Abstract:
A float mechanism for movably attaching an implement to a vehicle has a mounting frame that connects onto the vehicle and a fixed frame that affixes to the implement. A pivot bracket pivotally attaches to one of the frames and is slidably connected to the other to accommodate a limited degree of translational motion. The pivot bracket can slidably connect to the frame by a pair of guides in combination with a pair of sleeves. Rotational motion between the fixed frame and the mounting frame can be limited by slots in one of the frames that are slidably engaged by a stabilizing element on the other frame. When the stabilizing element is a horizontal bar, it can engage a pair of vertical slots. To optionally eliminate the free motion between the frames, movable blocks can be employed to limit the motion of each stabilizing element in its slot.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to a mechanism for attaching an implement such as a snowplow onto a vehicle while allowing some free motion of the implement in service. 
       BACKGROUND OF THE INVENTION 
       [0002]    Float mechanisms are employed for mounting material-moving implements such as loader buckets and snowplows onto vehicles. The float mechanism allows a limited degree of free motion of the implement, allowing it to accommodate uneven terrain surfaces. Preferably, the float mechanism is designed to attach to an instant transfer connector on the vehicle to allow the implement, with the float mechanism attached thereto, to be readily removed for transportation, use on a different vehicle, or to free the vehicle for other uses. One such float mechanism is taught in U.S. Publication 2008/0028643. 
         [0003]    While the float mechanism taught in the &#39;643 publication offers a significant improvement over earlier implement mounting structures, it has been found to suffer from limited stability under some operating conditions. When mounted to a wheeled vehicle having relatively low-pressure tires, it has been found the bouncing of such vehicles over relatively uneven surfaces results in an undesirable degree of pitching of the implement due to the free play in the float mechanism. 
       SUMMARY 
       [0004]    The present invention is for a float mechanism for attaching a material-moving implement such as is taught in the U.S. Pat. No. 7,360,327 to an instant transfer connector on a vehicle. One such instant transfer connector is available from Caterpillar Inc. The float mechanism allows the material-moving implement a limited degree of free motion relative to the instant transfer connector on the vehicle to accommodate irregularities in the surface over which the vehicle and the material-moving equipment travel. 
         [0005]    The float mechanism has a mounting frame which has a pair of substantially vertical supports affixed at a set separation configured to slidably and lockably engage the instant transfer connector which is attached to the vehicle. A fixed frame is attached to the material-moving implement, and may be formed as an integral part of the implement. 
         [0006]    A pivot bracket is pivotally attached with respect to one of the frames about a pivot bracket axis and is slidably connected with respect to the other of the frames so as to accommodate a limited degree of translational motion sliding along a nominally vertical axis. The pivot bracket serves to maintain the motion of the fixed frame relative to the mounting frame within the nominally vertical plane while allowing limited translation between the frames, and thereby prevents unintended pitching of the material-moving implement. 
         [0007]    The slidable connection of the pivot bracket to one of the frames can be provided by a pair of guides that are fixed to either the pivot bracket or the frame, in combination with a pair of sleeves that are affixed to the other of these elements. Stops on the guides can be employed to limit the translational motion between these elements. 
         [0008]    In some applications, it can also be beneficial to limit the rotational motion between the fixed frame and the mounting frame. This motion could be limited by one or more stops affixed to one of the frames or to the pivot bracket. However, to reduce the bending moments on the pivot bracket resulting from loads due to the scraping action of the material-moving implement, it is preferred to limit the rotation by a mechanism that is substantially spaced apart from the pivot bracket which, in addition to limiting the rotation of the frames, also serves to guide the motion along a path that maintains the two frames in parallel relationship. This action can be provided by one or more slots in one of the frames, and one or more corresponding stabilizing elements on the other of the frames, configured to slidably engage the slot(s), thereby providing limited motion in a plane that is substantially normal to the pivot bracket axis. 
         [0009]    In one embodiment, a horizontally-extending transfer bar affixed to either the mounting frame or the fixed frame slidably engages one or more substantially vertical slots in the other frame. Providing a pair of substantially vertical slots that are spaced apart will tend to balance the forces to reduce wear and reduce the likelihood of binding. 
