 , pull switch  748  and lower switch  750 . Release switch  744  releases spool  738 , allowing tether  740  to be unwound therefrom. Recoil switch  746  winds tether  740  on spool  738  using a spring mechanism (not shown) if there is a sufficiently minimal resistance from tether  740 . Pull switch  748  activates motor  734  to wind tether  740  on spool  738 . Lower switch  750  actuates motor  734  in the opposite direction, thereby releasing tether  740  from spool  738 . Optionally, controls  744 - 750  may be disposed externally to bed jacket  730 . If so, controls  744 - 750  may be contained within a remote control unit or mounted to a bed. External control units may communicate with winch mechanism  728  either through a wired or wireless (transmitter/receiver) communication in a similar manner to control unit  278  on the clamp embodiments depicted in FIGS. 15 and 16. 
     Exemplary ring  742  may be attached to head board  720 , to an elevated support on wheel chair  722  or to ceiling mount  52 . Thus, motorized bed jacket  730  may be used in the same way as its non-motorized counterpart  702 . Winch-bed jacket combination  730  is more versatile because it may be used without separate winches. Furthermore, controls  744 - 750  are conveniently located. Hence, a health care worker can operate controls  744 - 750  while being close enough to the patient to assist in the transfer thereof. 
     Bed jacket  702  may also be connected by way of three axis control cylinder  752  to three ceiling mounted winches  754 , as shown in FIGS. 59 and 60. Control cylinder  752  may connect to bed jacket  702  by way of ball  756 . Ball  756  fits into ball joint  758 . Control cylinder  760  may include three switches  760 . Each switch  760  controls motion along one of three axes. Referring to FIG. 61, switches  760  are in electrical communication with microprocessor  753 . Microprocessor  753  may be preprogrammed to include the locations of winches  754  in its memory. Thusly programmed, microprocessor  753  may calculate instructions for winches  754  to perform selected motions. Microprocessor  753  may be connected to winches  754  by way of wires  755 . This versatile system can be used in a variety of ways including transferring a patient from bed  762  to a wheel chair  724  and pulling the patient up in either bed  762  or wheel chair  724 . Padded vest  724  may also be used with three axis control cylinder  752 . 
     FIGS. 62-95 further relate to features of a portable patient transfer system of the present invention. Each component thereof, is consistent with the patient care and health care injury reduction goals stated above. Referring to FIGS. 62-64, exemplary engaging mechanism  800  is shown. Engaging mechanism  800  is designed for engaging or clamping a sheet bearing a patient. Engaging mechanism  800  includes forwardly opening element  802 , arcuate engaging element  804 , belt engaging element  806  and cylindrical member  807 . In this embodiment, elements  802 ,  804  are elongated and may have a length of at least greater than about 60 cm and preferably at least about 100 cm. Element  802  includes interiorly disposed movable extension  808 . A laterally disposed edge, such as convex edge  810 , is present on extension  808 . Arcuate engaging element  804  displays exterior surface  812  and interior surface  814 . Interior surface  814  defines cavity  816 . A plurality of belt engaging elements  806  are affixed to element  802 . Elements  806  extend through engaging element  804 . At least one engaging slot  817  is defined exterior to engaging element  804  on belt engaging element  806 . Disposed on each end of element  802  is pivot means  818 . Pivoting member  820  is slidingly and rotatingly affixed about pivot means  818 . Pivoting member  820 , in turn, is rigidly affixed to portions of cylindrical member  807 . The exterior surface of cylindrical member  807  may be smooth or may present a roughened surface to enhance gripping. A rubberized or tacky substance may be present on the surface of cylindrical member  807 . Other means to enhance gripping such as an increased surface area or greater gripping features of the existing surface area may also be present. A plurality of biasing springs or other biasing means (not shown) are optionally and operably disposed within engaging mechanism  800 . 
     Functionally, elements  802 ,  804  of engaging mechanism  800  are biased away from each other by means one or more biasing springs (not shown). When a user desires to place a transfer sheet within engaging mechanism  800 , the user first wraps a portion of the transfer sheet around cylindrical member  807 . Subsequently, cylindrical member  807  is pivoted proximate convex interior surface  810 . Elements  802  and  804  are then forced toward each other, thereby extending engaging slot  817  on belt engaging element  806  away from element  804 . When elements  802 ,  804  are in a closed position, cylindrical member  809  and the portion of the transfer sheet wrapped around cylindrical member  809  are enclosed within clamp  800 . Engaging slot  817  is displaced by forcing elements  802 ,  804  toward each other. Hence, when elements  802 ,  804  contact and grip cylindrical member  809  and the enwrapped transfer sheet, engaging slot  817  is sufficiently distant from element  804  for belt buckle  822  to firmly latch onto belt engaging element  806 . Belt buckles  822 , when firmly attached onto engaging element  806 , thereby hold elements  802  and  804  in a closed position. Elements  802 ,  804  enclose cylindrical member  809  therein and exert a gripping force on the portion of the transfer sheet enclosed. When a patient is being transferred, a transfer force is exerted on belt engaging elements  806 , further forcing elements  802  and  804  toward each other and thus exerting an additional, or further, gripping force on the transfer sheet disposed therein. 
     Exemplary clamp  830  is shown in FIGS. 65 and 66. Clamp  830  is another embodiment of the present invention. Clamp  830  includes large U-channel member  832 , small U-channel member  834 , cylindrical member  836 , a plurality of belt engaging elements  838 , and a plurality of cams  840 . Large U-channel member  832  displays outer surface  842 , inner surface  844  and defines a plurality of slots  846 . Each slot  846  is optionally configured with a horizontal and a vertical dimension. Small U-channel member  834  displays outer surface  848  and inner surface  850 . In this embodiment, U-channel members  832 ,  834  are at least about 60 cm, preferably greater than about 100 cm, in length. Cylindrical member  836  has a circumference sufficient to enable cylindrical member  836  to fit within the confines of inner surface  846  with a transfer sheet wrapped therearound. Cylindrical member  836  may have a length substantially the same as U-channel members  832 ,  834 . The outer surface of cylindrical member  836  may be smooth, but may also be somewhat rough, thereby further facilitating gripping, as described above. Belt engaging elements  838  are rigidly affixed to, and extend from, small U-channel member  834 . Disposed on each belt engaging element  838 , as part of cam attachment element  838 , is engaging means  852 . 
     In use, a portion of a transfer sheet (not shown) is wrapped around cylindrical member  836 . Cylindrical member  836  and the enwrapped sheet portion are disposed proximate inner surface  850  of small U-channel member  834  and adjacent belt engaging element  838 . Belt engaging elements  838  are then passed through slots  846 . Large U-channel member  832  and small U-channel member  834  are forced toward each other until cylindrical member  836  and the enwrapped sheet contact inner surface  844  of large U-channel member  832 . At this point, the vertical notch component of slots  846  has served as a passageway for cam attachment elements  854 . Cams  840  then lock members  832  and  834  together. Belt buckles or equivalent attaching means (not shown) are then affixed to belt engaging elements  838 . As in previous embodiments, when a transfer force is exerted on clamp  830 , members  832  and  834  are further forced together, thereby exerting an additional, or further, gripping force on the transfer sheet disposed therein. 
     Clamps  800  and  830  may be made from resilient, rather stiff materials. Suitable materials include various gauges of metal or synthetic resins. Buckle mechanisms, similar to those commonly used in automobiles, as well as the belts attached thereto, are possible for use as one embodiment of attaching means of the present invention. 
     Exemplary clamp  860 , depicted in FIGS. 67 and 68, includes base member  862 , pivoting upper member  864 , two locking levers  866 , locking mechanism  868  and a plurality of belt attachment sites  870 . Pivoting upper member  864  pivots onto base member  862 , with a pivot site at the base of member  864  and coincident with locking mechanism  868 . A rubberized substance  869  or other material with increased tack may be present on the inner surfaces of base member  862  and upper member  864 . A pair of locking levers  866  is present atop base member  862  and proximate the pivotal end of pivoting upper member  864 . Locking mechanism  868  cooperates with locking levers  866  to secure pivoting upper member  864  in a locked position. Pivoting upper member  864  may be biased in an open position by such means as a leaf or helical spring. Two belt attachment sites  870  may be disposed adjacent to each locking lever  866 . 
     In practice, a portion of a transfer sheet (not shown) is disposed between base member  862  and pivoting upper member  864 . Alternatively, a portion of the transfer sheet may be wrapped around a cylindrical element or other suitable member (not shown), and then placed between base member  862  and pivoting upper member  864 . Pivoting upper member  864  is then pressed toward base member  862  until locking mechanism  868  locks, thereby securing base member  862  and pivoting upper member in a closed, locked position with the transfer sheet gripped securely therewithin. Alternatively, pivoting upper member  864  and locking levers  866  may be mechanically connected by a linkage or lever combination in which locking lever  866  is pressed down by a user, thereby forcing pivoting upper member  864  down until locking mechanism  868  securely locks base member  862  and pivoting member  864  in closed contact. Finally, belt or strap  872  is affixed to clamp  860  by disposing hook  874  within the slots located at belt attachment sites  870 . 
     As depicted in FIG. 68, when transfer sheet  876  is secured within clamp  860 , base member  862  and pivoting upper member  864  are in a closed and locked position. When belt  872  is then retracted away from transfer sheet  876 , a transfer force is exerted onto transfer sheet  876  in the direction of arrow  880 . Due to the upper placement of belt attachment sites  870  and the angular configuration of the bottom portion of clamp  860 , a pivot point is thereby formed proximate locking mechanism  868 . This transfer motion simultaneously pivots upper member  864  upwardly and the portion of clamp  860  proximate hook attachment site  870  downwardly, thus rotating clamp  860  about the pivot point located proximate locking mechanism  868  and as indicated in arrow  880 . The angular orientation of the portion of transfer sheet  876 , secured within clamp  860 , relative to the remainder of transfer sheet  876  exerts a further gripping force thereon. 
     Patient transfer system  900 , as depicted in FIGS. 69-71, broadly includes bed  902 , cart  904 , motor-winch unit  906 , perpendicular transfer units  908 ,  910 ,  912 , clamp  914  and a plurality of belts discussed below. Although depicted as cart  904 , a bed or other horizontal surface may be used and still be within the spirit and scope of the present invention. Motor-winch unit  906  may be attached to base  916  of bed  902 . Perpendicular transfer unit  908  is attached to the upper frame of bed  902 . Another perpendicular transfer unit  910  is attached to the upper frame on adjoining cart  904 . Still another perpendicular transfer unit  912  is attached to the lower frame of cart  904 . As shown in FIG. 69, a pair of belts  918  may extend generally upwardly from motor-winch unit  906  through perpendicular transfer unit  908 , finally extending horizontally on mattress  915 . Belts  918  are then attached to clamp  914  in any manner such as described herein. Alternately, belts  918  may proceed horizontally from motor-winch unit  906 , beneath bed  902  and cart  904  and through perpendicular transfer unit  912 . Extending generally upwardly and vertically from perpendicular transfer until  912 , belts  918  pass through perpendicular transfer unit  910 , then onto mattress  917 . On mattress  917 , belts  918  may be attached to a clamp such as a clamp of the present invention. Motor-winch unit  906  may be attached to bed  902  by means of rings  922  extending from housing  920 . Rings  922  may enclose an upper portion of casters  924  on which bed  902  is mounted. 
     In use, bed  902  and cart  904  are aligned and may be secured together. If a patient is to be transferred from bed  902  onto cart  904 , clamp  914  is attached to a transfer sheet upon which the patient is disposed. The belts attaching to clamp  914  have been routed under bed  902  and cart  904 , then upwards, and then horizontally by means of perpendicular transfer units  910  and  912 . Once motor-winch unit  906  is activated, belts  918  are retracted. The transfer force exerted thereby will transport the patient in the direction of arrow  926  from bed  902  onto cart  904 . Once the patient has been transferred onto cart  904 , motor-winch unit  906  is disengaged. Alternatively, a sensing device (not shown) may be attached to perpendicular transfer unit  910 . This sensing device may be either mechanical, electronic, magnetic, optical or a combination thereof in its operation and may detect the presence of the patient, the buckle, the belt portion proximate the buckle, or the clamp within a predetermined distance from perpendicular transfer unit  910 . 
     If the patient is to be transferred from cart  904  onto bed  902 , belts  918  are routed through perpendicular transfer unit  908  and onto mattress  915  where they are attached to clamp  914 . Clamp  914  is then securely attached to a transfer sheet upon which the patient is disposed. Motor-winch unit  906  is then activated, thereby retracting belt  918  in the direction of arrow  930 , thereby generating a transfer force upon clamp  914 . The transfer force acts upon the transfer sheet upon which the patient is disposed, thereby transferring the patient from cart  904  onto bed  902  and thereby further, or additionally, gripping the transfer sheet secured within clamp  914 . Again, patient proximity sensing devices may be included in perpendicular transfer unit  908  as discussed hereinabove. Perpendicular transfer units  908 ,  910 , and  912  may include either a pulley system or a roller system onto which belts  918  are emplaced prior to a patient transfer. Clamp  914  may be any of the clamps disclosed herein. Some exemplary embodiments of motor-winch unit  906  are discussed in more detail herein. 
