Patent Publication Number: US-2022211463-A1

Title: Medical device support system including rotational control mechanism

Description:
RELATED APPLICATIONS 
     This application claims the benefit of U.S. Provisional Application No. 63/134,248, filed Jan. 6, 2021, U.S. Provisional Application No. 63/134,254, filed Jan. 6, 2021, U.S. Provisional Application No. 63/134,263, filed Jan. 6, 2021, which are hereby incorporated herein by reference in their entireties. 
    
    
     FIELD OF INVENTION 
     This application relates generally to a rotational control mechanism for a medical device suspension system or carry system for use in, for example, a hospital examination room, a clinic, a surgery room or an emergency room, and more particularly to a rotational control mechanism that simplifies rotational control of an extension arm about a shaft of the medical device support system and provides at least 360° (360 degrees) rotation of the extension arm about the shaft. 
     BACKGROUND 
     Medical device suspension systems or carry systems are used in health treatment settings such as hospital examination rooms, clinics, surgery rooms and emergency rooms. These systems may suspend or support any variety of medical devices or components including surgical lights, supply consoles, patient monitors, camera detector heads, medical instruments, ventilator systems, suction devices, among others. The systems typically include a shaft or support spindle that is suspended from the ceiling or mounted to a wall or stand, and one or more generally horizontal extension arms mounted for rotational movement about the shaft. Each extension arm typically has a hub at its proximal end mounted to the shaft for pivotable movement about the shaft, and a support at its distal end for supporting a medical device. The extension arm can be rotatably adjusted about the shaft to a desired angular position to provide appropriate access to medical devices and components associated with the arm. 
     It is desirable to limit the rotation of the extension arm about the shaft for example to prevent collision of medical devices at the distal ends of the arms, or to prevent undue strain on electrical or communication lines passing through the shaft and the extension arm. In most current support systems, the extension arm is equipped with a fixed feature in the hub that contacts a fixed feature on the shaft that prevents further rotation. 
     For rotational control mechanisms in some medical device suspension systems or carry systems, there remain various shortcomings, drawbacks, and disadvantages relative to certain applications. For example, in some systems the rotational control mechanism limits rotation of the extension arm to below 360° (360 degrees), which may limit options for some installations. Other rotational control mechanisms require multiple stacked components, which increase the volumetric footprint of the mechanisms and complicates their integration into the hub of the extension arm. 
     Accordingly, there remains a need for further contributions in this area of technology. 
     SUMMARY OF INVENTION 
     The application relates to a rotational control mechanism for a medical device support system, in which the rotational control mechanism enables at least 360° (360 degrees) rotation of the extension arm about the shaft, and also embodies fewer components and a smaller volumetric footprint than heretofore attained, thus simplifying and adding efficiency to the factory assembly and field service of the medical device support system. 
     According to one aspect of the invention, a medical device support system includes a shaft, an extension arm, a guide channel member, and a floating stop. The extension arm may have a support for a medical device and a hub at its proximal end mounted to the shaft for pivotable movement about a rotation axis of the shaft. The guide channel member may be fixed to the shaft. The guide channel member may include an elongated cavity that defines first and second contact faces at opposite ends of the cavity. The floating stop may be movable within the elongated cavity of the guide channel member and movable relative to the hub. The hub may be pivotably mounted for a range of at least 360° (360 degrees) rotation about the rotation axis, wherein the at least 360° (360 degrees) rotation range is based on a compound of a first rotation range and a second rotation range, wherein the first rotation range is defined by a fixed stop of the hub configured to move between first and second contact faces of a radially outer portion of the floating stop, wherein the second rotation range is defined by a radially inner portion of the floating stop configured to move between the first and second contact faces of the elongated cavity of the guide channel member. 
     Embodiments of the invention may include one or more of the following additional features separately or in combination. 
     The guide channel member may include a rotation boundary member that is fixed to the shaft, the rotation boundary member defining as boundaries the first and second contact faces at opposite ends of the cavity. 
     The rotation boundary member may include a ring shape structure and the ring shape structure may be fixed to the shaft. 
     The elongated cavity may have an arc shape. 
     The guide channel member may include a lower guide wall for axially supporting the floating stop. 
     The guide channel member may include an arc shape track and the floating stop may include an arc shape groove, wherein the arc shape groove slidably receives the arc shape track to angularly guide the floating stop within the elongated cavity and about the rotation axis. 
     The floating stop may be configured to prevent rotation of the hub about the rotation axis beyond the at least 360° (360 degrees) rotation range. 
     The hub may be pivotably mounted for at least 360° (360 degrees) rotation from a first stop to a second stop and vice versa, wherein the first stop limits counterclockwise rotation of the hub about the rotation axis and the second stop limits clockwise rotation of the hub about the rotation axis. 
     The first stop may include the fixed stop of the hub in engagement with the first contact face of the radially outer portion of the floating stop, and the radially inner portion of the floating stop in engagement with the first contact face of the elongated cavity of the guide channel member. 
     The second stop may include the fixed stop of the hub in engagement with the second contact face of the radially outer portion of the floating stop, and the radially inner portion of the floating stop in engagement with the second contact face of the elongated cavity of the guide channel member. 
     The radially outer portion of the floating stop and the radially inner portion of the floating stop may lie in the same plane and the plane may be perpendicular to the rotation axis. 
     The fixed stop of the hub and the radially inner portion of the floating stop may lie in the same plane and the plane may be perpendicular to the rotation axis. 
     The radially outer portion of the floating stop may include a tab, and the first and second contact faces of the radially outer portion of the floating stop may be on opposite peripheral sides of the tab. 