         [0010]    When one or more slots in combination with one or more stabilizing elements are employed to limit rotational motion between the fixed frame and the mounting frame, movable blocks can be employed to deactivate the float mechanism and prevent free movement. These blocks can be positioned to block a portion of the slot(s) to prevent movement of the stabilizing element(s) therein. Preventing free movement can be particularly advantageous when the float mechanism is employed with a loading bucket during loading operations, to prevent any motion that could result from uneven loading. 
     
    
     
       BRIEF DESCRIPTION OF THE FIGURES 
         [0011]      FIG. 1  is a partially-exploded isometric view showing a float mechanism that forms one embodiment of the present invention, the float mechanism serving to support a material-moving implement. The float mechanism has a fixed frame that is affixed to the implement and a mounting frame that has a pair of vertical members configured to attach to an instant transfer connector of a vehicle (not shown). The fixed frame has a centrally-positioned cross-brace with a pivot shaft affixed thereto. A pivot bracket is pivotably attached to the pivot shaft so as to rotate with respect to the fixed frame about a pivot bracket axis. The pivot bracket in turn has a pair of guides that are slidably engaged by sleeves on the mounting frame. The guides extend along a plane that is normal to the pivot bracket axis; in service, the guides are positioned so as to generally extend vertically. The guides pass through top and bottom plates that limit the translation of the sleeves thereon. The rotation of the pivot bracket with respect to the fixed frame can be limited by a bracket stop protrusion that extends from the top plate so as to engage the cross brace of the fixed frame to limit rotation of the pivot bracket. 
           [0012]      FIG. 2  is an exploded view showing further details of how the pivot bracket shown in  FIG. 1  is connected to the remaining structures. The pivot bracket has a bracket passage therethrough configured to slidably engage the pivot shaft, and a retaining collar is provided that attaches to the pivot shaft to trap the pivot bracket thereon. To engage the pivot bracket with the mounting frame, the guides are provided by a pair of guide pins that slide into guide passages in the top and bottom plates of the pivot bracket. The guide pins are inserted into the passages while the sleeves of the mounting frame are positioned between the top and bottom plates with sleeve passages aligned with the guide passages. When the guide pins are installed, the sleeves are trapped on the guide pins between the top and bottom plates. 
           [0013]      FIG. 3  is an isometric view showing the pivot bracket shown in  FIGS. 1 and 2  when connected to the fixed frame and the mounting frame. 
           [0014]      FIG. 4  is an isometric view that illustrates another float mechanism of the present invention; this embodiment provides greater stability for the implement attached to the fixed frame. In this float mechanism, pivoting of the fixed frame relative to the mounting frame is further limited by a pair of substantially vertical slots that are slidably engaged by a transfer bar that serves as a stabilizing element as well as reducing bending moments on the pivot bracket. As illustrated, the transfer bar is affixed to the fixed frame, spaced apart vertically from the pivot shaft, and the slots are provided on the mounting frame. The slots are formed by slot plates affixed to the mounting frame in combination with closure plates that attach to the slot plates to close the remaining side of the slots. The use of a pair of slots to engage the transfer bar provides an effective three-point support for the implement to increase stability and reduce bending moments on the pivot shaft. 
           [0015]      FIG. 5  is an isometric view of the embodiment shown in  FIG. 4  when partially exploded to show further details of the structure associated with the vertical slots, including extendable blocks that can be positioned to immobilize the transfer bar in the slots to provide a rigid connection between the mounting frame and the fixed frame. 
           [0016]      FIG. 6  is an isometric view illustrating an embodiment similar to that shown in  FIGS. 4 and 5 , but where two vertical slots are provided on the fixed frame and engage a transfer bar attached to the mounting frame. 
           [0017]      FIGS. 7 and 8  are isometric views showing an embodiment having a fixed frame that is provided with a pair of horizontal guide slots, each of which is slidably engaged by a vertically-extending transfer post affixed to the mounting frame.  FIG. 7  shows the float mechanism partly exploded. 
           [0018]      FIG. 8  is an isometric view showing the float mechanism shown in  FIG. 7  when assembled and where relative motion between the frame members can be prevented by locking pins that engage both a mounting frame and at least one of the bars that define the horizontal guide slots. 
