Wheeled carriage having auxiliary wheel spaced from center of gravity of wheeled base and cam apparatus controlling deployment of auxiliary wheel and deployable side rails for the wheeled carriage

Information

  • Patent Grant
  • 6256812
  • Patent Number
    6,256,812
  • Date Filed
    Friday, January 15, 1999
    25 years ago
  • Date Issued
    Tuesday, July 10, 2001
    23 years ago
Abstract
A wheeled carriage for supporting a patient in a substantially horizontal position, the wheeled carriage has thereon a patient support having head and foot ends and a wheeled base supported by castered wheels. An auxiliary wheel and a wheel support structure therefor suspendedly mount the auxiliary wheel at its axis to the wheeled base at a distance L in a horizontal direction from the center of gravity of the wheeled carriage along the length of the wheeled base when the auxiliary wheel is engaged with the floor surface. A moment Mmass is defined by the distance L multiplied by a force Fmass, the force Fmass being defined by the mass of the carriage or carriage and patient at the center of gravity. The moment Mmass is greater at all times than a moment Mforce to prevent teetering of the wheeled carriage, where moment Mforce is defined by multiplying the height H by a force Fmax. The force Fmax is the force required to move the wheeled carriage. The height H is defined by the vertical distance between the axis of the auxiliary wheel and the relative height of the gripping location where the force Fmax is applied.
Description




FIELD OF THE INVENTION




This invention relates to a wheeled carriage for supporting a patient in a substantially horizontal position, and, more particularly, to a wheeled carriage having at least one auxiliary wheel selectively positionable with the floor surface. The auxiliary wheel can be raised or lowered by activation of control elements. In the alternative, the foot end casters can be raised and lowered by control elements to accomodate engagement of the auxiliary wheel with the floor surface. The wheeled carriage also includes brakes for selectively preventing movement of the wheeled carriage.




The invention also relates to a side rail assembly for use with the wheeled carriage. The side rail between lower stored positions and a raised deployment position to protect a patient from falling from the carriage.




BACKGROUND OF THE INVENTION




Wheeled carriages for supporting a patient in a substantially horizontal position are well-known in the art and a representative example of an early version of such a device is illustrated in Dr. Homer H. Stryker's U.S. Pat. No. 3,304,116, reference to which is incorporated herein. Dr. Stryker's innovative wheeled carriage included a fifth wheel which is raisable and lowerable by an attendant directly manually manipulating the wheel support frame oriented beneath the patient supporting portion of the wheeled carriage. The fifth wheel is positioned at substantially the center of the undercarriage such that ;usually the rear castered wheels and the fifth wheel support the carriage when the fifth wheel is deployed. However, the front castered wheels and the fifth wheel may also support a patient on the wheeled carriage depending on the position of the patient. Therefore, the wheeled carriage of U.S. Pat. No. 3,304,116 can teeter between the front and rear castered wheels when a patient is being moved thereon with the fifth wheel deployed.




U.S. Pat. No. 3,304,116 to Stryker also shows a top plate for receiving a downward force and positioning the fifth wheel in engagement with a floor surface. Such top plate is located at the top of the undercarriage location which is difficult for an attendant to reach.




A side rail assembly including side rail posts supporting side rails are well known in the art. One such side rail assembly is set forth in U.S. Pat. No. 5,187,824 to Martin Stryker. FIG. 1 thereof illustrates a top rail in a deployed position and FIG. 2 shows the top rail in a collapsed position.




In many side rail assemblies for beds, the side rail posts are made from tubular metal having diameter tolerance variations as well as a plating or a coating surface finish applied thereto. The plating or coating surface finish can extend about an outer circumference thereof. Such a finish improves the feeling and appearance of metal side rail posts. However, such finishes generally have an uneven thickness thus providing a wider range of diameters for the side rail posts. Such a finish interferes with proper seating of the side rail posts because of variations in the radius about a circumference thereof and thus changes tolerances for the posts. Therefore, the tolerances required for support structure supporting the side rail posts must be increased.




However, in general, when the support structure has increased tolerances, pushing or pulling of the deployed side rail, when patients attempt to raise themselves or when support personnel desire to move the bed, causes sway or lateral movement of the rail. Thus, because of the variations in size at the circumference of the side rail posts at their lower end, play exists between a support bracket and a conventional side rail post bolted to the bracket. Thus the side rail can sway in a direction perpendicular to the length of the side rail. Therefore, an arrangement having the side rail posts positively secured to a bracket to prevent swaying is needed.




Accordingly, it is an object of this invention to provide a wheeled carriage for supporting a patient in a substantially horizontal position having at least one auxiliary wheel spaced from the center of gravity of the wheeled carriage such that one set of the castered wheels and the deployed auxiliary wheel, in combination, support the patient during every use of the wheeled carriage generally regardless of the position of the patient.




It is a further object of this invention to provide a cam apparatus having a cam and a cam follower adjacent and below the wheeled base of the wheeled carriage for facilitating a movement of the auxiliary wheel to a position contacting the floor surface. The cam apparatus includes linkages, one linkage having a position control member. The position control member prevents the linkages of the cam apparatus from contacting the floor surface. This arrangement enables the cam apparatus to be a compact part of the wheeled base, thus allowing the wheeled carriage to move the patient support to a lowered position, as needed, to receive a patient from the floor or other location.




It is a further object of the invention to provide an alternate mechanism for raising and lowering the foot end casters to accommodate engagement of the auxiliary wheel with the floor surface.




An object of the invention is to provide a side rail assembly including a support structure for securely mounting the lower end of side rail posts to the frame of a wheeled carriage. Such an arrangement preferably includes having the side rail posts rotatable about their own axes.




SUMMARY OF THE INVENTION




The objects and purposes of the invention are met by providing a wheeled carriage for supporting a patient in a substantially horizontal position, the wheeled carriage having a center of gravity and a force F


mass


due to the mass of the carriage or the mass of a combination of the carriage and a patient thereon at the center of gravity. The wheeled carriage includes a patient support having a length, opposing ends of the length comprising a head end and a foot end of the patient support. The patient support has a pair of lateral sides intermediate the head and foot ends. The patient support is mounted on a wheeled base. The wheeled base includes at least four floor surface engaging and castered wheels spaced from one another. The wheeled base of the wheeled carriage has a first edge at a first end corresponding to the head end of the patient support and a second edge at a second end corresponding to the foot end of the patient support. A gripping device at the head end of the patient support can be used to apply a force F


max


to the carriage sufficient to overcome friction and move the wheeled carriage. An auxiliary wheel mechanism includes an auxiliary wheel support structure for suspendedly supporting at least one auxiliary wheel at an axis thereof to the wheeled base, the auxiliary wheel being uncastered. The auxiliary wheel is secured at its axis to the wheeled base at a distance L in a horizontal direction from the center of gravity along the length of the wheeled base when the auxiliary wheel engages the floor surface, a moment M


mass


being defined by the distance L multiplied by the force F


mass


. The wheeled carriage includes a control apparatus for effecting a movement of the auxiliary wheel support structure and the auxiliary wheel between a first position whereat the auxiliary wheel engages the floor surface and a second position whereat the auxiliary wheel is out of engagement with the floor surface. When the auxiliary wheel is in engagement with the floor surface, the height H defined by the axis of the auxiliary wheel and the relative height of the gripping device creates a moment M


force


defined by multiplying the height H by the force F


max


. The distance L is designed to be great enough such that the moment M


mass


is greater than the moment M


force


when any size and weight of patient is placed on the patient support having their head toward the head end thereof, such that the wheeled carriage does not teeter between the castered wheels on respective ends of the carriage during movement thereof.