     The radially inner portion of the floating stop may have first and second contact faces on opposite sides thereof, and the second rotation range may be defined by movement of the radially inner portion between a location at which the first contact face of the radially inner portion engages the first contact face of the elongated cavity of the guide channel member and a location at which the second contact face of the radially inner portion engages the second contact face of the elongated cavity of the guide channel member. 
     The shaft may have an axial hollow and a radial aperture and the ring shape structure may be fixed to the shaft at a position to allow passage of electrical and communication lines through the axial hollow, through the ring shape structure, through the radial aperture, and into a longitudinally extending cavity in the extension arm. 
     The hub of the extension arm may include upper and lower pivot bearings configured to pivotably engage the hub with the shaft, and a radial opening positioned axially between the upper and lower pivot bearings, and the ring shape structure may be positioned to allow passage of the electrical and communication lines between the upper and lower pivot bearings, through the radial opening of the hub, and into the longitudinally extending cavity in the extension arm. 
     According to another aspect of the invention, a medical device support system includes a shaft, an extension arm, a guide channel member, and a floating stop. The extension arm may have a support for a medical device and a hub at its proximal end mounted to the shaft for pivotable movement about a rotation axis of the shaft. The guide channel member may be fixed to the shaft. The guide channel member may include an elongated cavity that defines first and second contact faces at opposite ends of the cavity. The floating stop may be movable within the elongated cavity of the guide channel member and movable relative to the hub. The hub may be pivotably mounted for a range of at least 360° (360 degrees) rotation about the rotation axis from a first stop to a second stop and vice versa, wherein the first stop limits counterclockwise rotation of the hub about the rotation axis and the second stop limits clockwise rotation of the hub about the rotation axis, wherein the first stop includes a radially inner portion of the floating stop in engagement with the first contact face of the elongated cavity of the guide channel member, and wherein the second stop includes the radially inner portion of the floating stop in engagement with the second contact face of the elongated cavity of the guide channel member. 
     Embodiments of the invention may include one or more of the following additional features separately or in combination. 
     The hub may include a fixed stop movable between first and second contact faces of a radially outer portion of the floating stop. 
     The first stop may include the fixed stop of the hub in engagement with the first contact face of the radially outer portion of the floating stop, and the second stop may include the fixed stop of the hub in engagement with the second contact face of the radially outer portion of the floating stop. 
     According to another aspect of the invention, there is provided a method of rotating an extension arm about a shaft of a medical device support system, the extension arm having a support for a medical device and a hub at its proximal end mounted to the shaft for pivotable movement about a rotation axis of the shaft, wherein a guide channel member is fixed to the shaft, wherein the guide channel member includes an elongated cavity that defines first and second contact faces at opposite ends of the cavity, wherein a floating stop is movable within the elongated cavity of the guide channel member and movable relative to the hub, the method including rotating the hub over a range of at least 360° (360 degrees) about the rotation axis, wherein the at least 360° (360 degrees) rotation range is based on a compound of movement over a first rotation range and movement over a second rotation range, wherein movement over the first rotation range includes moving a fixed stop of the hub between first and second contact faces of a radially outer portion of the floating stop, and wherein movement over the second rotation range includes moving a radially inner portion of the floating stop between the first and second contact faces of the elongated cavity of the guide channel member. 
     The following description and the annexed drawings set forth certain illustrative embodiments of the invention. These embodiments are indicative, however, of but a few of the various ways in which the principles of the invention may be employed. Other objects, advantages and novel features according to aspects of the invention will become apparent from the following detailed description when considered in conjunction with the drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The annexed drawings, which are not necessarily to scale, show various aspects of the invention. 
         FIG. 1  is a front elevational view of a medical device support system in accordance with an embodiment of the invention. 
         FIG. 2  is a cross section view of a shaft and extension arm hub connection of the  FIG. 1  medical device support system, showing a rotational control mechanism in accordance with an embodiment of the invention. 
         FIG. 3  is a bottom isometric view of the  FIG. 2  shaft and extension arm hub connection, showing a rotation boundary member attached to the shaft. 
         FIG. 4  is a view similar to the  FIG. 3  view but omitting the rotation boundary member on the shaft to show underlying detail. 
         FIG. 5  is an exploded bottom isometric view of the  FIG. 2  shaft and extension arm hub connection. 
         FIG. 6  is a top isometric view similar to the  FIG. 4  view but omitting extension hub structure to show underlying detail. 
         FIG. 7  is an exploded top isometric view of the rotational control mechanism, showing a guide channel member and a floating stop of the rotational control mechanism, the guide channel member including a rotation boundary member attached to the shaft and an elongated cavity that accommodates the floating stop. 
         FIG. 8  shows a top cross section view of the rotational control mechanism of the medical device support system of  FIG. 1 , showing a maximum counterclockwise position of a floating stop of the rotational control mechanism. 
         FIG. 9  shows a top cross section view of the rotational control mechanism of the medical device support system of  FIG. 1 , showing a mid-rotation position of the floating stop of the rotational control mechanism. 
         FIG. 10  shows a top cross section view of the rotational control mechanism of the medical device support system of  FIG. 1 , showing a maximum clockwise position of the floating stop of the rotational control mechanism, where the rotation is at least 360° (360 degrees) rotation from that shown in  FIG. 8 . 
         FIG. 11  is an exploded top isometric view of the rotational control mechanism, similar to the  FIG. 7  view but showing the fasteners inserted in the rotation boundary member of the guide channel member. 
         FIG. 12  is a top cross section view of the guide channel member and floating stop of the rotational control mechanism. 
         FIG. 13  is a side cross section view of the  FIG. 12  rotational control mechanism. 