           [0019]      FIG. 9  is a partially-exploded isometric view showing an embodiment similar to that shown in  FIGS. 4 and 5 , but where the pivot bracket is provided with sleeves that slidably engage guides provided on the mounting frame. 
           [0020]      FIG. 10  is a partially-exploded isometric view showing an embodiment similar to that shown in  FIG. 9 , but where the pivot bracket engages a pivot shaft on the mounting frame, and has sleeves that slidably engage guides mounted to the fixed frame. 
       
    
    
     DETAILED DESCRIPTION 
       [0021]      FIGS. 1-3  illustrate a float mechanism  10  that is designed for supporting a material moving implement such as a snowplow  12  to allow the snowplow  12  to move freely to traverse uneven ground surfaces while being supported on a vehicle (not shown). The float mechanism  10  has a fixed frame  14  that is affixed to the snowplow  12 , and can be made an integral part thereof. The float mechanism  10  also has a mounting frame  16  that is connected to the fixed frame  14  by a pivot bracket  18 . The mounting frame  16  in turn has a pair of substantially vertical supports  20  that are configured to releasably engage a conventional instant transfer connector on the vehicle, such as the instant transfer provided by Caterpillar Inc. 
         [0022]    The fixed frame  14  has a pivot shaft  22  that extends along a pivot axis  24 . The pivot axis  24  is substantially horizontal when the float mechanism is in service, and extends in the direction of travel of the vehicle. In the float mechanism  10 , the pivot shaft  22  is mounted to a centrally-located cross-brace  26  that is affixed to the remainder of the fixed frame  14 . The pivot bracket  18  has a bracket passage  28  therethrough, which is lined with an appropriate weight-bearing low-friction bracket bushing  30  that slidably engages the pivot shaft  22  on the fixed frame  14 . The bracket bushing  30  can be a conventional grooved metal bushing. The pivot shaft  22  has a length sufficient that it extends beyond the bracket passage  28 . As shown in  FIG. 2 , a pivot shaft passage  32  is provided through the pivot shaft  22  to accommodate a pivot shaft bolt  34 . A retaining collar  36  is configured to slidably engage the portion of the pivot shaft  22  that extends beyond the bracket passage  28 , and has a collar passage  38  into which the pivot shaft bolt  34  can be threadably secured. When the pivot bracket  18  and the retaining collar  36  are slidably engaged on the pivot shaft  22 , the collar passage  38  is aligned with the pivot shaft passage  32  and the pivot shaft bolt  34  can be inserted into the aligned passages ( 32 ,  38 ) to retain the retaining collar  36  on the pivot shaft  22  with the pivot bracket  18  trapped between the retaining collar  36  and the fixed frame  14 , as shown in the assembled view of  FIG. 3 . Preferably, bracket washers  40  of a durable, low-friction material such as nylon are interposed between the pivot bracket  18  and the fixed frame  14 , and between the pivot bracket  18  and the retaining collar  36  (as best shown in the exploded view of  FIG. 2 ). 
         [0023]    The pivot bracket  18  in turn is connected to the mounting frame  16  by a slide mechanism  42  that allows limited translation between the pivot bracket  18  and the mounting frame  16 , this motion being limited to translation in a plane that is normal to the pivot axis  24 . As shown in  FIG. 2 , the pivot bracket  18  is provided with a top plate  44  and a bottom plate  46 , each having a pair of guide passages  48  into which guide pins  50  can be inserted. The guide passages  48  are centered on guide axes  52  which reside in a plane that is normal to the pivot axis  24 ; typically, the guide axes  52  are substantially vertical. 
         [0024]    The mounting frame  16  has a pair of sleeves  54 , each having a sleeve passage  56  that is sized to slidably engage one of the guide pins  50 . When the sleeves  54  are placed between the top plate  44  and the bottom plate  46  with the sleeve passages  56  aligned with the guide passages  48 , the guide pins  50  can be inserted into the aligned passages ( 48 ,  56 ) and secured to the pivot bracket  18  by guide pin bolts  58  that each pass through a bracket pin passage  60  on the pivot bracket  18  and a guide pin passage  62  through one of the guide pins  50 . The sleeve passages  56  are preferably lined with sleeve bushings  64  of a durable, low friction material such as nylon. 
