Patent Publication Number: US-8112833-B2

Title: Table assembly for patient transfer device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of U.S. patent application Ser. No. 11/837,671 filed Aug. 13, 2007, now U.S. Pat. No. 7,861,336, which is a continuation-in-part of U.S. patent application Ser. No. 11/534,535 filed Sep. 22, 2006, now U.S. Pat. No. 7,540,044, which is a continuation-in-part of U.S. patent application Ser. No. 11/246,426 filed Oct. 7, 2005, now U.S. Pat. No. 7,603,729, each of which is hereby incorporated. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to devices for moving objects, and more particularly to a tray or table assembly for a patient transfer device wherein the table assembly includes upper and lower tables having counter-rotating, endless belts. 
     2. Description of the Related Art 
     A wide variety of products have been designed to move objects from one location to another and, in particular, transfer mobility-impaired individuals such as patients. In a hospital setting, patients must often be transported from their beds to an examination table or operating table, and back again. Basic devices for transferring patients include stretchers that are carried manually by two attendants, and wheeled gurneys that can more easily be handled by a single attendant. 
     There can still be problems, however, in getting a patient from a bed or other support surface onto a stretcher or gurney. If the patient is cooperative and not injured or disabled, it is a simple matter for the individual to slide over to the gurney with the assistance of a nurse, but if the patient is unconscious or has a disability or an injury (e.g., a broken bone) that might be worsened by movement, then great care must be taken in transferring the patient from the bed to the gurney. This problem is exacerbated when the patient is unusually heavy. 
     One solution to this problem is to slide a tray or sheet under the person and then, after the person is resting atop it, pull the tray or sheet off the bed and onto the gurney. A rigid tray can be forcibly inserted between the patient and the bed, and a sheet can be incrementally pushed under the person by first rocking him away from the gurney and then rocking back toward the gurney as the sheet is drawn under. This approach can still be difficult if the patient is uncooperative (i.e., unconscious), and can further be very uncomfortable even if the patient is cooperative, due to the frictional engagement of the tray with the body or the lack of firm support by the sheet. 
     Some transfer devices incorporate a rigid tray into the gurney that can move to the side and slide under a patient, and then slide back (while supporting the patient) to a centered position for transportation. In a further variation on this concept, the transfer device may use counter-rotating, endless belts to substantially eliminate friction against both the patient and the bed as support trays crawl under the patient. One example of such a design is shown in U.S. Pat. No. 5,540,321. A first endless belt surrounds a set of upper trays and a second endless belt surrounds a set of lower trays, so the portions of the belts that are in contact (between the upper and lower tray sets) move in the same direction at the same rate as they counter-rotate. As the trays are inserted under the patient, the belt on the upper tray everts outwardly at the same rate as the translational movement of the trays to crawl under the patient without introducing any significant friction, and the belt on the lower tray similarly everts along the bed sheet. Once the patient is supported by the trays, the entire tray assembly is raised off the bed and the device can be rolled on casters to transport the patient. 
     There are still several serious problems with the counter-rotating belt designs. The entire transfer device (including the base and support members) moves as the trays are inserted under the patient, and the base must extend under the bed or table in order to prevent the device from tipping over when the patient is carried (see, e.g., FIG. 10 of &#39;321 patent). Because of this limitation, such devices cannot be used in all settings, i.e., wherein there is insufficient clearance space under the bed or table (a situation becoming more common as more accouterments are added to beds and tables that occupy the space underneath). These devices further only allow loading and unloading along one side of the device, which can present problems when the patient is not suitably oriented (head-to-feet) on the device with respect to the bed or table. Designs such as that shown in the &#39;321 patent are also not particularly comfortable as there is only a thin layer of the belt interposed between the patient and the hard surface of the metal support trays. Moreover, hospitals are becoming increasingly concerned with potential contamination from patient fluids, and the prior art belt-type transfer devices are difficult if not impossible to properly clean. 
     Another problem relates to the initial impact of the trays as they acquire a patient. The height of the trays and the large diameter edge rollers in the &#39;321 design present an abrupt bump along the patient&#39;s side during acquisition, and result in a similar bumpy delivery of the patient back to a support surface. The tray can be inclined, for example as shown in U.S. Pat. No. 4,914,769, but a large angle of inclination makes it more difficult to acquire the patient and can increase patient discomfort during loading and unloading. It is also more likely that a patient will roll off the table assembly if the edge portions can incline downward. 