         FIG. 14  shows a flowchart of a method of rotating an extension arm about a shaft of a medical device support system in accordance with an embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION 
     While the present invention can take many different forms, for the purpose of promoting an understanding of the principles of the invention, reference will now be made to the embodiments illustrated in the drawings and specific language will be used to describe the same. It will nevertheless be understood that no limitation of the scope of the invention is thereby intended. Any alterations and further modifications of the described embodiments, and any further applications of the principles of the invention as described herein, are contemplated as would normally occur to one skilled in the art to which the invention relates. 
       FIGS. 1-8  show a medical device support system  10  that includes a shaft  14 , at least one extension arm  16  having a support  20  for a medical device  30  and a hub  34  at its proximal end mounted to the shaft  14  for pivotable movement about a rotation axis A-A of the shaft  14 , and a rotational control mechanism  40  integrated into the hub  34  for controlling the amount of rotation of the extension arm  16  about the shaft  14 . The rotational control mechanism  40  includes a guide channel member  44 , a fixed stop  70  connected to a wall of the hub  34 , and a floating stop  60  having a radially outer portion  80  and a radially inner portion  90 , the radially inner portion  90  being relatively closer to the rotation axis A-A than the radially outer portion  80 . The guide channel member  44  in the illustrative embodiment includes a rotation boundary member  46  that is fixed to the shaft  14 . The guide channel member  44  includes an elongated cavity  50  that defines first and second contact faces  52 ,  54  at opposite ends of the cavity  50 . The floating stop  60  is movable within the elongated cavity  50  of the guide channel member  44  and movable relative to the hub  34 . The hub  34  is pivotably mounted for a range of at least 360° (360 degrees) rotation about the rotation axis A-A, wherein the at least 360° (360 degrees) rotation range is based on a compound of a first rotation range and a second rotation range. The first rotation range is defined by the fixed stop  70  of the hub  34  configured to move between first and second contact faces  82 ,  84  of the radially outer portion  80  of the floating stop  60 . The second rotation range is defined by the radially inner portion  90  of the floating stop  60  configured to move between the first and second contact faces  52 ,  54  of the elongated cavity  50  of the guide channel member  44 . Referring to  FIGS. 1 and 2 , the illustrative medical device support system  10  is a suspension type carrying support system for use in a hospital examination room, a clinic, a surgery room, an emergency room, among others. The shaft  14  extends along an axis A-A, which also represents the rotation axis A-A of the shaft  14  about which the extension arm  16  pivots. The shaft  14  may be fixed to a ceiling support  110  to remain stationary relative to the ceiling. It will be appreciated, of course, that the medical device support system  10  may have any suitable suspension or carrying structure and that the shaft  14  may be attached to a ceiling as shown, or to a wall, floor, movable cart, or a combination of the foregoing. The shaft  14  of the medical device support system  10  has a cylindrical shape in axial cross section and defines an axial hollow  112  and radial aperture  116  therein, and extends vertically downward from the ceiling support  110 . A column section  114  surrounds an upper portion of the shaft  14 . The axial hollow  112  and the column section  114  house upper portions of accessory and service lines such as power cables for surgical lights and other power requirements, control wiring for control electronics, optical fibers for data communication, and/or tubing for irrigation, suction, etc. A plurality of extension arms  16 , three in the illustrative embodiment, are mounted for rotatable movement to the shaft  14  and extend laterally outward from the shaft  14 . In the  FIG. 1  embodiment, the extension arms  16  extend horizontally, or perpendicularly, relative to the shaft  14 . An additional extension arm  130 , support arm  132 , and medical device  134  may be pivotably mounted to a separate central shaft  136  radially offset from the central shaft  14 . 
     The hub  34  is located at the proximal end of the extension arm  16 . In the illustrative embodiment, to aid in the pivotable movement of the extension arm  16  about the shaft  14 , each extension arm hub  34  may include upper and lower bearing mounts  150 ,  152 , shown in  FIGS. 2-6 , that house respective upper and lower pivot bearings mounted to the shaft  14 . Any suitable pivot bearings may be used to enable the relative rotational movement between the extension arm  16  and the shaft  14 , including for example ball bearings, sleeve bearings, bushings, rotary joints and/or swivel joints. A brake assembly  160  may be secured in the hub  34  for rotation therewith to selectively increase and decrease a frictional braking force to the shaft  14 . In the illustrative embodiment, the brake assembly  160  is positioned below the upper bearing  150  and above the guide channel member  44  or the rotation boundary member  46  of the guide channel member  44 . Each hub  34  provides a radial opening  164  positioned axially between the upper and lower pivot bearings  150 ,  152  for routing accessory and service lines from the axial hollow  112  and/or the upper column section  114  through the radial aperture  116  and to a longitudinally extending cavity  166  of the extension arm  16 , and/or vice versa. Each hub  34  is also provided with an access opening  168  to enable access to the shaft  14 , the rotational control mechanism  40 , the upper and lower pivot bearings  150 ,  152 , the brake assembly  160 , accessory and service lines, and/or other components within the hub  34 . A suitable brake assembly  160  and access opening  168  for the illustrative embodiment are described in U.S. patent application Ser. Nos. 16/517,703; 16/517,704; 16/517,707; and 16/517,708, which are incorporated by reference for all purposes as if fully set forth herein. 
     Reference is now made to  FIGS. 8-10 , which show greater detail of the rotational control mechanism  40 . The rotational control mechanism  40  is made up of a combination of components from the hub  34  of the extension arm  16 , the guide channel member  44 , and the floating stop  60 . The hub  34  includes the fixed stop  70 . The floating stop  60  includes the radially outer portion  80  and the radially inner portion  90 . The guide channel member  44  includes an elongated cavity  50 . In  FIGS. 8-10 , it can be seen that the extension arm  16  and its hub  34  and the fixed stop  70  of the rotational control mechanism  40  are movable relative to the shaft  14 . As is also apparent from  FIGS. 8-10 , the floating stop  60  including its radially outer and inner portions  80 ,  90 , is movable within the elongated cavity  50  of the guide channel mechanism  44  and movable relative to the hub  34  and the fixed stop  70 . 