         [0025]    When the fixed frame  14 , the mounting frame  16 , and the pivot bracket  18  are so connected, the snowplow  12  is free to rotate about the pivot axis  24  to accommodate changing angles of road surfaces over which the snowplow  12  is operated. Additionally, the slidable engagement between the pivot bracket  18  and the mounting frame  16  allows the snowplow  12  a limited degree of vertical translation along the guide axes  52  to allow the snowplow  12  to ride over small obstructions. 
         [0026]    While the position of the snowplow  12  is typically limited by the ground surface to be traversed, it is frequently desirable to limit the rotation of the snowplow  12  to maintain it in a generally horizontal position when lifted from the ground. The rotation of the snowplow  12  can be limited by means for limiting the rotation between the fixed frame  14  and the mounting frame  16 . One example of such means, shown in  FIGS. 1-3 , is to provide a stop protrusion  66  affixed to the pivot bracket  18  and positioned to engage the cross-brace  26  of the fixed frame  14  when the fixed frame  14  rotates relative to the pivot bracket  18  by a predetermined angle. 
         [0027]    While the float mechanism  10  can provide more stable support to the snowplow  12  than earlier float mechanisms, it relies solely on the connections of the pivot bracket  18  to maintain the motion of the fixed frame relative to the mounting frame constrained within a plane. This places great requirements for structural integrity on the pivot bracket, and makes it highly susceptible to wear. These disadvantages can be reduced by employing means for limiting the rotation between the fixed frame and the mounting frame that also aid in limiting the motion between these elements to motion within a plane. 
         [0028]      FIGS. 4 and 5  illustrate a float mechanism  100 , which provides greater stability for an implement  102  attached to a fixed frame  104  compared to the float mechanism  10  discussed above. Again, a pivot bracket  106  is rotatably mounted to a pivot shaft  108  on the fixed frame  104 , and is connected and to a mounting frame  110  by a slide mechanism  112 . However, the float mechanism  100  differs in the means for limiting rotation between the fixed frame  104  and the mounting frame  110  that are employed. 
         [0029]    In the float mechanism  100 , the pivot shaft  108  is located in a lower region  114  of the fixed frame  104 ; this position of the pivot shaft  108  will tend to reduce the moment of torques on the pivot bracket  106  resulting from forces transmitted by the implement  102  when in operation. Rotation of the fixed frame  104  relative to the mounting frame  110  is limited by a transfer bar  116  that is slidably restrained by engagement with a pair of guide slots  118 . The use of a pair of guide slots  118  to engage the transfer bar  116  provides an effective three-point support for the implement  102  to further reduce bending moments on the pivot shaft  108  and the pivot bracket  106 , as well as increasing the stability of the implement  102  when in motion. 
         [0030]    The transfer bar  116  in this embodiment is affixed to the fixed frame  104  so as to extend substantially horizontally, and is spaced apart vertically from the pivot shaft  108  so as to be located in an upper region  120  of the fixed frame  104 . The guide slots  118  are provided on the mounting frame  110 , and extend substantially vertically, extending parallel to the direction of motion provided by the slide mechanism  112 . The guide slots  118  are each formed by a slot plate  122  affixed to the mounting frame  110 , in combination with a closure plate  124  that attaches to the slot plate  122  to close the remaining side of the guide slot  118 . The slot plate  122  and the closure plate  124  are each provided with a replaceable bearing surface ( 126 ,  128 ) of a durable, low-friction material such as nylon. The transfer bar  116  has a pair of opposed bar vertical sides  130 , and when the closure plate  124  is attached to the slot plate  122  with the transfer bar  116  interposed therebetween, the bearing surfaces ( 126 ,  128 ) are positioned against the bar vertical sides  130  to limit the motion of the transfer bar  116  relative to the guide slot  118  to motion within a nominally vertical plane. Each of the closure plates  124  can be attached to its associated the slot plate  122  by bolts  132  that are inserted through aligned passages ( 134 ,  136 ) in the closure plate  124  and the slot plate  122 . 