     In light of the foregoing, it would be desirable to devise an improved patient transfer device that provided more flexibility in deployment while still being easy to operate and maneuver. It would be further advantageous if the device were more comfortable for the patient, yet could still maintain the patient in a stabilized manner during transport. 
     SUMMARY OF THE INVENTION 
     It is therefore one object of the present invention to provide an improved table assembly for a patient transfer device wherein the table assembly includes upper and lower tables having counter-rotating, endless belts. 
     It is another object of the present invention to provide such a table assembly that can adjust the upper table geometry to more easily and comfortably acquire, transport and deliver a patient. 
     It is yet another object of the present invention to provide a table assembly for a patient transfer device that does not require clearance space under the patient&#39;s bed or table during operation. 
     The foregoing objects are achieved in a patient transfer device generally comprising a base, a support member attached to the base, a slide assembly attached to the support member which is movable between a home position over the base and an extended position to a side of the base, and a table assembly attached to the slide assembly having upper and lower tables surrounded by respective upper and lower belts which counter-rotate as the table assembly moves between a patient and a surface supporting the patient, the table assembly also having integrated means for laterally retracting a pair of side plates of the upper table while vertically separating the upper table from the lower table. In one embodiment the lower table is fixed to the slide assembly, and the integrated means includes end plates attached to the slide assembly having guide slots which slidably retain positioning posts attached to ends of the side plates. The slots are inclined upwardly toward a longitudinal centerline of the table assembly. Crank assemblies for moving the side plates have rotating disks and linkage arms with a first end pivotally attached to a peripheral region of a disk and a second end pivotally attached to one of the positioning posts. The rotating disks are attached to a central frame of the upper table such that retraction of the side plate raises the central frame. The table assembly may further adjust an incident angle of the side plate as it retracts by providing guide slots having different angles of inclination. The side plate is downwardly inclined in an extended position and is generally flat in a retracted position. 
     The above as well as additional objectives, features, and advantages of the present invention will become apparent in the following detailed written description. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. 
         FIGS. 1A-1D  are front elevational views of one embodiment of the patient transfer device of the present invention illustrating (i) patient acquisition, (ii) initial separation of the upper and lower tables of the table assembly while supporting the patient, (iii) further separation and partial retraction of the table assembly, and (iv) the separated table assembly supporting the patient at the centered (home) position for transport; 
         FIG. 2  is a top plan view of the table assembly used with the patient transfer device of  FIG. 1  in accordance with one embodiment of the present invention, with the upper belt removed; 
         FIGS. 3A-3C  are front elevational views of the table assembly of  FIG. 2  illustrating (i) the upper table with fully extended edge rollers and the upper belt in forcible contact with the lower belt, (ii) an intermediate separation of the upper table from the lower table with the upper table edge rollers beginning to retract, and (iii) the fully retracted and separated upper table; and 
         FIG. 4  is a front elevational view of the upper table end plate having guide slots which slidably retain positioning posts attached to ends of the retracting side plates in the upper table. 
     
    
    
     The use of the same reference symbols in different drawings indicates similar or identical items. 
     DESCRIPTION OF THE PREFERRED EMBODIMENT(S) 
     With reference now to the figures, and in particular with reference to  FIGS. 1A-1D , there is depicted one embodiment  10  of a patient transfer device constructed in accordance with the present invention. Patient transfer device  10  is generally comprised of a frame or base  12  mounted on four or more wheels or casters  14 , two vertical support members or columns  16  mounted on base  12 , a horizontal slide assembly  18  attached to support columns  16 , a table assembly  20  attached to slide assembly  18 , and side rails  22  attached to support columns  16 . 
       FIG. 1A  illustrates a patient acquisition position of slide assembly  18  and table assembly  20  wherein a leading edge of table assembly  20  has crawled about halfway under the patient  24  who is resting on a bed or other support surface  26 . Table assembly  20  includes an upper table  20   a  and a lower table  20   b  each of which is surrounded by a respective endless belt or web. In the patient acquisition position, upper table  20   a  is in forcible contact with lower table  20   b , and the upper and lower belts counter-rotate. The movement of slide assembly  18  is synchronized with the belt drive mechanism so that the extending carriages slide sideways to or from the home position at a speed that matches the eversion rate of the upper and lower belts. In this manner, table assembly  20  can move under (or away from) the patient with essentially no frictional engagement between patient  24  and the upper belt, or between bed  26  and the lower belt and in doing so, only gently lift or lower the patient without pushing the patient to the side, and further performs this operation without requiring that base  12  also move sideways. 
