Dock leveler

Abstract

The present invention pertains to a mechanically actuated dock leveler with a mounting frame secured in a pit of a loading dock, and a deck assembly with a deck and extendable lip. A deck lift assembly biases the deck to move from a parked position to a raised position to activate a lip extension assembly. As the deck is “walked down”, the lip is extended and the lip extension assembly is deactivated in a controlled manner so that the deck and lip reach an engaged position against the trailer and are kept in place by a hold down mechanism. The deck assembly has a float housing with a slot for releasably engaging the lift assembly to achieve a range of float positions where the deck and lip rest on and float with the trailer as it is loaded and unloaded. The deck assembly has a durable combined lip lug and header plate hinge construction.

1 . A dock leveler for forming a bridge between a floor of a loading dock and a trailer bed, the trailer bed being adapted to support a load and rise when that load is removed, said dock leveler comprising: 
 a deck assembly with a first hinged end, a second outer end and a deck with a lip, said deck being movable through a range of inclined positions between raised and lowered positions;    a lift assembly including a lift member and a biasing mechanism, said lift member releasably supporting said deck assembly and being upwardly and downwardly movable through a range of positions between upper and lower positions, said biasing mechanism biasing said lift member upwardly toward its said upper position and said deck toward its said raised position;    a hold down mechanism joined to said lift member, said hold down mechanism being operable to selectively prevent said lift member from moving upwardly toward its said upper extended position, said lift assembly and hold down mechanism combining to operably raise and lower said deck while said lift member remains in supporting engagement with said deck assembly to position said lip on the trailer bed; and,    wherein said deck assembly releases from its said supporting engagement with said lift member when the load is removed and the trailer bed rises, said deck and lip being supported by and rising with the trailer bed.    
   
   
       2 . The dock leveler of  claim 1 , and wherein said outer end of said deck assembly is suspended when supportably engaged by said lift assembly, said lift assembly supporting said suspended deck assembly as it moves said deck through its said range of inclined positions.  
   
   
       3 . The dock leveler of  claim 2 , and wherein said lift assembly and hold down mechanism combine to biasingly hold said deck at a desired inclined position and allow said deck to move to a lower incline position under a predetermined condition when said outer end of said deck assembly is suspended.  
   
   
       4 . The dock leveler of  claim 3 , and wherein said predetermined condition is an operator walking onto said deck and toward said outer end.  
   
   
       5 . The dock leveler of  claim 4 , and wherein said deck is horizontally, flush with the floor of the loading dock when said deck is in a parked position.  
   
   
       6 . The dock leveler of  claim 5 , and wherein said lip is positioned above the bed of the trailer when in said raised position, said deck and lift member moving down when the operator walks onto said deck until said deck assembly and lip reach an engaged position where said lip engages the trailer bed.  
   
   
       7 . The dock leveler of  claim 3 , and wherein said lip is hingably secured proximal said outer end of said deck assembly, said lip being operably movable between pendant and extended positions.  
   
   
       8 . The dock leveler of  claim 1 , and wherein the loading dock floor has a pit and said dock leveler further includes a mounting frame rigidly secured inside the pit, and wherein said first hinged end of said deck assembly is hingably secured to said mounting frame proximal the floor of the loading dock, said first hinged end being flushly aligned with the floor of the loading dock and said second outer end being pivotable about said first hinged end, and said lift member and hold down mechanism are pivotally secured to said mounting frame.  
   
   
       9 . The dock leveler of  claim 8 , and wherein said lift member is formed by lower and upper lift arms, said lower lift arm being pivotally secured to said mounting frame, and said upper lift arm being pivotally secured to said lower lift arm.  
   
   
       10 . The dock leveler of  claim 9 , and wherein said deck has a float housing that forms a slot, and said upper end of said slot forms an abutment against which said upper lift arm engages to releasably support said deck.  
   
   
       11 . The dock leveler of  claim 10 , and wherein said lift member has an upper end, and said hold down mechanism is pivotally connected to an upper end of said upper lift arm at a joint, said joint being restricted to move in said slot.  
   
   
       12 . The dock leveler of  claim 11 , and wherein said slot is substantially perpendicular to said deck.  
   
   
       13 . The dock leveler of  claim 11 , and wherein said hold down mechanism includes a pivotally fixed member and a telescoping member extendably joined to said fixed member, said telescoping member being extended through a range of extend positions between a retract position and a fully extended position, and said locking mechanism locks said telescoping member to its said fixed member to prevent outward extension of said telescoping member and said upward movement of said lift member.  
   