The wheeled base of the wheeled carriage has a first edge at a first end corresponding to the head end of the patient support and a second edge at a second end corresponding to the foot end of the patient support. The wheeled base has an imaginary transverse centerline located at a midpoint of the length of the wheeled base, the distance L having a value such that, when the auxiliary wheel is engaged with the floor surface, the axis of the at least one auxiliary wheel is spaced away from the centerline located at the midpoint and toward the second edge of the wheeled base. In a preferred embodiment, the distance L is measured from the center of gravity of the wheeled base, rather than the imaginary transverse centerline.




The wheeled carriage includes a cam apparatus having a first cam linkage having a first end secured to a rotary shaft of a control apparatus and a second cam linkage secured to a second opposing end of the first cam linkage. An end of the second cam linkage is secured to a cam. A cam follower is manipulated by the cam. The cam follower is fixedly secured to the auxiliary wheel support structure. The first cam linkage has a position control member and the second cam linkage has an extended portion. The position control member and the extended portion contact one another during movement of the auxiliary wheel to prevent the linkages of the cam apparatus from contacting a floor surface.




In the alternative, the castered wheels at the foot end of the wheeled carriage are raised and lowered to accommodate engagement of the auxiliary wheel with the floor surface.




The wheeled carriage includes a side rail assembly having a bracket including first and second arms, each arm including an aperture therethrough. A first bushing is mounted through the aperture of the first arm of the bracket, and a first end of a hollow spacer is positioned adjacent the first bushing and between the first and second arms. Another bushing is positioned adjacent the opposing end of the spacer and extends through or into the aperture of the second arm of the bracket. The bushings have inner flat sides about respective inner circumferences and outer flat sides about outer circumferences thereof, and a tubular side rail post has a first end inserted into the bushings and extends through the hollow interior of the spacer, wherein insertion of the tubular side rail post elastically expands outwardly the inner flat sides of the bushings to form substantially rounded edges in the inner circumference and bows out the outer flat sides of the bushings. Elastic expansion of the inner flat sides of the bushings into a generally circular shape adjusts for variations in tolerance of the tubular side rail post. The side rail post and the support bracket therefor generally includes a coating or plating, chrome plating in this case, surface finish about an entire outer circumference thereof, the finish varying the tolerances of the dimensions of the bracket and the side rail post and thus requiring the unique support structure having the bushings.




The side rail assembly embodiment for use with a bed can include a plurality of support structures secured to the bed. A plurality of side rail posts have respective lower ends secured to respective support structures, the lower ends having an axis along a length thereof, and a side rail secured to respective upper ends of the side rail posts, wherein the side rail posts are rotatable about the axis of the lower ends thereof.











BRIEF DESCRIPTION OF THE DRAWINGS




Other objects and purposes of this invention will be apparent to persons acquainted with an apparatus of this general type upon reading the following specification and inspecting the accompanying drawings, in which:





FIG. 1

is a side view of a wheeled carriage for supporting a patient in a substantially horizontal position and embodying the invention;





FIG. 2

is a top view of the wheeled base and some of the support elements of the aforesaid wheeled carriage illustrated in

FIG. 1

with the patient support structure having been removed;





FIG. 3

is a sectional view of one side of the wheeled carriage taken at


3





3


of FIG.


2


and having the auxiliary wheel in a raised position;





FIG. 4

is an enlarged sectional view of a fragment taken at


4





4


of

FIG. 3

showing the cam apparatus when the auxiliary wheel is in the raised position;





FIG. 5

is a front view of the cam apparatus where the cam follower has been moved toward a cam surface location placing the auxiliary wheel in a raised position, the auxiliary wheels and other elements being removed, to better show the cam apparatus.





FIG. 6

is a front view of the cam apparatus and similar to the view of

FIG. 5

except that the cam follower is at the portion of the cam surface leading to the lowered position for the auxiliary wheel;





FIG. 7

is a front view of the cam apparatus and similar to

FIG. 6

except the cam follower has moved to the lowered wheel position;





FIG. 8

is a front view similar to the view of the cam apparatus of

FIG. 7

, except the cam follower is detented into the lowered position thus retaining the auxiliary wheel in contact with the floor surface;





FIG. 9

is an enlarged top view of a fragment of the wheeled base of

FIG. 2

showing the cam apparatus and surrounding elements adjacent the auxiliary wheels when the auxiliary wheels are in the raised position;





FIG. 10

is a sectional view of the cam apparatus and the auxiliary wheel support structure supporting the auxiliary wheel in a raised position and taken at


10





10


of

FIG. 9

;





FIG. 11

is a sectional view similar to the view shown in

FIG. 3

, except that the auxiliary wheel is in a lowered position and contacting the floor surface;





FIG. 12

is an enlarged view of a fragment of the wheeled base similar to the view of

FIG. 9

showing the cam apparatus and surrounding elements adjacent the auxiliary wheels except the auxiliary wheel is in the lowered position;





FIG. 13

is a sectional view of the cam apparatus and the auxiliary wheel support structure supporting the auxiliary wheel in a lowered position contacting the floor surface and taken at


13





13


of

FIG. 12

;





FIG. 14

is an enlarged isometric view of a brake activation structure;





FIG. 15

is a perspective side view of side rail assemblies mounted to a patient support and in a deployed position;





FIG. 16

is a cross-sectional view of a side rail bracket and bushings;





FIG. 17

is a cross-sectional view of a support structure for a side rail post;





FIG. 18

is an end view of a bushing;





FIG. 19A

is a partial view showing deformation of a bushing when a side rail post is inserted therein;





FIG. 19B

is an enlarged fragment of

FIG. 19A

;





FIG. 20

is a side view of a patient support having a side rail assembly in a deployed position and a side rail assembly in a stored position;





FIG. 21

is a top view of a patient support having a side rail assembly in a deployed position and a side rail assembly in a stored position; and





FIG. 22

is a cross-sectional view of a support structure including torsion springs.











DETAILED DISCUSSION




Certain terminology will be used in the following description for convenience in reference only and will not be limiting. The words “up”, “down”, “right” and “left” will designate directions in the drawings to which reference is made. The words “in” and “out” will refer to directions toward and away from, respectively, the geometric center of the wheeled carriage and designated parts thereof. Such terminology will include derivatives and words of similar importance.





FIG. 1

is an illustration of a wheeled carriage


16


for supporting a patient in a substantially horizontal position. A known wheeled carriage is disclosed in Dr. Homer H. Stryker's U.S. Pat. No. 3,304,116. The wheeled carriage


16


of

FIG. 1

, includes a wheeled base


18


, a patient support


20


and a pair of hydraulically operated jacks


22


and


24


interposed between the wheeled base


18


and the underside of the patient support


20


. The jacks


22


and


24


are mounted to the wheeled base


18


and are fixedly secured in place by brackets


26


and


28


, respectively. A plurality of castered wheels


30


,


31


,


32


,


33


, are provided on the wheeled base


18


at the four corners thereof defining a theoretical polygon P, in this case, a rectangle as shown in FIG.