     Once the patient is acquired, i.e., generally centered on top of table assembly  20 , upper and lower tables  20   a ,  20   b  begin to separate while table assembly  20  remains positioned over bed  26 .  FIG. 1B  shows table assembly  20  with an initial separation between upper and lower tables  20   a ,  20   b  while supporting the patient. As the upper and lower tables separate, left and right edge rollers of upper table  20   a  also retract, as described below in conjunction with  FIGS. 3A-3C . 
     This retraction of the upper table edge rollers introduces slack into the upper belt which allows a shaped air mattress within upper table  20   a  to be inflated.  FIG. 1C  depicts table assembly  20  with the upper and lower tables  20   a ,  20   b  fully separated and the air mattress inflated to its full shape by which side lobes  30  are formed in the upper belt. Side lobes  30  help prevent patient  24  from rolling off table assembly  20  as it moves to the home position, as well as during transport using patient transfer device  10 . As further explained below, left and right edge sections of upper table  20   a  also change their downward inclination to a horizontal orientation which additionally raises side lobes  30  for patient transfer. 
     The separation of the belt tables now allows the lower belt around lower table  20   b  to roll effortlessly as it is driven in the reverse direction over the top surface of bed  26  while table assembly  20  moves toward the home position without engaging upper belt  20   a , which would otherwise disrupt patient  24 . The contact maintained between lower table  20   b  and bed  26  imparts stability so patient transfer device  10  will not tip over from the lateral weight of the patient as table assembly  20  moves back to the home position illustrated by  FIG. 1D . This feature thus allows base  12  to be relatively narrow, i.e., the width of table assembly  20 , without any portion of the base extending underneath bed  26 . This design still takes advantage of counter-rotating belts to reduce frictional engagement while loading or unloading, but leaves the patient undisturbed on the upper table portion as the patient is safely transferred from the bed to the device. 
     Once the patient is acquired and in the home position shown in  FIG. 1D , side rails  22  are raised and patient transfer device  10  can be wheeled to another location and the patient delivered onto a support surface such as an operating table or another bed by simply reversing the acquisition process described above. The patient may be placed along either side of device  10 , and the carriage slide in slide assembly  18  may include extensions such that the entire table assembly can move laterally up to 43″ to the right or left for a device that can move a 500 lb. patient. Similar devices can be built to transfer bariatric patients, and in these devices, the right or left extension of the slide assemblies will be greater. Device  10  may have multiple transportation modes, and is preferably provided with a pivoting handle to control steering such that a light pressure will make the device turn slightly while continuous force on the handle will make the device turn sharply at a 90° angle, such as for parking the device along a wall of a hallway or room. Various details relating to the construction of base  12 , support columns  16 , and slide assembly  18 , the steerage of wheels  14 , designs for the belts, foam padding, slip sheet and air mattress, exemplary dimensions, and other features can be found in U.S. patent application Ser. No. 11/246,426 which is hereby incorporated. 
     Referring now to  FIG. 2 , there is depicted a top plan view of upper table  20   a  with the upper belt removed to reveal internal details. In this embodiment, the primary patient support members of upper table  20   a  are a fixed central plate section  32 , a movable left side plate section  34 , and a movable right side plate section  35 , each of which generally extends the full length (75″) of upper table  20   a . Plate sections  32 ,  34  and  35  are made of extruded aluminum. Central plate section  32  has a flat upper surface and two curved walls depending from its lower surface defining a semi-tubular channel  36 . Central plate section  32  is 2.875″ wide, nominally 0.25″ thick, and channel  36  has an effective diameter of 1.125″. 