   
       14 . The dock leveler of  claim 13 , and wherein said fixed member of said hold down mechanism is pivotally secured to said pivot end of said lower lift arm and said telescoping member is pivotally secured to said an outer end of said upper lift arm, said lower and upper lift arms and said hold down mechanism each forming a side of a triangle, said sides of said triangle formed by said lift arms remaining a constant length, and said side of said triangle formed by said hold down mechanism varying through a range of lengths between retracted and fully extended lengths.  
   
   
       15 . The dock leveler of  claim 14 , and wherein said lift arms from an angle greater than 90 degrees when said hold down mechanism is at its said fully extended length.  
   
   
       16 . The dock leveler of  claim 9 , and wherein said lift assembly includes a deck damper secured between said deck assembly and said lower lift arm, said damper controlling a rate of relative movement between said deck and lift assembly when said deck moves from supported engagement with the trailer bed into supported engagement with said lift assembly.  
   
   
       17 . The dock leveler of  claim 1 , and wherein said biasing mechanism is a spring that continuously biases said lift member upwardly toward its said upper position and said deck toward its said raised position.  
   
   
       18 . The dock leveler of  claim 17 , and wherein said hold down mechanism has a locking mechanism selectively moveable between locked and unlock positions, said hold down mechanism allowing said lift member to move upwardly and downwardly through its said range of positions when said locking mechanism is in its said unlocked position, said hold down mechanism preventing said movement of said lift member toward said upper position when said locking mechanism is in its said locked position, said lift assembly and hold down mechanism combining to biasingly hold said lift member at a specific position when said locking mechanism is locked, said hold down mechanism allowing downward movement of said lift member when said locking mechanism is in said locked position.  
   
   
       19 . The dock leveler of  claim 18 , and wherein said locking mechanism is biased to its locked position, and is operably movable to its unlocked position.  
   
   
       20 . A dock leveler for forming a bridge between a floor of a loading dock and a trailer bed, said dock leveler comprising: 
 a deck assembly including a deck with first and second ends, said deck being movable through a range of inclined positions between raised and lowered inclined positions;    a lip assembly including a lip plate with inner and outer ends, said lip plate being operably movable between pendant and extended positions, said lip plate being biased toward said pendant position, and said lip plate being substantially flush with said deck when in said extended position;    a lip extension assembly having a series of linked components including a drive member and a drive link, said lip extension assembly being movable between engaged and disengaged positions, said drive member having a load bearing end offset from said deck assembly, said drive member and said drive link being in driving communication with said lip plat when in said engaged position, and one of said series of linked components being released from pushing engagement with an other of said linked components when in said disengaged position, said lip plate being movable between its said extended and pendent positions when said lip extension assembly is in its said disengaged position, said lip extension assembly being biased into said engaged position when said deck is in said raised position and biased into said disengaged position when said deck is below an intermediate inclined position, and said lip extension assembly driving said lip plate toward its said extended position as said deck is lowered toward said intermediate inclined position and said lip extension assembly is in its said engaged position.    
   
   
       21 . The dock leveler of  claim 20 , and wherein said drive link is releasably joined to said drive member, said drive link being movable between engaged and disengaged positions, said drive link being in pushing engagement with said drive member when in said engaged position, and said drive link being released from said pushing engagement with said drive member when said lip extension assembly is in its said disengaged position.  
   
   
       22 . The dock leveler of  claim 21 , and wherein said lip extension assembly includes a crank connector to releasably join said drive link to said drive member when in said engaged position, said crank connector being pivotally secured to said deck assembly and releasably secured to said link when in said engaged position.  
   
   
       23 . The dock leveler of  claim 22 , and wherein said crank connector is a lever having a fixed end and a free end, said fixed end of said lever being pivotally secured to said deck assembly, said mid-section being secured to said drive member at a mid-location, and said lever being releasably secured to said link between said mid location and said free end.  
   
   
       24 . The dock leveler of  claim 23 , and wherein said load bearing end of said drive member is fixed relative to said deck assembly, and said drive member has an outer end pivotally secured to said crank connector.  
   
   
       25 . The dock leveler of  claim 23 , and wherein said lip extension assembly includes a first lip assist mechanism, said lip assist mechanism being connected to said deck assembly and proximal said free end of said lever, said first lip assist mechanism biasing said lip from said pendant position toward said extended position when said deck is in said raised position.  
   
   
       26 . The dock leveler of  claim 25 , and wherein said first lip assist mechanism is a spring stretchable through a range of lengths between relaxed and activated positions.  
   
   
       27 . The dock leveler of  claim 25 , and wherein said lip extension assembly includes a bracket secured to said deck assembly, said bracket being connected to said drive link and abuttingly engaging said lip plate when in said engaged position.  
   
