Patent Abstract:
A caster comprises a body including a stem cavity with a stem of the caster rotatably mounted in the stem cavity to permit rotation of the stem relative to the body about a stem access. The stem may comprise a spline shaft extending from the stem into the stem cavity. The stem and spline shaft are operatively connected. The stem cavity may have a spline bushing. The spline bushing and the body are operatively connected to each other. The spline shaft and the spline bushing are releasbeably interlockable. One of the spline bushing and the spline shaft may be movable in a direction along the stem axis between the swivel position wherein the spline shaft is not engaged with the spline bushing, and a fixed position wherein the spline shaft is engaged with the spline bushing.

Full Description:
BACKGROUND AND SUMMARY 
       [0001]    The disclosure relates to a swivel lock for a caster. In particular, the swivel lock may be configured to be actuated by a brake lever of the caster. The swivel lock comprises a male spline shaft and a female spline bushing which are releasably interlockable to prevent rotation of the caster about a swivel axis. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0002]      FIG. 1  shows a perspective view of a caster with a swivel lock as described herein. 
           [0003]      FIG. 2  shows a top view of the caster of  FIG. 1 . 
           [0004]      FIG. 3  is a front view of the caster of  FIG. 1 . 
           [0005]      FIG. 4  is a right side view of the caster of  FIG. 3 . 
           [0006]      FIG. 5  is an exploded view of the caster of  FIG. 1 . 
           [0007]      FIG. 6  is a cross-sectional view taken along lines  6 - 6  of  FIG. 2 . 
           [0008]      FIG. 7  is a cross-sectional view taken along lines  7 - 7  of  FIG. 2 . 
           [0009]      FIGS. 8-9  are perspective views of the caster of  FIG. 1  with a body and wheels of the caster removed to provide additional detail of one embodiment of the swivel lock. 
           [0010]      FIG. 10  is a perspective view of an embodiment of a stem assembly and a spline bushing comprising the swivel lock described herein. 
       
    
    
     DETAILED DESCRIPTION 
       [0011]    The caster  20  has a body  22  which serves as a frame for the components of the caster. The caster  20  has first and second wheels  24 , 26  that rotate about a wheel axis  28 . The body  22  may have a portion  30  extending generally perpendicular to the wheel axis  28 . The perpendicular extending portion  30  may have a stem cavity  32  that receives a stem  34  of the caster. The stem  34  rotates relative to the body  22  along a stem or swivel axis  36 . The stem or swivel axis  36  is generally perpendicular to the wheel axis  28 . The caster  20  may have a leading brake lever  38  generally adjacent to perpendicular extending portion  30  of the body  22 , and a trailing brake lever  40  on the opposite side of the body. In the drawings, a two-wheeled caster is shown. In such a configuration, the leading brake lever  38  may be configured to prevent rotation of one wheel  26 , and the trailing brake lever  40  may be configured to prevent rotation of the opposite wheel  24 . The wheels  24 , 26  may be rotatably coupled to the body  22  with an axle  42 . 
         [0012]    As best shown in  FIG. 6 , the trailing brake lever  40  may be pivotally connected with the body with a pivot pin  44 . The trailing brake lever  40  may have a finger  46  extending from the lever that engages one or more detents  48  in the body to maintain the lever in a desired position. The body  22  may be provided with the detent  48  to fix the position of the trailing brake lever  40  in the unlocked position. The finger  46  of the trailing brake lever  40  may cooperate with the detent  48  and may have a curved distal end to allow the finger  46  to slide and transition into and out of the detent  48 . The trailing brake lever  40  may have a notch  50 , and a lock block  52  may be coupled to the trailing brake lever at the notch. The lock block  52  may be configured to slide (for instance, vertically as shown in  FIG. 6 ) within the body  22 . The lock block  52  may be coupled to a wheel teeth lock  54 . The wheel teeth lock  54  may move within the body (for instance, vertically as shown in  FIG. 6 ) to engage wheel teeth  56  formed on an inner diameter surface of the wheel  26 . The assembly of the lock block  52  and the wheel teeth lock  54  may be biased away from the wheel teeth  56  by a spring (not shown). 