         [0031]    Rotation of the fixed frame  104  with respect to the mounting frame  110  is limited by the motion of the transfer bar  116  in the guide slots  118 . Each of the slot plates  122  has a slot upper plate  138  that defines an upper end of the guide slot  118 , while a lower end of the guide slot  118  is defined by a blocking plate  140  that slidably engages a block mounting bracket  142  affixed to the slot plate  122 . Both the slot upper plate  138  and the blocking plate  140  are preferably provided with resilient pads  144  for respectively engaging a bar upper surface  146  and a bar lower surface  148  of the transfer bar  116  to limit its movement with respect to the guide slot  118 . As the fixed frame  104  rotates with respect to the mounting frame  110  about a pivot axis  150  defined by the pivot shaft  108 , at some point the bar upper surface  146  or the bar lower surface  148  will engage one of the resilient pads  144 , this engagement serving to block further rotation in that direction. 
         [0032]    When the blocking plates  140  that form the lower ends of the guide slots  118  are movably mounted to the mounting frame  110 , they can allow the float mechanism  100  to be disabled to provide a rigid connection between the mounting frame  110  and the fixed frame  104 . This can be beneficial when the implement  102  is capable of being used as a loader bucket; such an implement that can be configured to operate either as a plow or as a loader bucket is taught in U.S. Pat. No. 7,360,327. 
         [0033]    In the float mechanism  100 , each of the blocking plates  140  has an upper block passage  152  and a lower block passage  154  therethrough, either of which can be aligned with a block bracket passage  156  in the block mounting bracket  142  to allow a block pin  158  to be passed through the aligned passages ( 152  or  154 ,  156 ) to fix the position of the blocking plate  140  with respect to the slot plate  122 . When the block upper passage  152  is aligned with the block bracket passage  156  and pinned, the blocking plate  140  is fixed in a retracted position (as shown in  FIG. 4 ) where it is spaced apart from the slot upper plate  138  by a sufficient distance to allow the desired degree of movement of the transfer bar  116  in the guide slot  118 . However, when the blocking plate  140  is positioned such that the block lower passage  154  is aligned with the block bracket passage  156 , passing the block pin  158  through the aligned passages ( 154 ,  156 ) fixes the blocking plate  140  in an extended position (shown in  FIG. 5 ) where its separation from the slot upper plate  138  (measured between the opposed surfaces of the resilient pads  144 ) is about the same as the separation between the bar upper surface  146  and the bar lower surface  148  of the transfer bar  116 , thereby preventing vertical movement of the transfer bar  116  in the guide slot  118 . Since horizontal motion of the transfer bar  116  relative to the guide slot  118  is prevented by the connection of the pivot bracket  108  to the fixed frame  104  and the mounting frame  110 , pinning the blocking plates  140  into their extended positions effectively immobilizes the fixed frame  104  relative to the mounting frame  110 , allowing the implement  102  to be used as a loading bucket without undesirable free movement resulting from shifting of loads supported by the implement  102 . 
         [0034]      FIG. 6  is an isometric view of a float mechanism  200  which shares many features in common with the float mechanism  100  discussed above, having a fixed frame  202  that is pivotably connected to a pivot bracket  204  which in turn is slidably connected to a mounting frame  206 . In the float mechanism  200 , rotation of the fixed frame  202  with respect to the mounting frame  206  is again provided by a transfer bar  208  that is slidably engaged in a pair of guide slots  210 . However, in this embodiment, the transfer bar  208  is affixed to the mounting frame  206 , while the guide slots  210  are formed by slot plates  212  affixed to the fixed frame  202 , in combination with closure plates  214 . The closure plates  214  attach to the slot plates  212  with the transfer bar  208  trapped therebetween. Again, the slot plates  212  are each provided with a block mounting bracket  216  in which a blocking plate  218  can be affixed in either an extended or retracted position. With respect to the third stabilizing element to prevent tilting between the frames ( 202 ,  206 ) such is provided by the pivot bracket  204  which engages a pivot shaft  220  and is further stabilized by washers  222  and a retaining collar  224 . 