     Referring to FIGS. 72-74, exemplary patient transfer system  940  is depicted. Patient transfer system  940  broadly includes bed  942 , portable transfer unit  944  and clamp  946 . Bed  942  includes mattress  948  and side rail  950 . Side rail  950  may include a plurality of horizontal bars  951 . Portable transfer unit  944  includes housing  952 , one or more belts  954 , an equal number of attaching means or buckles  956  and a motor-winch unit. Further included in portable transfer unit  944  is mounting bracket  958  which will be further described below. Handle  960  on portable transfer unit  944  enables an attendant to easily grasp and carry portable transfer unit  944  as desired. Housing  952  is preferably a light weight resilient plastic or other suitable light weight material. Portable transfer unit  944  has the advantage of being light in weight, hence readily transportable by an attendant of virtually any size and lifting ability with little likelihood of injury therefrom. Portable transfer unit  944  may weigh between about 20 and 35 pounds. Portable transfer unit  944  may also weigh between about 15 and 25 pounds. 
     FIGS. 73 and 74 depict two of many possible embodiments  966 ,  968  of control units  966 ,  968 . Control units  966 ,  968  control the operation of exemplary portable transfer unit  944 . Controls  970  of control units  966 ,  968  serve to operate portable transfer unit  944 . Control unit  966  may communicate with portable transfer unit  944  by means of electromagnetic radiation, more particularly by radio frequency, or by other means. Controls  970  include on/off simultaneous transfer power control  974  and left and right transfer actuator controls  976 ,  977 . Control unit  968  communicates with portable transfer unit  944  by means of a cord or other suitable connecting means. The cord is mechanically and electrically attached to control unit  968  and may be disposed on a spool or other retaining means within portable transfer unit  944 . The spool may be biased so that cord  974  winds thereon when control unit  968  is released by the operator. Control units  966  and  968  may be housed in a recess contained within portable transfer unit  944  when not in use. An alternative to the control units of this patient transfer system is via voice actuation. Voice actuation would enable the patient to effect the patient&#39;s own transfer and to halt a transfer in progress if the need to do so arose. 
     FIG. 75 depicts another embodiment of a portable transfer unit according to the present invention. In this embodiment, shaft  978  extends laterally from housing  952 . By being exposed, shaft  978  facilitates mounting spools  980  thereon. Spools  980  provide means upon which belts  982  are wound. Since shaft  978  is exposed, each spool  980  may be easily and quickly detached from shaft  978  to facilitate cleaning and disinfecting shaft  978 , spools  980  and belts  982 . 
     Exemplary portable transfer unit  944 ′ is depicted in FIG.  93 . In this embodiment, receiving cavity  962  is formed in lateral portions of housing  952 ′. A drive shaft (not shown) is disposed within cavity  962 . Spool  980 ′ may be reversibly mounted on the shaft drive. Belt  988  is routed through slot  963  so that buckle  956  may be used to engage a clamp. Cap  964  may be used to cover cavity  962 . 
     Referring again to FIGS. 72-76, bed  942  and exemplary portable transfer unit  944  are depicted. Portable transfer unit  944  is secured to side rail  950  by means such as those described below. Bed  942  is then placed beside a bed or cart onto which a patient is disposed upon a transfer sheet. The transfer sheet is then secured proximate the patient with clamp  946 . Belts  954  are then extended from portable transfer unit  944  and attached to clamp  946 . Either control unit  966  or  968  is detached from portable transfer unit  944  and used to operate the motor-winch within unit  944  by means such as on/off controls  974 . Upon actuation of the motor-winch mechanism, transfer unit  944  begins to wind belts  954  and thereby move clamp  946 , the transfer sheet, and the patient toward transfer unit  944 . The motor-winch assembly may cease operation when the attendant operates control unit  966 ,  968  or when an above-described sensing device functions. 
     During transfer, it is desirable that the longitudinal axis of the patient be generally parallel to the longitudinal axis of the bed or cart onto which transfer is to be effected. If not, the patient may not be transferred completely onto the bed or cart and may require further manual adjustment by the attendant, possibly obviating some of the advantages of this system. Thus, left or right transfer actuator controls  976 ,  977  may be used. For example, if left control  976  is actuated, the belt  982 , attached toward the patient&#39;s head, continues to be wound and the other belt  982  either ceases to be wound or is wound more slowly. In a similar manner, when right control  977  is actuated, belt  982 , attached closest to the patient&#39;s feet, continues to be wound and the other belt  982  either ceases to be wound or is wound more slowly. 
     When patient transfer is complete, patient transfer system  940  may be disengaged from the transfer sheet and detached from bed  942 . Belts  954  may then be retracted until attached clamp  946  is proximate portable transfer unit  944 . Control unit  968  (or  966 ) is then stowed within a niche in portable transfer unit  944 . The attendant then grasps handle  960  and carries portable transfer unit  944  and attached clamp  946  to another location (FIG.  95 ), or shows the unit on the cart or bed for subsequent use. 
     Exemplary portable transfer unit  984  is depicted in FIG.  76 . In this embodiment, belt  986  is bound onto spool  988 . Spool  988 , in turn, is detachably mounted onto bracket  990 . Bracket  990  is mounted onto the back of housing  952 . Bracket  990  includes upper member  992  and lower member  994 . An automatic sensing and motor disconnect may be included in this, as well as other, embodiments. The sensing mechanism detects the presence of either the patient, the clamp, or the terminus of an attached belt. Upon sensing one or more of these, portable transfer unit  984  ceases to wind belt  988 , thereby stopping or easing (slowing) patient transfer. 
     The portable devices, as well as the other devices of the present invention, preferably also contain an automatic recording and/or display mechanism  998 , representatively shown in FIG.  77 . Mechanism  998  records each patient transfer event. Recording is via a printout on paper or other means. Recording may also comprise storage or transfer of relevant information electronically. The stored information may then be transferred to a computer or other device as desired. Relevant information with regard to a transfer event may include the time of day, the patient&#39;s number and name, the attendant&#39;s name and number, and the time length of the transfer event. Other items, such as motor performance and torque received by the motor-winch assembly, speed, acceleration, alignment, or other parameters of the patient or the clamp when transferring the patient may also be recorded. 
     Referring to FIGS. 77 and 78, exemplary patient transfer system  1000  broadly includes bed  1002  and portable transfer unit  1004 . Bed  1002  includes mattress  1006  and side rail  1008 . Portable transfer unit  1004  includes housing  1010 , control unit  1012 , belts  1014  and an engaging mechanism, such as clamp  1016 . Belts  1014  and clamp  1016  may include any of the embodiments discussed herein. Portable transfer unit  1004  combines a housing which encloses the motor and winch assembly and which is easily and reversibly mounted onto side rail  1008 . Mounting bracket  1018  may be integral to housing  1010  of portable transfer unit  1004 . Mounting bracket  1018  readily and securely mounts onto side rail  1008 . A side view of one embodiment of mounting bracket  1018  is depicted in FIG.  78 . While shown as unitary to the embodiment of FIG. 77, the concept depicted in FIG. 78 is applicable to any of the portable transfer units of the present invention. Mounting bracket  1018  includes engaging side  1020  of portable transfer unit housing  1010 , horizontal extension  1022  and substantially vertical member  1024 . 
     In use, portable transfer unit  1004  is situated onto side rail  1008  such that the lower surface of horizontal extension  1022  rests on side rail  1008 . Pin  1026  is then inserted in opening  1027 , extending through member  1024  and into a slot or receiving orifice  1028 , securely fastening therein. Mounting bracket  1018 , thereby securely holds portable transfer unit  1004  onto side rail  1008  during a transfer event. Moreover, transfer unit  1004  is easily detachable from side rail  1008  by removing pin  1026 . 
     An end view of another embodiment of a portable transfer unit  1004 ′ is depicted in FIG. 94, where an alternate mounting bracket  1018 ′ is disclosed. Mounting bracket  1018 ′ includes horizontal extension  1022 ′ extending integrally from housing  1010 ′. Extending generally vertically from horizontal extension  1022 ′ are fixed upper vertical member  1030  and pivotally mounted, lower vertical member  1032 . A locking mechanism, actuated by cam lever  1034 , is included. To install portable transfer unit  1004  on a bed with side rails  1008 , portable transfer unit  1004 ′ is tilted, allowing upper vertical member  1030  to be disposed such that an upper side rail is between member  1030  and housing  1010 ′. Lower vertical member  1032 , extended in an open position, allows portable transfer unit  1004 ′ to be disposed in position and lower side rails  1008  to be disposed proximate housing  1010 ′. Lower vertical member  1032  is pivoted to a closed position, generally coaxial to that of upper vertical member  1030 . Finally, cam lever  1034  is pivoted into a locked position in the direction of arrow  1036 . 
     In FIGS. 79 and 80, another embodiment of a self-contained portable transfer unit  1040  of the present invention is depicted. Portable transfer unit  1040  broadly includes handle-control unit  1042 , housing  1044 , clamp  1046 , belt  1048 , hook  1050 , and locking devices  1052 . Portable transfer unit  1040  is self contained, including a belt, clamp, and enclosed motor-winch assembly. The motor-winch assembly of portable transfer unit  1040  may be totally enclosed within housing  1044 . Belts  1048  may be extended to hook onto the framework of a bed or cart or they may be retracted to a position almost completely within housing  1044 . Locking devices  1052  may be embodiments previously discussed with respect to the clamps of the present invention. Handle-control unit  1042  may be detached during a transfer event. Handle-control unit  1042  may include controls  1056  disposed within housing  1058 . Alternatively, handle-control unit  1042  may include the controls depicted in FIGS. 73,  74  and discussed hereinabove. Cord  1054  physically and electrically connects control unit  1042  to the remainder of portable transfer unit  1040 . Cord  1054  may be mounted to a pulley within housing  1044  so that cord  1054  is retracted unless pulled away by a user. Clamp  1046  may open downwardly to admit a transfer sheet therein. 
     In use, portable transfer unit  1040  is placed onto a bed, onto which a patient to be transferred is disposed upon a sheet. As shown in FIGS. 79-84, locking devices  1052  are unlocked and the jaws of clamp  1046  are separated. A portion of the transfer sheet is placed between the jaws of clamp  1046 , the jaws are then closed and locking devices  1052  locked. Belts  1048  are extended away from portable transfer unit  1040 , across the bed or cart onto which the patient is to be transferred and hooks  1050  are hooked onto the bed frame. The attendant detaches handle-control unit  1042  and then begins the transfer by actuating the motor-winch assembly. When the patient has been transferred onto the desired bed or cart, the attendant turns the motor-winch off. The transfer sheet is then freed from clamp  1046  and hooks  1050  are unhooked from the bed and retracted within housing  1044 . Finally, handle-control unit  1042  is reconnected to portable transfer unit  1040 . The attendant then may carry portable transfer unit  1040  away by grasping and holding handle-control unit  1042 . 
     In FIGS. 81 and 82, other embodiments are shown for securing the clamps of the present invention. Referring to FIG. 81, clamp  1070  is secured in a closed position by the operation of clip  1072 . Clamp  1070  includes lower pivoting member  1074  and upper clamp member  1076 . Clip  1072  includes free end  1078  and pivot  1080 . When in an open position, free end  1078  has been pivoted away from the body of clamp  1070  and lower pivoting member  1074  is pivoted away from upper clamp member  1076 . Functionally, a transfer sheet (not shown) is placed between lower pivoting member  1074  and upper clamp member  1076 . Lower pivoting member  1074  and upper clamp member  1076  are then pressed together. Free end  1078  is then pivoted toward the body of clamp  1070 , then snapped around the front thereof. A locking mechanism is thereby actuated, locking lower pivoting member  1074  and upper clamp member  1076  securely together and gripping the sheet therewithin. 
     Clamp assembly  1088  is shown in FIG. 82 includes clamp  1090  and locking assembly  1092 . Clamp  1090  further includes upper pivoting clamp member  1094  and lower clamp member  1096 . Locking assembly  1092  includes handle  1098 , which actuates the locking mechanism of clamp assembly  1088 . Handle  1098  is affixed to the remainder of locking assembly  1092  via an elongated member. Handle  1098  and the elongated member are slidable within slot  1100 . When clamp assembly  1088  is in an open position, upper pivoting clamp member  1094  is pivoted away from lower clamp member  1096  and handle  1098  is disposed toward rear edge  1102  of clamp  1090 . In use, a transfer sheet is placed between upper pivoting clamp member  1094  and lower clamp member  1096  and clamp members  1094 ,  1096  are pressed together, firmly securing the transfer sheet within. Handle  1098  is then grasped by the attendant and pushed away from rear edge  1102 , thereby activating locking assembly  1092  and securing upper pivoting clamp member  1094  and lower clamp member  1096  together in a secure, closed position. 