     Left side plate section  34  is constructed of two separate portions  34   a ,  34   b  held together by screws and interlocking surfaces, and right side plate section  35  is similarly constructed of two separate portions  35   a ,  35   b  (in an alternative embodiment the side plate sections are unitary structures). The edge portions  34   a ,  35   a  have generally wedge-shaped transverse cross-sections and include integrally formed fingers  46  which support the axles of a plurality of edge rollers  48 . The size of fingers  46  and edge rollers  48  is relatively small, e.g., 0.625″ in diameter, and the thinnest region of edge portions  34   a ,  35   a  (which overlies edge rollers in lower table  20   b ) is 0.3″ thick, which together present less of a bump as the patient is acquired or delivered. Edge rollers  48  are made of aluminum tubing and are 8.5″ long. In the depicted embodiment there are sixteen edge rollers  48 , i.e., eight along the left edge and eight along the right edge. The interior portions  34   b ,  35   b  also have generally wedge-shaped cross-sections but are slightly larger and hollow to reduce weight and accommodate the frame ribs described below when the side plate sections are retracted. Interior portions  34   b ,  35   b  have semi-tubular channels  40  formed therein near their inside edge. The walls of interior portions  34   b ,  35   b  are nominally 0.15″ thick, channels  40  are 0.75″ in diameter, and the maximum overall thickness of the wedge profile is 1.25″. Each side plate section  34 ,  35  is 12″ wide, and in the fully extended position of the side plate sections upper table  20   a  is 32″ wide. 
     Holes are formed along the side walls of channel  36  to receive six transverse ribs  38  which are held in place with metal clips. The ends of ribs  38  also pass through channels  40  in interior portions  34   b ,  35   b  of the side plate sections and are secured by bearings  42  which loosely slide into channels  40  with sufficient tolerance to allow movement of the side plate sections. Ribs  38  are made of aluminum rods and are 8.5″ long and 0.375″ in diameter. The inside edges of interior portions  34   b ,  35   b  have integrally-formed flanges which support the axles of a plurality of pinch rollers  44 . The flanges are inclined toward the bottom of upper table  20   a  so that pinch rollers  44  are in contact with the inside surface of the bottom portion of the upper belt. Pinch rollers  44  are made of aluminum tubing, and are 0.625″ in diameter and 8.5″ long. In the depicted embodiment there are ten pinch rollers  44 , i.e., five on each side equidistant from the centerline of upper table  20   a . Air tubes  45  are attached near the ends of central plate section  32  for filling the air mattress. 
     With further reference to  FIGS. 3A-3C , left and right side plate sections  34 ,  35  are extended outwardly or retracted inwardly by the action of crank assemblies  50  located at the front and rear ends of upper table  20   a . Each crank assembly  50  includes a rotating disk  52 , a left linkage arm  54  and a right linkage arm  56 . Disk  52  is constructed of steel, is 3″ in diameter, and houses a 4:1 planetary gear drive coupled to an output shaft that is further connected to a planetary gear of a respective electric motor  58  ( FIG. 2 ). The housing around the output shaft is inserted into an end of channel  36  in central plate section  32 . In the exemplary embodiment motors  58  are 30 mm planetary gear motors manufactured by Dunker Motors (a division of Alcatel-Lucent in Bonndorf, Germany) with a torque of 1.8 N-m, and are responsive to an electronic control system which can selectively instruct the motor shaft to rotate at various speeds either clockwise or counterclockwise. Although the preferred embodiment provides such electronic actuation of the gears in disks  52 , those skilled in the art will appreciate that the gears may alternatively be driven manually through appropriate mechanical linkages to a crank handle. It is desirable, but not necessary, to provide crank assemblies at each end to drive the side plate sections. Linkage arms  54 ,  56  may have a protrusion or beak portion which engages a switch sensor  59  mounted near disk  52  to provide feedback to the control electronics regarding the current position/orientation of disk  52 . 
     Each linkage arm  54 ,  56  is preferably comprised of two separate pieces which are attached with pairs of bolts inserted in slots to provide some tolerance during the assembly of upper table  20   a . The linkage arm pieces are constructed of aluminum. Linkage arms  54 ,  56  are pivotally attached at one end to a peripheral region of disk  52  such that, as disk  52  rotates, the attached end of a given linkage arm moves from one side of the disk to the other side. The plane of rotation of disk  52  is the same as the plane of movement of linkage arms  54 ,  56 , viz., a vertical plane generally located at an end of table assembly  20 . The ends of linkage arms  54 ,  56  attached to disk  52  are bent in opposite directions to accommodate their widths as the disk turns to an extreme rotation point, i.e., the pivotally attached end of linkage arm  54  is bent downward and the pivotally attached end of linkage arm  56  is bent upward, each at an angle of 45° with respect to the main extent of the linkage arms. Linkage arms  54 ,  56  have an effective length of 10″. The other ends of linkage arms  54 ,  56  are pivotally attached to outer positioning posts  60 . Posts  60  are press fit into the ends of respective left and right side plate sections  34 ,  35  at an outer point thereof (near the boundary between the edge portion and the interior portion). Thus, as disk  52  rotates clockwise or counter-clockwise, linkage arms  54 ,  56  pull or push left and right side plate sections  34 ,  35  via posts  60 , thereby laterally retracting or extending edge rollers  48 . Linkage arms have a stroke length of 1.875″. 