         [0035]      FIGS. 7 and 8  illustrate an alternative float mechanism  300 , which again has a fixed frame  302  pivotably connected to a pivot bracket  304  that in turn slidably engages a mounting frame  306 . In this embodiment, the fixed frame  302  is stabilized with respect to the mounting frame  306  by a pair of guide slots  308  that extend horizontally along the fixed frame  302 , in combination with a pair of vertically-extending guide bars  310  affixed to the mounting frame  306 . However, in the float mechanism  300  illustrated, the guide slots  308  and the guide bars  310  are not employed to limit the rotation of the fixed frame  302  relative to the mounting frame  306 . 
         [0036]    The fixed frame  302  is provided with a horizontally-extending slot bar  312  that is provided with a slot bearing surface  314  of a durable, low-friction material. A series of slot brackets  316  are also provided, to which a closure bar  318  can be attached by slot bar bolts  320 . The closure bar  318  has a bar bearing surface  322  of a durable, low-friction material, positioned so as to be opposed to the slot bearing surface  314  when the closure bar  318  is secured to the slot brackets  316 , these opposed surfaces ( 314 ,  322 ) defining parallel sides of the guide slots  308 . 
         [0037]    The guide bars  310  are each provided on a guide plate  324  affixed to the mounting frame  306 . The guide bars  310  have opposed guide surfaces  326  spaced apart to slidably engage the slot bearing surface  314  and the bar bearing surface  322 , to provide additional support regions between the frames ( 302 ,  306 ), thereby reducing the torques on the pivot bracket  304 . 
         [0038]    While the slot brackets  316  which serve to terminate the guide slots  308  and the guide bars  310  could serve to limit the rotation of the fixed frame  302  with respect to the mounting frame  306 , in this embodiment such rotation is more restrictively limited by stops  328  on the fixed frame  302  that are positioned to engage the guide plates  324  to limit such rotation, thereby providing a narrower limit of motion. Preferably, the stops  328  are each provided with a resilient pad  330 . 
         [0039]    This embodiment also employs a different scheme for deactivating the float mechanism  300  for use supporting a loading bucket. The guide plates  324  are each provided with a guide plate passage  332 , which can be aligned with closure bar passages  334  provided in the closure bar  318 . When so aligned, deactivation pins  336  can be inserted into the aligned passages ( 332 ,  334 ) to prevent movement of the fixed frame  302  with respect to the mounting frame  306 . 
         [0040]      FIG. 9  illustrates a float mechanism  400  that has many features in common with the float mechanism  100  shown in  FIGS. 4 and 5 , but which differs in the connection between a pivot bracket  402  and a mounting frame  404 . In this embodiment, the pivot bracket  402  is provided with bracket sleeves  406  that are configured to slidably engage guides  408  that are attached to the mounting frame  404  so as to provide a slide mechanism  410 . The guides  408  each terminate at a top plate  412  and a bottom plate  414  to limit the slidable engagement between the pivot bracket  402  and the mounting frame  404 . The pivot bracket  402  in turn is pivotably mounted to a fixed frame  416  in a manner similar to the connection between the pivot bracket  18  and the fixed frame  14  discussed in detail above with regard to  FIGS. 1 - 3 . 
         [0041]      FIG. 10  illustrates another alternative embodiment, a float mechanism  450  where a pivot bracket  452  is pivotably connected to a mounting frame  454  and slidably connected to a fixed frame  456 . In this embodiment, the mounting frame  454  is provided with a pivot shaft  458  that slidably engages a bracket passage  460  through the pivot bracket  452 . A retaining collar  462  attaches to the pivot shaft  458  to trap the pivot bracket  452  thereon to pivotably connect the pivot bracket  452  to the mounting frame  454 . 
         [0042]    The pivot bracket  452  in turn has a pair of bracket sleeves  464  that slidably engage a pair of guides  466  that are mounted to the fixed frame  456  to allow a limited degree of translational motion between the pivot bracket  452  and the fixed frame  456 . The translation is limited by a top plate  468  and a bottom plate  470 . 
         [0043]    While the novel features of the present invention have been described in terms of particular embodiments and preferred applications, it should be appreciated by one skilled in the art that substitution of materials and modification of details can be made without departing from the spirit of the invention.