     FIG. 83 is a side view of a self-contained portable transfer unit  1110 . Portable transfer unit  1110  may include any of the self-contained portable transfer units described herein. Included are upper clamp member  1112  and lower pivoting clamp member  1114 . When pivoted between an open and a closed position, lower pivoting clamp member  1114  may be moved in either direction as indicated by arrow  1116 . 
     FIG. 84 depicts self-contained portable transfer unit  1120 . In addition to other features described for the self-contained portable transfer unit embodiments herein, transfer unit  1120  includes upper pivoting clamp member  1122 , lower clamp member  1124  and housing  1126 . Venting  1128  is present within housing  1126 . As indicated by arrow  1130 , upper pivoting clamp member  1122  pivots upwardly toward an open position or downwardly toward lower clamp member  1124  when in a closed position. Venting  1128 , present in housing  1126 , facilitates air exchange and, consequently, enhances cooling of the motor-winch assembly within portable transfer unit  1120 . 
     FIGS. 85 and 86 disclose one embodiment of motor-winch assembly  1150  of the present invention. Motor-winch assembly  1150  broadly includes frame  1152 , upon which are mounted motor bracket  1154 , control board  1156 , hook member  1158 , right clutch bracket  1160  and left clutch bracket  1162 . Motor  1164  is operationally mounted on an upper portion of motor bracket  1154 . Gear  1166  (which in one embodiment is a 42-tooth gear) is attached to a shaft (not shown) extending from motor  1164 . Gear  1166 , in turn, operably engages gear  1168  which is mounted on shaft  1169 . Also mounted on shaft  1169  are right clutch  1170  and left clutch  1172 . Right clutch  1170  is disposed within right clutch bracket  1160 . Left clutch  1172  is disposed within left clutch bracket  1162 . Spring  1174  is disposed about right clutch  1170  and about left clutch  1172 . Spring  1174 , in turn, is enclosed by spring cover  1176 . Spring cover  1176  is attached to spring hub  1178 . A spring hub  1178  is affixed to right clutch bracket  1160  and left clutch bracket  1162 . Spool  1182  may be detachably disposed on the outboard portion of shaft  1169 . Motor-winch assembly  1150  is suitable for providing the necessary power to operate the transfer units described herein. 
     Optimized patient transfer requires smooth transition of the patient from one platform to another. One means for achieving such optimization is through use of a transfer bridge  1200 , shown in FIGS. 87-90. A modified transfer bridge  1200 ′, depicted in FIG. 87, differs from transfer bridge  1200 . Transfer bridge  1200  broadly includes one or more sections  1202 . A stabilizer  1204  is ideally present on the underside of each section  1202 . Where multiple sections are used, such sections  1202  are joined by hinge  1206  (discussed hereinbelow), and stabilizer  1204  extends generally perpendicularly from each section. Functionally, transfer bridge  1200  is placed between a bed or cart onto which a patient is lying and another bed or cart onto which the patient is to be transferred. Stabilizer  1204  is disposed between the platforms, thereby securely holding transfer bridge  1200  in place and preventing transfer bridge  1200  from being displaced by patient contact during a transfer. After use, transfer bridge  1200  is folded along hinge  1206  for storage or transport. 
     One embodiment of hinge  1206  is depicted in FIG.  89 . Hinge  1206  may be manufactured as a “living hinge,” i.e., a hinge made by removing a narrow, linear portion of the material along a portion of transfer bridge  1200  or transfer bridge  1200 ′. 
     Transfer bridge  1200 ′, shown in FIG. 88, includes a plurality of sections  1202 ′ and a stabilizer  1204 ′, mounted on the underside of each section  1202 . As in the case of transfer bridge  1200 , hinge  1206  is present and divides  1202 . Leading edge  1210  is present on the portion of transfer bridge  1200 ′ opposite stabilizers  1204 ′. Although not depicted, transfer bridge  1200  and  1200 ′ may include one or more carrying handles. The carrying handles may be attachable, unitary to transfer bridge  1200 ,  1200 ′ or may be cutouts within sections  1202  or  1202 ′. Preparing transfer bridge  1200 ′ for a patient transfer is essentially done in an identical manner as preparing transfer bridge  1200 , the only exception being that leading edge  1210  is oriented toward the patient to be transferred. 
     Both transfer bridge  1200  and  1200 ′ may be constructed using a smooth polyethylene sheet material, which is generally about 1.5 millimeters in thickness. Alternatively, hinge  1206  may be reinforced with a thin sheet of polyethylene on the underside of transfer bridge  1200 ,  1200 ′. Stabilizer  1204 ′ may be centered about 7.5 centimeters from edge  1214 . One embodiment of transfer bridge  1200 ′ is about 31 centimeters wide at hinge  1206 , tapering to about 25 centimeters in width at each end. The cambered radius for a side section of transfer bridge  1200 ′ is about 105 centimeters. The cambered radius for the leading edge of transfer bridge  1200 ′ is about 225 centimeters. The side camber insures that leading edge  1210  will firmly contact the mattress on which the patient is disposed such that transfer bridge  1200 ′ will not be displaced during a patient transfer. The leading edge camber allows for a gradually increasing amount of patient contact during transfer, rather than immediate total contact. The gradually increasing contact also tends to allow the patient to be pulled atop transfer bridge  1200 ′, rather than abutting and possibly displacing transfer bridge  1200 ′. Transfer bridge  1200 ′ is advantageously positioned when leading edge  1210  is placed under at least a portion of the patient. 
     In an average male patient, approximately 90% of the patient&#39;s weight resides in the portion between the patient&#39;s buttocks and shoulders. Hence, the overall length of transfer bridge  1200  or  1200 ′ should minimally provide support therefor. Accordingly, lengths for transfer bridge  1200  or  1200 ′ may be between 65 and 173, centimeters or about 65, 120 and 173 centimeters. 
     Clamp  1230  is yet another embodiment of an engaging means for use with this invention. Clamp  1230  is depicted in FIGS. 91 and 92. Clamp  1230  broadly includes U-channel member  1232  and pivot assembly  1234 . Pivot assembly  1234 , in turn, includes pivot member  1236  and pivot rod  1238 . Defined laterally on each end of pivot member  1236  is pivot point orifice  1240 . Tab  1241  is laterally present proximate pivot point orifice  1240 . Symmetrically affixed to pivot member  1236  is a plurality of belt engaging elements  1242 . Each belt engaging element  1242  generally includes tongue section  1244  and planar member  1246 . Each tongue section  1244  defines engaging slot  1245 . Tongue section  1244  and planar member  1246  are joined in a stair step fashion. A pair of pivot rod brackets  1248  may be laterally attached to pivot member  1236  by means of a rivet or bolt. Orifice  1249  is defined by each pivot rod bracket  1248  and provides the opening through which pivot point  1240  may be disposed. At least one cylindrical member  1250  is affixed to each pivot rod bracket  1248 . U-channel member  1232  may include a plurality of slots  1252  and a plurality of brackets  1254 . U-channel member  1232  displays leading edge  1256  and inner surface  1258 , discussed hereinbelow. Mounted on brackets  1254  is a plurality of cam levers  1260  and springs  1262 . 
     Operationally, a portion of transfer sheet  1263  is wrapped about cylindrical member  1250 . Cylindrical member  1250  and the enwrapped portion of transfer sheet  1263  are then pivoted in the direction of arrow  1264  until brackets  1248  rest upon tabs  1241 . Slots  1252  on U-channel member  1232  are aligned with belt engaging elements  1242 . U-channel member  1232  and pivot assembly  1234  are then pressed together, thus allowing belt engaging elements  1242  to pass through slots  1252  and protrude forwardly therefrom. U-channel member  1232  and pivot assembly  1234  may be biased away from each other by means of a plurality of springs. Another alternative embodiment of clamp  1230  employs a spring (not shown) to bias cylindrical member  1250  in an open position. Cam levers  1260  are then rotated over pivot member  1236 , thereby biasing pivot member  1236  against U-channel member  1232  and cylindrical member  1250  firmly against inner surface  1258 . Finally, a belt buckle may be affixed to belt engaging elements  1242 . Leading edge  1256  of U-channel member  1232  is may be arcuate in cross-section, thereby allowing clamp  1230  to be more positively pulled upon a transfer bridge during a patient transfer, rather than abutting and displacing the transfer bridge. 
     Referring to FIGS. 96-97, exemplary patient transfer system  1300  enables a single operator to transfer or reposition a patient disposed on a substantially pliable underlayment, such as a transfer sheet described herein. Patient transfer may be effected from a first horizontal surface to a second horizontal surface or from a first transfer position to a second transfer position. This invention may also advantageously and ergonomically reposition a patient disposed on a substantially pliable underlayment, for example, from a slumped position to a position more toward the head of the bed on which the patient is disposed. Embodiments of this invention may further enable a single operator to ergonomically roll or reposition a patient, for instance, from the patient&#39;s left side to the patient&#39;s right side (a rollover). Patient transfer is effected with minimum risk of back injury to the operator. Moreover, patient transfer system  1300  is compact, easily transported to and from the site of a transfer event, and self-contained. 
     Moreover, patient transfer system  1300  is compact and thus easily fits through hospital and elevator doors and other small spaces. A single attendant may easily roll patient transfer system  1300  to the site of a patient transfer, conduct the patient transfer, then roll patient transfer system  1300  to the site of another transfer or place of storage. Patient transfer system  1300  is self-contained in that every component necessary to transfer a patient disposed on a sheet from a first horizontal surface to a second horizontal surface is self-contained. 
     As seen in FIGS. 96-99,  134 , patient transfer system  1300  broadly includes transfer caddy  1302 , transfer bridge  1304 , and transfer rod  1306 . Transfer caddy  1302 , in turn, includes head assembly  1308 , hook and web assembly  1310 , base assembly  1312  and electrical and switching system  1314 . 
     Referring to FIGS. 98,  114 , head assembly  1308  includes top frame  1316 , power train  1318 , and upper shield assembly  1320 . Top frame  1316  includes front panel  1322 , base panel  1324 , motor bracket  1326 , retractor bracket  1328 , left clutch bracket  1330 , a pair of interlock switch brackets  1334 , and right clutch bracket  1336 . 
     Front panel  1322  includes lobes  1342  which extend laterally from upper edges of front panel  1322 . Lobes  1342  and front panel  1322  cooperate in defining generally rectangular openings  1344 . Front panel  1322  presents planar inner surface  1346 . Base panel  1324  extends generally transversely from a bottom edge of front panel  1322 . Base panel  1324  presents upper surface  1348 . A pair of laterally disposed peripheral lips  1350  extend upwardly from a rear edge of base panel  1324 . Arcuate extension  1352  is a rearward extension of base panel  1324  and is flanked by peripheral lips  1350 . 
     Motor bracket  1326  includes planar member  1354 , a lateral pair of generally perpendicular members  1356 , and generally perpendicular lower member  1358 . Motor bracket  1326  is affixed to top frame  1316 . More specifically, one of members  1356  is affixed to surface  1346  and lower member  1358  is affixed to surface  1348 . 
     Retractor bracket  1328  includes horizontal member  1362  and vertical member  1364 . Vertical member  1364  extends upwardly and generally transversely from horizontal member  1362 . A generally cylindrical or conical element  1365  extends from vertical member  1364  generally toward right clutch bracket  1336 . Retractor bracket  1328  is affixed to top frame  1316  slightly to the right and rearwardly from motor bracket  1326 . Motor bracket  1326  defines orifices  1366 ,  1368 ,  1370  and cutout  1372 . Orifice  1366  is defined generally centrally on planar member  1326 . Orifice  1368  is defined generally below orifice  1366 . One or more smaller orifices  1370  may also be defined within planar member  1354 . Generally arcuate cutout  1372  may be defined proximate a central portion of an upper edge of member  1354 . 
     Left clutch bracket  1330  generally includes inboard planar member  1376 , outboard planar member  1378  and connecting member  1380 . Front edges of inboard planar member  1376  and outboard planar member  1378  are unitary to connecting member  1380  and are joined at a bend in this embodiment. Inboard planar member  1376  defines central orifice  1382  and one or more smaller orifices  1384 . Orifices  1384  may be peripherally disposed with respect to central orifice  1382 . Outboard planar member  1378  defines opening  1388 , cutouts  1390 , opening  1392 , cutout  1394 , and generally rectangular opening  1396 . Opening  1388  is generally circular, with four cutouts  1390  extending generally radially therefrom. Opening  1392  is defined above a rear portion of opening  1388 . Generally arcuate cutout  1394  is defined proximate an upper edge of outboard planar member  1378 . Rectangular opening  1396  is disposed generally centrally, below clutch opening  1388 . A plurality of smaller openings  1398 , flanking opening  1396 , may also be defined by planar member  1378 . 