     Outer positioning posts  60  pass through and are slidably retained by slots  62  formed in end plates of upper table  20   a . One end plate  80  is shown in  FIG. 4 . Another pair of inner positioning posts  64  slide into lengthwise bores in side plate sections  34  and  35  and are attached with screws to the ends of respective channels  40  in left and right side plate sections  34 ,  35 . Posts  64  pass through and are slidably retained by another pair of slots  66  formed in end plate  80 . The position and orientation of left and right side plate sections  34 ,  35  are accordingly limited by guide slots  62 ,  66 . End plate  80  also has a larger slot  82  which slidably receives a bushing of motor  58  mounted adjacent to disk  52 . Other slots or holes may be provided for passage of electrical wiring or pneumatic tubes. End plate  80  is pivotally attached to slide assembly  18  by a pin which passes through a hole  84  at one corner, while a latch  86  mounted at the other corner releasably secures end plate  80  to another pin of slide assembly  18 . In this manner, the entire upper table  20   a  can be rotated upwardly 90° for cleaning or maintenance of the table assembly. End plate  80  is constructed of aluminum, and is 32.75″ long, 4.5″ wide and 0.25″ thick. 
       FIG. 3A  illustrates the almost fully extended position of side plate sections  34 , wherein fingers  46  and edge rollers  48  project 1.3″ beyond the edges of lower table  20   b . In this position, upper table  20   a  is in forcible contact with lower table  20   b , that is, pinch rollers  44  are forcibly pressing upper belt  70   a  against lower belt  70   b  and opposing drive rollers inside lower belt  70   b , such that any movement of the lower belt  70   b  will in turn drive the upper belt  70   a  through the frictional engagement of the belts&#39; outer surfaces. Lower table  20   b  contains an internal framework (not shown) to which are mounted sets of belt support and the drive rollers. The drive rollers are rotated by two small-diameter planetary gear drive motors that are also mounted to the internal framework. The lower table framework is comprised of two trapezoidal-shaped, hollow aluminum extrusions 75″ long by 12.5″ wide. The thickness of the two extrusions tapers from 1.15″ at one edge to 0.5″ at the opposite edge. The nominal wall thickness of the extrusions is 0.15″. The extrusions are adjustably mounted along their front and rear ends to slide assembly  18 . The adjustable mounting for the two extrusions allows them to be moved laterally closer for installation of lower belt  70   b  and then moved apart for tensioning of lower belt  70   b.    
     Eight roller supports  72  having a common shaft are positioned at regular intervals along the outside edge of each aluminum extrusion, and support seven drive rollers  74  on each side of lower table  70   b . Drive rollers  74  are rubber covered, 8.75″ long, and 0.774″ in diameter. Each drive roller  74  contains a timing belt pulley located at one end. The pitch diameter of the timing belt pulley is selected so that the outside surface of a timing belt operating in the pulley is the same as the diameter of the rubber coating on the roller (0.774″). The thicker (inner) edge of each aluminum extrusion also contains seven bearing support blocks for mounting a second set of six larger diameter, rubber-covered drive rollers along an inner corridor of lower table  20   b . An open space is left in this corridor at one end of the extrusion for mounting a drive motor. The inner drive rollers are 8.75″ long and 1.729″ in diameter. A single drive shaft passes through all six inner drive rollers and the seven bearing blocks attached to one extrusion. The drive rollers are keyed to the drive shaft so rotation of the shaft positively drives all of the rollers. Each drive shaft is coupled to a respective 1.653″ outside diameter planetary gear motor, and torque restraints attach the motors to the wide edge of the extrusion. The drive motors are located in the open spaces at opposite side ends of the extrusions, with their output shafts oppositely directed. The drive rollers also contain a timing belt pulley at each end, aligned with the timing belt pulleys on five of the six idler rollers  74 , so the timing belts can operate between these pulleys. Rotation of the planetary gear drive motor thus causes the drive shaft to rotate which in turn causes the drive rollers to rotate. Rotation of the drive rollers also drives the seven drive rollers  74  through the timing belts, all of which causes lower belt  70   b  to rotate. 