2


. The orientation of the wheels


30


-


33


is similar to that illustrated in Dr. Stryker's aforementioned patent. All of the aforesaid structure is generally conventional and forms the environment for the invention which will be discussed in more detail below.




An auxiliary wheel mechanism


34


is provided on the wheeled base


18


and, in this particular embodiment, is oriented so that its plane of rotation is fixed and parallel to a longitudinal axis A of the wheeled base


18


. The auxiliary wheel mechanism


34


includes a pair of fifth and sixth auxiliary wheels


36


,


38


having respective axes


37


,


39


, and an auxiliary wheel support structure


40


for interconnecting the auxiliary wheels


36


,


38


to the wheeled base


18


. The auxiliary wheels


36


,


38


are connected to the support structure at respective axles


41


,


43


corresponding to the location of axes


37


,


39


. The support structure


40


includes a yoke


42


pivotally secured via a bracket


40


A and axle


40


B to a pair of horizontally spaced longitudinally extending frame members


44


and


46


of the wheeled base


18


. Axles


41


,


43


are provided at opposed lateral sides of the yoke


42


as shown in FIG.


2


.




In the particular embodiment of

FIG. 1

, a control apparatus


47


includes manually manipulatable members such as foot pedals


48


,


49


secured at opposing ends of a rotatable shaft


50


of the wheeled base


18


. As shown in

FIG. 2

, the rotatable shaft


50


extends beyond the length of the wheeled base


18


. Either of the foot pedals


48


,


49


can be utilized to set a brake or adjust the position of the auxiliary wheels


36


,


38


of the wheeled carriage


16


by rotating the shaft


50


, as will be described in more detail later.




Side rail brackets


52


extending along an edge of the patient support


20


enable mounting of side rails to the wheeled carriage


18


. Such brackets


52


having downwardly extending flanges, with respective first and second spaced openings therein, are well known in the art to support side rails. Such an arrangement is set forth in U.S. Pat. No. 5,187,824 issued Feb. 23, 1993 and is hereby incorporated by reference in its entirety. Therefore, explanation of the features of the side rails is not detailed herein. Crossing bracket


53


secures portions of the patient support


20


to each other.




A handle


54


in

FIG. 1

enables a handler or driver of the wheeled carriage


16


to push the carriage in selected directions. Turning of the wheeled carriage


16


is simplified when the auxiliary wheels


36


,


38


are deployed onto a floor surface


56


. This is so, because the auxiliary wheels


36


,


38


are not castered, and are relatively large compared to the other castered wheels


30


-


33


of the wheeled base


18


and the resulting shorter wheelbase between the wheels


32


,


33


and


36


,


38


.




The handle


54


can be replaced by an end rail or any other known gripping device enabling persons to move or push the wheeled carriage


16


. Even the frame of the patient support


20


can be utilized as the gripping device in some embodiments.




As shown in

FIG. 1

, a force F


mass


is applied to the wheeled carriage


16


along a line G representing the center of gravity of the carriage with or without a patient thereon. The force F


mass


equals the sum of the overall mass of the wheeled carriage


16


with or without a patient thereon, depending upon the situation. Likewise, the center of gravity (line G) can vary depending upon the position of the patient on the wheeled carriage


16


or the location of other equipment such as batteries, oxygen tanks, or other devices secured to the wheeled base


18


, the patient support


20


, or other parts of the wheeled carriage. These factors can cause variations for the location of the center of gravity G for the wheeled carriage


16


.




A force F


max


, shown in

FIG. 1

, represents the force required to move the wheeled carriage


16


when the auxiliary wheels


36


,


38


are deployed in contact with the floor surface


56


. The force F


max


is the force required to overcome the friction of the auxiliary wheels


36


,


38


and the friction of the castered wheels


32


,


33


. Because of the larger diameter, and because the auxiliary wheels


36


,


38


are uncastered, the auxiliary wheels decrease the amount of force F


max


required to move the wheeled carriage


16


as compared to a carriage only having the castered wheels


30


-


33


. Such an arrangement is shown in

FIGS. 1 and 11

.




More importantly, when the auxiliary wheels


36


,


38


are deployed and the wheeled carriage


16


is utilized, one must be sure that the carriage does not teeter between the castered wheels


30


,


31


at a first end or foot end, and the castered wheels


32


,


33


at a second end or head end of the wheeled carriage. Such teetering during use could be uncomfortable to the patient, annoying to the clinician and even prevent proper cardio-pulmonary resuscitation of the patient.




To prevent teetering of the wheeled carriage


16


, the axes


37


,


39


of the auxiliary wheels


36


,


38


are spaced from the center of gravity G of the carriage by a horizontal distance L along the length of the wheeled base


18


corresponding to the longitudinal axis A thereof. In this manner, a moment M


mass


defined by multiplying the distance L times the force F


mass


at the center of gravity can be calculated. Such a moment M


mass


resists elevation of the castered wheels


32


,


33


and ensures the castered wheels


30


,


31


remain elevated when the auxiliary wheels


36


,


38


are deployed.




Height H represents the vertical distance between the axes


37


,


39


of the auxiliary wheels


36


,


38


and the vertical height of the handle


54


. A moment M


force


is created when a user pushes the wheeled carriage


16


with a force F


max


to move the wheeled carriage in a horizontal direction. The force F


max


is limited, as described earlier, to the maximum possible amount of humanly applied force needed to overcome the friction of the wheels


32


,


33


,


36


,


38


supporting the wheeled carriage


16


and to effect a desired acceleration of the wheeled carriage


16


.




In use, the moment M


mass


must always be greater than the moment M


force


to prevent teetering of the wheeled carriage


16


. Therefore, the axes


37


,


39


of the auxiliary wheels


36


,


38


, are spaced in the horizontal direction away from the center of gravity of the wheeled carriage


16


the distance L sufficient to prevent the moment M


force


from becoming greater than the moment M


mass


and teetering the wheeled carriage. Therefore, the axes


37


,


39


of the auxiliary wheels


36


,


38


are spaced a sufficient distance from the center of gravity to ensure that the moment M


mass


always is greater than the moment M


force


.




The distance L from the center of gravity G to the auxiliary wheels


36


,


38


is sufficient to ensure that the wheeled carriage


16


will not teeter even if the center of gravity G shifts a distance due to the weight of the patient. Likewise, the distance L is sufficient to overcome any negative effects due to the line G defining the center of gravity moving because of placement of the wheeled carriage


16


on a ramp or other angled floor surface when transporting a patient.




Generally, the distance L must be great enough so that the axes


37


,


39


of the auxiliary wheels


36


,


38


are located beyond a vertical midpoint line M of the wheeled base


18


dividing the wheeled base into two sections of equal length as shown in FIG.


1


.

FIG. 1

shows the axis


37


spaced beyond the midpoint line M and away from the line G representing the center of gravity. Therefore, when the auxiliary wheels


36


,


38


are deployed, the wheeled carriage


16


of

FIG. 1

will not teeter during use.