     Interlock switch bracket  1334  is disposed proximate openings  1344  and affixed to front panel  1322  proximate surface  1346 . 
     Right clutch bracket  1336  generally includes inboard planar member  1400 , outboard planar member  1402  and connecting member  1404 . Front edges of inboard and outboard planar members  1400 ,  1402  may be unitarily joined to connecting member  1404  at a bend. Orifices defined within inboard planar member  1400  and outer planar member  1402  are generally similar to those formed or defined by inboard planar member  1376  and outboard planar member  1338 . Therefore, these openings are designated by identical numerals. 
     Motor bracket  1326  is mounted such that planar member  1354  is generally transverse to panels  1322 ,  1324 . Inboard planar members  1376 ,  1400 , outboard planar members  1378 ,  1402 , and vertical member  1364  are disposed generally parallel to planar member  1354  in this embodiment. 
     Front panel  1322 , base panel  1324 , motor bracket  1326 , retractor bracket  1328 , left clutch bracket  1330 , interlock switch brackets  1334 , and right clutch bracket  1336  may be formed from a 16-18 gauge sheet metal. However, other suitable materials are known to the art. 
     Also as seen in FIGS. 98,  114 , power train  1318  broadly includes motor  1410 , motor gear  1412 , shaft gear  1414 , shaft bearing  1416 , shaft  1418 , and pluralities of magnetic clutch assemblies  1420 , slip plates  1422 , and drum assemblies  1424 . Motor  1410  includes housing  1430  and motor shaft  1432 . Motor shaft  1432  may define a key way (not shown). A generally coaxial bore  1434  is defined in motor gear  1412 . Bore  1434  accommodates motor shaft  1432 . Gear  1412  may be further affixed to motor shaft  1432  by means of a key (not shown) inserted in the key way. Motor  1410  may be affixed to motor bracket  1326  by fasteners, such as a plurality of screws. When motor  1410  is attached to motor bracket  1326  and motor gear  1412  is mounted on motor shaft  1432 , motor shaft  1432  extends through motor orifice  1368  and motor gear  1412  is disposed outboard planar member  1354 . When power train  1318  is assembled, shaft  1418  extends through orifices  1366 ,  1382 , and  1388 . 
     Shaft gear  1414  may be mounted on shaft  1418  in a similar manner as motor gear  1412  is mounted on motor shaft  1432 . Shaft gear  1414  may further be disposed on shaft  1418  such that shaft gear  1414  meshes with motor gear  1412 . Shaft  1418  extends through shaft bearing  1416  when power train  1318  is assembled. Shaft bearing  1416  may be further affixed to planar member  1354  by fasteners, such as a plurality of screws  1433 . In one embodiment, gears  1412 ,  1414  respectively possess thirty-sixty and forty teeth. Gears  1412 ,  1414  may be formed from such materials as steel, cast iron, as well as from other materials known to the art. Shaft  1418  may be formed from similar materials as gears  1412 ,  1414 . In this embodiment, motor  1410  is a permanent magnet, parallel shaft, DC brush gear motor, operating at 12 volts DC and generating approximately ⅛ hp. Also in this embodiment, motor  1410  rotates motor shaft  1432  at an output speed of between about 25 and 75 rpm and attains an output torque range of between approximately 300 in-lbs at 25 rpm and 100 in-lbs at 75 rpm. Motor  1410  may be approximately 10″ (±0.5″) long, 5″ (±0.5″) high, and 4″ (±0.5″) wide. An exemplary motor may be obtained from Byson Gear and Engineering Corporation, Downers Grove, Ill. 
     Each magnetic clutch assembly  1420  includes disk  1436  and cylindrical housing  1438 . A generally coaxial bore  1440  extends through magnetic clutch assembly  1420 . In this embodiment, bore  1440  has a ½″ diameter and disk  1436  has a diameter of approximately 4.9″ (±0.5″). Cylindrical housing  1438  has a diameter of approximately 4.2″ (±0.5″) and a height of approximately 1.8″ (±0.5″). An exemplary magnetic clutch develops a torque of 22 lb-ft, and attains a coil power of 28 watts, an armature hub inertia of 161×10-4 lb-ft 2, a rotor inertia of about 172×10-4 lb-ft 2, and generates 3 hp at 1800 rpm. Disk  1436  may be mounted to an outboard surface of inboard planar member  1376  by fasteners, such as a plurality of screws. When magnetic clutch assembly  1420  is mounted to inboard member  1376 , cylindrical housing  1438  extends through opening  1388 . Magnetic clutch assembly  1420  is mounted such that shaft  1418  extends generally coaxially through bore  1440 . Shaft  1418  and magnetic clutch  1420  may be affixed by a key way combination (not shown). Each slip plate  1422  defines bore  1466 , a plurality of peripheral holes  1446 , and presents an inboard surface  1444 . 
     Each exemplary drum assembly  1424  includes cylindrical member  1450 . Four threaded extensions  1452  may extend peripherally from cylindrical member  1450 . Disk  1454  may be unitarily joined to cylindrical member  1450 . Disk  1454  presents an outboard surface  1455  and defines a threaded aperture  1456 . Cylindrical member  1457  coaxially extends from outboard surface  1455 . Outboard disk  1458  extends generally coaxially and radially from the outboard terminus of cylindrical member  1457 . Outboard disk  1458  defines an aperture  1460  and presents an outboard surface  1462 . Aperture  1460  is generally aligned with threaded aperture  1456  in this embodiment. 
     Also in this embodiment, a fastener such as a screw extends through each aperture  1446  and is threadably disposed within each threaded extension  1452 . Screw  1464  is extended through aperture  1460  and is threadably received within threaded aperture  1456  as will be discussed below. Bores  1466 ,  1468  are coaxially formed within slip plate  1422  and drum assembly  1424 , respectively, such that shaft  1418  is received within bores  1466 ,  1468 . Drag cap spring  1470  is compressibly held in place by drag cap  1472  cooperating with a fastener such as a screw. If a screw is used, the screw is threadably received within an aperture proximate a terminus of shaft  1418 . 
     As seen in FIGS. 96,  98 , upper shield assembly  1320  includes upper shield  1478  and respective left, and right end caps  1480 ,  1482 . Upper shield  1478 , in turn, includes front panel  1486 , upper panel  1488 , and rear panel  1490 . Front panel  1486  includes conical protrusion  1492 . Respective planar members  1493 ,  1494  flank protrusion  1492  and present an interior surface  1496 . Lower lip  1498  extends generally transversely from interior surface  1496 , proximate a lower edge thereof. In this embodiment, upper panel  1488  includes planar member  1502  and presents upper surface  1504 . Planar member  1502 , in turn, defines switch aperture  1506 , on-off light aperture  1508 , and charge light aperture  1510 . Apertures  1506 - 1510  are generally and centrally aligned transverse a longitudinal axis of planar member  1502 . Rear panel  1490  includes respective left and right planar members  1514 ,  1516 . Conical protrusion  1518  unitarily extends from, and is flanked by, left and right planar members  1514 ,  1516 . An upper edge of rear panel  1490  unitarily joins a rear edge of upper panel  1488  at a bend. Upper and rear panels  1488 ,  1490  cooperate in defining remote aperture  1522 . Remote aperture  1522  generally aligns with apertures  1506 - 1510  and extends downwardly into a portion of conical protrusion  1518 . 
     Another lower lip (not shown) protrudes from an interior surface of rear panel  1490  in a similar manner as lower lip  1498 . Extending from respective left and right edges of panels  1486 - 1490  are left and right peripheral extensions  1524 ,  1526 , respectively. Extensions  1524 ,  1526  are formed by inward recesses from the exterior edges of panels  1486 - 1490 . 
     Respective left and right end caps  1480 ,  1482  are essentially mirror images in this embodiment. Hence, they will be described with like-numbered elements. Each end cap  1480 ,  1482  includes an outboard member  1530 , an upper member  1532  and a rear member  1534 . Outboard member  1530  is generally arcuate in cross-section. Upper member  1532  further includes generally planar member  1536  and generally conical element  1538 . Element  1538  extends above a forward portion of planar member  1536 . Lip  1540  extends forward from a lower edge of rear member  1534 . 
     Referring to FIGS. 98,  114 - 120 , hook and web assembly  1310  includes web  1550  and transfer hook  1552 . First and second loops  1556 ,  1558  are formed within web  1550  by stitching  1560 . In this embodiment, transfer hook  1552  is a unitary structure, which includes strap retaining member  1564  and hook member  1566 . Strap retaining member  1564 , in turn, displays exterior surface  1565  and defines a generally cylindrical bore  1568 . A slot  1570  is further defined in a lower portion of strap retaining member  1564 . Extending from strap retaining member  1564  is flange  1572 . Flange  1572  displays lower surface  1573 . Hook member  1566  extends from an upper portion of strap retaining member  1564 . Hook member  1566  may be envisioned as including planar member  1574 , arcuate member  1575 , and terminal lip  1576 . Planar member  1574  extends from strap retaining member  1564 . Arcuate member  1575  extends from planar member  1574 . Terminal lip  1576  extends from arcuate member  1575  toward strap retaining member  1564 . Planar member  1574 , arcuate member  1575  and terminal lip  1576  display respective exterior surfaces  1577 ,  1579 ,  1581  and interior surfaces  1578 ,  1580 ,  1582 . Terminal lip  1576  displays tip  1583 . Viewed cross-sectionally in FIG. 120, lines  1584 ,  1585  represent sites on interior surfaces  1565 ,  1580 . Plane  1587  extends through point  1585  and is generally perpendicular to surfaces  1578 ,  1582 . Planes  1588 ,  1589  extend through tip  1583  and line  1584  and are generally parallel to plane  1587 . Plane  1590  extends from surface  1578  and plane  1591  extends from surface  1582 . Gap  1592  is the distance between planes  1587 ,  1588 ; gap  1593  is the distance between planes  1588 ,  1589 ; and gap  1594  is the distance between planes  1590 ,  1591 . Plane  1600  extends from surface  1577 . Plane  1601  extends from surface  1573  and is generally perpendicular to plane  1600 . Plane  1605  extends tangentially from the tip of flange  1572  and is generally perpendicular to planes  1600 ,  1601 . Gap  1607  is the distance between planes  1587 ,  1595 . Plane  1595  is generally perpendicular to surface  1577  and extends through a center of bore  1568 . Plane  1596  extends through the center of bore  1568  and bisects slot  1570 . Angle  1597  is formed by the intersection of planes  1595 ,  1596 . 
     Exemplary transfer hook  1552  is about 4.03″ (±0.05″) in length and about 1.50″ (±0.05″) wide. Flange  1572  and members  1574 ,  1576  may be respectively about 0.25″ (±0.05″) and 0.325″ (±0.05″) in thickness. Strap retaining member  1564  may be about 0.25″ (±0.05″) thick, but may be thicker proximate planar member  1574 . Respective gaps  1592 ,  1593 ,  1594 ,  1586 ,  1607  may be about 1.00″ (±0.05″), 1.50″ (±0.05″), 0.75″ (±0.05″), 2.75″ (±0.05″), 1.03″ (±0.05″). Bore  1568  may be about 0.42″ (±0.05″) in diameter. Slot  1570  may be about 0.23″ (±0.05″) wide. Angles  1596 ,  1603  may be about 20° (±10°) and 80° (±20°), respectively. Both terminal lip  1576  and flange  1572  may be rounded. If so, the edges of terminal lip  1576  may be rounded to a radius of about 0.50″ (±0.05″) and flange  1572  may be rounded to a radius of about 0.80″ (±0.05″). In this embodiment, transfer hook  1552  is made from extruded aluminum. 
     Webbing  1550  connects to transfer hook  1554  by means of joint connector bolt  1598  and joint connector  1599 . Joint connector  1599  disposes within loop  1558 . Joint connector  1599  and loop  1558  are placed within bore  1568 . Webbing  1550  is extended through slot  1570 . To secure the attachment of webbing  1550  to transfer hook  1552 , joint connector bolt  1598  is threadably received onto joint connector  1599 . Dimensionally, exemplary web  1550  is about 60″ in length and about 1.50″ in width. However, it should be appreciated that the dimensions of web  1550  may be altered as necessary. Web  1550  may include materials suitable for automobile seat belts. 
