Abstract:
A dock leveler includes a lip that not only pivots between an extended operative position and a pendant position relative to a deck but also translates in its pendant position between blocking and non-blocking positions and does so at multiple deck elevations. In the blocking positions, the lip provides a safety barrier that helps prevent material and material handling equipment from accidentally falling off the front edge of the deck when a truck is not present at the dock. The lip can serve as the safety barrier when the deck is at its stored, cross-traffic position or when the deck is at a below-dock position for end loading operations. If required, the lip can be lowered below the top surface of the deck so as not to provide an obstacle during some below-dock end loading operations.

Description:
BACKGROUND OF THE INVENTION  
       [0001]     1. Field of the Invention  
         [0002]     The subject invention generally pertains to dock levelers and more specifically to a dock leveler whose pivotal lip can provide a barrier that helps prevent material handling equipment from accidentally driving off the front edge of the dock leveler&#39;s pivotal deck.  
         [0003]     2. Description of Related Art  
         [0004]     A typical truck loading dock of a building includes an exterior doorway with an elevated platform for loading and unloading vehicles such as trucks and trailers. Many loading docks have a dock leveler to compensate for a height difference that may exist between the floor of the loading dock platform and an adjacent bed of a truck or trailer. A typical dock leveler includes a deck that is hinged along its back edge at or near the elevation of the floor so that the deck can pivotally adjust the height of its front edge to an elevation that generally matches the height of the rear edge of the truck bed to provide a ramp for material handling equipment.  
         [0005]     In addition, a front hinge may pivotally connect an extension plate or lip to the front edge of the deck. The front hinge allows the lip to pivot between a stored, pendant position and an extended, operative position. In the extended position, the lip can rest upon the truck bed to form a bridge between the deck and the bed. This allows personnel and material handling equipment, such as a forklift truck, to readily move on and off the truck during loading and unloading operations.  
         [0006]     With some dock levelers, the lip is connected to the deck in such a way that the lip can also be used as a barrier to help prevent material handling equipment from accidentally driving off the edge of the deck when no truck is parked at the dock and the deck is at its stored, cross-traffic position (i.e., the deck is flush with the top surface or floor of the dock platform). An example of such a dock leveler is disclosed in U.S. Pat. No. 4,920,598. With the &#39;598 dock leveler, the lip includes a series of slots through which a corresponding series of bolts extend to fasten the lip to a deck hinge. Sliding clearance between the bolts and the slots allow the lip to slide between a raised barrier position and a nonobstructing cleared position.  
         [0007]     With the dock leveler of the &#39;598 patent, when the lip is pendant with its front distal edge vertically supported by a stationary lip keeper, relative sliding motion between the lip and the deck allows the deck to descend to the cross-traffic position, while a back edge of the lip can protrude above the deck to create the runoff barrier.  
         [0008]     The sliding connection between the deck and the lip also accommodates end-loading operations, where loads are added or removed from the very back end of the truck or trailer bed. To prevent the lip from interfering with the placement or removal of end loads, the deck can lift the lip up from the back edge of the truck and allow the lip to hang pendant between the lip keeper and the back end of the truck. With the lip unsupported by the trailer bed or the lip keeper, the deck can descend to a below-dock position without the lip creating a barrier, thereby facilitating below-dock, end-loading operations.  
         [0009]     If, for example, the dock leveler were to remain in that position after a truck has departed from the dock position, a dockworker using a forklift could find himself exposed to the unprotected front edge of the dock leveler.  
         [0010]     Thus, a need may exist for a dock leveler with an automatic barrier that can provide runoff protection during some below-dock end-loading operations, yet the barrier can be cleared if necessary.  
       SUMMARY OF THE INVENTION  
       [0011]     In some embodiments, a dock leveler includes a deck with a pivotal lip that automatically provides a runoff barrier when the deck is at a certain below-dock position.  
         [0012]     In some embodiments, the lip provides a runoff barrier when the deck is at a cross-traffic position and certain below-dock positions.  
         [0013]     In some embodiments, the deck can be moved to various below-dock positions, such that in one position the lip provides a runoff barrier and in another position the lip recedes to a nonobstructing position.  
         [0014]     In some embodiments, it is the deck&#39;s weight that moves the deck to where a front edge of the deck is below a back edge of the lip, whereby the lip&#39;s higher back edge provides a runoff barrier.  
         [0015]     In some embodiments, the lip can pivot and translate relative to the deck.  
         [0016]     In some embodiments, a lip keeper of a dock leveler includes a plurality of vertically spaced apart resting points that can support the lip at different elevations.  
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0017]      FIG. 1  is a side view of a dock leveler whose deck is in a stored cross-traffic position and whose lip is in blocking position.  