FIG. 1

shows the axis


37


spaced a short distance from the midpoint line M of the wheeled base


18


, and away from the center of gravity G. The distance of such spacing of the axis


37


from the midpoint line M can be greater. For example, the axes


37


,


39


of the auxiliary wheels


36


,


38


can be spaced from a first edge


58


on a longitudinal end of the wheeled base


18


corresponding to the end of the patient support


20


for supporting the head of the patient and toward a second edge


59


of the wheeled base corresponding to the end of the patient support


20


corresponding to the feet of the patient.




In some embodiments, the axis


37


of the auxiliary wheel


36


can be spaced toward the second edge


59


of the wheeled base


18


a distance corresponding to at least 15% of the distance from the midpoint line M of the wheeled base toward the second edge. In a most preferred embodiment, the axis


37


of the auxiliary wheel


36


is located on the wheeled base


18


at a position corresponding to about two-thirds of the length of the wheeled base. Of course, the above lengths or distances are calculated when the auxiliary wheels


36


are deployed on the floor surface


56


and thus support the wheeled carriage


16


as shown in FIG.


11


.





FIG. 3

shows details of the auxiliary wheel support structure


40


. Return spring


60


supports the auxiliary wheels


36


,


38


in the raised position shown in

FIGS. 1 and 3

. The return spring


60


connects at one end to a spring cross support


62


as shown in

FIGS. 2 and 9

.

FIGS. 2 and 9

further show the other end of the return spring


60


secured to an eyelet bolt


64


having an adjusting nut thereon. The eyelet bolt


64


connects to a U-shaped linkage element


66


fixedly connected to the yoke


42


. The U-shaped linkage element


66


is fixedly secured to the central part of the yoke


42


. While

FIGS. 10 and 13

show the linkage element


66


as a separate element secured to the yoke


42


, the linkage element


66


can be an integral part of an L-shaped section of the yoke


42


. As shown in

FIGS. 3 and 11

, the linkage element


66


and the yoke


42


are fixedly secured so that the return spring


60


can raise the yoke when cam follower


70


is in the raised position of FIG.


3


. The yoke


42


supports the auxiliary wheels


36


,


38


on opposing lateral sides thereof as partially illustrated in FIG.


4


. As shown in

FIGS. 3

,


10


and


13


, the yoke


42


includes a securement element


68


fixedly securing an axle


75


of the cam follower


70


thereto. In response to movement upwardly or downwardly of the cam follower


70


about the axle


40


B, caused by movement of a cam


72


, the yoke


42


pivots or moves, raising or lowering the auxiliary wheels


36


,


38


. In the position shown in

FIG. 3

, the cam follower


70


is in a raised position, and the return spring


60


ensures the cam follower and thus the auxiliary wheels


36


and


38


will stay in such a raised position. Further, when the cam follower


70


is released from a lower position on the cam


72


, the return spring


60


, the eyelet bolt


64


, and the fixedly secured U-shaped linkage element


66


of the yoke


42


enable the yoke to be raised such that the auxiliary wheels


36


,


38


do not contact the floor surface


56


.





FIG. 4

shows a front view of a cam apparatus


69


, which includes the aforementioned cam follower


70


and the cam


72


. The auxiliary wheel support structure


40


is in a raised position, in

FIG. 4

, so that the auxiliary wheels


36


and


38


do not touch the floor surface


56


. The rotatable shaft


50


secures to a first end of a cam linkage


74


having a position control member


76


thereon. A second end of the cam linkage


74


has a pin or roller element


78


secured thereto. The pin or roller element


78


mounts through a closed slot


80


in a slotted cam linkage


82


. The closed slot


80


extends through a substantial portion of the length of the slotted cam linkage


82


. The slotted cam linkage


82


also includes an extended portion


84


on the top thereof. The extended portion


84


of the slotted cam linkage


82


is aligned to physically contact the position control member


76


as will be described in more detail with respect to

FIGS. 5-8

. Dashpot


86


secured to one end of the cam


72


prevents the cam from moving too forcefully in response to the weight on the auxiliary wheels


36


and


38


when the cam follower


70


moves past a dead center raised part


99


and when the cam roller


70


enters an open slot


88


of the cam


72


. The cam


72


pivots about a cam axle


90


secured to a cam support bracket


91


when moving the cam follower


70


to raised and lowered positions.





FIGS. 5-8

merely show the operation of the cam apparatus


69


including the cam


72


and the cam follower


70


as well as the linkages


74


,


82


from the control apparatus


47


defined by the rotatable shaft


50


that operates the auxiliary wheel support structure


40


to raise and lower the auxiliary wheels


36


,


38


.

FIG. 5

corresponds to the view of

FIG. 4

(wheels raised) except that the elements of the auxiliary wheel support structure


40


, such as the yoke


42


, have been removed for purposes of clarity.




In operation, and to effect a lowering of the auxiliary wheels


36


,


38


, the rotatable shaft


50


is rotated in a clockwise direction from the neutral position shown in FIG.


5


. The rotatable shaft


50


is fixedly secured to the cam linkage


74


and thus rotates the cam linkage


74


as shown in FIG.


6


. The pin or roller element


78


of the cam linkage


74


moves along the closed slot


80


of the slotted cam linkage


82


. Movement of the cam linkages


74


and


82


toward the left in

FIG. 6

causes the cam


72


to pivot clockwise to the left and thus the cam follower


70


rolls, moving the cam follower


70


downward. As the cam


72


rotates in a clockwise direction about the axle


90


, or pivots to the left, the dashpot


86


is slowly extended.




As the cam follower


70


leaves the open slot


88


of the cam


72


, it is moved past the raised part


99


on the cam


72


and into a depression


92


as shown in

FIG. 8

corresponding to a wheels lowered position corresponding to FIG.


13


.




As shown in

FIG. 8

, when the cam follower


70


reaches an extended position, the cam follower rests in the depression


92


in the surface of the cam


72


. In this position, the auxiliary wheel support structure


40


has moved to a lower position, and with the downward movement of the axle


75


of the cam follower


70


, the auxiliary wheels


36


,


38


contact the floor surface


56


.




When the auxiliary wheel support structure


40


is released and is to be returned to the raised position shown in

FIGS. 4

,


5


and


10


, the rotatable shaft


50


(

FIG. 8

) rotates in a counterclockwise direction and the elements described above move in opposite directions. The extended portion


84


of the slotted cam linkage


82


contacts the position control member


76


of the cam linkage


74


as shown in FIG.


7


. Contact between the position control member


76


and the extended portion


84


prevents the linkage


82


from pivoting downwardly and contacting the floor surface


56


. Therefore, the control member


76


and the extended portion


84


perform the important function of preventing failure or damage to the cam linkages


74


,


82


. Furthermore, the control member


76


and the extended portion


84


also enable the elements of the cam apparatus


69


to fit in a lower, smaller, more compact area. Such an arrangement requires less space between the bottom of the jacks


22


,


24


and the floor surface


56


. Therefore, the patient support


20


can be lowered farther or closer to the floor surface


56


on the hydraulic jacks


22


,


24


than many other wheeled carriages


16


. In addition, and more importantly, the position control member


76


serves to push on the extended portion


84


to push the cam


72


counterclockwise to force the cam follower


70


out of the depression


92


and past the raised part


99


. Further, the length of the slot


80


facilitates rapid deployment of the brake when in, for example, the

FIG. 6

position of movement, in response to a rapid counterclockwise rotation of the linkage


74


to the broken line position in

FIG. 5

, without having to wait for the cam


72


to return to the fully returned position illustrated in FIG.