     Hook and web assembly  1310  is installed onto drum assembly  1424  as depicted in FIGS. 117,  118 . First loop  1556  is extended through opening  1344 . First loop  1556  is then aligned with apertures  1456 ,  1460  (FIG.  98 ). Screw  1464  is passed through aperture  1460  and first loop  1556 , then threadably received within aperture  1456 . 
     Exemplary base assembly  1312  is depicted in FIG.  99  and broadly includes leg assembly  1602 , vertical adjusting means such as actuator assembly  1604 , trunk and skirt assembly  1606 , handle assembly  1608 , and base shield assembly  1610 . Leg assembly  1602 , in turn, includes two front legs or bumpers  1622  and two rear legs or bumpers  1624  unitarily extending from central portion  1626 . A caster  1628  is attached to a lower surface of each bumper  1622 ,  1624 . Central portion  1626  may display a generally planar surface  1630  which is recessed downwardly from bumpers  1622 ,  1624 . Central portion  1626  further defines a plurality of recessed portions  1632 , used as discussed below. 
     Exemplary actuator assembly  1604  is shown in FIGS. 99,  121  and includes actuator  1640 , left actuator support  1642 , right actuator support  1644 , plunger bracket  1646 , plunger pivot arm  1648 , actuator cable  1650 , and foot pedal assembly  1652 . Actuator  1640 , in turn, includes base member  1660 , actuator body  1664 , actuator piston  1666 , actuator pump piston  1668 , and disk  1670 . Actuator body  1664  extends generally transversely from generally horizontal base  1660 . The portion of actuator body above base  1660  is generally cylindrical. The portion of actuator body  1664  proximate base  1660  houses a hydraulic reservoir and pump. Actuator piston  1666  is slidingly and coaxially disposed within an upper portion of actuator body  1664 . Pump piston  1668  extends from base  1660  generally transversely to actuator body  1664 . Disk  1670  is fixed to pump piston  1668  a distance away from a terminus of pump piston  1668 . Actuator cable  1650  includes a stiff, flexible wire element  1678  slidingly disposed within jacket  1680 . Further included are a plurality of fastening devices, such as ferrules  1682 . 
     Exemplary foot pedal assembly  1652  includes pedal bracket  1686 , a plurality of pedal levers  1688 , pedal pivot bearings  1690 , foot pedal  1692 , and foot pedal pad  1694 . Pedal lever  1688 , in turn, includes lever portion  1696 , pedal mounting bracket  1698 , and bearing mounting bracket  1700 . Pedal mounting bracket  1698  is disposed generally transversely to lever portion  1698  at a first end thereof. Bearing mounting bracket  1700  extends generally transversely from a second end of lever portion  1698 . Pedal bracket  1686  attaches to a lower surface of central portion  1626 . Pedal lever  1688  is disposed within pedal bracket  1686 . Each extension of bearing mounting bracket  1700  is disposed within a pedal pivot bearing  1690 . Each pedal pivot bearing  1690  is affixed to a lower surface of central portion  1626 . Foot pedal  1692 , in turn, is affixed to an upper surface of pedal mounting bracket  1698 . Foot pedal pad  1694  is then disposed atop an upper surface of foot pedal  1692 . 
     Referring to FIG. 99, exemplary trunk and skirt assembly  1606  includes trunk  1710 , two hat sections  1712 , skirt plate  1714 , and skirt  1716 . Trunk  1710 , in turn, includes front panel  1720 , left side panel  1722 , right side panel  1724 , and rear panel  1726 . Front panel  1720  is a generally planar member. Left side panel  1722  and right side panel  1724  extend generally transversely from lateral edges of front panel  1720  and include a extended portions  1728 ,  1729 . Extended portions  1728 ,  1729  are generally rectangular in cross-section. Cord pocket  1730  is attached to an exterior surface of extended portion  1728 . Rear panel  1726  extends from rear edges of left and right side panels  1722 ,  1724 . Rear panel  1726  includes planar member  1732 . Flange  1734  extends outwardly from an upper edge of planar member  1732 . Another flange  1736  extends from an exterior surface of planar member  1732 . Bracket  1738  extends rearwardly proximate a right edge of flange  1736 . In this embodiment, bracket  1738  is disposed generally transverse to planar member  1732 . Cutout  1740  is defined in a lower portion of rear panel  1726  in this embodiment. A cutout may also be defined in a corresponding location of front panel  1720 . 
     Each exemplary hat section  1712  includes base member  1744 , front vertical member  1746 , rear vertical member  1748 , and inboard vertical member  1750 . Front, rear and inboard vertical members  1746 - 1750  extend generally transversely from base member  1744  and join base member  1744  at a bend. A peripheral flange  1752  extends generally transversely from an upper edge of each of vertical members  1746 - 1750 . Inboard vertical member  1750  and an adjoining portion of base member  1744  cooperate to define an inwardly curved surface  1754 . Generally planar top skirt plate  1714  coextends with a mated pair of hat sections  1712  when trunk and skirt assembly  1608  is assembled. 
     Skirt  1716  includes front panel  1760 , left side panel  1762 , right side panel  1764 , and rear panel  1766 . Panels  1760 - 1766  are generally planar. Front flange  1768  and rear flange  1770  extend inwardly from top edges of front panel  1760  and rear panel  1766 , respectively. Front panel  1760  and rear panel  1766  further and respectively define cutouts  1772 ,  1774  on lower-most portions thereof. A multiplicity of wear strips  1776  may be attached to exterior surfaces of panels  1760 - 1766 . In this embodiment, a wear strip  1776  is attached to lower portions of front and rear panels  1762 ,  1766 , proximate cutouts  1772 ,  1774 . 
     Actuator assembly  1604  and trunk and skirt assembly  1606  are assembled in a cooperative relationship as depicted in FIGS. 99,  121 . Left and right actuator supports  1642 ,  1644  are mated to actuator  1640  and then accommodated in one of recessed portions  1632  within central portion  1626 . Left and right actuator supports  1642 ,  1644  are then affixed to central portion  1626  by threading screws into pre-drilled and pre-threaded holes therefor. Plunger pivot arm  1648  is then seated and pivotally affixed to a recessed portion  1632  on an upper surface of central portion  1626 . A portion of pump piston  1668 , disposed distally to disk  670 , is then mounted to an upper portion of plunger bracket  1646  by being disposed through a slot (not shown) defined therein. One end of wire  1678  is extended through an upper slot defined in plunger bracket  1646 . One of ferrules  1682  is then affixed to the end of wire  1678 . Trunk  1710  is then lowered into place atop central portion  1626 . Two hat sections  1712  are mated around actuator piston  1666  and affixed thereto by fastening means, such as a plurality of bolts threadably mated to nuts. Top skirt plate  1714  is then affixed to mated hat sections  1712  by fasteners such as screws or bolts through pre-drilled holes within top skirt plate  1714  and peripheral flanges  1752 . Top skirt plate  1714  and attached hat sections  1712  are affixed to lower surfaces of flanges  1768 ,  1770  by such means as screws or bolts. The unattached end of wire  1768  is attached to pedal lever  1688  proximate pedal mounting bracket  1698  and secured thereto by a ferrule  1682 . 
     As also shown in FIGS. 99,  121 , handle assembly  1608  includes a plurality of handle supports  1788  and handle  1790 . Respective holes  1792 ,  1794  are defined in handle supports  1788  and handle  1790 . A first end of each handle support  1788  is accommodated in a recessed portion  1632  within central portion  1626  and affixed thereto. The free ends of handle  1790  then telescopically fit over exposed second ends of each handle support  1788 . Handle  1790  is then affixed to each handle support  1788  by such means as bolts or pins extending through holes  1788 ,  1790 . 
     Exemplary base shield assembly  1610  broadly includes front base shield  1800 , rear base shield  1802 , and battery cover  1804 . Front base shield  1800 , in turn, includes front panel  1810 , left side panel  1812 , and right side panel  1814 . Left and right side panels  1812 ,  1814  extend generally perpendicularly from lateral edges of front panel  1810 . Left side panel  1812  defines arcuate cutout  1816  proximate a rear edge thereof. 
     Exemplary rear base shield  1802 , in turn, includes rear panel  1822  and left and right panels  1824 ,  1826 . Rear panel  1822  is generally outwardly curved in cross-section. Flange  1834  extends from an upper edge of rear panel  1822 . A lower portion of rear panel  1822  defines recessed portion  1836 . Recessed portion  1836 , in turn, defines cutout  1838  centrally proximate a lower edge thereof. A pair of laterally disposed handle moldings  1840  are formed proximate an upper and each lateral edge of rear panel  1822 . Rear panel  1822  defines bracket slot  1842 . Bracket slot  1842  is disposed such that bracket  1738  will extend therethrough when rear panel  1822  is in place. Left and right panels  1824 ,  1826  extend respectively from left and right edges of rear panel  1822 . Left panel  1824  defines cutout  1848  proximate a front edge thereof and coordinate with cutout  1816  defined on left side panel  1812 . Label  1850  may be affixed to a predetermined portion  1852  of left panel  1824  in this embodiment. Label  1850  may display such indicia as operating and safety instructions. 
     Recessed edge  1828  extends from upper surfaces of panels  1810 - 1814  and  1822 - 1826 . A flange  1830  extends generally perpendicularly from lower edges of panels  1810 - 1814  and panels  1822 - 1826 . 
     Exemplary battery cover  1804  is unitary in this embodiment and includes rear panel  1860  and left and right panels  1862 ,  1864 . Rear panel  1860  may be envisioned as including left and right lobes  1868 ,  1870 . Curved surface  1872  presents vertical wall  1873 . Both curved surface  1872  and vertical wall  1873  are defined by lobes  1868 ,  1870 . In this embodiment, four generally vertical walls  1876  extend downwardly from rear panel  1860  to form pocket  1874  in an upper portion of right lobe  1870 . When battery cover  1804  is in place, plate  1878  is affixed to the bottom of pocket  1874 . Left and right panels  1862 ,  1864  extend generally perpendicularly from lateral edges of rear panel  1860 . Also when battery cover  1804  is in place, forward edges of left and right panels  1862 ,  1864  are proximate lateral edges of recessed area  1836 . 
     Referring to FIGS. 98,  99 ,  134 , the components of exemplary electrical and switching system  1314  broadly include charger  1902 , battery  1904 , AC sensor  1906 , logic board  1908 , interlock switches  1910 , proximity switches  1912 , remote coil assembly  1914 , remote switch  1916 , hour meter  1918 , and panel  1920 . Charger  1902 , in this embodiment, receives AC current via power cable  1900  and converts the AC current to DC current for charging battery  1904  via power cable  1901 . Charger  1902  is protected by cover  1903 . Input ratings for charger  1902  may include 90-264 VAC, line frequencies of 47-63 Hz, and currents between 0.80 A-0.35 A. Output ratings for charger  1902  may include, an initial charge voltage of 14.7 VDC, an end of charge voltage of 13.80 VDC, a current of 2.0 A, and a switchover current of 160 mA. Battery  1904  receives DC current from charger  1902  to operate the electrical components of transfer caddy  1302 . Battery  1904  is held in place by bracket  1905 . In this embodiment, battery  1904  is a rechargeable sealed lead acid battery with an output rating of 12 V and a nominal capacity of 12 Amp-hours or more. Also in this embodiment, AC sensor  1906  senses whether charger  1902  is plugged into 110 VAC or 220 VAC. This sensing is relayed to logic board  1908 . A pair of interlock switches  1910  are present as indicated in FIGS. 98,  114 . In this embodiment, proximity switches  1910  are affixed to base panel  1324 , proximate left and right end caps  1480 ,  1482 . Proximity switches  1910  disable electrical and switching system  1314  when either left or right end caps  1480 ,  1482  are not in place. 
     As may be seen in FIGS. 115-116,  134 , another pair of proximity switches  1912  are disposed proximate each interlock switch bracket  1334 . Each proximity switch pair  1912  includes a pair of single switches  1926  and pivot  1927 . Each single switch  1926  within switch pair  1912  operates from a separate circuitry. Switches  1926  are actuated by pivot  1927 . Exemplary remote coil assembly  1914  feeds out or retracts cable  1928 . 
     Referring to FIGS. 100,  101 ,  134 , remote switch  1916  is in electrical communication with logic board  1908  via cable  1928 , and remote coil assembly  1914 . Remote switch  1916  includes bottom cover  1940 , top cover  1942 , membrane switch  1944 , and button assembly  1946 . A plurality of moldings  1952  and a segmented platform  1954  may be present in bottom cover  1940 . Top cover  1942  includes another plurality of moldings (not shown), each molding generally aligned with a molding  1952  in bottom cover  1940 . Top cover  1942  also defines switch opening  1960 . Switch opening  1960  is defined proximate platform  1954  when top and bottom covers  1940 ,  1942  are mated. Membrane switch  1944  includes planar member  1964 , conductor  1966  and tab  1968 . Conductor  1966  generally extends from planar member  1964 . Tab  1968  represents a dielectric extension of conductor  1966 . 
