Patent Publication Number: US-7913336-B2

Title: Shearless pivot for bed

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application claims priority to U.S. provisional application Ser. No. 60/955,682, filed Aug. 14, 2007 by Marco Morin et al. and entitled SHEARLESS PIVOT FOR BED, the complete disclosure of which is incorporated by reference herein. 
    
    
     BACKGROUND OF THE INVENTION 
     The present invention relates generally to patient supports, such as those used in health care facilities, and more specifically to a pivoting assembly for a head portion of the patient support. 
     It is known in the prior art to provide a patient support, such as a hospital bed or stretcher, that includes a pivotable section for supporting the back and head of a patient. For example, U.S. Pat. No. 5,423,097 issued to Brule, discloses a hospital bed having a moveable upper body support. This upper body support is pivotable between a generally horizontal orientation in which the patient will be lying flat and a raised orientation in which the patient&#39;s upper body will be raised from the flat position. In many prior art beds, the pivoting of the upper body section—which is commonly referred to as the Fowler section of the bed—to and from the horizontal orientation creates shear forces between the patient and the hospital bed. 
     More specifically, as the Fowler section is rotated upwardly from the horizontal orientation, the patient&#39;s back and/or buttocks may be forced by the movement of the Fowler section to slide along the Fowler section and/or the seat section of the bed, respectively. This sliding motion is due to shear forces. In general, these shear forces are created because the patient&#39;s hip joint, which defines the axis of rotation for the patient&#39;s upper body, does not coincide with the axis of rotation about which the upper body section of the bed pivots. While attempts have been made in the past to mitigate these shear forces, such as by the reduced shear pivot disclosed in U.S. Pat. No. 7,017,208 issued to Weismiller, none of the prior art reduced shear pivots have offered a solution as simple, effective, and advantageous as that of the present invention. 
     SUMMARY OF THE INVENTION 
     The present invention provides an improved pivot assembly for a patient support that reduces the shear forces that would otherwise be generated between the patient support and the patient&#39;s back and buttocks. The shearless pivot of the present invention offers a simple, elegant, and effective solution to the problem of shear forces generated between a patient and the patient support. 
     According to one aspect of the present invention, a patient support apparatus is provided that includes a frame, a deck, a pivot axis, and an actuator. The deck is supported by the frame and is configured to support a patient. The deck includes a foot end and a head end, as well as a head section oriented adjacent the head end of the deck and a second section oriented adjacent the head section. The pivot axis enables the pivoting of the head section from a generally horizontal orientation to an intermediate orientation that defines a first angle with respect to the horizontal orientation. The pivot axis also enables the pivoting of the head section from the intermediate orientation to a raised orientation that defines a second angle with respect to the horizontal orientation wherein the second angle is greater than the first angle. The actuator is coupled to the frame and the head section and is adapted to pivot the head section about the pivot axis from the generally horizontal orientation to the raised orientation. The pivot axis remains stationary with respect to the frame while the head section pivots from the generally horizontal orientation to the intermediate orientation, and the pivot axis moves with respect to the frame while the head section pivots from the intermediate orientation to the raised orientation. 
     According to another embodiment of the present invention, a patient support apparatus is provided that includes a frame, a deck, a pivot axis, an actuator, a plurality of generally horizontal tracks, and a plurality of low-friction members. The deck is supported by the frame and configured to support a patient. The deck includes a foot end and a head end, along with a head section oriented adjacent the head end of the deck, an intermediate section oriented adjacent a foot end of the head section, and a third section oriented adjacent a foot end of the intermediate section. The pivot axis defines an axis about which the head section is able to pivot from a generally horizontal orientation to a raised orientation. The actuator is coupled to the frame and the head section and is adapted to pivot the head section about the pivot axis from the generally horizontal orientation to the raised orientation. The plurality of generally horizontal tracks are fixedly attached to the frame. The plurality of low-friction members are coupled to the intermediate section. The low-friction members are adapted to translate horizontally in the tracks as the head section is pivoted from the generally horizontal orientation to the raised orientation. 