         [0018]      FIG. 2  is a side view similar to  FIG. 1  but showing the dock leveler moving to another position.  
         [0019]      FIG. 3  is a side view similar to  FIG. 1  but showing the deck in an operative position with the lip in an extended, operative position.  
         [0020]      FIG. 4  is a side view similar to  FIG. 1  but showing the deck in a first below-dock position with the lip in a pendant, blocking position.  
         [0021]      FIG. 5  is a side view similar to  FIG. 1  but showing the deck in a second below-dock position with the lip in a pendant, nonblocking position.  
         [0022]      FIG. 6  is a side view similar to  FIG. 1  but showing the deck in an intermediate below-dock position with the lip in a pendant, blocking position.  
         [0023]      FIG. 7  is a front view of the dock leveler of  FIG. 1  but with a portion of the lip cut away.  
         [0024]      FIG. 8  is a side cross-sectional view taken along line  8 - 8  of  FIG. 7 .  
         [0025]      FIG. 9  is a cross-sectional side view similar to  FIG. 8  but showing the deck in the second below-dock position with the lip in a pendant, nonblocking position. 
     
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0026]     Referring to  FIGS. 1-6 , in order to compensate for a height differential that may exist between a loading dock platform  10  and the bed of a truck  12 , a dock leveler  14  includes a ramp or deck  16  that can pivot about its back edge  18  to adjust the height of its front edge  20 . A back hinge  22  pivotally couples deck  16  to a frame  24 , which in turn may be installed within a dock leveler pit  26 . To bridge the gap between the deck&#39;s front edge  20  and the rear edge of truck  12 , a front hinge  28  pivotally connects a lip  30  to the deck&#39;s front edge  20 .  
         [0027]     To perform various operations at the loading dock, deck  16  may be movable to a cross-traffic position ( FIG. 1 ) for storage, a raised position ( FIG. 2 ) for repositioning the deck and lip, an operative position ( FIG. 3 ) for normal loading and unloading operations, a first below-dock position ( FIG. 4 ) for below-dock end loading operations with lip  30  serving as a runoff barrier, a second below-dock position ( FIG. 5 ) with lip  30  lowered so as not to pose an obstacle for some below-dock end loading operations, and perhaps even an intermediate below-dock position ( FIG. 6 ) with lip  30  serving as a runoff barrier.  
         [0028]     In some embodiments, the various configurations or operating positions of dock leveler  14  can be achieved using a unique multi-step lip keeper  32  that can be attached to frame  24 . Lip keeper  32  works in conjunction with a lip that can both pivot and translate linearly relative to the deck. Lip  30 , for instance, can pivot between a pendant position ( FIG. 5 ) and an extended operative position ( FIG. 3 ). Lip  30  can also translate relative to deck  16  between a blocking position ( FIG. 1 ) and a non-blocking pendant position ( FIG. 5 ). A detailed description of a lip that can both pivot and translate is disclosed in U.S. Pat. No. 4,920,598, which is specifically incorporated by reference herein.  
         [0029]     In operation, truck  12  backs into the loading dock, adjacent to platform  10 , as shown in  FIG. 1 . A bumper  34 , as shown in  FIG. 2 , may be used to ensure that dock leveler  14  has adequate space to operate between truck  12  and the dock face  39 .  FIG. 1  shows deck  16  at its stored, cross-traffic position where a driveway surface  36  of deck  16  is generally flush with an upper surface  38  ( FIG. 2 ) of platform  10 , and a tip  40  of lip  30  rests upon a storage rest point  42  of lip keeper  32 , thereby supporting deck  16  at an elevation that allows traffic to move between surfaces  36  and  38 . Although just one lip keeper  32  is shown, dock leveler  14  preferably includes two or more lip keepers  32  for additional support of deck  16  and lip  30 . To prevent items such as a forklift and other material handling equipment from accidentally falling off the deck&#39;s front edge  20 , a back edge  44  of lip  30  protrudes above the deck&#39;s front edge  20  to create a safety barrier. This is accomplished by providing a sliding connection between lip  30  and deck  16 , which will be explained later.  