     Each of the components of the rotational control mechanism  40  provides contact faces, that is, faces for abutting engagement, to control the amount of rotation of the extension arm  16  about the rotation axis A-A of the shaft  14 . The fixed stop  70  has first and second contact faces  72 ,  74  on opposite peripheral ends of the fixed stop  70 . The radially outer portion  80  has first and second contact faces  82 ,  84  on opposite peripheral ends of the radially outer portion  80 . The radially inner portion  90  has first and second contact faces  92 ,  94  on opposite peripheral ends of the radially inner portion  90 . The elongated cavity  50  defines first and second contact faces  52 ,  54  at opposite ends of the cavity  50 . In this way, the rotational control mechanism  40  embodies fewer components and a smaller volumetric footprint than heretofore attained and simplifies and adds efficiency to the factory assembly and field service of the medical device support system  10 . 
     The floating stop  60  is configured to prevent rotation of the hub  34  about the rotation axis A-A beyond the at least 360° (360 degrees) rotation range. The hub  34  is pivotably mounted for at least 360° (360 degrees) rotation from a first stop shown in  FIG. 8  to a second stop shown in  FIG. 10 , and vice versa. As shown in  FIG. 8 , the first stop limits counterclockwise rotation of the hub  34  about the rotation axis A-A. Thus, the first stop defines the most counterclockwise rotation the hub  34  and thus the extension arm  16  obtain about the shaft  14 . In  FIG. 8 , the first stop, or most counterclockwise rotation of the extension arm  16 , positions the extension arm  16  at 54° (54 degrees) relative to a horizontal line across the page. As shown in  FIG. 10 , the second stop limits clockwise rotation of the hub  34  about the rotation axis A-A. Thus, the second stop defines the most clockwise rotation the hub  34  and associated extension arm  16  obtain about the shaft  14 . In  FIG. 10 , the second stop, or most clockwise rotation of the extension arm  16 , positions the extension arm  16  at 54° (54 degrees) relative to the horizontal line across the page. As is apparent from  FIGS. 8 and 10 , the rotation of the extension arm  16  and its hub  34  about the shaft  14  is 360° (360 degrees), which, going from  FIG. 8  to  FIG. 10 , is 360° (360 degrees). 
     Two abutting engagements form the first or most counterclockwise stop and two abutting engagements form the second or most clockwise stop. Referring to  FIG. 8 , the first stop includes the fixed stop  70  of the hub  34  in engagement with the first contact face  82  of the radially outer portion  80  of the floating stop  60 , and the radially inner portion  90  of the floating stop  60  in engagement with the first contact face  52  of the elongated cavity  50  of the guide channel member  44 . Referring to  FIG. 10 , the second stop includes the fixed stop  70  of the hub  34  in engagement with the second contact face  84  of the radially outer portion  80  of the floating stop  60 , and the radially inner portion  90  of the floating stop  60  in engagement with the second contact face  54  of the elongated cavity  50  of the guide channel member  44 . 
     The rotational control mechanism  40  facilitates the at least 360° (360 degrees) rotation range based on a compound of a first rotation range and a second rotation range. As previously noted, the first rotation range is defined by the fixed stop  70  of the hub  34  being configured to move between the first and second contact faces  82 ,  84  of the radially outer portion  80  of the floating stop  60 . In the illustrated embodiment, the angular span between the first and second contact faces  72 ,  74  of the fixed stop  70  is about 20-degrees. The radially outer portion  80  of the floating stop  60  has an angular span of about 20-degrees between its first and second contact faces  82 ,  84 . With reference to  FIG. 8 , and assuming that the floating stop  60  remains idle with rotation of the hub  34 , the first rotation range is defined by movement of the fixed stop  70  between a location shown in  FIG. 8  at which the first contact face  72  of the fixed stop  70  engages the first contact face  82  of the radially outer portion  80  of the floating stop  60  and a location at which the second contact face  74  of the fixed stop  70  engages the second contact face  84  of the radially outer portion  80  of the floating stop  60 . In other words, and again with reference to  FIG. 8  and assuming the floating stop  60  remains stationary, the first rotation range is defined by the fixed stop  70  moving from the position shown in  FIG. 8  where the first contact face  72  abuttingly engages the first contact face  82 , to a position where the second contact face  74  abuttingly engages the second contact face  84 ; that is, in  FIG. 8 , the fixed stop  70  moves from the first contact face  82  of the radially outer portion  80  (or right side thereof in  FIG. 8 ) clockwise to the second contact face  84  of the radially outer portion  80  (or left side thereof in  FIG. 8 ). In the  FIGS. 8-10  embodiment, the first rotation range of the rotational control mechanism  40  is approximately 320° (320 degrees) (360 minus 20 minus 20). 