5


. The angled section


80


A of the slot prevents the linkage


82


from striking the floor. The dashpot


86


prevents the return spring


60


and the weight of the patient and wheeled carriage from driving the cam follower


70


upwardly fast or quickly, when the cam follower passes the raised part


99


and reaches the open slot


80


of the cam


72


. The dashpot


86


slows the descent of the wheeled carriage back onto all four casters and enables return of the auxiliary wheel support structure


40


to a raised position in a controlled manner.





FIG. 10

shows the auxiliary wheel support structure


40


in a raised position.

FIG. 10

also illustrates a contoured or rounded surface


73


of the cam


72


. The surface


73


of the cam


72


is rounded along its entire contact surface with the cam follower


70


, including the open slot


80


and the depression


92


. In this manner, the surface


73


of the cam


72


mates with the surface of the cam follower


70


.




As shown in

FIG. 10

, the cam follower


70


has extended edges along both sides thereof. Bearings


77


secure the cam follower to the axle


75


enabling rotation of the cam follower. The surface of the cam follower


70


matches or fits the surface


73


of the cam


72


. The main reason for this arrangement is because of the movement or pivoting of the axle


75


of the cam follower


70


, depending on the position of the auxiliary wheels


36


,


38


. This movement is clear from a comparison of the auxiliary wheel support structure


40


of

FIG. 10

with the section view of

FIG. 13

showing the auxiliary wheel support structure


40


in the lowered position. As the elements


66


,


42


, and


70


are moved as a unit to lower the auxiliary wheel


38


, the cam follower


70


rotates or pivots a significant amount. By having contoured mating surfaces on the cam


72


and the cam follower


70


, any problem in functioning of the auxiliary wheel support structure


40


in moving between the lowered and raised positions is obviated.





FIG. 11

is similar to the view of

FIG. 3

, except the auxiliary wheel


38


is in a lowered position supporting the wheeled carriage


16


. The distances and forces set forth in

FIG. 1

for the force F


mass


at the center of gravity, distance L in a horizontal direction between the axis of the auxiliary wheels, the height H representing the vertical distance between the axes


37


,


39


of the auxiliary wheels and the handle


54


, and the force F


max


capable of moving the wheeled carriage


16


in a horizontal direction, are all similar to the values set forth in FIG.


1


.

FIG. 11

better shows the various forces and moments for the wheeled carriage


16


having auxiliary wheels


36


,


38


deployed to contact the floor surface


56


. As stated before, the moment M


mass


must always be greater than the moment M


force


to prevent teetering of the wheeled carriage


16


. Therefore, the axes


37


,


39


of the auxiliary wheels


36


,


38


, are spaced in the horizontal direction away from the center of gravity of the wheeled carriage


16


, the distance L sufficient to prevent the moment M


force


from becoming greater than the moment M


mass


and teetering the wheeled carriage. This spacing or distance L is great enough to ensure that the moment M


mass


always is greater than the moment M


force


. The axes


37


,


39


, also have the same distance from the center of gravity and actually form the same line if extended toward each other. Therefore, the auxiliary wheels


36


,


38


are parallel with respect to each other.





FIG. 14

shows a view of a brake activation structure


93


for the wheeled carriage


16


. The brake activation structure


93


generally can be located near the brackets


26


and


28


in FIG.


1


.




Much of the detail of the brake activation structure


93


is disclosed in copending application Ser. No. 09/003,777, titled Unitary Pedal Control Of Brake And Fifth Wheel Deployment Via Side And End Articulation With Additional Unitary Pedal Control of Height Of Patient Support, filed Jan. 7, 1998, the disclosure of which is hereby incorporated by reference.




As shown in

FIG. 14

, the bracket


28


on the wheeled base


18


has thereon structure that defines a guideway


94


. Only one such guideway


94


is illustrated in FIG.


14


. The guideway


94


slidably supports a catch or slide mechanism


95


lengthwise of the guideway


94


, in a direction that is lateral to the longitudinal axis A. A latch in the form of a roller


96


is rotatably supported on the lower end of a vertically reciprocal rod


97


and is adapted to roll along a lower edge of the catch mechanism


95


between respective recesses


98


,


99


and


100


in the aforesaid lower edge of the catch mechanism


95


. The latch or the roller


96


is capable of vertical movement against the continual urging of a compression spring


101


, a lower end of which abuts the guideway


94


as shown in FIG.


14


. An upper end of the rod


97


passes through a hole (not shown) in a brake bar


102


and has a collar


103


secured thereto on a side of the brake bar


102


remote from the spring


101


. A link


104


interconnects one end of the catch mechanism


95


to a lever arm


105


fixedly secured to the rotatable shaft


50


and is movable therewith. As a result, a clockwise rotation of the shaft


50


will not activate a deployment of the auxiliary wheel


38


but will, instead, cause the lever arm


105


to move therewith and apply a pulling force to the aforesaid one end of the catch mechanism


95


through the interconnecting link


104


to cause the roller


96


to roll on the edge of the catch mechanism


95


out of the central recess


99


and into the recess


98


while the compression spring


101


maintains the engagement of the contoured edge of the catch mechanism


95


with the roller


96


. The rod


97


and the brake bar


102


will be pulled downwardly against the urging of the spring


101


to lower the rings


106


on the opposite ends of the brake bar


102


into engagement with the castered wheels


32


,


33


in a known manner. The brake rings


106


prevent any movement of the castered wheels. Deactivation of the brake rings


106


can be accomplished by a reverse rotation of the foot pedals


48


,


49


such that upward movement of the brake bar


102


will occur, while bumpers


107


dampen unwanted metal to metal contact noise. A counterclockwise rotation of the shaft


50


will cause the link


104


to push the catch mechanism


95


to the left and cause the roller


96


to enter the recess


100


. In this position, the auxiliary wheels


36


,


38


are deployed as described earlier. On the other hand, a movement of the roller


96


into the central recess


99


places the pedals


48


,


49


into a neutral position where neither the brake rings


106


nor the auxiliary wheels


36


,


38


are deployed.




While two of the auxiliary wheels


36


,


38


are shown throughout the drawings, a single auxiliary wheel may be utilized in some embodiments. At least one auxiliary wheel is required for the invention to function properly.




In the alternative, the castered wheels


30


,


31


adjacent the foot end of the wheeled carriage can be supported for elevatable movement so that when lowered, the auxiliary wheels


36


,


38


will be elevated above the floor (

FIG. 1

) and when elevated or retracted away from the floor, the auxiliary wheels


36


,


38


will be in engagement with the floor (FIG.


11


). This could be accomplished, for example, by vertically adjustably mounting the bracket


26


to which the wheels


30


,


31


would be mounted to the adjacent jack


22


by means of a separate jack or like cam operated device (not shown).




