Abstract:
A positioning assembly is disclosed herein. An example includes a guide shaft having a longitudinal axis and a housing movable along and rotatable about the longitudinal axis of the guide shaft. The housing is also transversely movable and transversely rotatable with respect to the longitudinal axis of the guide shaft. The example of the positioning assembly additionally has a brake mechanism including at least one shoe and a caliper eccentrically mounted on the guide shaft and moveable from a first position that permits movement and rotation of the housing to a second position that impedes movement and rotation of the housing. Other elements and features of the positioning assembly are disclosed herein, as are other examples of positioning assemblies.

Description:
BACKGROUND 
       [0001]    Devices may need to be positioned within a certain degree of accuracy. Such devices may, alternatively or additionally, need to be maintained in an arranged position and/or subsequently repositioned within the same degree of accuracy. Designers and manufacturers may, therefore, endeavor to create and supply products that accomplish one or more of these objectives for such devices. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]    The following detailed description references the drawings, wherein: 
           [0003]      FIG. 1  is an example of a perspective view of a positioning assembly. 
           [0004]      FIG. 2  is an example of an exploded perspective view of the positioning assembly of  FIG. 1 . 
           [0005]      FIG. 3  is an example of movement of a housing of the positioning assembly of  FIG. 1  along a longitudinal axis. 
           [0006]      FIG. 4  is an example of rotation of the housing of the positioning assembly of  FIG. 1  about the longitudinal axis. 
           [0007]      FIG. 5  is an example of rotation of the housing of the positioning assembly of  FIG. 1  about a first axis that is transverse to the longitudinal axis. 
           [0008]      FIG. 6  is an example of movement of the housing of the positioning assembly of  FIG. 1  along the first axis. 
           [0009]      FIG. 7  is an example of movement of the housing of the positioning assembly of  FIG. 1  along a second axis that is transverse to the longitudinal axis. 
           [0010]      FIG. 8  is an additional example of movement of the housing of the positioning assembly of  FIG. 7  in a different direction along the second axis. 
           [0011]      FIG. 9A  is an example of a cross-sectional view of the positioning assembly taken along line  9 - 9  of  FIG. 1  illustrating a brake mechanism in a first position. 
           [0012]      FIG. 9B  is another example of a cross-sectional view of the positioning assembly taken along line  9 - 9  of  FIG. 1  illustrating the brake mechanism in a second position. 
           [0013]      FIG. 10A  is an example of a cross-sectional view of the positioning assembly taken along line  10 - 10  of  FIG. 1  illustrating the brake mechanism in the first position. 
           [0014]      FIG. 10B  is another example of a cross-sectional view of the positioning assembly taken along line  10 - 10  of  FIG. 1  illustrating the brake mechanism in the second position. 
           [0015]      FIG. 11  is an example of a perspective view of a device coupled to the housing of the positioning assembly of  FIG. 1 . 
           [0016]      FIG. 12  is another example of a perspective view of a positioning assembly. 
           [0017]      FIG. 13  is an example of an exploded perspective view of the positioning assembly of  FIG. 12 . 
           [0018]      FIG. 14A  is an example of a cross-sectional view of the positioning assembly taken along line  14 - 14  of  FIG. 12  illustrating a brake mechanism in a first position. 
           [0019]      FIG. 14B  is another example of a cross-sectional view of the positioning assembly taken along line  14 - 14  of  FIG. 12  illustrating the brake mechanism in a second position. 
           [0020]      FIG. 15A  is an example of a cross-sectional view of the positioning assembly taken along line  15 - 15  of  FIG. 12  illustrating the brake mechanism in the first position. 
           [0021]      FIG. 15B  is another example of a cross-sectional view of the positioning assembly taken along line  15 - 15  of  FIG. 12  illustrating the brake mechanism in the second position. 
           [0022]      FIG. 16  is an example of rotation of a housing of an alternative positioning assembly about a first axis that is transverse to the longitudinal axis. 
           [0023]      FIG. 17  is an example of movement of the housing of the positioning assembly of  FIG. 16  along the first axis. 