     The second rotation range is defined by the radially inner portion  90  of the floating stop  60  being configured to move between the first and second contact faces  52 ,  54  of the elongated cavity  50  of the guide channel member  44 . In the illustrated embodiment, the angular span between the first and second contact faces  52 ,  54  of the elongated cavity  50  is about 60-degrees. The radially inner portion  90  of the floating stop  60  has an angular span of about 20-degrees between its first and second contact faces  92 ,  94 . With continued reference to  FIG. 8 , it is assumed that the hub  34  has rotated clockwise the first rotation range, that is, the second contact face  74  of the fixed stop  70  is in abutting engagement with the second contact face  84  of the radially outer portion  80  of the floating stop  60 , and thus continued clockwise rotation of the hub  34  causes the hub  34  and floating stop  60  to rotate together clockwise in unison. The second rotation range is defined by movement of the radially inner portion  90  of the floating stop  60  between a location at which the first contact face  92  of the radially inner portion  90  engages the first contact face  52  of the elongated cavity  50  of the guide channel member  44  and a location shown in  FIG. 10  at which the second contact face  94  of the radially inner portion  90  engages the second contact face  54  of the elongated cavity  50  of the guide channel member  44 . In other words, and again with reference to  FIG. 8  and assuming the second contact face  74  is in abutting engagement with the second contact face  84 , the second rotation range is defined by the radially inner portion  90  moving from the position shown in  FIG. 8  where the first contact face  92  abuttingly engages the first contact face  52 , to a position where the second contact face  94  abuttingly engages the second contact face  54 ; that is, in  FIG. 8 , the radially inner portion  90  moves from the first contact face  52  of the elongated cavity  50  clockwise to the second contact face  54  of the elongated cavity  50 . In the  FIGS. 8-10  embodiment, the second rotation range of the rotational control mechanism  40  is approximately 40° (40 degrees) (60 minus 20). 
     As will be appreciated, in operation the first and second rotation ranges usually will not be completed in serial fashion but rather at least partially in parallel fashion. This is illustrated in  FIG. 9 , for example, where the hub  34 , relative to the  FIG. 8  position, has been rotated clockwise about the shaft  14  about 180° (180 degrees) to a position at which the fixed stop  70  has reached 180° (180 degrees) from the radially outer portion  80  of the floating stop  60 , that is, the middle of the first rotation range, and the radially inner portion  90  has reached the middle of the elongated cavity  50 , that is, the middle of the second rotation range. It will be appreciated that the movement of the fixed stop  70  between the first and second contact faces  82 ,  84  of the radially outer portion  80 , and the movement of the radially inner portion  90  between the first and second contact faces  52 ,  54  of the elongated cavity  50 , will vary depending on the friction between the respective rotating sliding surfaces of the guide channel member  44 , the hub  34 , and the floating stop  60 . Thus, while  FIG. 8  shows the start of the first and second rotation ranges, and  FIG. 10  shows the completion of the first and second rotation ranges, what occurs between the start and completion of the first and second rotation ranges will depend on the friction between the rotating sliding surfaces. 
     It will be appreciated that the rotational control mechanism  40  can provide a greater than 360° (360 degrees) rotation range by adjusting any of its components, for the example the width (angular span) of any of the elongated cavity  50 , the fixed stop  70 , the radially outer portion  80  of the floating stop  60 , and/or the radially inner portion  90  of the floating stop  60 . As an example, in the case where the fixed stop  70  is 1.0° (1.0 degree) smaller in width in  FIGS. 8-10 , then in  FIG. 8 , the first stop, or most counterclockwise rotation of the extension arm  16 , positions the extension arm  16  at 55° (55 degrees) relative to a horizontal line across the page, and in  FIG. 10 , the second stop, or most clockwise rotation of the extension arm  16 , positions the extension arm  16  at 54° (54 degrees) relative to the horizontal line across the page. The total rotation of the extension arm  16  and its hub  34  about the shaft  14  is then 361° (361 degrees), where the first rotation range is 321° (321 degrees) (360 minus 19 minus 20) and the second rotation range is 40° (40 degrees) (60 minus 20). 
     In exemplary embodiments, the angular span between the first and second contact faces  72 ,  74  (e.g., width of fixed stop  70 ) may be in a range from about 1-degree to about 60-degrees, even more particularly between 1-degree and 45-degrees, such as about 20-degrees in the illustrated embodiment. In exemplary embodiments, the radially outer portion  80  of the floating stop  60  may have an angular span in a range from about 1-degree to about 60-degrees, even more particularly between 1-degree and 45-degrees, such as about 20-degrees in the illustrated embodiment. In exemplary embodiments, the elongated cavity  50  forms an arcuate segment defined by an angular span between the opposite first and second contact faces  52 ,  54  that may be in a range from about 1-degree to about 180-degrees, and even more particularly from about 10-degrees to about 90-degrees, such as about 60-degrees in the illustrated embodiment. In exemplary embodiments, the radially inner portion  90  of the floating stop  60  may have an angular span in a range from about 1-degree to about 60-degrees, even more particularly between 1-degree and 45-degrees, such as about 20-degrees in the illustrated embodiment. In exemplary embodiments, the at least 360-degrees range provided by the rotational control mechanism  40  may be in a range from 360-degrees to less than 720-degrees, more particularly from 360-degrees to 540-degrees, and even more particularly from 360-degrees to 450-degrees, such as about 360-degrees in the illustrated embodiment. 
       FIGS. 7 and 11-13  show greater detail of the guide channel member  44  and the floating stop  60  of the rotation control mechanism  40 . The guide channel member  44  includes the rotation boundary member  46 , an upper guide member  200 , and a lower guide member  202 . In the illustrative embodiment, the rotation boundary member  46  includes a ring shape structure wherein the inner diameter of the ring shape structure is slightly greater than the outer diameter of the shaft  14  to enable the rotation boundary member  46  to be slid axially onto the shaft  14  during assembly. The central axis of the ring shape structure coincides with the rotation axis A-A. The rotation boundary member  46  is fixed to the shaft  14  by four fasteners  210 . In the illustrative embodiment, the fasteners  210  are socket set screws. The fasteners  210  are threaded into respective threaded openings  220  in the rotation boundary member  46  and into respective blind holes  230  in the shaft  14 . In the illustrative embodiment, the centerlines of the fasteners  210 , the threaded openings  220 , and the blind holes  230  protrude radially from and perpendicular to the rotation axis A-A. When the fasteners  210  are tightened, the guide channel member  44  is fixed to the shaft  14  and, as shown in  FIG. 12 , the tops of the fasteners  210  are below the outer radius of the ring shape structure. As such, the tops of the fasteners  210  will not interfere with the fixed stop  70  during rotation of the extension arm  16  about the rotation axis A-A. 
     The fasteners  210  and the threaded openings  220  are positioned angularly outside of the arcuate span of the elongated cavity  50 , and angularly outside of the upper and lower guide members  200 ,  202 . It will be appreciated that the quantity and location of the fasteners  210  and the threaded openings  220  need not be limited as such, and other embodiments are contemplated. Any number of fasteners  210  may be used so long as the rotation boundary member  46  is securely fastened to the shaft  14 . For example, three fasteners  210  and three threaded openings  220  may be used, where two are located adjacent to the respective opposite sides of the elongated cavity  50  and angularly outside of the upper and lower guide members  200 ,  202  and one is located diametrically opposite the angular center of the elongated cavity  50 . In this case, the shaft  14  would have three blind holes  230  to accommodate the corresponding three fasteners  210 . As another example, the fasteners  210 , or even a single fastener  210 , and a corresponding threaded opening or openings  220  in the rotation boundary member  46 , may be located within the arcuate span of the elongated cavity  50 , that is, between the opposite first and second contact faces  52 ,  54  of the elongated cavity  50 . In this case, the threaded openings  220  may be in the arc shape wall of the cavity  50  for example. When the fasteners  210  are tightened, the guide channel member  44  is fixed to the shaft  14  and the tops of the fasteners  210  are below the outer radius of the arc shape wall such that the tops of the fasteners  210  will not interfere with the movement of the floating stop  60  within the elongated cavity  50  during rotation of the extension arm  16  about the rotation axis A-A. 
     In the illustrative embodiment, the rotation boundary member  46  includes a ring shape structure. Other shape structures may be suitable and are contemplated. For example, the rotation boundary member  46  may instead include an arc shape structure wherein the inner radius of the arc shape structure is slightly greater than the outer radius of the shaft  14  to enable the rotation boundary member  46  to be snugly fitted on the shaft  14  during assembly. Such arc shape structure would have an arcuate span sized to provide the elongated cavity  50  and the two fasteners  210  located adjacent to the respective opposite sides of the elongated cavity  50  and angularly outside of the upper and lower guide members  200 ,  202 , in which case the shaft  14  would have two corresponding blind holes  230  to accommodate the two fasteners  210 . 
     The upper guide member  200  and the lower guide member  202  are mounted to the rotation boundary member  46  by respective upper and lower fasteners  240 ,  242 . In the illustrative embodiment, the fasteners  240 ,  242  are socket flat head cap screws. The upper fasteners  240  are inserted through through hole openings  250  in the upper guide member  200  and threaded into respective threaded openings  260  in the rotation boundary member  46 . Similarly, the lower fasteners  242  are inserted through through hole openings  252  in the lower guide member  202  and threaded into respective threaded openings  262  in the rotation boundary member  46 . In the illustrative embodiment, the centerlines of the fasteners  240 ,  242 , the through hole openings  250 ,  252 , and the threaded openings  260 ,  262  extend axially and are parallel to the rotation axis A-A. When the upper fasteners  240  are tightened, the upper guide member  200  is secured to the rotation boundary member  46  and the tops of the flat heads of the upper fasteners  240  are substantially flush with or slightly below the upper surface of the upper guide member  200 . Similarly, when the lower fasteners  242  are tightened, the lower guide member  202  is secured to the rotation boundary member  46  and the tops of the flat heads of the lower fasteners  242  are substantially flush with or slightly below the lower surface of the lower guide member  200 . As will be appreciated, the upper and lower guide members  200 ,  202  add relatively little height to the guide channel member  44 , thereby contributing to the rotational control mechanism  40  having a relatively smaller volumetric footprint than heretofore attained. 
     As shown in  FIGS. 7, 11 and 12 , the fasteners  240 ,  242 , the through hole openings  250 ,  252 , and the threaded openings  260 ,  262  are positioned angularly outside of the arcuate span of the elongated cavity  50 , and angularly inside of the fasteners  210  and threaded openings  220  used for securing the rotation boundary member  46  to the shaft  14 . Also, in the illustrative embodiment, the upper and lower guide members  200 ,  202  have an identical geometry for economy of manufacture. As such, the upper guide member  200  and the upper fasteners  240  are staggered angularly relative to the lower guide member  202  and the lower fasteners  242 , in the illustrative embodiment approximately 10° (10 degrees). As will be appreciated, the quantity and location of the fasteners  240 ,  242 , the through hole openings  250 ,  252  and the threaded openings  260 ,  262  may be different from that illustrated, and other embodiments are contemplated. Any number of fasteners  240 ,  242  may be used so long as the upper and lower guide members  200 ,  202  are securely fastened to the rotation boundary member  46 . For example, a single fastener may be used to secure the upper guide member  200  to the rotation boundary member  46 , and a single fastener may be used to secure the lower guide member  202  to the rotation boundary member  46 , where the guide members  200 ,  202  are provided with projections and/or recesses that engage respective recesses and/or projections in the rotation boundary member  46  to prevent movement therebetween. Also, the fasteners  240 ,  242 , the through hole openings  250 ,  252 , and the threaded openings  260 ,  262  may instead be positioned angularly outside of the fasteners  210  and the threaded openings  220  used for securing the rotation boundary member  46  to the shaft  14 ; in this way, the fasteners  210  and the threaded openings  220 , as well as the blind holes  230  in the shaft  14 , may be evenly spaced, i.e. equally angularly spaced, about the rotation axis A-A. It will further be appreciated that the upper and lower guide members  200 ,  202  may have different geometries and different corresponding locations for the through hole openings  250 ,  252  to accommodate the fasteners  240 ,  242 . 