     Lower belt  70   b  may be provided with two flexible, inwardly-projecting V-shaped ribs, one near each end. The ribs ride in matching grooves formed in both ends of the aluminum extrusions, and also in matching grooves formed on the outer surfaces of four of the idler rollers  74  (at the four corners of lower table  20   b ). This arrangement prevents lower belt  70   b  from inadvertently tracking toward one end or the other as it is driven by the sets of idler and drive rollers. Plates constructed of a low friction material such as ultra-high molecular weight polyethylene may be mounted to the lower side of each aluminum extrusion between the timing belts to reduce the tension in the belt generated by sliding friction when table assembly  20  moves across a mattress or table surface. 
     When the patient is first acquired as shown in  FIG. 1A , upper table  20   a  is in the fully extended position illustrated in  FIG. 3A . In this position, the incident angle of the table assembly as it approaches the patient (i.e., the angle between the plane formed by the left side bottom of lower table  20   b  and the plane formed by the leading portion of left side plate section  34 ) is in the range of 7°-10°. Lower belt  70   b  rotates in response to the drive mechanism in lower table  20   b , and drives upper belt  70   a  as table assembly  20  crawls under the patient. The timing of the belts&#39; rotation (eversion rate) is synchronized with the lateral movement of slide assembly  18 . 
     Once the patient is positioned over the center of table assembly  20 , motors  58  begin to actuate crank assemblies  50  which gradually retract side plate sections  34 ,  35 . Since posts  60 ,  64  must follow guide slots  62 ,  66  in end plates  80  and since the guide slots are inclined upwardly toward the longitudinal centerline of table assembly  20 , the retraction of left and right side plate sections  34 ,  35  also results in raising the side plate sections. As side plate sections  34 ,  35  rise, they lift ribs  38  which in turn raise central plate section  32 , thereby separating upper table  20   a  from lower table  20   b . An intermediate position with partial retraction of left and right side plate sections  34 ,  35  and partial separation of upper and lower tables  20   a ,  20   b  is shown in  FIG. 3B . Disk  52  has rotated to bring the pivotally attached ends of linkage arms  54 ,  56  to a lateral centerline of disk  52 , one above and one below. In this position, fingers  46  and edge rollers  48  of upper table  20   a  barely extend over the edge of lower table  20   b , and there is significant slack in upper belt  70   a  although it is still in loose contact with lower belt  70   b.    
     Outer guide slots  62  have a slightly higher angle of inclination)(26° than inner guide slots  66  (18°), so retraction of left and right side plate sections  34 ,  35  also results in lowering the inclination of the side plates, i.e., posts  60  will move vertically at a faster rate than posts  64 . This action generally flattens the patient support surface of upper table  20   a  to make it more stable and reduce the likelihood of the patient rolling off to one side. The side plate inclinations continue to change as crank assemblies  50  rotate further until table assembly  20  reaches the fully retracted/separated position illustrated in  FIG. 3C . Disk  52  has rotated further to bring the pivotally attached ends of linkage arms  54 ,  56  to opposing sides of disk  52 , i.e., the end of left linkage arm  54  is at the right periphery of disk  52  and the end of right linkage arm  56  is at the left periphery of disk  52 . Posts  60 ,  64  have moved to the inward ends of guide slots  62 ,  66 . In this position, the upper surfaces of side plates  34 ,  35  are advantageously inclined only 2° from the horizontal, although they could be perfectly flat or even slightly inclined upward. Guide slots  62 ,  66  are 2.75″ long, allow maximum lateral movement of each side plate section by 2.4″ although the crank stroke is only 1.875″, and result in maximum vertical movement of edge rollers  48  by 1.25″. 
     This construction thus provides the integrated and synchronized movement of (i) the refraction of the side plate sections, (ii) the separation of the upper and lower tables, and (iii) the adjustment of the angle of the side plate sections. The result is smoother patient acquisition, and more comfortable and safe patient transport. While other means may be provided to achieve these actions such as gears, cams or 4-bar linkages, the use of end plates having guide slots with positioning posts on the side plate sections has fewer moving parts and can drive all the actions with only two motors for the crank assemblies. 
     Although the invention has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternative embodiments of the invention, will become apparent to persons skilled in the art upon reference to the description of the invention. It is therefore contemplated that such modifications can be made without departing from the spirit or scope of the present invention as defined in the appended claims.