       
    
    
     DETAILED DESCRIPTION 
       [0024]    Accurate positioning of devices is desirable in many applications, such as pen-to-paper spacing in inkjet printing, as well as service station alignment for such inkjet pens. Other non-limiting application examples requiring accurate positioning include manufacturing, surgery, photography, acoustics, test and measurement, and certain military uses. The ability to adjust such positioning to bring things back into tolerance ranges is also helpful to compensate for incorrect positioning resulting from, for example, extended and/or rough use, as well as wear and tear of various components over time. 
         [0025]    An example of a positioning assembly  10  that is directed to addressing these challenges is illustrated in  FIG. 1 . As can be seen in  FIG. 1 , positioning assembly  10  includes a guide shaft  12  having a longitudinal axis  14 , a first axis  16 , and a second axis  18 . In this example, longitudinal axis  14  represents a z-axis, first axis  16  represents an x-axis that is substantially perpendicular to longitudinal axis  14 , and second axis  18  represents a y-axis (substantially perpendicular to first axis  16 ) of a three-dimensional coordinate system. It is to be understood, however, that in other examples, longitudinal axis  14 , first axis  16  and/or second axis  18  may represent one or more other axes of the same or a different type of coordinate system. 
         [0026]    As can also be seen in  FIG. 1 , positioning assembly  10  also includes a housing  20  disposed on guide shaft  12  and a brake mechanism  22  disposed on guide shaft  12 . As discussed more fully below, brake mechanism  22  is moveable between a first position that permits movement of housing  20  along and about longitudinal axis  12 , along and about first axis  16 , and along second axis  18 , and a second position that impedes movement of housing  20  along and about longitudinal axis  12 , along and about first axis  16 , and along second axis  18 . 
         [0027]    An example of an exploded perspective view of positioning assembly  10  is shown in  FIG. 2 . As can be seen in  FIG. 2 , housing  20  of positioning assembly  10  defines a first opening  24  and a second opening  26  through which guide shaft  12  is disposed. In this example, both respective first and second openings  24  and  26  have a generally oval or elliptical shape that helps to facilitate the above-described movements of housing  20  along and about longitudinal axis  14 , along and about first axis  16 , and along second axis  18 . Although first and second openings  24  and  26  of housing  20  have a generally oval or elliptical shape, it is to be understood that either or both of first and second openings  24  and  26  may have a different shape in other examples of positioning assembly  10 . Housing  20  additionally includes cut-outs  28  and  30  that receive and provide clearance for first arm  32  and second arm  34  of caliper  36  of brake mechanism  22 , as described more fully below. 
         [0028]    As can also be seen in  FIG. 2 , first arm  32  includes a first lobe  38  and second arm  34  includes a second lobe  40  having a first portion  42  and a second portion  44 . First lobe  38  of first arm  32  defines an opening  46  that allows first arm  32  to be mounted on guide shaft  12  and respective first and second portions  42  and  44  of second lobe  40  of second arm  34  define openings  48  and  50  that allow second arm  34  to be mounted on guide shaft  12 . First and second portions  42  and  44  of second arm  34  are spaced apart relative to one another so as to receive first lobe  38 , as shown, for example, in  FIG. 3 . 
         [0029]    Referring again to  FIG. 2 , first arm  32  additionally includes a first raised portion  52  and a second raised portion  54  that contact respective portions  56  and  58  of second arm  34  as brake mechanism  22  is moved from the first position shown, for example, in  FIG. 9A  to the second position shown, for example, in  FIG. 9B . This contact between first and second raised portions  52  and  54  and respective portions  56  and  58  helps to limit or stop movement of brake mechanism  22  from the first position to the second position. 
         [0030]    As can additionally be seen in  FIG. 2 , brake mechanism  22  includes a first pad or shoe  60  and a second pad or shoe  62  that are disposable in interior or cavity  63  of housing  20 . First pad or shoe  60  includes a recess  64  that receives first lobe  38  of first arm  32  and second pad or shoe  62  includes a recess  66  that receives first portion  42  of second lobe  40  of second arm  34  and a recess  68  that receives second portion  44  of second lobe  40  of second arm  34 . First pad or shoe  60  additionally includes a cut-out  70  that receives and provides clearance for first arm  32  of caliper  36  of brake mechanism  22 , and second pad or shoe  62  additionally includes a cut-out  72  that receives and provides clearance for second arm  34  of caliper  36  of brake mechanism  22 . 