AUXILIARY SIDE RAIL ASSEMBLY




Side rail assemblies


118


,


119


of the embodiment of

FIGS. 15-22

provide improved strength for the side rail assemblies in a lateral direction across the bed or wheeled carriage


16


.




The patient support


20


and the side rail assemblies


118


,


119


are illustrated in

FIG. 15

which is a partial view of the wheeled carriage


16


of

FIG. 1

that additionally includes the side rail assemblies.

FIG. 15

does not include the jacks


22


,


24


, the wheels


30


,


32


, or other elements of the bottom support section of the wheeled carriage


16


. Side rail assembly


119


is a mirror image of side rail assembly


118


.




Side rail brackets


52


A are secured to the patient support


20


by welding or the like. The side rail brackets


52


A are generally secured at an angle relative to the length of the patient support


20


as shown in FIG.


15


. The side rail brackets


52


A have a U-shape and include bracket apertures


121


,


122


for receiving other elements of a support structure


124


as illustrated in FIG.


16


. The side rail brackets


52


A generally comprise a metal, such as steel or aluminum, although other materials can be utilized.




The support structure


124


shown in the cross-sectional view of

FIG. 17

includes the side rail bracket


52


A and a spacer


126


. The spacer


126


is hollow and positioned between apertures


121


,


122


of the side rail bracket


52


A. The spacer


126


has a cylindrical shape. Spacer


126


includes an outer circumference and a lesser inner circumference defining an opening through the length of the cylinder. The spacer


126


includes a support aperture


128


mounted near the center thereof and extending through the spacer in a direction substantially perpendicular to a longitudinal axis along the length of the spacer.




The spacer


126


can comprise a plastic material such as polyethylene, polypropylene, polyvinyl chloride, or other well known plastics. The spacer


126


can have a thickness of about 0.6 cm between the outer circumference and the inner circumference.




The support structure


124


includes bushings


131


,


132


extending through and supported in bracket apertures


121


,


122


of the side rail bracket


52


as shown in FIG.


16


. As shown in

FIG. 17

, bushings


131


,


132


are located at opposing ends of the spacer


126


.




As shown in

FIG. 18

, the bushing


131


includes an opening


134


therethrough having ten equidistant inner flat sides or edges


135


A about the inner circumference of portions of the bushing


131


. Opening


134


extends through the entirety of the bushing


131


thus forming a passageway therethrough. Besides having ten flat sides


135


A on the interior of the bushing


131


, such flat sides


135


B can also be provided about the exterior of the bushing. While ten flat sides


135


A,


135


B extending the length of the bushing are shown, any number of flat sides greater than five can be utilized in other embodiments of the invention.




Bushing


131


includes a radially outwardly extending lip


136


at one end thereof as shown in

FIGS. 16-18

. Likewise bushing


132


includes another radially outwardly extending lip


137


at a corresponding end thereof as shown in

FIGS. 16-17

. Lip


136


is positioned on the interior side of bracket aperture


121


and thus contacts an end of the spacer


126


. Bushing


132


is located at a similar position adjacent the interior side of bracket aperture


122


such that the lip


137


contacts an opposing end of the spacer


126


as shown in FIG.


17


.




The bushing


131


generally comprises a plastic material, such as polypropylene, polyethylene, polyvinyl chloride or other well known plastics. The lip


136


generally is an integral plastic member having a diameter and thickness substantially equivalent to the diameter and thickness of the spacer


126


, for example, about 0.6 cm. The portion of the bushing


131


having flat sides


135


A,


135


B, however, generally has a lesser thickness. In some embodiments, such a thickness can be about 0.3 cm. Such a thickness enables the inner flat sides


135


A of the bushing


131


to deform and elastically expand outwardly to receive a post, while maintaining sufficient rigidity so that the inner flat sides prevent sway or pivoting of the post. The bushing


131


has a length L extending the length of opening


134


. The bushing


132


is made from the same materials and is a mirror image of the bushing


131


.




As best illustrated in

FIG. 17

, the support structure


124


receives a side rail post


140


. The side rail post has a generally cylindrical shape. The side rail post


140


preferably comprises a hollow metal tube having an inner surface about an inner radius and an outer surface about an outer radius thereof. A surface finish preferably is applied to the outer surface about an outer circumference of the side rail post


140


as well as to the outer surface of the bracket


52


A. The surface finish preferably is a chrome plating extending about an entire outer circumference of the side rail post


140


and the bracket


52


A. Such a surface finish improves the appearance of the metal side rail posts


140


and the bracket


52


A. However, such surface finishes have an uneven thickness which provides a wider range of diameters about the outer circumference of the side rail posts


140


, and thus the surface finish varies the tolerance of dimensions for the side rail posts and the diameter of the openings


121


,


122


into which the bushings


131


,


132


and the side rail posts are received. Therefore, the tolerances required for the support structure


124


receiving the side rail posts


140


must be increased while maintaining a snug or tight fit.




The side rail post


140


extends through the opening


134


of the bushing


131


positioned in bracket aperture


121


, through the opening along the length of the spacer


126


and into the opening of the bushing


131


positioned in bracket aperture


122


.




The outside edge of the lower end


142


of the side rail post


140


is intended to be flush with the edge of the end of the bushing


131


opposite from the lip


137


when mounted to the support structure


124


. However, in some embodiments the lower end


142


of the side rail post


140


can extend outwardly, a distance beyond the end or edge of the bushing


131


.




As shown in

FIG. 19

, when the side rail post


140


is forced through the opening


134


of the bushing


132


for securement to the support structure


124


, the flat sides


135


A,


135


B at inner and outer circumferences of the bushing


132


elastically expand outwardly, without necessitating an expansion of the areas at mutually adjacent sections


132


A of the bushing


132


, enabling the side rail post


140


to be snugly engaged therein despite variations in the diameter of the side rail post. The inner and outer flat sides


135


A,


135


B are aligned with each other as shown in FIG.


18


. The inner opening defined by the spacer


126


has a diameter such that the side rail post can pass therein. The second bushing


131


receives the side rail post


140


in a manner that is a mirror image of the first bushing


132


. The second bushing


131


also elastically expands or deforms outwardly in the same manner as the bushing


132


shown in FIG.


19


. As the inner flat sides


135


A of both of the bushings


131


,


132


deform outwardly, the outer flat sides


135


B of the bushing expand or bow outwardly as shown in

FIG. 19

, to a more circular shape conforming to or nearly conforming to the internally facing wall surface


121


A,


122


A (

FIG. 19A

) of the bracket apertures


121


,


122


. In other words, elastic expansion of the inner flat sides of the bushings into a generally circular shape adjusts for variations in the tolerances of manufacturing and finishing of the individual components. Thus, the side rail post


140


is snugly secured to the bushings


131


,


132


along the entire length of the bushing. Deformation of the inner flat sides


135


A about the inner circumferences of the bushings


131


,


132


enable a snug and stable connection between the support structure


124


and the side rail post


140


despite variations in the diameter of the side rail post. Due most importantly to the snug connections at the bushings


131


,


132


, along the lengths thereof, and the spacer between the bushings, the side rail post


140


does not sway or have any significant movement in a perpendicular direction when forces are applied laterally thereto. Such a result is obtained whether the side rail post


140


is stationary or being moved upwardly or downwardly between deployed and stowed positions, except for movement away from or under and toward the lateral edge of the patient support


20


due to the curved shape of the side rail post


140


. However, even during such movement, especially the snug connections between the side rail post


140


and the bushings


131


,


132


prevent play or movement of the side rail post with respect to the bushings.