     According to another aspect of the present invention, a method of pivoting a head section of a patient support about a pivot axis from a horizontal orientation to a raised orientation is provided. The method includes maintaining the pivot axis in a stationary position as the patient support pivots from the horizontal orientation to an intermediate orientation wherein the intermediate orientation is defined between the generally horizontal orientation and the raised position. The method further includes moving the pivot axis vertically upward as the head section pivots from the intermediate orientation to the raised orientation. 
     According to various other aspects of the present invention, the intermediate orientation may have an angular measure of between 5 and 50 degrees with respect to the horizontal, although the design of the patient support apparatus can be modified in accordance with the principles of the present invention to include angles outside this range. The pivot axis may move upwardly from the frame and away from the second section of the deck toward the head end as the head section is pivoted from the intermediate orientation to the raised orientation. The head section may further include one or more extensions with each extension having a slot defined therein. A pin attached to the intermediate section of the deck may be inserted through each of the slots and engage an edge of the slot when the head section is pivoted to the intermediate orientation or a higher orientation. A finger may selectively limit movement of the pin within the slots when the head section has been pivoted to or past the intermediate orientation. The finger may be rotatably coupled to one of the extensions and may include a biasing spring. The finger may further include a lever arm that contacts an abutment on the frame. 
     The various aspects of the present invention provide a patient support surface with a pivotable head section that pivots in a manner that causes a reduced level of shear forces to be generated between the patient and the back and seat sections of the patient support. The patient support apparatus of the present invention provides a robust, stable, and user-friendly method and structure for pivoting the head section of a patient support apparatus. These and other advantages of the present invention will be apparent to one skilled in the art in light of the following written description and the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is perspective view of a patient support apparatus according to one aspect of the present invention; 
         FIG. 2  is a partial, elevational view of a pivoting assembly for a head section of a patient support according to a first embodiment of the present invention; 
         FIG. 2A  is an enlargement of a portion of  FIG. 2  illustrating more clearly some of the detail of the pivoting assembly; 
         FIG. 3  is a partial, elevational view of the pivoting assembly of  FIG. 2  shown pivoted to an angle of approximately twenty degrees; 
         FIG. 4  is a close-up view of the pivoting assembly of  FIG. 2  shown in an orientation of greater than twenty degrees but less than forty degrees; 
         FIG. 5  is a partial, elevational view of the pivoting assembly of  FIG. 2  shown pivoted to an angle of approximately forty degrees; 
         FIG. 6  is a partial, elevational view of the pivoting assembly of  FIG. 2  shown pivoted to an angle of approximately fifty degrees; 
         FIG. 7  is a perspective view of the pivoting assembly of  FIG. 2  shown from a first perspective; 
         FIG. 8  is a perspective view of the pivoting assembly of  FIG. 2  shown from a second perspective different from the first perspective of  FIG. 7 ; 
         FIG. 9  is an exploded, perspective view of various components of a patient support apparatus, including a pivoting assembly according to a second embodiment of the present invention; 
         FIG. 10  is an exploded, perspective view of a head deck section and the pivoting assembly of  FIG. 9 ; 
         FIG. 11  is an enlarged, exploded, perspective view of an intermediate deck section that is also illustrated in  FIG. 9 ; 
         FIG. 12  is an enlarged perspective view of a patient support apparatus frame that is also illustrated in  FIG. 9 ; 
         FIG. 13  is a close-up, perspective view of a central region of the patient support apparatus frame of  FIG. 12 ; 
         FIG. 14  is a perspective view of the central region of the frame of  FIG. 13  shown from a different perspective from that of  FIG. 13 ; 
         FIG. 15  is a close-up perspective view of a portion of the pivoting assembly illustrated in  FIG. 9  and labeled Detail B; 
         FIG. 16  is an enlarged, perspective view of a sensor that is also illustrated in  FIG. 9 ; 
         FIG. 17  is a side, sectional view of the pivoting assembly of  FIG. 9  taken along a vertical plane intersecting the patient support apparatus between a pair of head section extensions, the pivoting assembly shown pivoted to an angle of approximately ten degrees; 
         FIG. 18  is a side, sectional view similar to  FIG. 17  illustrating the pivoting assembly pivoted to an angle of approximately twenty degrees; 
         FIG. 19  is a side, sectional view similar to  FIG. 17  illustrating the pivoting assembly pivoted to an angle of approximately twenty-five degrees; 
         FIG. 20  is a perspective view of the region of the pivoting assembly shown in  FIG. 17  wherein the pivoting assembly is shown pivoted to an angle of approximately ten degrees; 
         FIG. 21  is a perspective view similar to  FIG. 20  illustrating the pivoting assembly pivoted to an angle of approximately twenty degrees; and 
         FIG. 22  is a perspective view similar to  FIG. 20  illustrating the pivoting assembly pivoted to an angle of approximately twenty-five degrees. 