         [0031]    As can further be seen in  FIG. 2 , positioning assembly  10  additionally includes an actuator  74  to move brake mechanism  22  between the first position shown, for example, in  FIG. 9A  and the second position shown, for example, in  FIG. 9B . In this example, actuator  74  includes a cable assembly  76  that is disposed through openings  78  and  80  of respective first and second arms  32  and  34 , as shown, for example, in  FIG. 1 . A sphere or ball  82  adjacent end  84  of cable assembly  76  has a larger diameter or radius than a diameter or radius of opening  78  in first arm  32  so that sphere or ball  82  does not pass through opening  78  when cable assembly  76  is actuated. Cable assembly  76  of actuator  74  also includes a clip  86  that fits on and attaches to second arm  34  via tabs  88  and  90  that are disposed in respective slots  92  and  94  in second arm  34 . 
         [0032]    Although in this example of positioning assembly  10 , actuator  74  is illustrated as including a cable assembly  76 , it is to be understood that actuator  74  may include different structures or mechanisms. For example, actuator  74  may include a motor with a shaft or gear assembly (such as an electric motor with a worm gear), a hydraulic cylinder, a pneumatic cylinder, etc. 
         [0033]    An example of movement of housing  20  of positioning assembly  10  along longitudinal axis  14  is shown in  FIG. 3 . As can be seen in  FIG. 3 , brake mechanism  22  is in the first position that permits movement of housing  20  along longitudinal axis  14  in either of the directions of double-headed arrow  96  which is substantially parallel to longitudinal axis  14 . 
         [0034]    An example of rotation of housing  20  of positioning assembly  10  about longitudinal axis  14  is shown in  FIG. 4 . As can be seen in  FIG. 4 , brake mechanism  22  is in the first position that permits movement of housing  20  about longitudinal axis  14  in the direction of arrow  98 , as shown. Although not shown in  FIG. 4 , it is to be understood that first position of brake mechanism  22  also permits movement of housing  20  about longitudinal axis  14  in the direction of arrow  100  as well. 
         [0035]    An example of rotation of housing  20  of positioning assembly  10  about first axis  16  that is transverse to longitudinal axis  14  is shown in  FIG. 5 . As can be seen in  FIG. 5 , brake mechanism  22  is in the first position that permits rotation of housing about first axis  16  in either of the directions indicated by double-headed arrow  102 . As can be seen in  FIG. 5 , the extent of this rotation is limited by contact between side  104  of first opening  24  and guide shaft  12  and side  106  of second opening  26  and guide shaft  12 . 
         [0036]    An example of movement of housing  20  of positioning assembly  10  along first axis  16  that is transverse to longitudinal axis  14  is shown in  FIG. 6 . As can be seen in  FIG. 6 , brake mechanism  22  is in the first position that permits movement of housing  20  along first axis  16  in either of the directions of double-headed arrow  108  which is substantially parallel to first axis  16 . As can also be seen in  FIG. 6 , the extent of this movement is limited by contact between side  104  of first opening  24  and guide shaft  12 . Contact between side  106  of second opening  26  (not shown in  FIG. 6 ) and guide shaft  12  also limits the extent of this movement. 
         [0037]    An example of movement of housing  20  of the positioning assembly  10  along second axis  18  that is transverse to longitudinal axis  14  is shown in  FIG. 7 . As can be seen in  FIG. 7 , brake mechanism  22  is in the first position and has been rotated about guide shaft  12  in the direction of arrow  110  which permits or results in movement of housing  20  along second axis  18  in the direction of arrow  112  which is substantially parallel to second axis  18 . As can also be seen in  FIG. 7 , the extent of this movement is limited by contact between side  104  of first opening  24  and guide shaft  12 . Contact between side  106  of second opening  26  (not shown in  FIG. 7 ) and guide shaft  12  also limits the extent of this movement. 
         [0038]    An additional example of movement of housing  20  of the positioning assembly  10  in a different direction along second axis  18  that is transverse to longitudinal axis  14  is shown in  FIG. 8 . As can be seen in  FIG. 8 , brake mechanism  22  is in the first position and has be rotated about guide shaft  12  in the direction of arrow  114  which is generally opposite to the direction of arrow  110 . This rotation permits or results in movement of housing  20  along second axis  18  in the direction of arrow  116  which is substantially parallel to second axis  18  and generally opposite to the direction of arrow  112 . As can also be seen in  FIG. 8 , the extent of this movement is limited by contact between side  104  of first opening  24  and guide shaft  12 . Contact between side  106  of second opening  26  (not shown in  FIG. 7 ) and guide shaft  12  also limits the extent of this movement. 
         [0039]    An example of a cross-sectional view of positioning assembly  10  taken along line  9 - 9  of  FIG. 1  illustrating brake mechanism  22  in the first position is shown in  FIG. 9A . Another example of a cross-sectional view of positioning assembly  10  taken along line  9 - 9  of  FIG. 1  illustrating brake mechanism  22  in the second position is shown in  FIG. 9B . As can be seen by comparison of  FIGS. 9A and 9B , respective first and second arms  32  and  34  are in closer proximity to one another in the second position illustrated in  FIG. 9B  than in the first position illustrated in  FIG. 9A . This movement of brake mechanism  22  from the first position illustrated in  FIG. 9A  to the second position illustrated in  FIG. 9B  results from the shortening of cable assembly  76  which pulls respective first and second arms  32  and  34  together. 
         [0040]    As can be seen, for example in  FIG. 9A , opening  46  is not located at geometric center  118  of first lobe  38  so that first arm  32  of caliper  36  is eccentrically mounted on guide shaft  12 . As can be seen in  FIG. 9B , when brake mechanism  22  is in the second position, this eccentric mounting of first arm  32  of caliper  36  on guide shaft  12  helps impede movement of housing  20  along and about longitudinal axis  14  of guide shaft  12  by virtue of contact between side  120  of first lobe  38  and guide shaft  12 . 
         [0041]    An example of a cross-sectional view of positioning assembly  10  taken along line  10 - 10  of  FIG. 1  illustrating brake mechanism  22  in the first position is shown in  FIG. 10A . Another example of a cross-sectional view of positioning assembly  10  taken along line  10 - 10  of  FIG. 1  illustrating brake mechanism  22  in the second position is shown in  FIG. 10B . As can be seen, for example in  FIG. 10A , opening  48  is not located at geometric center  122  of first portion  42  of second lobe  40  so that second arm  34  of caliper  36  is eccentrically mounted on guide shaft  12 . As can be seen in  FIG. 10B , when brake mechanism  22  is in the second position, this eccentric mounting of second arm  34  of caliper  36  on guide shaft  12  helps impede movement of housing  20  along and about longitudinal axis  14  of guide shaft  12  by virtue of contact between side  124  of first portion  42  of second lobe  40  and guide shaft  12 . Although not shown in  FIG. 10A , it is to be understood that opening  50  is also not located at the geometric center of second portion  44  of second lobe  40 . 
         [0042]    As can be seen, for example, by comparison of  FIGS. 10A and 10B , movement of brake mechanism  22  from the first position to the second position causes first lobe  38  of first arm  32  to actuate first pad or shoe  60  in the direction of arrow  126  against side  128  of housing  20 , thereby impeding movement of housing  20  along and about first axis  16 , as well as along second axis  18 . As can also be seen by comparison of  FIGS. 10A and 10B , movement of brake mechanism  22  from the first position to the second position also causes second lobe  40  of second arm  34  to actuate second pad or shoe  62  in the direction of arrow  130  against side  132  of housing  20 , thereby also impeding movement of housing  20  along and about first axis  16 , as well as along second axis  18 . 
         [0043]    An example of a device  134  (e.g., an inkjet printer carriage assembly) coupled to housing  20  of positioning assembly  10  is shown in  FIG. 11 . As can be seen in  FIG. 11 , device  134  defines a first opening  136  and a second opening  138  through which guide shaft  12  is disposed. In this example, both respective first and second openings  136  and  138  have a generally oval or elliptical shape that helps to facilitate tracking of the above-described movements of housing  20  to which device  134  is coupled. 
         [0044]    As can also be seen in  FIG. 11 , device  134  includes a first bushing  140  disposed in first opening  136  and a second bushing  142  disposed in second opening  138 . Guide shaft  12  is disposed through openings  144  and  146  defined by respective first and second bushings  140  and  142 , as shown. First and second bushings  140  and  142  help device  134  more smoothly track the movements of housing  20  to which device  134  is coupled. 
         [0045]    As discussed above and illustrated, for example, in  FIGS. 9B and 10B , brake mechanism  22  of positioning assembly  10  is moveable to a second position by actuator  74  that impedes movement of housing  20  along and about longitudinal axis  14 , along and about first axis  16 , and along second axis  18 . Movement of device  134  is also similarly impeded by virtue of the coupling between housing  20  and device  134 . However, such movement of device  134  is impeded independent of application of resistive forces on device  134 . This helps prevent deformation of device  134 , as well as wear and tear on device  134 . 
         [0046]    An example of another positioning assembly  148  is illustrated in  FIG. 12 . As can be seen in  FIG. 12 , positioning assembly  148  includes a guide shaft  150  having a longitudinal axis  152 , a first axis  154  that is transverse to longitudinal axis  152 , and a second axis  156  that is also transverse to longitudinal axis  152 . In this example, longitudinal axis  152  represents a z-axis, first axis  154  represents an x-axis that is substantially perpendicular to longitudinal axis  152 , and second axis  156  represents a y-axis (substantially perpendicular to first axis  154 ) of a three-dimensional coordinate system. It is to be understood, however, that in other examples, longitudinal axis  152 , first axis  154  and/or second axis  156  may represent one or more other axes of the same or a different type of coordinate system. 
         [0047]    As can also be seen in  FIG. 12 , positioning assembly  148  also includes a housing  158  disposed on guide shaft  150  and a brake mechanism  160  disposed on guide shaft  150 . As discussed more fully below, brake mechanism  160  is moveable between a first position that permits movement of housing  158  along and about longitudinal axis  152 , along and about first axis  154 , and along second axis  156 , and a second position that impedes movement of housing  158  along and about longitudinal axis  152 , along and about first axis  154 , and along second axis  156 . 
         [0048]    An example of an exploded perspective view of positioning assembly  148  is shown in  FIG. 13 . As can be seen in  FIG. 13 , housing  158  of positioning assembly  148  defines a first opening  162  and a second opening  164  through which guide shaft  150  is disposed. In this example, both respective first and second openings  162  and  164  have a generally oval or elliptical shape that helps to facilitate the above-described movements of housing  158  along and about longitudinal axis  152 , along and about first axis  154 , and along second axis  156 . Although first and second openings  162  and  164  of housing  158  have a generally oval or elliptical shape, it is to be understood that either or both of first and second openings  162  and  164  may have a different shape in other examples of positioning assembly  148 . Housing  158  additionally includes cut-outs  166  and  168  that receive and provide clearance for first arm  170  and second arm  172  of caliper  174  of brake mechanism  160 . 
         [0049]    As can also be seen in  FIG. 13 , first arm  170  includes a first lobe  176  and second arm  172  includes a second lobe  178 . First lobe  176  of first arm  170  defines an opening  180  that allows first arm  170  to be mounted on guide shaft  150  and second arm  172  defines opening  182  that allows second arm  172  to be mounted on guide shaft  150 . First and second arms  170  and  172  additionally include respective raised portions  184  and  186  on which a biasing member  188  is disposed. Biasing member  188  helps to retain caliper  174  in the first position, as shown, for example, in  FIG. 12 . 
         [0050]    Referring again to  FIG. 13 , brake mechanism  160  includes a first pad or shoe  190  and a second pad or shoe  192  that are disposable in interior or cavity  194  of housing  158 . First pad or shoe  190  includes a recess  196  that receives first lobe  176  of first arm  170  and a recess  197  that receives second lobe  178  of second arm  172 . Second pad or shoe  192  includes a recess  198  that receives second lobe  178  of second arm  172  and a recess  199  that receives first lobe  176  of first arm  170 . First pad or shoe  190  additionally includes a cut-out  200  that receives and provides clearance for first arm  170  of caliper  174  of brake mechanism  160  and second pad or shoe  192  additionally includes a cut-out  202  that receives and provides clearance for second arm  172  of caliper  174  of brake mechanism  160 . First pad or shoe  190  further includes a recess  204  that receives biasing member  188  and second pad or shoe  192  additionally includes a recess  206  that also receives biasing member  188 . 
         [0051]    Although not shown in  FIG. 13 , positioning assembly  148  additionally includes an actuator to move brake mechanism  160  against the urging of biasing member  188  from the first position shown, for example, in  FIG. 14A  to the second position shown, for example, in  FIG. 14B . This actuator may include a cable assembly, like cable assembly  76 , which is disposed through openings  208  and  210  of respective first and second arms  170  and  172 . This actuator may also include different structures or mechanisms such as a motor with a shaft or gear assembly (such as an electric motor with a worm gear), a hydraulic cylinder, a pneumatic cylinder, etc. 
         [0052]    An example of a cross-sectional view of positioning assembly  148  taken along line  14 - 14  of  FIG. 12  illustrating brake mechanism  160  in the first position is shown in  FIG. 14A . Another example of a cross-sectional view of positioning assembly  148  taken along line  14 - 14  of  FIG. 12  illustrating brake mechanism  160  in the second position is shown in  FIG. 14B . As can be seen by comparison of  FIGS. 14A and 14B , respective first and second arms  170  and  172  are in closer proximity to one another in the second position illustrated in  FIG. 14B  than in the first position illustrated in  FIG. 14A . This movement of brake mechanism  160  from the first position illustrated in  FIG. 14A  to the second position illustrated in  FIG. 14B  results from use of an actuator (not shown) which opposes the urging of biasing member  188  to move respective first and second arms  170  and  172  together. 
         [0053]    As can be seen, for example in  FIG. 14B , opening  180  is not located at geometric center  212  of first lobe  176  so that first arm  170  of caliper  174  is eccentrically mounted on guide shaft  150 . As can be seen in  FIG. 14A , when brake mechanism  160  is in the first position, this eccentric mounting of first arm  170  of caliper  174  on guide shaft  150  helps impede movement of housing  158  along and about longitudinal axis  152  of guide shaft  150  by virtue of contact between side  214  of first lobe  176  and guide shaft  150 . 
         [0054]    As can be seen in  FIG. 14A , in the first position of brake mechanism  160 , first lobe  176  of first arm  170  actuates second pad or shoe  192  against side  216  of housing  158 , thereby impeding movement of housing  158  along and about first axis  154 , as well as along second axis  156 . Brake mechanism  160  is retained in this first position shown in  FIG. 14A  under the urging provided by biasing member  188 . 
         [0055]    As can be seen, for example, by comparison of  FIGS. 14A and 14B , movement of brake mechanism  160  from the first position to the second position causes first lobe  176  of first arm  170  to release second pad or shoe  192  in the direction of arrow  218  from contact against side  216  of housing  158 , thereby permitting movement of housing  158  along and about first axis  16 , as well as along second axis  18 . As can also be seen by comparison of  FIGS. 14A and 14B , side  214  of first lobe  176  no longer contacts guide shaft  150  in the second position, thereby permitting movement of housing  158  along and about longitudinal axis  152  of guide shaft  150 . 
         [0056]    An example of a cross-sectional view of positioning assembly  148  taken along line  15 - 15  of  FIG. 12  illustrating brake mechanism  160  in the first position is shown in  FIG. 15A . Another example of a cross-sectional view of positioning assembly  148  taken along line  15 - 15  of  FIG. 12  illustrating brake mechanism  160  in the second position is shown in  FIG. 15B . As can be seen, for example, in  FIG. 15B , opening  182  is not located at geometric center  220  of second lobe  178  so that second arm  172  of caliper  174  is eccentrically mounted on guide shaft  150 . As can be seen in  FIG. 15A , when brake mechanism  160  is in the first position, this eccentric mounting of second arm  172  of caliper  174  on guide shaft  150  helps impede movement of housing  158  along and about longitudinal axis  152  of guide shaft  150  by virtue of contact between side  222  of second lobe  178  and guide shaft  150 . 
         [0057]    As can be seen in  FIG. 15A , in the first position of brake mechanism  160 , second lobe  178  of second arm  172  actuates first pad or shoe  190  against side  224  of housing  158 , thereby impeding movement of housing  158  along and about first axis  154 , as well as along second axis  156 . Brake mechanism  160  is retained in this first position shown in  FIG. 15A  under the urging provided by biasing member  188  (not shown in  FIG. 15A ). 
         [0058]    As can be seen, for example, by comparison of  FIGS. 15A and 15B , movement of brake mechanism  160  from the first position to the second position causes second lobe  178  of second arm  172  to release first pad or shoe  190  in the direction of arrow  226  from contact against side  224  of housing  158 , thereby permitting movement of housing  158  along and about first axis  154 , as well as along second axis  156 . As can also be seen by comparison of  FIGS. 15A and 15B , side  222  of second lobe  178  no longer contacts guide shaft  150  in the second position, thereby permitting movement of housing  158  along and about longitudinal axis  152  of guide shaft  150 . 
         [0059]    An example of rotation of housing  20  of an alternative positioning assembly  228  about first axis  16  that is transverse to longitudinal axis  14  is shown in  FIG. 16 . Were applicable, the same reference numerals have been used for positioning assembly  228  as were used for positioning assembly  10 . As can be seen in  FIG. 16 , positioning assembly  228  includes an actuator  230  to move housing  20  of positioning assembly  228  about first axis  16  in either of the directions indicated by double-headed arrow  102 . As can also be seen in  FIG. 16 , the extent of this rotation is limited by contact between side  104  of first opening  24  and guide shaft  12  and side  106  of second opening  26  and guide shaft  12 . 
         [0060]    Actuator  230  includes an arm  232  having a plurality of attachment points  234 ,  236 , and  238  in which respective joints or bushings  240 ,  242 , and  244  are disposed. As can additionally be seen in  FIG. 16 , first pad or shoe  60  of brake mechanism  22  of positioning assembly  228  includes a shaft  246  that is received in bushing or joint  244  and second pad or shoe  62  includes a shaft  248  that is received in bushing or joint  240  to help mount actuator  230 . As can further be seen in  FIG. 16 , housing  20  includes a shaft  250  that is received in bushing or joint  242  to also help mount actuator  230 . 
         [0061]    An example of movement of housing  20  of positioning assembly  228  along first axis  16  is shown in  FIG. 17 . As can be seen in  FIG. 17 , brake mechanism  22  is in the first position that permits actuator  230  to move housing  20  along first axis  16  in either of the directions of double-headed arrow  108  which is substantially parallel to first axis  16 . As can also be seen in  FIG. 17 , the extent of this movement is limited by contact between side  104  of first opening  24  and guide shaft  12 . Contact between side  106  of second opening  26  (not shown in  FIG. 17 ) and guide shaft  12  also limits the extent of this movement. 
         [0062]    Actuator  230  may move housing  20  along first axis  16  in either of the directions indicated by double-headed arrow  108  and about first axis  16  in either of the directions indicated by double-headed arrow  102  through any of a variety of different ways. For example, a motor (not shown) may be mounted to shaft  250 . As another example, shaft  250  may be magnetized and an electric coil (not shown) may be disposed in attachment point  236 . As a further example, one or more hydraulic cylinders (not shown) may be used by actuator  230  to control movement in either or both of the directions indicated by double-headed arrows  102  and  108 . 
         [0063]    Although several drawings have been described and illustrated in detail, it is to be understood that the same are intended by way of illustration and example only. These examples are not intended to be exhaustive or to be limited to the precise form disclosed. Modifications and variations may well be apparent to those of ordinary skill in the art. 
         [0064]    Additionally, reference to an element in the singular is not intended to mean one and only one, unless explicitly so stated, but rather means one or more. Moreover, no element or component is intended to be dedicated to the public regardless of whether the element or component is explicitly recited in the following claims.