     Button assembly  1946  is unitary in construction in this embodiment, and includes left and right lobes  1972 ,  1974  and base  1976 . Left and right lobes  1972 ,  1974  are joined at base  1976  in this embodiment. In practice, membrane switch  1944  is electrically connected to logic board  1908  via cable  1928 . Membrane switch  1944  is then disposed on platform  1954  and button assembly  1946  is disposed atop membrane switch  1944 . Top cover  1942  is then mated to bottom cover  1940  and secured thereto by a plurality of fasteners, such as screws  1978 . Each screw  1978  extends through bore  1953  of molding  1952  and is threadably received within a complimentary molding formed in top cover  1942 . 
     Another advantageous feature of exemplary transfer caddy  1302  is a switch controlling clutches  1420  after transfer caddy  1302  has effected a transfer, repositioning or rollover. In a first switch position, clutches  1420 , hence drum assemblies  1424 , turn freely or unwind slightly, thereby enabling the operator to more easily disconnect transfer hook  1552  from transfer rod  1306  after a transfer or repositioning. In a second switch position, clutches  1420  are still engaged with slip plates  1422 , thereby preventing drum assemblies  1424  from turning freely and holding the patient in a new rollover position. In the second switch position, drum assemblies are then reversed when the patient has been secured in the new desired position. Such a switch may be present on remote switch  1916  or proximate power switch  1988  on upper surface  1504  of upper panel  1488 . 
     Referring to FIGS. 96-98,  134 , panel  1920  includes power switch  1988 , on/off light  1990 , and charge light  1992 . Electrical and switching system  1314  is activated or deactivated by toggling power switch  1988 . On/off light  1990  displays a green color when electrical and switching system  1314  is activated in this embodiment. Charge light  1992  displays an amber light when the available charge in battery  1904  is less than 11.7±0.1 VDC. Charge light  1992  displays a blinking amber light when battery  1904  is being charged by charger  1902 . 
     As seen in FIG. 134, exemplary logic board  1908  includes terminals  2000 - 2016 . Terminal  2000  electrically connects logic board  1908  to left clutch  1420  and to one of redundant proximity switches  1926  of a first proximity switch pair  1912 . Terminal  2002  electrically connects logic board  1908  to right clutch  1420  and to one of redundant proximity switches  1926  of a second proximity switch pair  1912 . Terminal  2004  electrically connects logic board  1908  to motor  1410 . Terminal  2006  electrically connects logic board  1908  to charger  1902 , battery  1904 , and AC sensor  1906 . Terminal  2008  electrically connects logic board  1908  to panel  1920 . Terminal  2010  electrically connects logic board  1908  to right interlock switch  1910  and to another redundant proximity switch  1926  of second proximity switch pair  1912 . Terminal  2012  electrically connects logic board  1908  to remote switch  1916 . Terminal  2014  electrically connects logic board  1908  to yet another redundant proximity switch  1926  of first proximity switch pair  1912  and to left interlock switch  1910 . Terminal  2016  electrically connects logic board  1908  to hour meter  1918 . 
     Logic board  1908  controls and monitors the operation of transfer caddy  1302 . One function of the operation of logic board  1908  is controlling clutches  1420  and motor  1410  when a transfer event is in progress. Another function of logic board  1908  is monitoring the condition of battery  1904 . Still another function of logic board  1908  is monitoring charging of battery  1904  by charger  1902 . Yet another function of logic board  1908  is monitoring when charger  1902  is connected to an AC receptacle. 
     Logic board  1908  controls the operation of clutches  1420  in response to an operator pressing left or right lobes  1972 ,  1974  of remote switch  1916 . Logic board  1908  also actuates motor  1410  when either of clutches  1420  is energized. Logic board  1908  discontinues operation of one of clutches  1420  when a corresponding one of switches  1912 ,  1914  is activated. The deactivated clutch  1410  is locked-out until remote switch  1916  is cycled off and then on to prevent “chattering” of the clutch when an end of travel is reached. “Chattering” occurs when clutch  1420  is turned off and the tension on web  1550  is thereby released, causing web  1550  to disengage flange  1572  from proximity switch  1912 . An end of travel condition is reached when flange  1572  of transfer hook  1552  contacts pivot  1927 , thereby engaging proximity switch  1912 . Logic board  1908  further prevents operation of either of clutches  1420  or motor  1410  when either interlock switch  1910  is engaged. Either of interlock switches  1910  are engaged when an adjacent end cap  1480 ,  1482  is not in position. Logic board  1908  further prevents operation of either of clutches  1420  or motor  1410  when charger  1902  is connected to an AC receptacle. Logic board  1908  still further activates the event timer contained within hour meter  1918  when a current above  1 A originates from motor  1410 . A current above  1 A arbitrarily indicates that a transfer is being performed. 
     Logic board  1908  also functions as a battery condition monitor. Logic board  1908  monitors battery voltage and activates yellow indicator light  1992 . Logic board  1908  detects a condition wherein the voltage potential of battery  1904  is less than 11.7±0.1 VDC. Upon detecting this condition, logic board  1908  displays yellow light  1992  until battery  1904  is charged to above this level. If logic board  1908  detects a voltage potential below 11.7±0.1 VDC during a transfer event, there is sufficient energy still contained within battery  1904  to complete the transfer. Logic board  1908  monitors the condition of charger  1902 . Logic board  1908  detects when current between charger  1902  and battery  1904  exceeds 0.1 Amps. A current exceeding 0.1 Amps is above the “trickle charge level” charger  1902  typically supplies when battery  1904  is in a charged condition. Logic board  1908  activates light  1992  in response to a current between charger  1902  and battery  1904  exceeding 0.1 A. Logic board  1908  further locks out activation of light  1990  until charging is completed. 
     When charger  1902  is connected to an AC supply, logic board  1908 , via AC sensor  1906 , detects this condition for a value between 90-250 Vrms (volt-root mean square). When a value between 90-250 Vrms is detected, logic board  1908  locks out further operation of motor  1410  or clutches  1420 . Logic board  1908  further activates light  1990 , thus indicating that charger  1902  is connected to an AC supply. If charger  1902  is connected to an AC supply and light  1992  is activated, light  1990  will not be activated until the charging process for battery  1904  is complete. 
     Power switch  1988  controls power to motor  1410  and clutches  1420 . When switch  1988  is toggled to an on position, green light  1990  is activated, indicating that a relay has been energized. This relay (not shown) controls power output to motor  1410  and clutches  1420 . However, power for the electronics within logic board  1908  is otherwise not controlled by switch  1988 . Thus, the condition of battery  1904  may be continuously monitored. 
     Exemplary electrical and switching system  1314  may be configured so that between about  135  and  150  transfers may take place before charge light  1992  is illuminated, if battery  1904  is fully charged before initiation of transfers. Moreover, more than between about 200 transfers and 300 transfers may occur before battery  1904  is so drained of voltage that clutches  1420  disengage, thereby stopping the transfer process. More than between about 35 and 45 transfers may be effected between when charge light  1992  illuminates and when clutches  1420  disengage. Of course, these potential numbers of transfers would depend on factors such as the amperage of battery  1904  when fully charged, the weights of patients transferred, coefficients of friction between the transfer sheets, upon which the patients are disposed and the upper surfaces of transfer bridge  1304  and the surfaces from which and to which the patients are being transferred, and temperatures where transfer caddy  1302  is stored and used. 
     Transfer caddy  1302  may be about 36 inches wide, thereby enabling transfer caddy  1302  to be rolled through most hospital doorways. However, other embodiments of transfer caddy  1302  may be wider than  36  inches, yet be readily transportable through most doorways. 
     Another embodiment of the transfer caddy of this invention is depicted in FIG. 137 as transfer caddy  2350 . Transfer caddy  2350  differs from transfer caddy  1302  in that handle  2354  is mounted on front and rear bumpers. In this embodiment, handle  2354  is mounted on respective left front and rear bumpers  1622  and  1624  in mounts  2356 . Handle  2354  may be secured in mounts  2356  by such fasteners as pins, locking cam assemblies or nut-bolt combinations. Transfer caddy  2350  may further include pivotable handle  2360 . Handle  2360  pivots up in the direction of arrow  2362  from a recess in left end cap  1480 . Handle  2360  may be used singly or in combination with handle  1608  or handle  2354  in transporting and positioning transfer caddy  2350 . 
     Another embodiment to handle  1608  and  2354  is shown in FIG. 138 as handle assembly  2370 . Exemplary handle assembly  2370  includes upper section  2372 , left lower section  2374 , and a right lower section. Left lower section  2374  and the right lower section are joined to upper section  2372  by hinge assemblies  2378 . Hinge assemblies  2378  are mounted such that upper section  2372  folds toward head assembly  1308 . However, hinge assemblies  2378  may be mounted to enable upper section  2372  to fold away from head assembly  1308  and down as well. Upper section  2372  may be reversibly locked into an upright position by such means as pins and clip-pin combinations. 
     Transfer caddy  1302  may be proportioned such that webs  1550  are spaced apart about 26 inches on center. While spacings less than about 26 inches may produce satisfactory results, it becomes more important that the patient&#39;s center of mass be centered between webs  1550  as spacing therebetween decreases. 
     A transfer bridge, positionable between the horizontal surface on which the patient is disposed and the horizontal surface to which the patient will be transferred, is advantageously employed in the invention. Such an exemplary transfer bridge is depicted in FIGS. 108-110 as  1304 . Transfer bridge  1304  includes left and right inboard sections  2102 ,  2104  and left and right outboard sections  2106 ,  2108 . Each section  2102 - 2108  displays upper surface  2110  and lower surface  2112 . Each section  2102 - 2108  is hingedly connected to one or more adjacent sections by means of bridgespines  2116 . Each bridgespine  2116  includes a flexible low-friction material, such as Cordura®, laid proximate upper surface  2110  and a strip of enhanced friction material, such as Neoprene, placed proximate lower surface  2112 , thereby sandwiching the material of each of sections  2102 - 2108  therebetween. The layers are then stitched together in a manner known to the art. Inboard sections  2102 ,  2104  are joined together by bridgespine  2116  and include loops  2114 . Each loop  2114  may be 0.188″ diameter elastic (commonly known as bungee) cord. Each loop  2114  may be approximately 1″ in length. Each of sections  2102 - 2108  may include a material such as polypropylene overlaid with Cordova and reinforced Neoprene. The polypropylene may be 0.125″ (±0.05″) in thickness. A series of longitudinally oriented ribs  2118  may also be present on lower surface  2112 . In this embodiment, sections  2102  and  2104  and sections  2106 ,  2108  are generally mirror images. Each inboard section may extend outwardly approximately 17.25″ (±0.1″). Each outboard section may extend approximately 16.5″ (±0.1″). The depth of each inboard section  2102 ,  2104  may taper generally from a maximum proximate a central bridgespine  2116 . The maximum depth of sections  2102 ,  2104  may be approximately 14.0″ (±0.1″). In this embodiment, tapering continues on both the forward and rear edges. Exemplary transfer bride  1304  reaches a minimum depth of about 6.56″ (±0.1″) proximate each lateral edge of outboard sections  2106 ,  2108 . Each exemplary inboard section  2102 ,  2104  has a length of about 17.25″ (±0.1″). Each exemplary outboard section  2106 ,  2108  extends about 16.5″ (±0.1″). Indicia, such as arrow  2120 , may be present on upper surface  2110 . In this embodiment, arrow  2120  points toward the patient to be transferred. However, other indicia may be present on surfaces  2110 ,  2112  as well. 
     Referring to FIGS. 102-107, exemplary transfer rod  1306  includes first section  2140 , second section  2142 , and cord  2144 . First and second sections  2140 ,  2142 , respectively, include hollow rods  2146 ,  2148 . Each rod  2146 ,  2148  defines a generally coaxial bore  2150 . Bore  2150  is generally oval in cross-section. First section  2140  includes rod covers  2156 ,  2158 . Second section  2142  includes covers  2160 ,  2162 . Each section  2140 ,  2142  also includes several rod caps  2166 . Each rod cap  2166  is generally oval in cross-section and defines opening  2168  therein. Each rod cap  2166  further displays a flat surface  2170  and a rounded surface  2172 . A plurality of lips  2174  generally extend transversely from a midpoint of each flat surface  2170 . Opening  2168  generally conforms to an outer cross-sectional geometry of rods  2146 ,  2148 . Each transfer rod  1306  may further include a plurality of cord plates  2178 . In this embodiment, cord plate  2178  is generally planar and configures to a cross section of rods  2146 ,  2148 . Cord plate  2178  may further define a plurality of openings  2180 . A plurality of O-rings  2184  may also be present and, if present, are disposed as described below. In this embodiment, each rod  2146 ,  2148  is made of material which includes extruded aluminum. Each rod cover is extruded urethane overlaid with a material with a durometer, further enabling rods  2146 ,  2148  to grip a sheet. 