     
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The present invention will now described wherein the reference numerals appearing in the following written description correspond to like-numbered elements in the several drawings. A patient support apparatus  30  is depicted in  FIG. 1 . Patient support apparatus may be a hospital bed, stretcher, or other type of device that supports a patient in a healthcare or nursing home type of setting. Patient support apparatus  30  includes a base  32  having a plurality of wheels  34  that allow the patient support apparatus  30  to be easily transported from one location to another. In addition to base  32 , patient support apparatus  30  further includes a pair of elevation adjustment mechanisms  36 , a frame  38 , a deck  40 , a plurality of siderails  42 , a headboard  44 , and a footboard  46 . Elevation adjustment mechanisms  36  allow frame  38  and deck  40  to be raised and lowered to different heights with respect to base  32 . Deck  40  is divided into a plurality of sections, including a head or Fowler section  48 , a seat section  50 , and a foot section  52 . The different sections of the deck  40  are adapted to support a mattress or other type of cushioned surface on which a patient may sit or lie down. 
     The detailed construction of one embodiment of patient support apparatus  30  is described in commonly-assigned, copending U.S. patent application Ser. No. 11/612,361, filed Dec. 18, 2006 and entitled Hospital Bed, the complete disclosure of which is incorporated herein by reference. It will be understood that the present invention is applicable to patient support apparatuses having a wide variety of different configurations, designs, features, and constructions than what is illustrated in  FIG. 1 . 
     Head section  48  of deck  40  is pivotable about a generally horizontal axis  54  that is oriented perpendicularly to the longitudinal extent of support apparatus  30 . By longitudinal extent, it is meant the extent of support apparatus  30  in the direction extending from a head end  56  to a foot end  58 . Pivot axis  54  enables head section  48  to pivot so that a patient can be moved from an orientation in which the patient is entirely lying flat to an orientation in which the patient is partially or fully sitting up. 
     The pivoting of head section  48  about pivot axis  54  is carried out by a pivot assembly that may take on various forms in accordance with the present invention. Two different versions of the pivot assembly will be described and discussed herein. The first one is illustrated in  FIGS. 2-8 . The second one is illustrated in  FIGS. 9-22 . In both of these pivoting assemblies, head section  48  pivots upwardly from a generally flat orientation to a raised orientation, which may go as high as 70-90 degrees with respect to horizontal. As head section  48  pivots toward its maximum raised orientation, it passes through an intermediate orientation. During the pivoting from the horizontal orientation to the intermediate orientation, pivot axis  54  remains stationary. During pivoting from the intermediate orientation to the completely raised orientation, pivot axis  54  moves upwardly and along an axis extending from head end  56  to foot end  58 . Generally speaking, the intermediate orientation may be defined at approximately 20 degrees, such as twenty-one degrees, although various forms of the present invention can be practiced with an intermediate orientation substantially different, such as, but not limited to, orientations of 0 to 50 degrees. The movement of pivot axis  54  after the intermediate orientation has been achieved reduces the shear forces applied to a patient, thereby making the movement of the patient more comfortable and requiring less re-adjustment of the patient. 
     A pivot assembly  60  according to a first embodiment of the present invention is depicted in  FIGS. 2-8 . Pivot assembly  60  generally includes pivot axis  54 , an actuator  62 , an intermediate deck section  64 , one or more extensions  66 , a pair of links  68 , and a stopper or pin  70 . Actuator  62  is coupled at a foot end (not shown) to a fixed location on frame  38  of support apparatus  30 . A head end  72  of actuator  62  is pivotally coupled to a foot end  74  of extensions  66  by way of a pin  76 . Actuator  62  includes a telescoping member  78  that slidably expands out of, or contracts into, a base portion  80 . As telescoping member  78  extends out of base portion  80 , it pushes against foot end  74  of extension  66 . This causes head section  48  to rotate about pivot axis  54 . Pivot axis  54  remains in a stationary location as head section  48  is initially pivoted from a horizontal orientation to an intermediate orientation  82 . One example of such an intermediate orientation  82  is depicted in  FIG. 3 . 
     As can be seen in  FIG. 3 , head section  48  has been pivoted to an intermediate orientation  82  that defines an angle theta (θ) with respect to the horizontal. As noted above, the angle theta can vary greatly within the scope of the present invention. One suitable value for theta is 21 degrees. However, theta can be varied within the scope of the present invention to an angle anywhere from 0 degrees to up to 50 degrees, or more. (When theta is set to zero degrees, pivot axis  54  does not remain stationary for any portion of the pivoting of head section  48  from the horizontal orientation to the raised orientation). 
     After actuator  62  has rotated head section  48  up to intermediate orientation  82 , any further extension of telescoping member  78  and actuator  62  will cause the location of pivot axis  54  to change as head section  48  is rotated further upward. This change in the location of pivot axis  54  results because of the interaction of stopper  70  with a pair of slots  84  defined in extensions  66 . More specifically, slots  84  each include a head edge  86  and a foot edge  88 . Foot edge  88  is more clearly illustrated in  FIG. 2A . When head section  48  is oriented in the horizontal orientation ( FIG. 2A ), stopper  70  is positioned within slots  84  generally adjacent head edge  86 . As head section  48  pivots upwardly, the movement of extension  66  causes the location of stopper  70  to shift within slots  84  toward foot edge  88 . When head section  48  reaches intermediate orientation  82 , foot edges  88  of slots  84  will come into contact with stopper  70 . This contact will force stopper  70  to move with extensions  66  as head section  48  is pivoted further upwardly from intermediate orientation  82 . 
     The movement of stopper  70  as head section  48  pivots upwardly from intermediate orientation  82  is illustrated more clearly in  FIGS. 4 ,  5 , and  6 . In  FIG. 4 , which depicts head section  48  in an orientation having an angle theta that is greater than the angle of intermediate orientation  82 , stopper  70  has moved vertically and to the left (towards head end  56 ) from the position occupied prior to coming into contact with foot edge  88  (such as shown in  FIG. 2 ). In  FIG. 5 , which depicts head section  48  raised upwardly to an even greater angle than that of  FIG. 4 , stopper  70  has moved vertically upward an even greater amount than illustrated in  FIG. 4 .  FIG. 6  illustrates head section  48  rotated to an even greater angle than that depicted in  FIG. 5 , and, as can be seen, the position of stopper  70  has moved further upward. 
     The changing position of stopper  70  as head section  48  is rotated from intermediate orientation  82  to a higher orientation causes intermediate deck section  64  to also change its position and orientation. Stopper  70  is fixedly attached to a pair of plates  90  (one shown in  FIGS. 7 and 8 ) that extend vertically downward from an underside of intermediate deck section  64 . Plates  90  are fixedly secured to intermediate deck section  64 . As a consequence, any movement of stopper  70  will cause a corresponding movement of intermediate deck section  64 . Intermediate deck section  64  is pivotally attached to head section  48  by way of a pair of pins  92  ( FIG. 8 ). Pins  92  have a longitudinal extent that generally defines horizontal pivot axis  54 . Consequently, when foot edges  88  of slots  84  engage stopper  70 , the subsequent motion of stopper  70  will cause intermediate section  64  to change position. This change of position of intermediate deck section  64  will cause a change in the location of pin  92 , as well as pivot axis  54 . Thus, when head section  48  pivots upwardly beyond intermediate orientation  82 , the interaction of stopper  70  within slots  84  will cause horizontal pivot axis  54  to change its location. The change in location of pivot axis  54  as head section  48  is pivoted upwardly from intermediate orientation  82  is illustrated in  FIGS. 4 ,  5 , and  6 . In general, pivot axis  54  moves vertically upward and towards head end  56  of patient support apparatus  30 . 
     As stopper  70  engages foot edge  88  of slot  84 , any further upward pivoting of head section  48  will cause stopper  70  to move vertically upward and toward head end  56 . The movement of stopper  70  will, in turn, cause a corresponding movement of intermediate deck section  64  that has a horizontal component. The horizontal movement of intermediate deck section  64  is made possible by a pair of tracks  94  (one shown in  FIG. 6 ) defined in either side of frame  38  of patient support apparatus  30 . Intermediate deck section  64  includes a roller  96  ( FIG. 7 ) attached on either of its sides that rides in tracks  94 . Tracks  94  are oriented generally parallel to each other and in a horizontal orientation. Roller  96  is attached to intermediate deck section  64  generally adjacent a foot end  98  of intermediate deck section  64 . As head section  48  pivots upwardly from intermediate orientation  82 , intermediate deck section  64  moves away from seat section  50  of deck  40 . In the illustrated embodiment, this movement of intermediate deck section  64  away from seat section  50  creates a gap between these two sections. This gap, however, is relatively small and does not create any undesirable consequences. If desired, intermediate deck section  64  or seat section  50  could be modified to include an extension that provided support for a mattress positioned on top of the region between intermediate deck section  64  and seat section  50  in order to fill in this gap. However, such an extension is not necessary. 
     As intermediate deck section  64  moves toward head end  56  and away from seat section  50 , a head end  100  of intermediate deck section  64  will be raised vertically upward by way of the pivotable connection between intermediate deck section  64  and head section  48 , as defined by pins  92 . 
     As was noted above, pivot assembly  60  also includes a pair of links  68  (one shown in  FIGS. 7 and 8 ). Each link  68  is attached along a side of frame  38 .  FIGS. 7 and 8  illustrate more clearly the attachment of one of the links  68  to frame  38  and intermediate section  64 . The manner in which the other link  68  (not shown in  FIGS. 7 and 8 ) operates and attaches to frame  38  and intermediate section  64  is identical to that of the link  68  shown in  FIGS. 7 and 8 . Accordingly, it will only be necessary to describe the connections and operations of one link  68 . As can be seen more clearly in  FIG. 7 , link  68  is rotatably coupled via a pin  102  to a side beam  104  of frame  38 . Link  68  is thus free to rotate about a horizontal pivot axis  106  in the direction generally indicated in  FIG. 7 . An opposite end of link  68  is rotatably coupled via a pin  108  to an underside of intermediate deck section  64 . Each link  68  thus helps guide and support intermediate deck section  64  as it moves. 
       FIGS. 9-22  illustrate a pivot assembly  60 ′ according to another aspect of the present invention. All of the components of pivot assembly  60 ′ that are the same as those of pivot assembly  60  and that operate in a similar manner have been labeled in  FIGS. 9-22  with the same reference numerals as given in  FIGS. 1-8 . Accordingly, no new labels or descriptions will be given to those items of pivot assembly  60 ′ that have already been labeled and described with respect to pivot assembly  60 . An exploded, perspective view of pivot assembly  60 ′, as well as various structures of frame  38 , is illustrated in  FIG. 9 . In general, pivot assembly  60 ′ includes an actuator  62 , an intermediate deck section  64 , a plurality of extensions  66  ( FIG. 15 ), a pair of links  68  ( FIG. 11 ), and a stopper or pin  70 . Pivot assembly  60 ′ interconnects head section  48  with a seat section  50  (not shown in  FIGS. 9-22 ) in a manner similar to that described above with respect to pivot assembly  60 . More specifically, pivot assembly  60 ′ enables head section  48  to pivot about a pivot axis  54  ( FIG. 10 ) from a horizontal orientation to a raised orientation while passing through an intermediate orientation  82 . After head section  48  has reached the intermediate orientation  82 , pivot assembly  60 ′ causes pivot axis  54  to move in a similar manner to that described above with respect to pivot assembly  60  as head section  48  pivots upwardly from intermediate orientation  82 . 
     One manner of constructing head section  48  of deck  40  is illustrated in more detail in  FIGS. 9 and 10 . As can be seen therein, head section  48  includes a frame  110  to which may be mounted a support plate  112  ( FIG. 9 ). Head section  48  further includes a pair of handles  114  mounted on either side of head section  48 . A pair of flanges  116  ( FIG. 10 ) define a set of apertures  118  through which pins  92  are inserted. Extensions  66  are fixedly secured to a crossbar  120  of head section  48 . Extensions  66  include slots  84  defined therein having head and foot edges  86  and  88 , respectively ( FIG. 15 ). Extensions  66  attach to actuator  62  via a pin  76 , as has already been discussed above with respect to pivot assembly  60 . As is illustrated more clearly in  FIGS. 10 and 15 , pivot assembly  60 ′ includes, in addition to those items already mentioned, a finger member  122 . Finger member  122  includes a hook  124 , a first recess  126  ( FIG. 15 ), a second recess  128 , a low friction member  130  attached to a lever arm  131 , and a pivot aperture  132 . Finger member  122  sits between each extension  66  in a manner that is more clearly illustrated in  FIGS. 20-22 . Finger member  122  is rotatably attached to extension  66  by way of a pin  134  and a pair of bushings  136 . Pin  134  fits through pivot aperture  132  of finger member  122 , as well as a pivot aperture  138  defined in each of extensions  66 . 
     Pivot assembly  60 ′ further includes a spring  140  ( FIG. 10 ) having a head end  142  and a foot end  144 . Head end  142  of spring  140  attaches to hook  124  of finger member  122 . Foot end  144  of spring  140  attaches to pin  76 . Pin  76 , as described with respect to pivot assembly  60 , attaches actuator  62  to extensions  66 . Spring  140  exerts a biasing force against finger member  122  that urges finger member  122  to rotate about pin  134  in a generally clockwise direction as viewed in  FIG. 15 . 
     Actuator  62  includes an aperture  146  defined at a distal end of telescoping member  78  ( FIG. 10 ). Aperture  146  receives pin  76 . Pin  76  rotatably couples telescoping member  78  of actuator  62  to extensions  66 . When head section  48  is pivoted upwardly from the horizontal orientation, low friction member  130  of finger member  122  moves along an abutment  148 , which may be seen more clearly in FIGS.  12  and  17 - 22 . Low friction member  130  may include a roller rotatably coupled thereon (not shown) that enables it to ride more easily along abutment  148 , or such roller may be omitted. Abutment  148  is fixedly secured to one of the side beams  104  of frame  38  ( FIG. 12 ). Abutment  148  is secured to side beam  104  by way of a bracket  150 . Bracket  150  includes a pair of attachment apertures  152  which receive corresponding screws  154  for securing bracket  150  to side member  104 . Bracket  150  includes another pair of apertures (not shown) that are aligned with a pair of apertures  158  defined in abutment  148 . A pair of bolts  160  are inserted through apertures  158  (and those of bracket  150 ) to thereby secure bracket  150  and abutment  148  to side member  104 . Abutment  148  includes a top surface  162  ( FIG. 12 ) which is engaged by low friction member  130 . 