         [0030]     Next, in  FIG. 2 , deck  16  rises and lip  30  swings out to extend tip  40  of lip  30  out over the top of the truck bed. The movement of lip  30  and deck  16  can be carried out in any of a wide variety of ways that are well known to those of ordinary skill in the art. The movement, for example, can be powered, manually driven, or a combination of the two. Mechanisms for moving deck  16  or lip  30  include, but are not limited to, hydraulic cylinder or bladder, pneumatic cylinder or bladder, mechanical linkage, drive screw, rack and pinion, winch, mechanical spring, gas spring, and various combinations thereof, which are well known to those of ordinary skill in the art. Regardless of how deck  16  and lip  30  are moved, prior to extending the lip, deck  16  lifts lip  30  off lip keeper  32  where the sliding connection between lip  30  and deck  16  allows the lip&#39;s weight to urge the lip&#39;s back edge  44  downward to where edge  44  is below the deck&#39;s driveway surface  36 , so lip  30  has room to swing out to where the top surface of lip  30  and the deck&#39;s driveway surface  36  are generally flush with each other.  
         [0031]     Then, in  FIG. 3 , deck  16  descends to place the extended lip  30  upon the bed of truck  12 . Dock leveler  14  is now in its operative position where truck  12  can be loaded or unloaded of its cargo  48 .  
         [0032]     To add a load  50  to the very end of the truck bed, lip  30  can be lifted off the back end of the truck (to make room for the load), and deck  16  can be moved to one of its below-dock end loading position, such as the first below-dock end loading position of  FIG. 4 . Moving dock leveler  14  from its position of  FIG. 3  to that of  FIG. 4  can be accomplished in different ways. From the position of  FIG. 3 , for example, deck  16  may first rise to lift lip  30  off the truck bed. Slightly extending lip  30  would allow deck  16  to then lower the slightly extended lip between lip keeper  32  and the back end of the truck. With lip  30  slightly extended, the lip could descend past any of the rest points ( 42 ,  54 , and  52 ) of lip keeper  32  until deck  16  and lip  30  reach the position of  FIG. 5 . At this point, end load  50  could be added to the very back of the truck bed; however, lip  30  in this position would not provide a runoff barrier.  
         [0033]     If a barrier is desired in a below-dock end loading position, lip  30  could be allowed to lie pendant against the front face of lip keepers  32 , and deck  16  could lift the pendant lip until its tip  40  falls into a desired rest point of lip keeper  32 , such as a first rest point  52 . Once tip  40  falls into first rest point  52 , deck  16  can descend. While first rest point  52  supports tip  40 , the sliding connection between lip  30  and deck  16  allows front edge  20  of deck  16  to descend below back edge  44  of lip  30 , whereby below dock end-loading can be performed with lip  30  providing a runoff barrier as shown in  FIG. 4 .  
         [0034]     It should be noted that with deck  16  at the first below dock position of  FIG. 4 , back edge  44  of lip  30  is at or below the upper surface  38  of dock platform  10 . This may be beneficial when loading or unloading end loads of trucks whose truck bed lies at about the same elevation as surface  38 .  
         [0035]     It may also be beneficial to having a range of below dock loading positions with the barrier activated.  FIG. 6 , for example, shows an intermediate position that is between those of  FIGS. 1 and 4 . When deck  16  is at the intermediate below-dock position of  FIG. 6 , tip  40  of lip  30  is supported by an intermediate rest point  54  to create a runoff barrier. Moving dock leveler  14  from the position of  FIG. 4  to that of  FIG. 6  can be accomplished by first raising deck  16  and sliding pendant lip  30  upward across the front face of keeper  32  until tip  40  falls into intermediate rest point  54 . Once tip  40  falls into intermediate rest point  54 , deck  16  can descend. While rest point  54  supports tip  40 , the sliding connection between lip  30  and deck  16  allows front edge  20  of deck  16  to descend below back edge  44  of lip  30 , as shown in  FIG. 6 .  
         [0036]     Referring to  FIGS. 7 and 8 , although the actual hinge structure for connecting lip  30  to deck  16  may vary, in some embodiments, hinge  28  comprises a hinge pin  56  that pivotally joins a series of spools or deck-hinge members  58  to a series of lip-hinge members  60 . Deck-hinge members  58  are disposed about pin  56  and can be welded or otherwise attached to deck  16 . Lip-hinge members  60  may also include spools  62  disposed about pin  56 , whereby pin  56  pivotally connects spools  62  of the lip-hinge members  60  to the series of deck-hinge members  58 .  
         [0037]     To create the sliding connection between lip  30  and deck  16 , lip  30  includes a series of slots  64  along which fasteners  66  can slide. In some embodiments, fastener  66  is a shoulder screw that screws into lip-hinge member  60  and slides within slot  64 .  
         [0038]      FIGS. 7 and 8  show dock leveler  14  at its stored cross-traffic position, and  FIG. 9  shows dock leveler  14  at its second below-dock position.  
         [0039]     Although the invention is described with reference to a preferred embodiment, it should be appreciated by those of ordinary skill in the art that various modifications are well within the scope of the invention. Therefore, the scope of the invention is to be determined by reference to the following claims: