FIELD OF INVENTION  
       [0001]     The present invention relates to a supporting frame which is advantageous for use with an infant bed or the like and more particularly to a locking device for positively locking wheel assemblies in either of two operating positions.  
       BACKGROUND  
       [0002]     Wheeled support frames are well known. For example, devices to accommodate infants, such as bassinets, cribs, cradles and the like are often mounted upon wheeled supports. In some applications, it is advantageous to provide a wheeled support designed to enable the wheel assemblies to be selectively moved between retracted and extended positions. One such structure is described in U.S. Pat. No. 5,636,853, granted Jun. 10, 1997. A factor in the ease of use of these structures is the ease in which the rollers are moved between retracted and extended positions.  
         [0003]     The device disclosed in U.S. Pat. Number 5,636,853 provides retractable wheel supports on an infant bed support enabling it to roll on a suitable surface with the rollers extended, or rock on arcuate members when the rollers are retracted. Such a device provides both rocking and non-rocking modes for an infant bed. However, the mechanism used for releasing, retracting and extending each roller requires an awkward and difficult manual actuation which requires two (2) different manual operations to be performed substantially simultaneously. It is desirable to provide a mechanism which allows a support frame to adjust between stationary and rolling modes easily with a minimum of effort.  
       SUMMARY  
       [0004]     The present invention provides a support frame having a plurality of wheeled support assemblies, each mounted near corners of the support frame, each including a substantially identical mounting for extending and retracting an associated wheel assembly. When the wheel assemblies are extended downwardly, the support frame is able to roll on the wheel assemblies on any suitable surface. When the wheel assemblies are retracted the frame rests in a stationary mode on base support members.  
         [0005]     Each mounting includes a rotatable member mounted to rotate within its associated housing. Each wheel assembly is connected to an associated rotatable member and is swingable between an extended and retracted position. A locking mechanism is mounted on each wheeled support assembly and includes a movable locking member having an integral portion for selectively engaging one of the locking openings on the rotatable member to prevent rotation of the rotatable member and its associated wheel assembly.  
         [0006]     Moving the locking member in a first direction withdraws its integral portion from one of the locking openings, allowing the rotatable member and the wheel assembly to rotate freely. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0007]      FIG. 1  is an isometric view of a support frame incorporating the present invention according to a preferred embodiment.  
         [0008]      FIG. 2  is an isometric view showing one of the support assemblies of  FIG. 1  in greater detail.  
         [0009]      FIG. 2   a  is a side elevation view of a housing of the support assembly of  FIG. 2 .  
         [0010]      FIG. 2   b  is an end view of the housing of the support assembly of  FIG. 2 .  
         [0011]      FIG. 2   c  is a sectional view of the housing looking in the direction of arrows  2   c - 2   c  of  FIG. 2   b.    
         [0012]      FIG. 2   d  is a plan view of a control member of the support assembly of  FIG. 2 .  
         [0013]      FIG. 2   e  is an isometric view of a cylindrical member of the support assembly of  FIG. 2 .  
         [0014]      FIG. 2   f  is a profile view of the cylindrical member of the support assembly looking in the direction of arrows  2   f - 2   f  of  FIG. 2 .  
         [0015]      FIG. 3  is a cross-section of the support assembly looking in the direction of arrows  3 - 3  of  FIG. 2 .  
         [0016]      FIG. 3   a  is a cross-section of an alternative embodiment of the support assembly looking in the direction of arrows  3 - 3  of  FIG. 2 .  
         [0017]      FIG. 4  is an isometric view of the support frame of  FIG. 1  with the wheel assemblies retracted.  
         [0018]      FIG. 5  is a profile view illustrating a support assembly of  FIG. 1  in, both the extended and retracted positions.  
         [0019]      FIG. 6  is an isometric view of another alternative embodiment of the support assembly.  
         [0020]      FIG. 7  is a cross-section in the direction of arrows  7 - 7  of  FIG. 6 .  
         [0021]      FIG. 8  is an isometric view of another alternative embodiment of the support assembly.  
         [0022]      FIG. 8   a  is an isometric view of a locking member of the embodiment of  FIG. 8 . 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS  
       [0023]      FIGS. 1-3  show a support frame  10  having four wheeled support assemblies  12  according to a preferred embodiment of the present invention. Each of the wheeled support assemblies  12  includes a housing  16  preferably including molded plastic members.  
         [0024]     The ribs  72  in housing  16  cooperate with a fastener receiving aperture  74  to secure the base support member  20 , see  FIGS. 1 and 3 . Two of the ribs  72  are curved at their lower ends  72   a  to conform to the shape of the member  20 . An upper portion  18  of housing  16  comprises first and second hollow cylindrical projections  76 ,  78  which respectively receive first and second support members  22 ,  24  which cooperate to provide a structurally rugged support, see  FIGS. 2   a  and  2   b . The base support member  20  and first and second support members  22 ,  24  are preferably metallic members, however any suitable structural material may be used. The novel support assemblies of the present invention may be used with a variety of different support structures, the embodiments here being for illustrative purposes and not by way of limitation.  
         [0025]     The support assembly  12  includes a locking mechanism  82 ,  FIG. 2 , for selectively locking its associated wheel assembly in either a retracted or an extended position. With reference to  FIG. 3 , locking mechanism  82  is comprised of a locking member  26  having a knob  28  and a locking projection  30 . The locking projection  30  includes a flange  32  which receives one end of a spring  34 . Preferably, the flange  32  is integrally formed with the locking projection  30 . The spring  34  is shown as a coiled compression spring, however, other types of springs may be used. The locking projection  30  engages an inner portion of a hollow integral extension  58  of the housing  16 .  
         [0026]     The integral extension  58  includes a rim  58   a  which retains the spring  34  and provides a biasing force to contain the locking member  26 . The knob  28  includes a cylindrical guide portion  28   a  which engages an outer portion of the integral extension  58  to allow alignment of the locking member  26 . The member  26  is movable within a range limited by the spring  34 , when fully compressed, and an integral stop  36  which engages an end of the cylindrical guide portion  28   a  of knob  28 . To facilitate assembly, the locking member  26  may comprise multiple pieces, for example, the locking projection  30  may include a threaded end which removably engages a tapped portion of the knob  28 .  
         [0027]     The locking projection  30  selectively engages one of the locking openings  42   a ,  42   b  provided in cylindrical member  40  to prevent rotation of the cylindrical member  40 . The spring  34  provides a biasing force which urges the locking member  26  in a direction to cause locking projection  30  to engage the outer surface of cylindrical member  40 . When the locking projection  30  is aligned with one of the openings  42   a ,  42   b , it enters that opening to lock the cylinder against further rotation.  
         [0028]     In the alternative embodiment shown in  FIG. 3   a , the spring  34  is omitted and the locking member  126  and locking projection  130  are locked in position by detent  184  which selectively engages one of detent apertures  186   a ,  186   b . If desired, the detent may be provided on an inner wall of integral extension  58  and the detent openings provided as grooves on the locking projection  130 .  
         [0029]     In the alternative embodiment shown in  FIGS. 6 and 7 , a support assembly  212  includes a locking mechanism  282  which is comprised of a locking member  226  having first and second ends  228 ,  238 . First end  228  includes a cavity  232  which receives one end of a spring  234 . Preferably, an outer surface of the first end  228  includes ridges or a knurled portion to provide friction to facilitate actuation of the locking member  226 . The spring  234  is shown as a coiled compression spring. Alternatively, other types of springs may be used including leaf springs and torsion springs. Locking member  226  is positioned in a recess  258  surrounded by a continuous wall  258   a  to protect member  226  from damage and inadvertent actuation. Member  226  rotates about a pivot  236 , extending into opposing sides of wall  258   a  of the seat  258 , within a range limited by engagement between opposite ends of member  226  and the surface of the housing  216 .  
         [0030]     A projection  230 , preferably integral with the second end  238 , selectively engages one of the locking openings  42   a ,  42   b  provided in cylindrical member  40  to prevent rotation of the cylindrical member  40 . The spring  234  provides a biasing force which urges the locking member  226  in a direction to cause projection  230  to engage the outer surface of cylindrical member  40 . When the projection is aligned with one of the openings  42   a ,  42   b , it enters that opening to lock the cylinder against further rotation, functioning in the same manner as the preferred embodiment of  FIGS. 1-3 .  
         [0031]     Another alternative embodiment, similar to the embodiment of  FIG. 6 , is shown in  FIGS. 8 and 8   a . In this embodiment, the spring  224  is omitted and a locking member  326  and projection  330  are locked in position by detent  384  which selectively engages one of detent apertures  386   a ,  386   b . If desired, the detent may be provided on the inside of the continuous wall  358   a  and the detent openings provided on a side of the member  326  adjacent to the detent.  
         [0032]     Again referring to the preferred embodiment of  FIGS. 1-3 , the cylindrical member  40  is rotatably attached to the housing  16  and further includes a hollow integral protrusion  44  for receiving the shaft  50  in its hollow interior. By lifting the knob  28 , locking projection  30  is disengaged from the cylindrical member  40 , allowing free rotation of the cylindrical member  40 . The cylindrical member  40  also includes a stop  54 , which engages a lip  56  of the housing  16 , for limiting the range of rotation of the cylindrical member  40  in the counter-clockwise direction relative to  FIG. 3 .  
         [0033]     A control member  48  is inserted into the hollow interior of cylindrical member  40  and is secured to the cylindrical member by shaft  50 , of the wheel assembly  52 , which pivotably supports the wheel assembly  52 . Shaft  50  extends through hollow opening  46  of protrusion  44  and an opening  48   a  in the control member  48 . The control member  48  engages the marginal perimeters of apertures  80  on opposite sides of the housing  16 , which serve as bearings for member  48 . A boss  90  provides an additional bearing surface to support the control member  48 . Also, the control member  48  is preferably sized to form a press fit with the cylindrical member  40 . Alternatively, the shaft  50  may be omitted, and the wheel assembly may be integrally molded with the cylindrical member  40  or rigidly attached to the cylindrical member  40  by an adhesive or a plurality of fastening members.  
         [0034]     A finger grip  60 , integral with the control member  48 , facilitates rotation of the wheel assembly. The grip  60  is preferably molded integrally with the control member  48 , but may be joined by other means. To assemble the device, the cylindrical member  40  is placed in the hollow interior of housing  16  and aligned with the openings  80 . The control member  48  is inserted through one of the apertures  80  in the housing  16  and through the cylindrical member  40  and the end opposite the grip  60  is pushed into the boss  90 . The perimeter of grip  60  preferably engages an adjacent surface of the housing  16 . Support shaft  50  of wheel assembly  52  is inserted into protrusion  44  and opening  48   a  which are initially brought into alignment. Shaft  50  retains the assembly in place.  
         [0035]     Alternatively, the grip  60  may be rigidly attached to the cylindrical member  40  or omitted entirely; in such cases the control member  48  may be omitted as well. If the control member  48  is omitted, the cylindrical member  40  must be configured to pivot within apertures  80 .  
         [0036]     With reference to  FIG. 3 , the wheel assembly  52 , connected to both the control member  48  and the cylindrical member  40 , rotates about a first axis  84  which is also the axis of rotation of cylindrical member  40 , and also about a second axis  86  defined by the shaft  50 . The wheel assembly  52  includes a rotatable wheel  62  and preferably includes a wheel stop having a locking lever  64  for preventing rotation of the wheel  62  about a third axis  66 .  
         [0037]     The locking projection  30  engages the locking opening  42   a  to prevent rotation of the cylindrical member allowing the wheel assembly  52  to be retained in the retracted position within recess  68  in the housing  16 . When each wheel assembly is so positioned, the support  10  is permitted to rest on the base support members  20 . The locking projection  30  engages the locking opening  42   b  to permit the wheel assemblies  52  to be extended downwardly outside of the housing  16  allowing the support frame  10  to rest on the wheel assemblies  52 .  
         [0038]     The operation of the mechanism  82  follows:  
         [0039]     Making reference to  FIGS. 3, 4 , and  5 , the wheels are retractable into the housing  16 . Knob  28  of locking member  26  is pulled to withdraw the locking projection  30  from the locking opening  42   a . When the projection  30  is free of opening  42   a , grip  60  is rotated to rotate the wheel assembly to the extended position. Locking member  26  may be released after rotation of the grip  60  has begun. Projection  30  will snap into locking opening  47   b , under the force of the spring  34  when wheel assembly  52  is in the extended position shown in  FIGS. 1, 2 , and  3 . The rotation of the wheel assembly  52  about the axis  84  away from the recess  68  is arrested by the stop  54 , which engages lip  56  of the housing  16 . Stop  54  also assures alignment of projection  30  with locking opening  42   b.    
         [0040]     Making reference to  FIGS. 1, 2 , and  3 , the support assembly  12  is shown with each wheel assembly  52  extended. Each wheel assembly  52  is retractable into a respective recess  68  in a manner similar to the manner in which it was withdrawn. Member  26  is pulled to withdraw projection  30  from locking opening  42   b . Grip  60  is then rotated to rotate the wheel assembly to the retracted position. If desired, rather than operating grip  60 , wheel assembly  52  may be pushed into the recess. The operating grip may be eliminated if desired.  
         [0041]     Making reference to  FIG. 3   a , an alternative embodiment of the support assembly  112  eliminates need for a spring by providing a detent  184  and detent apertures  186   a ,  186   b  to lock a locking projection  130  into one of the locking openings  42   a ,  42   b  of the cylindrical member  40 . By lifting the knob  128 , the locking projection  130  is released from one of said locking openings  42   a ,  42   b , and the detent  184  engages a first detent aperture  186   a  allowing rotation of the wheel assembly  52  about axis  84 . By pressing the knob  128 , the projection  130  enters into one of said locking openings  42   a , 42   b  and the detent  184  engages a second detent aperture  186   b  retaining the projection in one of said locking openings  42   a , 42   b  without a biasing spring. If desired, detents may be provided on any suitable location on the locking projection  130  with associated detent apertures provided on corresponding portions of the integral extension  58 . Alternatively, detents may be provided on the inner wall of integral projection  58  with associated detent apertures formed as grooves on the locking projection  130 .  
         [0042]     Making reference to  FIGS. 6 and 7 , this alternative embodiment functions essentially the same as the embodiment of  FIGS. 1-3 , except that the end  228  of locking member  226  is pushed to withdraw the locking projection  230  from one of locking openings  42   a ,  42   b . Similarly, the alternative embodiment, shown in  FIGS. 8 and 8   a  functions essentially the same as the prior alternative embodiment of  FIG. 3   a . However, the end  328  is pushed to release the locking projection  330  from one of said locking openings  42   a ,  42   b  and to allow detent  384  to engage a first detent aperture  386   a  permitting rotation of the wheel assembly  52 . By depressing a second end  338 , the projection  330  enters into one of said locking openings  42   a , 42   b  and the detent  384  engages a second detent aperture  386   b  retaining the projection in one of said locking openings  42   a , 42   b  without a biasing spring.
A support frame having a plurality of wheeled assemblies, mounted at corners of the support frame, each wheeled assembly including a substantially identical mechanism for extending and retracting a respective wheel assembly. Each mechanism has a locking member which includes a locking portion for selectively engaging locking apertures on a rotatable member which rotatably supports the wheel assembly. Each mechanism also includes a grip, spaced from the locking member, to facilitate rotation of the rotatable member and the respective wheel assembly between extended and retracted positions when the locking portion is disengaged from the locking apertures. When each wheel assembly is in an extended position, the support frame is able to roll on a suitable surface. Each wheel assembly is also capable of being retained in a retracted position housed within a recess in its associated housing.