As shown in

FIG. 17

, the side rail post


140


, spacer


126


, and bushings


131


,


132


can rotate about a longitudinal axis


150


extending along a direction of the length of the side rail post adjacent the lower end


142


thereof. The bushings


131


,


132


may be frictionally fixed to the internally facing wall surface


121


A,


122


A (

FIG. 19A

) of the respective bracket apertures


121


,


122


, respectively. Thus, the lower end of the side rail post


140


acts as an axle when rotating about the longitudinal axis


150


. In this manner, the side rail post


140


can be rotated between stowed and deployed positions.




As shown in

FIG. 17

, the side rail post


140


has a post aperture


148


extending therethrough. The post aperture


148


is near the lower end


142


of the side rail post


140


. The post aperture


148


can be aligned with the support aperture


128


while the lower end


142


is substantially flush with the outer edge of bushing


132


. A rivet


152


, such as a pop rivet, is placed in the outside of the hollow side rail post


140


and extends inwardly of the post through the post aperture


148


and through the support aperture


128


. The inwardly extending end of the rivet


152


is deformed. A self-tapping screw could be used instead of the rivet. Such securement of the side rail post


140


to the spacer


126


prevents movement of the side rail post along the longitudinal axis


150


. Thus, the side rail post


140


can only rotate about the longitudinal axis


150


.




The side rail posts


140


have a contorted or multiple curved shape as shown in FIG.


15


. Such compound angle of the axis of rotation enables the side rail posts


140


to rotate underneath a metal beam of the patient support


20


allowing storage below a lateral side edge of the carriage


16


.




The side rail posts


140


are secured to upper support brackets


154


by support bolts


156


as shown in

FIGS. 15 and 20

. The upper support brackets


154


preferably have a U-shape and comprise a metal such as steel or the like, although other materials can also be utilized.




The support bolts


156


about which the side rail posts


140


pivot can also comprise metal such as steel, or other appropriate material.




A side rail


160


of the side rail assembly


118


is fixedly secured to a plurality of the upper support brackets


154


by welding or other means of attachment.




The side rail


160


generally comprises a metal tube made of aluminum, steel or other appropriate materials. Like the side rail posts, the side rail


160


can have a finished surface to improve the appearance of the rail.




The side rail


160


moves upwardly and downwardly with the plurality of side rail posts


140


pivotally secured thereto. However, the side rail


160


always remains in a substantially horizontal position. Movement sideways or in a direction along the length thereof, coupled with upward or downward movement between deployed and stowed positions does occur due to the compound angle of the axis of rotation


150


. The curved shape of the side rail posts


140


enable the posts to rotate or pivot the side rail


160


downwardly to a stowed or stored position under a lateral edge of the wheeled carriage


16


as shown in

FIGS. 20 and 21

. See also the aforementioned U.S. Pat. No. 5,187,824 to Martin Stryker.




The side rail assembly


118


is locked or latched in the upright or raised position to protect a patient as shown in

FIGS. 15

,


20


, and


21


. A latch mechanism


163


, illustrated in

FIG. 20

, maintains the side rail


160


, and the side rail posts


140


connected thereto, in a raised or upright position. The latch mechanism


163


has a release enabling downward movement of the side rail


160


to a stored position. Another exemplary latch mechanism, which can be utilized for the invention of

FIG. 15

, is disclosed in U.S. Pat. No. 5,187,824, which earlier in this disclosure has been incorporated by reference. Further, other conventional or known latch mechanisms may be utilized with the side rail assemblies


118


,


119


of the invention.




At least one of the support structures


124


for each side rail assembly


118


,


119


includes at least one torsion spring, and preferably two torsion springs


164


,


165


as shown in FIG.


15


. The torsion springs


164


,


165


preferably are metal springs. However, plastic or other materials having the appropriate elasticity can be utilized.





FIG. 22

better illustrates the torsion springs


164


,


165


. Respective first ends


171


,


172


of the torsion springs


164


,


165


are secured to the rivet


152


or other type fastener. Second ends


173


,


174


of the torsion springs


164


,


165


are secured by hooking them to the opposing arms of the side rail bracket


52


A.




When the respective side rails


160


are in the raised position shown in

FIG. 15

, the torsion springs


164


,


165


are generally relaxed or unstressed. When a respective side rail


160


is lowered, both of the torsion springs


164


,


165


oppose or resist the downward force of gravity acting on the side rail


160


and the side rail posts


140


. Thus the side rail assembly


118


does not quickly rotate to the storage position.




When the respective side rail


160


is in the stowed or stored position, the energy stored in the torsion springs


164


,


165


assists an attendant raising the side rail assembly


118


by decreasing the amount of force required to raise the side rail. As the side rail


160


is raised, the energy in the torsion springs


164


,


165


is released. Therefore, the torsion springs


164


,


165


assist in raising the side rail


160


from a stored position and oppose downward movement of the side rail.




In the above disclosure, references to and descriptions of a single support structure


124


, a single side rail post


140


, or other elements, disclosed and shown throughout the specification and drawings, can be considered a description of the plurality of other support structures, other side rail posts, and other duplicate elements having the same reference numeral.




Although particular preferred embodiments of the invention have been disclosed in detail for illustrative purposes, it will be recognized that variations or modifications of the disclosed apparatus, including the rearrangement of parts, lie within the scope of the present invention.