     The upper and lower guide members  200 ,  202  support, retain, and guide the floating stop  60 . Referring to  FIGS. 7 and 11 , the upper guide member  200  includes an upper arc shape wall  280  and an upper arc shape track  290  projecting downwardly from the upper arc shape wall  280 . The lower guide member  202  includes a lower arc shape wall  282  and a lower arc shape track  292  projecting upwardly from the lower arc shape wall  282 . As shown in  FIGS. 11 and 13 , the floating stop  60  has an arc shape and includes upper and lower arc shape grooves  300 ,  302  in respective upper and lower surfaces of the floating stop  60 . The floating stop  60  has an inner radius that is a first radial distance from the rotation axis A-A and an outer radius that is a second radial distance from the rotation axis A-A. The upper and lower arc shape grooves  300 ,  302  are located a radial distance from the rotation axis A-A that is greater than the first radial distance and less than the second radial distance. As shown in  FIGS. 12 and 13 , the upper and lower arc shape grooves  300 ,  302  are positioned at substantially the same radial distance from the rotation axis A-A as the respective upper and lower arc shape tracks  290 ,  292 . 
     Together, the rotation boundary member  46 , the upper and lower arc shape walls  280 ,  282  and the upper and lower arc shape tracks  290 ,  292  form the guide channel member  44  within which the floating stop  60  moves. The rotation boundary member  46  has an arc shape cut out that forms the elongated cavity  50 , the opposite ends of the arc shape cut out providing the boundaries that form the first and second contact faces  52 ,  54  at opposite ends of the cavity  50 . The arc shape cut out has an arc shape wall that is located a radial distance from the rotation axis A-A that is slightly less than the first radial distance that the inner radius of the floating stop  60  is located from the rotation axis A-A; this enables the inner radius of the floating stop  60  to slidably and/or freely move relative to the arc shape wall of the arc shape cut out during movement of the floating stop  60  within the elongated cavity  50  formed by the arc shape cut out. The upper and lower arc shape walls  280 ,  282  of the respective upper and lower guide members  200 ,  202  axially support the floating stop  60 . The lower arc shape wall  282  axially supports the floating stop  60  to prevent axially downward movement of the floating stop  60  due to for example gravitational forces or incidental downward forces exhibited by the floating stop  60  during movement within the elongated cavity  50 . The upper arc shape guide wall  280  axially supports the floating stop  60  to prevent axially upward movement of the floating stop  60  due to for example incidental upward forces exhibited by the floating stop  60  during movement within the elongated cavity  50 . The upper and lower arc shape grooves  300 ,  302  of the floating stop  60  slidably receive the respective upper and lower arc shape tracks  290 ,  292  to radially retain the floating stop  60  and to angularly guide the floating stop  60  within the elongated cavity  50  and about the rotation axis A-A. 
     The floating stop  60  includes the afore described radially outer portion  80  and radially inner portion  90 . In the illustrative embodiment, the radially outer portion  80  is located radially outward from the upper and lower arc shape tracks  290 ,  292  and the upper and lower arc shape grooves  300 ,  302 . The radially inner portion  90  of the floating stop  60  is located radially inward from the upper and lower arc shape tracks  290 ,  292  and the upper and lower arc shape grooves  300 ,  302 . As described above, the rotational control mechanism  40  can provide a greater than 360° (360 degrees) rotation range by adjusting the width (angular span) of the radially outer portion  80  of the floating stop  60 , and/or the radially inner portion  90  of the floating stop  60 . In one form, the angular span of the radially outer portion  80  of the floating stop  60 , i.e. the portion of the floating stop  60  radially outward from the upper and lower arc shape tracks  290 ,  292  and the upper and lower arc shape grooves  300 ,  302 , may be made relatively smaller than what is shown in the illustrative embodiment. In another form, the angular span of the radially inner portion  90  of the floating stop  60 , i.e. the portion of the floating stop  60  radially inward from the upper and lower arc shape tracks  290 ,  292  and the upper and lower arc shape grooves  300 ,  302 , may be made relatively smaller than what is shown in the illustrative embodiment. 
     As will be appreciated, in some embodiments the upper guide member  200  may be omitted, for example where upward forces exhibited by the floating stop  60  during movement within the elongated cavity  50  do not cause the floating stop  60  to shift and/or bind within the elongated cavity  50 . 
     Referring now to  FIGS. 8-10 and 12-13 , the amount of radially inward protrusion of the radially inner portion  90  of the floating stop  60  relative to the outer radius of the guide channel member  44 , or relative to the upper and lower arc shape tracks  290 ,  292 , is such that the first and second contact faces  92 ,  94  of the radially inner portion  90  are at the same radial distance from the rotation axis A-A (or on the same circumference) as the first and second contact faces  52 ,  54  of the elongated cavity  50 , and thus in operation abuttingly engage the respective first and second contact faces  52 ,  54 . 
       FIGS. 3-5 and 8-10  show greater detail of the fixed stop  70  of the rotational control mechanism  40 . In the illustrative embodiment, the fixed stop  70  is formed as part of the hub structure of the hub  34  and includes a block  70  with beveled edges forming the respective first and second contact faces  72 ,  74  on opposite peripheral sides of the block  70 . The block  70 , or fixed stop  70 , protrudes axially downward from the hub structure that houses the brake assembly  160 , which positions the fixed stop  70  and its first and second contact faces  72 ,  74  at the same axial location as the radially outer portion  80  of the floating stop  60  and its first and second contact faces  82 ,  84 . As will be appreciated, the fixed stop  70  need not be formed as part of the hub structure of the hub  34  and may instead be a separate block that is attached to the hub structure. 