         [0013]    The trailing brake lever  40  may be rotated between an unlocked position in which the lock block  52  lifts the wheel teeth lock  54  upward out of engagement with the wheel teeth  56  to allow rotation of the wheel  26  about the body  22 , and a locked position in which the lock block forces the wheel teeth lock downward into engagement with the wheel teeth to prevent rotation of the wheel about the body.  FIG. 6  show the trailing brake lever  40  in an unlocked position. Making reference to  FIG. 6 , to position the trailing brake lever  40  to the locked position, the brake lever may be pivoted counterclockwise to drive the lock block  52  and the wheel teeth lock  54  downward. Downward force on the trailing brake lever  40  causes the lever to pivot about its pivot pin  44 , releasing the finger  46  from the detent  48 . The downward motion of the lever also moves the lock block  52  downward and drives the wheel teeth lock  54  against the wheel teeth  56  thereby preventing rotation of the wheel  26  about the wheel axis  28 . To re-position the trailing brake lever  40  to the un-locked position, the brake lever may be pivoted clockwise to raise the assembly of the lock block  52  and the wheel teeth lock  54  and release the wheel teeth lock from the wheel teeth  56  thereby allowing rotation of the wheel  26  about the wheel axis  28 . 
         [0014]    Making reference to  FIG. 7 , the leading brake lever  38  has a similar configuration. The leading brake lever  38  may be pivotally connected with the body with a pivot pin  58 . The leading brake lever  38  may have a finger  60  extending from the lever that engages detents  62 , 63  in the body to maintain the lever in a desired position. The body  22  may be provided with the detents  62 , 63  to fix the position of the leading brake lever in the locked and unlocked positions, respectively. The finger  60  of the leading brake lever may cooperate with the detents  62 , 63  and may have a curved distal end to allow the finger to slide and transition into and out of the detents. The leading brake lever  38  may have a notch  64 , and a lock block  66  may be coupled to the leading brake lever at the notch. The lock block  66  may be configured to slide (for instance, vertically as shown in  FIG. 7 ) within the body  22 . The lock block  66  may be coupled to a wheel teeth lock  68 . The wheel teeth lock  68  may move within the body  22  (for instance, vertically as shown in  FIG. 6 ) to engage wheel teeth  56  formed on an inner diameter surface of the wheel  24 . The assembly of the lock block  66  and wheel teeth lock  68  may be biased away from the wheel teeth  56  by a spring (not shown). 
         [0015]    The leading brake lever  38  may be rotated between an unlocked position in which the lock block  66  lifts the wheel teeth lock  68  upward out of engagement with the wheel teeth  56  to allow rotation of the wheel  24  about the body  22 , and a locked position in which the lock block forces the wheel teeth lock downward into engagement with the wheel teeth to prevent rotation of the wheel about the body.  FIG. 7  show the leading brake lever  38  in an unlocked position. Making reference to  FIG. 7 , to position the leading brake lever  38  to the locked position, the leading brake lever  38  may be pivoted counterclockwise to drive the lock block  66  and the wheel teeth lock  68  downward. Downward force on the leading brake lever causes the lever to pivot about its pivot pin  58  releasing the finger  60  from the detent  62 . The downward motion of the lock block  66  also drives the wheel teeth lock  68  against the wheel teeth  56  thereby preventing rotation of the wheel  24  about the wheel axis  28 . To re-position the leading brake lever  38  to the un-locked position, the brake lever may be pivoted clockwise to raise the assembly of the lock block  66  and the wheel teeth lock  68  and release the wheel teeth lock from the wheel teeth  56  thereby allowing rotation of the wheel  24  about the wheel axis  28 . 
         [0016]    The stem  34  is rotatably mounted in the stem cavity  32  to permit rotation of the stem relative to the body about the stem axis  36 . A bearing  70  may be provided to facilitate rotation of the stem  34  in the stem cavity  32 . The bearing  70  and stem  34  may be retained in the stem cavity with a stem cap  72 . Once installed in the application, weight applied downward to the stem  34  may also facilitate engagement of the stem and the bearing  70  in the stem cavity  32 . The stem  34  may comprise a spline shaft  74 . The spline shaft  74  may be disposed within a hollow interior  76  formed within the stem. A spring  78  may also be disposed in the hollow interior  76  of the stem  34 . The spline shaft  74  is prevented from rotation within the hollow interior of the stem  34  by a pin  80 . The pin  80  allows the spline shaft  74  to reciprocate (vertically in  FIGS. 6 and 7 ) within the hollow interior  76  of the stem  34  without rotation about the stem axis  36 . The spline shaft  74  comprises a plurality of splines  82  extending around an intermediate section  84  of the spline shaft. The intermediate section  84  of the spline shaft  74  may be tapered. A distal end  86  of the spline shaft  74  may extend away from the intermediate section  84  along a center axis of the spline shaft. 