Claims
  • 1. A wheeled carriage for supporting a patient in a substantially horizontal position, said wheeled carriage having a center of gravity and a force Fmass at the center of gravity due to the mass of said carriage or the mass of a combination of said carriage and a patient thereon, said wheeled carriage comprising:a patient support having a length, opposing ends of the length comprising a head end and a foot end of said patient support, said patient support having a pair of lateral sides intermediate the head and foot ends; a wheeled base having a length and supporting said patient support and enabling movement of said patient support, said wheeled base including at least four floor surface engaging and castered wheels spaced from one another, said wheeled base of said wheeled carriage having a first edge at a first end corresponding to the head end of said patient support and a second edge at a second end corresponding to the foot end of said patient support; a gripping location at the head end of said patient support, said gripping location being utilized to apply a force Fmax to said carriage sufficient to overcome friction and move said wheeled carriage; an auxiliary wheel mechanism including an auxiliary wheel support structure for rotatably supporting at least one auxiliary wheel at an axis thereof to said wheeled base, said at least one auxiliary wheel being uncastered, the axis of said at least one auxiliary wheel being secured to said wheeled base at a distance L in a horizontal direction from the center of gravity along the length of said wheeled base when said auxiliary wheel is engaged with the floor surface, a moment Mmass being defined by the distance L multiplied by the force Fmass; and control apparatus for effecting a movement of said support structure and said at least one auxiliary wheel between a first position whereat said auxiliary wheel is engaged with the floor surface and a second position whereat said auxiliary wheel is out of engagement with the floor surface, wherein, when said auxiliary wheel is in engagement with the floor surface, the height H defined by the axis of said auxiliary wheel and the relative height of said gripping location creates a moment Mforce defined by multiplying the height H by the force Fmax, the distance L being great enough such that the moment Mmass is greater than the moment Mforce when any size and weight of patient is placed on the patient support having their head toward the head end thereof, such that said wheeled carriage does not teeter between said castered wheels on respective ends of said carriage during movement thereof.
  • 2. The wheeled carriage of claim 1, wherein said wheeled base of said wheeled carriage has a first edge at a first end corresponding to the head end of said patient support and a second edge at a second end corresponding to the foot end of said patient support, said wheeled base of said wheeled carriage having an imaginary transverse centerline located at a midpoint of the length of said wheeled base, the distance L having a value such that, when said auxiliary wheel is engaged with the floor surface, the axis of said at least one auxiliary wheel is spaced away from the centerline located at the midpoint and toward the second edge of said wheeled base.
  • 3. The wheeled carriage of claim 2, wherein the axis of said auxiliary wheel is spaced toward the second edge of said wheeled base by a distance corresponding to at least 15% of the distance from the centerline at the midpoint of said wheeled base to the second edge of said wheeled base.
  • 4. The wheeled carriage of claim 1, wherein the distance L has a value such that the axis of said 10 auxiliary wheel is located at a position corresponding to about two-thirds of the length of said wheeled base, and toward the second edge thereof, when said at least one auxiliary wheel contacts the floor.
  • 5. The wheeled carriage of claim 1, wherein said at least one auxiliary wheel includes a second auxiliary wheel parallel to said first auxiliary wheel and having the same axis.
  • 6. The wheeled carriage of claim 1, wherein said control apparatus includes support means for elevating and lowering two of said floor surface engaging wheels adjacent said foot end.
  • 7. A wheeled carriage for supporting a patient in a substantially horizontal position, comprising:a patient support having a length, opposing ends of the length comprising a head end and a foot end of said patient support, said patient support having a pair of lateral sides intermediate the head and foot ends; a wheeled base having a length and supporting said patient support and enabling movement of said patient support, said wheeled base including at least four floor surface engaging and castered wheels spaced from one another, said wheeled carriage having a first edge corresponding to the head end of said patient support and a second edge corresponding to the foot end of said patient support, said wheeled base having an imaginary transverse centerline located at a midpoint of the length of said wheeled base and dividing said wheeled base; an auxiliary wheel mechanism including an auxiliary wheel support structure for suspendedly supporting at least one auxiliary wheel at an axis thereof to said wheeled base, said at least one auxiliary wheel being uncastered; and control apparatus for effecting a movement of said auxiliary wheel support structure and said at least one auxiliary wheel between a first position whereat said auxiliary wheel is engaged with the floor surface, the axis of said auxiliary wheel being spaced from the centerline at the midpoint of said wheeled base toward the second edge of said wheeled base, and a second position whereat said auxiliary wheel is out of engagement with the floor surface.
  • 8. The wheeled carriage of claim 7, wherein the axis of said auxiliary wheel is spaced toward the second edge of said wheeled base by a horizontal distance corresponding to at least 15% of the distance from the centerline at the midpoint of said wheeled base to the second edge of said wheeled base, the distance from the centerline at the midpoint of said wheeled base to the first edge of said wheeled base being substantially the same as the distance from the centerline at the midpoint of said wheeled base to the second edge of said wheeled base.
  • 9. The wheeled carriage of claim 7, wherein the axis of said auxiliary wheel is located on said wheeled base at a position corresponding to about two-thirds of the length of said wheeled base when said auxiliary wheel contacts the floor surface.
  • 10. The wheeled carriage of claim 7, wherein said at least one auxiliary wheel includes a second auxiliary wheel parallel to said first auxiliary wheel and having the same axis.
  • 11. The wheeled carriage of claim 7, wherein said control apparatus includes a manipulatable member, a rotatable shaft, and a cam apparatus linked to said rotatable shaft to move a cam follower in response to rotation of said shaft, said cam follower being secured to said auxiliary wheel support structure.
  • 12. A wheeled carriage for supporting a patient in a substantially horizontal position, comprising:a patient support having head and foot ends and a pair of lateral sides intermediate said head and foot ends and a wheeled base supported on at least four floor surface engaging and castered wheels spaced from one another at locations defining corners of a theoretical polygon; an auxiliary wheel mechanism including an auxiliary wheel support structure for suspendedly mounting at least one auxiliary wheel to said wheeled base, said at least one auxiliary wheel being oriented inside a boundary of the theoretical polygon and including an axle about which said wheel rotates, said axle being mounted to said auxiliary wheel support structure and being uncastered; control apparatus for effecting a movement of said wheel support structure and said at least one auxiliary wheel between a first position whereat said auxiliary wheel is engaged with said floor surface and a second position whereat said at least one auxiliary wheel is out of engagement with the floor surface, said control apparatus including a rotatable shaft oriented on an axis parallel to a longitudinal axis of said rectangular patient support and having a first manually manipulatable member connected to said rotatable shaft, said first manually manipulatable member being oriented adjacent at least one of said head and foot ends; and cam apparatus including a first cam linkage having a first end secured to said rotary shaft of said control apparatus, a second cam linkage secured to a second end of said first cam linkage, an end of said second cam linkage being secured to a cam, and a cam follower being manipulated by said cam, said cam follower including an axle fixedly secured to said auxiliary wheel support structure, said first cam linkage having a position control member, said position control member preventing said cam linkage from contacting a floor surface during movement thereof.
  • 13. The wheeled carriage of claim 12, wherein said second cam linkage comprises a slotted cam linkage for receiving a roller element at the second end of said first cam linkage.
  • 14. The wheeled carriage of claim 12, wherein rotation of said rotatable shaft in a first direction moves said at least one auxiliary wheel to a raised position and rotation of said rotatable shaft in an opposing second direction moves said at least one auxiliary wheel to a second position in contact with the floor surface.
  • 15. The wheeled carriage of claim 12, wherein said control apparatus includes a return spring secured to said auxiliary wheel support structure to move said cam follower to a raised position when said cam follower is released from a depression at an end of said cam and is free to enter an open slot of said cam.
  • 16. The wheeled carriage of claim 15, wherein said control apparatus further includes a dashpot secured to the end of said cam to prevent sudden movement of said cam follower after release from the depression at the end of said cam.
  • 17. The wheeled carriage of claim 12, wherein said cam has a rounded surface for contact with a roller of said cam follower.
  • 18. The wheeled carriage of claim 17, wherein said roller of said cam follower has a contoured shape and raised edges to enable the surface of said roller to fit the surface of said cam.
  • 19. The wheeled carriage of claim 12, wherein said at least one auxiliary wheel includes a second spaced auxiliary wheel parallel to said one auxiliary wheel.
  • 20. The wheeled carriage of claim 19, wherein said auxiliary wheel support structure includes a yoke secured to both of said auxiliary wheels.
  • 21. The wheeled carriage of claim 12, wherein said second cam linkage includes an extended portion, said extended portion contacting said position control member during movement of said first and second linkages to prevent said linkages from contacting the floor surface.
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Entry
Stryker Model 1001, stretcher having a fifth wheel (7 photographs—A through G), Aug. 1994.