     Intermediate deck section  64  is illustrated in more detail in  FIG. 11 . Intermediate deck section  64  includes a pair of head end crossbars  166 , a foot end crossbar  168 , an inverted U-shaped member  170  positioned between each of the head end crossbars  166 , a pair of inner brackets  172 , and two sets of outer brackets  174 . Inverted U-shaped member  170  includes a pair of sidewalls  176   a  and  176   b . While not illustrated in  FIG. 11 , sidewalls  176   a  and  176   b  of inverted U-shaped member  170  each include an aperture through which stopper  70  is inserted. These apertures are dimensioned to be approximately the same size as the circumference of stopper  70 . Thus, when a clip  178  ( FIG. 10 ) is attached to stopper  70  after stopper  70  has been inserted through the apertures in sidewalls  176   a  and  176   b , stopper  70  becomes fixedly secured to intermediate deck section  64 . In addition to passing through the apertures of sidewalls  176   a  and b, stopper  70  also passes through slots  84  in extensions  66  and a pair of washers  180  positioned between each of extensions  66 . 
     The two sets of outer brackets  174  of intermediate deck section  64  each include apertures  182  ( FIG. 11 ). A first pin  92  ( FIG. 10 ) passes through a pair of these apertures  182  on a first side of deck section  64 , and a second pin  92  passes though a pair of these apertures  182  on the opposite side of intermediate section  64 . Each pin  92  also passes through the pair of apertures  118  defined on each side of head section  48  ( FIG. 10 ). Thus, intermediate deck section  64  and head section  48  are pivotally linked via pins  92  passing through apertures  182  and  118 . 
     Inner brackets  172  each include an aperture  185  ( FIG. 11 ) which receives pin  108  that pivotably secures link  68  to intermediate deck section  64 . Pins  108  may be secured through apertures  185  by way of a washer  189  and a nut  192 . A bushing  193  may also be partially inserted into apertures  185  on the link  68  side of apertures  185 . 
     Inner brackets  172  of intermediate deck section  64  also each include a horizontal tube  186  ( FIG. 11 ) to which roller  96  is rollingly coupled. A washer  190  is inserted between roller  96  and tube  186 . Rollers  96  slide in tracks  94  attached to frame  38 . As can be seen in more detail in  FIGS. 12 and 13 , frame  38  includes a pair of track members  194  fixedly attached to a top surface of each of side beams  104 . Track members  194  define tracks  94 , in which rollers  96  roll. 
     Actuator  62  includes a foot end  196  ( FIG. 11 ) that is pivotally coupled to a pair of vertical flanges  198  attached to an underside of a frame crossbar  200  ( FIG. 13 ). A pin  202  ( FIG. 9 ) is inserted through apertures defined in flanges  198  and a corresponding aperture in the foot end  196  of actuator  62 . Pin  202  thereby pivotally secures actuator  62  to flanges  198  of crossbar  200 . 
     A sensor  204  ( FIGS. 10 and 16 ) may be attached to extension  66  by way of a pair of pins  206  that are received in corresponding pin apertures  208  ( FIG. 15 ) defined in extensions  66 . Sensor  204  detects its angular orientation with respect to horizontal. Because sensor  204  is mounted to extensions  66 , which in turn are mounted to head section  48 , sensor  204  will detect the angular orientation of head section  48  with respect to horizontal. Sensor  204  may be any conventional sensor capable of detecting an angle with respect to horizontal. Such sensors include accelerometers, inclinometers, inertial sensors, or any other type of sensor capable of detecting an angular deviation from a horizontal orientation. Sensor  204  may also be a sensor that detects an angular orientation of head section  48  relative to another component of patient support apparatus  30 , such as frame  38 . When sensor  204  detects such a relative orientation, the actual angle of head section  48  with respect to horizontal may be slightly different than the reading output by sensor  204  because patient support apparatus  30  may be positioned on a floor that is not horizontal. Such a relative orientation of head section  48  may desirably be used in some versions of support apparatus  30  instead of an absolute measurement with respect to true horizontal. The output of sensor  204 , whether an absolute or relative measure, may be fed to an electronic controller positioned on patient support apparatus  30  (not shown) or transmitted to a memory or processor located off of patient support apparatus  30 . If the output is sent to a processor on patient support apparatus  30 , it may then be displayed on a display positioned at a convenient location on patient support apparatus  30 . 