     Referring now to  FIGS. 8-10 , the amount of radially outward protrusion of the radially outer portion  80  of the floating stop  60  relative to the outer radius of the guide channel member  44 , or relative to the upper and lower arc shape tracks  290 ,  292 , is such that the first and second contact faces  82 ,  84  of the radially outer portion  80  are at the same radial distance from the rotation axis A-A (or on the same circumference) as the first and second contact faces  72 ,  74  of the fixed stop  70 , and thus in operation abuttingly engage the respective first and second contact faces  72 ,  74 . 
     Turning now to  FIGS. 2-6 and 8-10 , in the illustrative embodiment, the radially outer portion  80  of the floating stop  60  and the radially inner portion  90  of the floating stop  60  lie in the same plane and the plane is perpendicular to the rotation axis A-A. In this way, the rotational control mechanism  40  embodies fewer components and a smaller volumetric footprint than heretofore attained and simplifies and adds efficiency to the factory assembly and field service of the medical device support system  10 . Also, the radially outer portion  80  of the floating stop  60  and the elongated cavity  50  of the guide channel member  44  lie in the same plane and the plane is perpendicular to the rotation axis A-A. Thus, in the embodiment of  FIGS. 2-6 and 8-10 , the radially outer portion  80 , the radially inner portion  90 , and the elongated cavity  50  lie in the same plane perpendicular to the rotation axis A-A. Of course, the invention need not be limited as such and other embodiments are contemplated. For example, the radially outer portion  80  may be located in a plane axially above or axially below the plane in which the radially inner portion  90  and the elongated cavity  50  lies. In another example, the radially outer portion  80  may be located in a plane axially above or axially below the plane in which the radially inner portion  90  lies, and the elongated cavity  50  may have an axial height such that the radially outer portion  80  and the radially inner portion  90 , although themselves in different planes, both lie in the axial height plane of the elongated cavity  50 . 
     In the illustrative embodiment, the fixed stop  70  of the hub  34  and the radially inner portion  90  of the floating stop  60  lie in the same plane and the plane is perpendicular to the rotation axis A-A. In this way, the rotational control mechanism  40  embodies fewer components and a smaller volumetric footprint than heretofore attained and simplifies and adds efficiency to the factory assembly and field service of the medical device support system  10 . Also, the fixed stop  70  of the hub  34  and the elongated cavity  50  of the guide channel member  44  lie in the same plane and the plane is perpendicular to the rotation axis A-A. Thus, in the embodiment of  FIGS. 2-6 and 8-10 , the fixed stop  70 , the radially inner portion  90 , and the elongated cavity  50  lie in the same plane perpendicular to the rotation axis A-A. Of course, the invention need not be limited as such and other embodiments are contemplated. For example, the fixed stop  70  may be located in a plane axially above or axially below the plane in which the radially inner portion  90  and the elongated cavity  50  lies. In another example, the fixed stop  70  may be located in a plane axially above or axially below the plane in which the radially inner portion  90  lies, and the elongated cavity  50  may have an axial height such that the fixed stop  70  and the radially inner portion  90 , although themselves in different planes, both lie in the axial height plane of the elongated cavity  50 . 
     In the illustrative embodiment, the radially outer portion  80 , the radially inner portion  90 , the elongated cavity  50 , and the fixed stop  70  all lie in the same plane perpendicular to the rotation axis A-A. In this way, the rotational control mechanism  40  embodies fewer components and a smaller volumetric footprint than heretofore attained and simplifies and adds efficiency to the factory assembly and field service of the medical device support system  10 . 
     Referring now to  FIG. 14 , there is shown a flowchart  400  of a method of rotating an extension arm  16  about a shaft  14  of a medical device support system  10  such as shown in  FIG. 1 . The extension arm  16  has a support  20  for a medical device  30  and a hub  34  at its proximal end mounted to the shaft  14  for pivotable movement about a rotation axis A-A of the shaft  14 . A guide channel member  44  is fixed to the shaft  14  and includes an elongated cavity  50  that defines first and second contact faces  52 ,  54  at opposite ends of the cavity  50 . A floating stop  60  is movable within the elongated cavity  50  of the guide channel member  44  and movable relative to the hub  34 . The method includes at step  410  rotating the hub  34  over a range of at least 360° (360 degrees) about the rotation axis A-A, wherein the at least 360° (360 degrees) rotation range is based on a compound of movement over a first rotation range and movement over a second rotation range. At step  420 , the movement over the first rotation range includes moving a fixed stop  70  of the hub  34  between first and second contact faces  82 ,  84  of a radially outer portion  80  the floating stop  60 . At step  430 , the movement over the second rotation range includes moving a radially inner portion  90  of the floating stop  60  between the first and second contact faces  52 ,  54  of the elongated cavity  50  of the guide channel member  44 . 
     Although the invention has been shown and described with respect to a certain embodiment or embodiments, it is obvious that equivalent alterations and modifications will occur to others skilled in the art upon the reading and understanding of this specification and the annexed drawings. In particular regard to the various functions performed by the above described elements (components, assemblies, devices, compositions, etc.), the terms (including a reference to a “means”) used to describe such elements are intended to correspond, unless otherwise indicated, to any element which performs the specified function of the described element (i.e., that is functionally equivalent), even though not structurally equivalent to the disclosed structure which performs the function in the herein illustrated exemplary embodiment or embodiments of the invention. In addition, while a particular feature of the invention may have been described above with respect to only one or more of several illustrated embodiments, such feature may be combined with one or more other features of the other embodiments, as may be desired and advantageous for any given or particular application.