     Prior to assembly, a rod cap  2166  is installed in each end of each rod cover  2156 - 2162 . Installation includes contacting each lip  2174  to an interior surface of each rod cover  2156 - 2162  until flat surfaces  2170  contact the end of each rod cover  2156 - 2162 . Rods  2146 ,  2148  are then forced inside the assembled rod cover-rod cap combinations, for example by a hydraulic press, such that a gap  2188  is assured therebetween. Gap  2188  will accommodate transfer hook  1552  as discussed below. An O-ring  2184  is then inserted onto rod  2146 . Elastic cord  2144  is then installed within bores  2150  of rods  2146 ,  2148 . Each end of cord  2144  is passed through each opening  2180  in a cord plate  2178 . A knot is then formed in each free end of cord  2144 , thereby holding cord plates  2178  in place by the resulting tension. 
     In this embodiment, rods  2146 ,  2148  are about 27″ (±0.5″) and 20″ (±0.5″), respectively, with a cross-sectional width of 1.5″ (±0.007″) and a cross-sectional height of 0.5″ (±0.007″). Bore  2150  has a cross-sectional height of about 0.25″ (±0.01″) and a cross-sectional width of 0.75″ (±0.01″). Rod covers  2156 - 2162  are about 17″ (±0.5″), 10.5″ (±0.5″), 14.38″ (±0.5″), and 14.38″ (±0.5″), respectively, with a cross-sectional width of about 2.0″ (±0.03″), and a cross-sectional height of about 1.0″ (±0.02″). 
     When assembled, a free end of rod  2146  extends from first section  2140 . An inboard portion of rod cover  2160  does not contact rod  2148 . Thus, the free end of rod  2146  slidingly fits within rod cover  2160  and results in an assembled transfer rod  1306  of approximately 66″ (±1.0″) in length. Of course, other lengths for transfer rod  1306  are possible as well. Transfer rod  1306  may, for example, be between about 45 inches and 72 inches long. However, longer transfer rods tend to better distribute the loads generated by patients. Moreover, centering of patient mass becomes less important as transfer rods increase in length. 
     Assembled transfer rod  1306  is broken down for storage by separating sections  2140 ,  2142  in the directions indicated by arrows  2192 , then by folding sections  2140 ,  2142  together in the directions indicated by arrows  2194 . 
     FIGS. 122-132, depict exemplary steps in a patient transfer using the lateral patient transfer system of the present invention. A patient is lying on a first support  2304 . Disposed between the patient and first support  2304  is sheet  2306 . The patient is to be transferred to second support  2308 . First support  2304  and second support  2308  display respective upper surfaces  2310 ,  2312 . An attendant has previously transported second support surface  2308  and transfer caddy  1302  into the room. Second support  2308  has been positioned such that it angles away from first support  2304 , thereby providing working space for the attendant. The attendant has locked wheels present on first support  2304  where possible. The attendant has further withdrawn transfer rod  1306  from pocket  1874  and mated first and second sections  2140 ,  2142 . Transfer caddy  1302  has been positioned on a side of second support  2308  opposite first support  2304 . Side rails on first and second supports  2304 ,  2308  have been lowered, if present. Transfer rod  1306  is then placed atop sheet  2306  and centered to align generally with the center of the patient&#39;s body, as depicted by line  2314 . Sheet  2306  is untucked and folded over transfer rod  1306 . Transfer rod  1306  is rolled at least once toward the patient. However, transfer rod  1306  may be rolled until transfer rod  1306  and an enwrapped portion of sheet  2306  are as close to the patient as possible. Transfer bridge  1304  is then unfolded and placed under transfer rod  1306 . Transfer bridge  1304  is positioned such that the cambered edge is proximate the patient. Indicia such as arrows will point toward the patient to be transferred in some embodiments of transfer bridge  1304 . Each hook and web assembly  1310  is unrolled from transfer caddy  1302  and placed upon second support  2308 . Hooks  1552  are then emplaced about rods  2146 ,  2148  and enwrapped sheet  2306  at gaps  2188 . Second support  2308  is then brought into contact with first support  2304  as depicted by arrow  2316  in FIG.  127 . First and second supports,  2304 ,  2308  are then docked if possible. Also, wheels on second support  2308  are locked if possible. Finally, supports  2304 ,  2308  may be adjusted such that surface  2312  is approximately 1 inch lower than surface  2310 . Transfer caddy  1302  is then positioned as close to second support  2308  as possible and aligned with the center of the patient. 
     The vertical height of head assembly  1308  is then adjusted by foot pedal  1692 . Head assembly  1308  may be raised by pumping foot pedal  1692  as shown by arrow  2315 . Head assembly  1308  may be lowered by depressing and holding foot pedal  1692  until head assembly  1308  is at the desired vertical height. The desired vertical height of head assembly  1308  is such that a distance H (FIG. 126) is formed between webbing  1550  and surface  2312 . Distance H in this example is about 1 inch. A value of about 1 inch for distance H will result in stable contact between transfer caddy  1302  and second support  2308 . As seen in FIG. 113, head assembly  1308  is raised or lowered as indicated by arrows  2313  by foot pedal  1692 . In this embodiment, head assembly  1308  may be raised a distance  2317  from its lowest position. Exemplary distance  2317  is about 11 inches (±2 inches). Alternately, an electric motor may be used to actuate raising and lowering head assembly  1308 , for example, by powering a hydraulic pump. If an electric motor is employed, foot pedal assembly  1652  would be replaced with an electric switch. Alternately, an electric switch could be mounted proximate switch  1506  on upper panel  1488 . 
     Returning to FIGS. 122-132, the attendant then removes remote switch  1916  from remote aperture  1522  and withdraws a desired length of power cable  1928 . Left and right lobes  1972 ,  1974  are depressed as needed until the slack in webs  1550  has been taken up and webs  1550  are taut. The transfer event begins when lobes  1972 ,  1974  are depressed simultaneously and the patient begins to be moved atop transfer bridge  1304  and toward second support  2308 . The attendant may insure that transfer bridge  1304  is not displaced by holding transfer bridge  1304  until the patient is atop thereof. Once the patient has been transported generally to a center position on second support  2308 , the attendant discontinues depressing left and right lobes  1972 ,  1974 . However, if for some reason the patient transfer continues past this point, a safety mechanism provided in transfer caddy  1302  will automatically discontinue the transfer. 
     As depicted in FIGS. 115,  116 , transfer hook  1552 , transfer rod  1306 , and an enwrapped portion of sheet  2306  are being retracted toward head assembly  1308 . If the patient transfer is not discontinued by an attendant, flange  1572  will contact and displace pivot  1927 . Pivot  1927  actuates proximity switch  1912 , when displaced and thereby discontinues the transfer. 
     Once the patient has been transferred to second support  2308 , the transfer event is ended. Transfer hooks  1552  are disconnected from transfer rod  1306  and sheet  2306  is then unwrapped from transfer rod  1306 . Sections  2140 ,  2142  of transfer rod  1306  are then separated and returned to their storage position on transfer caddy  1302 . Transfer bridge  1304  is removed, refolded, and returned to its storage position on transfer caddy  1302  as well. Side rails are then raised on second support  2308 , if present. Transfer caddy  1302  may be then rolled away and transported to another desired location. 
     The beginning and end of a patient transfer event are characterized by an advantageous feature of the present invention. Web  1550  is wound on drum assembly  1424  to effect the transfer. If drum assembly  1424  were directly connected to shaft  1418 , rather than to magnetic clutch assembly  1420 , the transfer would begin and end abruptly. That is, drum assembly  1424  would begin to wind and cease winding at full speed. Thus, an abrupt and potentially uncomfortable beginning and ending of the patient transfer event might occur. However, addition of magnetic clutch assembly  1420  and slip plate  1422  results in a more gradual acceleration and deceleration in the rotation of drum assembly  1424 . Hence, the patient transfer effected by the present invention begins and ends in gradually increasing rates of transfer. 
     Another embodiment of the invention is depicted in FIG. 135 as exemplary patient transfer system  2330 . Exemplary patient transfer system  2330  is similar to patient transfer system  1330  with the exception that extended bumpers  2334  are present in place of bumpers  1484 . As seen in FIGS. 98 and 135, bumpers  2334  differ from bumpers  1484  by the presence of extended member  2338 . Extended member  2338  mates to front portions of left and right end caps  1480 ,  1482 . Other features of bumper  2334  may be similar to those of bumper  1484 . Another embodiment of bumper  2334  is extendible and retractable within endcaps  1480 ,  1482  in the direction of arrow  2340 . Bumpers  2334  may be extended or retracted by such means as a worm gear drive (not shown). Still another embodiment of bumpers  2334  includes a plurality of telescoping sections to comprise member  2338  (not shown). Normally, front bumpers  1622  are disposed beneath a bed so that bumpers  1484  can contact the bed frame. Extended bumpers  2334  are advantageous if front bumpers  1622  cannot be positioned beneath the surface on which the patient is to be transferred, because extended bumper  2334  may nonetheless contact the frame. 
     Alternate embodiments of transfer caddy  1302  are depicted in FIGS. 139-144. These embodiments employ measures such as weights to enhance the stability of transfer caddy  1302  during a transfer event. Referring to FIGS. 139-141 transfer caddy  1302  is depicted as including weight  2390  mounted on upper surface  2388  of rear bumper (or leg)  1624 . In this embodiment one or more orifices  2392  extend from upper surfaces  2388  to lower surfaces  2394  of rear bumpers  1624 . Threaded apertures may be formed in weights  2390  to coincide with locations of orifices  2392 . Bolts are then extended through orifices  2392  from lower surfaces  2394  of rear bumpers  1624  and threaded into the threaded apertures in weights  2390 . 
     Referring to FIGS. 142-144, weight  2398  includes central portion  2404  and respective front and rear extensions  2400 ,  2402 . Weight  2398  is formed to conform to the peripheral contours of leg assembly  1602 . Central portion  2404  conforms to the periphery of central portion  1626  of leg assembly  1602 . Respective front and rear extensions  2400 ,  2402  conform to peripheries of respective front and rear bumpers  1622 ,  1624 . Orifices may be formed in weight  2398  to coincide with the locations of casters  1628  and to accommodate mounting bolts. In this embodiment, weight  2398  is mounted to the underside of leg assembly  1602  by mounting bolts extending therethrough and threaded into apertures formed in leg assembly  1602 . Casters  1628  may then be mounted through weight  2398  into leg assembly  1602 . 
     Weights  2390 ,  2398  may be used singly or in combination with other weights or stability enhancing means. Moreover, weights such as  2390 ,  2398  may be mounted by other mounting means such as glues and clamps. Exemplary weights  2390 ,  2398  may include such materials as lead, cast iron, steel and other metal alloys. Furthermore, some or all of the desirable stability enhancing means achieved by exemplary weights  2390 ,  2398  may be attained by forming all or part of leg assembly  1602  from the same heavier materials as used to form exemplary weights  2390 ,  2398 . 
     Still other stability enhancing means include extending the length of bumpers  1622 ,  1624  of leg assembly  1602 . Leading edges  2410  of front bumpers  1622  and trailing edges of rear bumpers  2412  are about 12.5 inches and 8.8 inches, respectively, from center point  2408  in exemplary leg assembly  1602 . Increasing the distance between center point  2408  and leading edges  2410  would be more effective than increasing the distance between center point  2408  and trailing edges  2412 . 
     Referring to FIG. 136, a pair of sheet gripping devices  2380  are shown. Each gripping device  2380  includes a pair of extended gripping members  2384  and a connecting member  2386 . Gripping member pairs  2384  work together in jaw-like fashion and grip a portion of a transfer sheet in a similar manner to several of the embodiments herein. Connecting member  2386  may include means to mate with another connecting member such as transfer hook  1552 . Alternately, connecting member  2386  may include means to allow web  1550  to attach directly thereto. In this embodiment each pair of gripping devices  2380  may grip a sheet portion of about 12 inches in length and a combined sheet portion of about 24 inches. 
     Referring to FIGS. 145-150, one embodiment of a pliable underlayment for patient transfer and repositioning is depicted as transfer sheet  2450 . Transfer sheet  2450  includes mantle  2452 , one or more reinforced edges  2454 , and one or more attaching members  2456 . Reinforced edge  2454  may include a number of embodiments discussed below. 