     The manner in which pivot assembly  60  operates as head section  48  is pivoted upwardly from a horizontal orientation is depicted in more detail in  FIGS. 17-22 .  FIGS. 17 ,  18 , and  19  depict a side, cross-sectional view of pivot assembly  60 ′ after it has been rotated to 10 degrees, 20 degrees, and 25 degrees, respectively.  FIGS. 20-22  illustrate perspective views of pivot assembly  60 ′ after it has been rotated upwardly from the horizontal orientation to angles of 10 degrees, 20 degrees, and 25 degrees, respectively. While head end  142  of spring  140  is illustrated in  FIGS. 17-22  as not being connected to any structure, it will be understood that this has been done merely for purposes of illustration. In actuality, head end  142  of spring  140  is hooked around hook  124  of finger member  122 . Spring  140  is connected to hook  124  at all orientations of head section  148 , including the horizontal orientation. Spring  140  exerts a biasing force against finger member  122 , which in turn urges low friction member  130  against top surface  162  of abutment  148 . This causes rotation of finger member  122  as head section  48  is pivoted upwardly. When head section  48  has been pivoted to within the vicinity of intermediate orientation  82 , finger member  122  is urged by spring  140  into a position in which stopper  70  generally fits within first recess  126 . The movement of finger member  122  into this orientation generally shortens the length of slots  84  such that stopper  70  is more tightly constrained within slots  84 . This reduces the amount of leeway between head section  48  and intermediate deck section  64 . Any looseness in head section  48  after it has been pivoted past intermediate orientation  82  is thereby reduced or eliminated via finger member  122 . Stated in another manner finger  122  effectively shortens the length of slots  84  after intermediate orientation  82  has been reached. 
     The interaction of finger  122  with stopper  70  serves to lock the angular orientation of intermediate section  64  with respect to head section  48 . More specifically, after head section  48  has been pivoted to intermediate orientation  82 , any further upward pivoting of head section  48  will cause head end  100  of intermediate section  64  to also pivot upwardly, as was explained previously. The interaction of finger  122  with stopper  70  helps ensure that head section  48  and intermediate section  64  maintain the same angular orientation with respect to each other as they both continue to pivot further upwardly. The interaction of finger  122  with stopper  70  creates a sufficiently rigid interconnection between head section  48  and intermediate section  64  such that even significant downward forces applied against head section  48  will not disturb the angular orientation of head section  48  with respect to intermediate section  64 . This is particularly true as head section  48  pivots upwardly past intermediate orientation  82 , and also true, though to a somewhat lesser extent, as head section  48  pivots downwardly toward intermediate orientation  82 . 
     It will be understood that the present invention is applicable to a variety of different patient support apparatuses that are differently configured than that illustrated in  FIG. 1 . For example, while  FIG. 1  depicts a patient support apparatus  30  having three deck sections, it will be understood that the present invention is applicable to patient support apparatuses having different numbers of deck sections. The pivot assemblies  60  and  60 ′ of the present invention can be applied to patient support apparatuses having separate seat and foot sections of the deck  40 , or patient support apparatuses having only a seat section or only a foot section of deck  40 . Still further, the pivot assemblies of the present invention can be applied to patient support apparatuses in which seat section  50  or foot section  52 , or both, are pivotable to orientations other than horizontal. In general, pivot assemblies  60  and  60 ′ of the present invention are applicable to any patient support apparatuses having a pivotable head section. 
     While the present invention has been described herein in terms of the several embodiments illustrated in the attached drawings, it will be understood by those skilled in the art that the present invention can be modified to include any and all variations that are within the spirit and scope of the following claims.