         [0017]    In the stem cavity  32 , a spline bushing  88  is provided. The spline bushing  88  has an interior with a plurality of splines  90  and an exterior with a tab  92  which cooperates with the stem cavity  32  to prevent the spline bushing from rotation within the stem cavity. The splines  90  of the spline bushing  88  may cooperate with the splines  82  of the spline shaft  74  to allow releasably interlocking of the bushing  88  and shaft  74  together. The splines  90  of the spline bushing  88  may also be tapered to facilitate releasably interlocking of the bushing and shaft together. The stem cavity  32  may have an interior geometry to allow the spline bushing  88  to be inserted therein and constrained from movement. For instance, the spline bushing  88  may have features, including its tab  92 , which interlock with the body  22  in the stem cavity  32  so that the body and spline bushing may become integral, moving together as a unit relative to the stem when disengaged from the spline shaft. 
         [0018]    The spline bushing  88  has a center axis, which may be co-linearly aligned with the center axis of the spline shaft  74 . While the drawings show the center axis of the spline shaft  74  co-linearly aligned with the stem center axis  36 , the spline shaft center axis may also be offset from the stem center axis. The spline shaft  74  may be movable along the spline shaft center axis toward the spline bushing  88  to engage with the spline bushing in the fixed position, and the spline shaft may be movable along the spline shaft center axis away from the spline bushing to disengage from the spline bushing in the swivel position. In the swivel position, the spline shaft  74  is spaced from the spline bushing  88  so as to allow free rotation of the stem  34  relative to the body  22  about the stem axis  36 . In the fixed position, the spline shaft  74  interlocks with the spline bushing  88  to prevent rotation of the stem  74  relative to the body  22  about the stem axis  36 . While the drawings show the spline shaft  74  moving relative to the spline bushing  88 , the arrangement may be reversed. For instance, in an alternate configuration, the spline bushing may be movable along the spline bushing center axis to engage with and disengage from the spline shaft. By way of example, this configuration may be employed where the stem is integral with the spline bushing and the spline shaft is integral with the body in the stem cavity. 
         [0019]    The leading brake lever  38  may have a spline shaft stop  94 . When the leading brake lever is in the unlocked position, the spline shaft stop  94  may engage the distal end  86  of the spline shaft, maintaining the spline shaft  74  in a spaced-apart relationship with the spline bushing  88  and allowing the stem  34  and spline shaft to rotate together relative to the body  22  about the swivel axis (i.e., the swivel position). When the leading brake lever  38  is moved downward (for instance, clockwise in  FIG. 6 ), the spline shaft stop  94  may disengage from the distal end  86  of the spline shaft  74 . The spring  78  housed in the hollow interior  76  of the stem  34  may force the spline shaft  74  downward ( FIG. 6 ) to engage the spline bushing  88  (i.e., the fixed position). The cooperating tapered features of the male and female splines  82 , 90  may facilitate engagement of the spline shaft  74  with the spline bushing  88  and provide good locking properties with little play. With the leading brake lever  38  in the locked position, and the spline shaft  74  and spline bushing  88  interlocked together in the fixed position, the stem  34  is locked with the body  22  and rotation of the stem relative to the body about the stem axis  36  is prevented. 
         [0020]    To reposition the spline shaft  74  and spline bushing  88  to the swivel position, the leading brake lever  38  may be moved upward (for instance clockwise in  FIG. 7 ) such that the spline shaft stop  94  may engage the distal end  86  of the spline shaft  74  and forces the spline shaft upward, releasing the spline shaft from the spline bushing  88 . Upward motion (for instance clockwise in  FIG. 7 ) of the leading brake lever  38  acts against the pressure of the spring  78 . With the finger  60  of the leading brake lever engaging its upward detent  62 , the spline shaft  74  is moved upward so that the spline shaft spaced away from the spline bushing  88  (i.e., the swivel position). 
         [0021]    While the drawings show a leading brake lever that is movable to engage the spline shaft and the wheel, the brake lever may operate solely to prevent rotation of the wheels, and a separate lever may be provided actuate the swivel or stem lock. To lighten the weight of the body, the body may be formed with interior radial spokes  96  in the stem cavity  32 . The stem bearing  70  may be mounted on upper flat faces on the spokes  96  in the stem cavity. Additionally, the brake levers  38 , 40  may be formed with clearance grooves  98  to allow relative motion of the brake levers relative to pivot pins  44 , 58  and the axle  42  within the body  22 . 
         [0022]    The embodiments were chosen and described in order to best explain the principles and their application to thereby enable others skilled in the art to best utilize the various embodiments and with various modifications as are suited to the particular use contemplated. As various modifications could be made in the constructions and methods herein described and illustrated without departing from the scope of the invention, it is intended that all matter contained in the foregoing description or shown in the accompanying drawings shall be interpreted as illustrative rather than limiting. Thus, the breadth and scope of the present invention should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with the following claims appended hereto and their equivalents.

Technology Classification (CPC): 1