     Each attaching member  2456  is attached to, and cooperates with, mantle  2452  to define a pocket  2459 . Each attaching member  2456  in this embodiment is attached to mantle  2452  by stitching  2462 . A plurality of slots  2460  may be formed proximate a lateral edge of each pocket  2459 . Exemplary pockets  2459  are about 22 inches in length and about 2 inches wide. 
     Transfer bar  2470  is used in conjunction with transfer sheet  2450 . Exemplary transfer bar  2470  includes first and second bar segments  2472 ,  2473 . However, other embodiments of transfer bar  2470  may be unitary or one-piece in construction. Transfer bar  2470  defines first and second ends  2474 ,  2475  and first and second slots  2476 ,  2477 . Exemplary transfer bar  2470  is proportioned, and first and second slots  2476 ,  2477  are spaced apart, such that slots  2476 ,  2477  are exposed when transfer bar  2470  is disposed in pocket  2459 . In one embodiment slots  2476 , 2477  are spaced apart about 24 inches on center and transfer bar is about one inch wide, one-fourth inch in depth, and 26¾ inches in length. While slots  2476 ,  2477  are shown generally centered in first and second bar segments  2472 ,  2473 , first and second slots  2476 ,  2477  may be offset as well. Offset slots tend to maintain transfer bar  2470  in a flattened position during a patient transfer or pullup, thereby decreasing the likelihood of transfer bar  2470  being bent. Slots  2476 ,  2477  are dimensioned to accommodate a transfer or repositioning hook such as hook  2480  or transfer hook  1552 . Slots  2460  are formed proximate pockets  2459  and are also proportioned to accommodate connecting members such as hook  2480  or transfer hook  1552 . Hook  2480 , in this example, may extend through slot  2460  and attach to transfer bar  2470  disposed therein. 
     Transfer sheet  2450  displays respective first, second, third, and fourth edges  2484 ,  2486 ,  2488 ,  2490 . In FIG. 145, a plurality of pockets  2459  are depicted extending generally parallel to respective first, third, and fourth edges  2484 ,  2488 ,  2490 , corresponding to a patient&#39;s head and sides. FIG. 146 depicts a plurality of pockets  2459  extending generally parallel to respective third and fourth edges  2488 ,  2490 , corresponding to portions of transfer sheet  2450  normally flanking a patient. In FIG. 147 a plurality of pockets  2459  are depicted extending generally parallel to each respective first and second edge  2484 ,  2486 . Edges  2484 ,  2486 , respectively, correspond to edges proximate a patient&#39;s head and foot. While pockets  2459  are depicted as generally contiguous or adjoining in FIGS. 145-150, pockets  2459  may be spaced apart as well. 
     In FIGS. 151-161 other embodiments of the substantially pliable underlayment of this invention are depicted. FIG. 151 depicts transfer sheet  2500 . Transfer sheet  2500  includes mantle  2502 . Mantle  2502 , in turn, includes reinforced edges  2504 , a plurality of generally elliptically-shaped slots  2506 , and respective first and second stitchings  2508 ,  2510 . In this embodiment, slots  2506  are defined within reinforced edges  2504 . Slots  2506  are configured to accommodate a connecting device such as transfer hook  1552 . A plurality of respective first and second stitchings  2508 ,  2510  is present within mantle  2502 . First stitchings  2508  extend generally obliquely (diagonally) from edges  2504 . Second stitchings  2510  extend generally perpendicularly to first stitchings  2508  and extend generally obliquely to reinforced edges  2504  as well. Other reinforcing means may be present within mantle  2502 , either in addition to stitchings  2508 ,  2510  or to the exclusion thereof. These reinforcing means include reinforcing fibers, woven into the material of mantle  2502 . These reinforcing means reduce distortion to transfer sheet  2500  to less than about 10% during a patient transfer, repositioning, or rollover event. These reinforcing means may further reduce distortion to less than about 8%. These reinforcing means may still further reduce distortion to less than about 5%. 
     Transfer sheet  2520  is depicted in FIG.  152 . Transfer sheet  2520  includes mantle  2522 . Mantle  2522 , in turn, includes reinforced edges  2524  and a plurality of generally elliptically-shaped slots  2526 . Though not depicted, reinforcing means such as stitchings  2508 ,  2510  may be present as well. Reinforced edges  2524  are partially formed and bordered by hems  2528 . Slots  2526  are bordered by stitching (not depicted) in this embodiment. Slots  2526  are configured to accommodate a plurality of grasping or connecting members such as transfer hook  1552  to accommodate other grasping members requiring wider sights of attachment. 
     FIG. 153 depicts another embodiment of the pliable underlayment of this invention as transfer sheet  2540 . Transfer sheet  2540  includes mantle  2542 , reinforcements  2544  and apertures  2546 . In contrast to previous embodiments, reinforcements  2544  surround each aperture  2546 , but do not form a continuous reinforced edge. Reinforcements  2544  cooperate with apertures  2546  to form reinforced, discrete connector points. These connector points function to accommodate gripping mechanisms for patient transfers, repositionings, and rollovers. While not depicted, reinforcing means as discussed above may also be present. 
     Referring to FIGS. 154,  155  another embodiment of the pliable underlayment of the present invention is depicted generally as transfer sheet  2560 . Transfer sheet  2560  includes mantle  2562  and a plurality of reinforced portions  2564 . A slot  2566  is defined within each reinforced portion  2564  in this embodiment. Adjacent reinforced portions  2564  cooperate to form reinforced edges  2568 . In this embodiment slots  2566  are configured to accommodate a grasping or connecting member such as transfer hook  1552 . In this invention, any of slots  2506 ,  2526 ,  2566 , aperture  2546  or any opening formed in a pliable underlayment such as any of the transfer sheets described above, may be bordered by such protective and reinforcing means such as grommets. 
     Another embodiment of the substantially pliable underlayment of this invention is depicted in FIG. 156 as drawsheet  2600 . Drawsheet  2600  offers the advantages of maintaining its shape during a transfer or repositioning event when gripped by clamps or connected to connecting members. Drawsheet  2600  offers the additional advantage of including an absorptive means, whereby fluids from a patient disposed thereon are transmitted away from the patient. Thus, the absorptive means help keep the patient dry. Drawsheet  2600  offers the further advantages of being washable in normal laundering facilities and eliminating the expense and waste involved when sanitary pads are used to absorb fluids from a patient. 
     Drawsheet  2600  includes mantle  2602 . Mantle  2602  may include a plurality of layers. Exemplary mantle  2602 , as depicted in FIG. 157, includes permeable layer  2606 , absorptive layer  2608 , drawsheet layer  2610  and impermeable layer  2612  and any combination thereof. Permeable layer  2606  overlays absorptive layer  2608 . Permeable layer  2606  may include fabrics which allow liquids to pass through to absorptive layer  2608  and which impart a sensation of comfort to a patient lying thereon. Permeable layer  2606  may include fabrics such as cotton, linen, various polyesters such as nylon and rayon, as well as various blends thereof. 
     Absorptive layer  2608  includes a substance which will absorb liquids, thereby wicking them away from a patient disposed thereon. Absorptive layer  2608  may also include an anti-microbial substance such as Microban® or Biocryl®. These or other anti-microbial agents (biocides) may be capable of killing BRSA bacteria, such as Staphylococcus aureus. An absorptive acrylic spun-laced fabric disclosed in U.S. Pat. No. 5,350,625, assigned to DuPont and incorporated herein by reference, is one example of a suitable material for absorptive layer  2608 . 
     Drawsheet layer  2610 , as depicted in FIG. 158, is designed to impart a resistance to distortion due to forces applied during a transfer, repositioning, or rollover event. Drawsheet  2600  thus includes fabrics designed to minimize the “parabolic” effects otherwise occurring in sheets which fail to resist stretching or distortion. One means of reinforcing drawsheet layer  2610  includes stitchings such as  2508 ,  2510  as described above. Materials used in drawsheet layer  2610  may include cotton, linen, and polyesters such as nylon, rayon or any blend thereof. 
     Impermeable layer  2612  is disposed exterior to drawsheet layer  2610 . Impermeable layer  2612  is impermeable to liquids, thus protecting an underlying mattress from fluids originating from a patient disposed thereon. Impermeable layer  2612  may also include materials which reduce friction as drawsheet  2600  is drawn across a bed. Vinyl or silicone applied to a nylon substrate are examples of friction-reducing materials. Impermeable layer  2612  may further include antimicrobial or antibacterial compounds. 
     As seen in FIG. 156, absorptive layer  2608  may extend over a central portion of drawsheet  2600 . Absorptive layer  2608  may be disposed on drawsheet  2600  so that absorptive layer  2608  underlies the portion of the patient between the patient&#39;s waistline and thighs. Drawsheet layer  2610  in this embodiment, is about 60 inches wide and 72 inches long. Absorptive layer  2608  is about 33 inches wide and about 33 inches long. As seen from FIG. 157, absorptive layer  2608  is generally centrally disposed on drawsheet layer  2610 . Permeable layer  2606  may extend to within approximately one foot of beaded edge  2604 . Layers  2606 - 2612  present a tapering to reduce the density of drawsheet  2600 , thereby reducing the thickness of any seam which may contact a patient disposed thereon. By tapering, it is meant that layers  2606 - 2612  are dimensioned so that their edges do not coincide. For example, the edges of permeable layer  2606  are disposed outside the edges of absorptive layer  2608 ; the edges of impermeable layer  2612  are disposed outside the edges of permeable layer  2606 ; and the edges of drawsheet layer  2610  are disposed outside the edges of impermeable layer  2612 . Tapering has the effect of reducing localized pressure on a patient&#39;s skin which a thick seam might otherwise impart. The reduced pressure on the patient&#39;s skin reduces or eliminates irritation. Methods of bonding layers  2606 - 2612  to each other include stitching. 
     Also seen in the cross-section depicted in FIGS. 157,  159  are enhanced beads (beaded edges)  2604 . Enhanced beads  2604  may be hems which include doubled or rolled materials from drawsheet layer  2610 . Electrically conductive, yet flexible materials may also be included in beads  2604 . One advantage of enhanced bead  2604  is that drawsheet  2600  may be more securely gripped during a transfer or repositioning event. 
     Also depicted in FIG. 156 are exemplary conductors  2614 ,  2616 . Conductors  2614 ,  2616  extend. generally parallel to each other in a non-contacting fashion within absorptive layer  2608 . Conductors  2614 ,  2616  further extend from absorptive layer  2608  to logic board  2618 . When absorptive layer  2608  is dry, the electrical potential between conductors  2614 , 2616  is not expressed. However, when absorptive layer  2608  contacts a sufficient amount of liquids with electrolytes, such as urine or perspiration, current flows between conductors  2614 ,  2616 . The current originates in a battery such as a 12-volt battery (not shown). Logic board  2618  thereby detects a closed circuit and may transmit an electromagnetic signal to a receiver (not shown), in response, thus alerting an attendant that drawsheet  2600  should be changed. The electromagnetic signal may also be transmitted via a conductor, which may be present in enhanced bead  2604 . 
     Absorptive layer  2608 , or other layers  2606 ,  2610 ,  2612 , may also include sensors  2620 . Sensors  2620  may generally extend from absorptive layer  2608  to logic board  2618 . Sensors  2620  may be designed to monitor such phenomena as the patient&#39;s temperature and heartbeat rate. These and other vital signs may also be transmitted electromagnetically to a receiver for automated monitoring and recording. 
     An alternative embodiment of permeable layer  2606  changes color when exposed to perspiration or urine due to a change in pH, thereby further alerting attendants that sheet  2600  needs to be changed. 
     FIG. 159 depicts drawsheet  2630 , another embodiment of the present invention. Drawsheet  2630  includes permeable layer  2606 , absorptive-drawsheet layer  2632 , impermeable layer  2612  and beaded edge  2604 . Layers  2606 ,  2632 , and  2612  are bonded together, and cooperate in a tapering fashion as described above, except that the material of  2632  serves the dual functions of layers  2608 ,  2610  of drawsheet  2600 . 
     Referring to FIGS. 160,  161 , yet another embodiment of the substantially pliable underlayment of the present invention is depicted as transfer or repositioning sheet  2640 . Transfer sheet  2640  includes mantle  2642  and beaded edge  2644 . Material from mantle  2642  is wrapped about substantially flexible member  2646  and hemmed against itself, thereby forming beaded edge  2644 . Beaded edges  2604 ,  2644  are desirable for attachment by a connecting member such as several of the clamps discussed herein. Affixing means, such as stitching  2648 , is used to affix the overlapping portions of the material of mantle  2642  proximate beaded edge  2644 . Transfer sheet  2640  may further include reinforcing means as discussed above. 
     Because numerous modifications may be made to this invention without departing from the spirit thereof, the scope of the invention is not to be limited to the embodiments illustrated and described. Rather, the scope of the invention is to be determined by appended claims and their equivalents.