   
       28 . The dock leveler of  claim 27 , and wherein said lip extension assembly includes a second lip assist mechanism, said second lip assist mechanism being connected to said bracket and said lever, said second lip assist mechanism biasing said lip plate toward said extended position when said deck moves from said raised position toward said lowered position.  
   
   
       29 . The dock leveler of  claim 28 , and wherein said second assist mechanism is a damper movable between a retracted and extended lengths, said damper being adapted to freely expand toward said extended length and resist compression back toward a retracted length, and said damper is connected to said lever proximal its said, mid location.  
   
   
       30 . The dock leveler of  claim 29 , and wherein said damper extends to an activated position when said deck is at its said raised position and remains activated when said deck is moved toward its said intermediate incline position, said damper continuing to bias said lip plate toward its said extended position when said deck is lowered below said intermediate position toward said lowered position.  
   
   
       31 . The dock leveler of  claim 24 , and further including a mounting frame, said first end of said deck assembly being pivotally secured to said mounting frame, and said load bearing end of said drive member being pivotally secured to said mounting frame, said lever moving toward said first end of said deck assembly when said deck is raised toward said raised position, and said lever moving toward said second end of said deck assembly when said deck is lowered toward said lowered position.  
   
   
       32 . The dock leveler of  claim 28 , and wherein and said lever has first and second studs, said inner end of said drive link drivingly engaging said first stud when in said engaged position, and said second stud forcibly engaging said drive link to dislodge said drive link from its said engaged position with said first stud to release said drive link to its said disengaged position when said deck is lowered past its said intermediate incline position.  
   
   
       33 . The dock leveler of  claim 20 , and further including a lift assembly”, adapted to move said deck between its said inclined positions, said lift assembly biasing said deck toward its said raised position, said lift extension assembly cocking said lip extension assembly into its said engaged position when said deck is in said raised position.  
   
   
       34 . The dock leveler of  claim 33 , and further comprising a hold down mechanism connected to said lift assembly, said hold down mechanism being operable to selectively prevent said lift assembly from biasing said deck toward its said raised position, said lip extension assembly, lift assembly and hold down mechanism combining to operably position said deck and lip atop the trailer bed.  
   
   
       35 . The dock leveler of  claim 34 , and wherein said lip plate is biased by its own weight toward its said pendant position.  
   
   
       36 . A dock leveler comprising: 
 a deck assembly including a deck and a support frame, said deck having upper and lower surfaces, inner and outer longitudinal ends and first and second lateral sides, said support frame having a plurality of spaced apart, substantially parallel support beams including two outermost beams, each of said beams being supportably positioned beneath said lower surface of said deck, and each beam having an outer longitudinal end substantially aligned with said outer longitudinal end of said deck, and said outermost beams extending along said lateral sides of said deck;    a header plate having inner and outer surfaces and upper, lower and lateral edges, said upper edge of said header plate being flushly aligned with and rigidly secured to said lower surface of said deck proximal its said outer longitudinal end and said inner, surface being rigidly secured proximal said outer end of each of said beams, said outermost beams being rigidly secured to said lateral edges of said header plate, said header plate extending from one side of said deck to said other side of said deck, and said header plate being substantially perpendicular to said lower surface of said deck and substantially perpendicularly to said beams;    a set of header lugs rigidly secured to and extending outwardly from said outer surface of said header plate along its said upper edge, each header lug being substantially linearly aligned with one of said beams of said support frame;    a lip plate having upper and lower surfaces and inner, outer and lateral edges, said lateral edges of said lip plate being in substantial registry with said lateral edges of said header plate;    a set of lip lugs rigidly secured to and extending from said lower surface of said lip plate along its said inner edge, each of said lip lugs hingably joining one corresponding lug of said set of header lugs, and said lip plate is hingably movable between pendant and extended positions relative to said deck, said upper surface of said lip plate being substantially flushly aligned with said upper surface of said deck when in said extended position.    
   
   
       37 . The dock leveler of  claim 36 , and wherein each header lug and lip lug has a hinge opening, each of said hinge opening being linearly aligned to matingly received a continuous rod, said lip plate being hingably movable between said pendant and extended positions about said rod.  
   
   
       38 . The dock leveler of  claim 37 , and wherein said support beams are formed by two sets of beams and a central beam, each of said support beams in said two, sets of beams being uniformly spaced apart.  
   
   
       39 . The dock leveler of  claim 38 , and wherein said inner edge of said lip plate abuts said outer longitudinal end of said deck when in said extended position..  
   
   
       40 . The dock leveler of  claim 39 , and wherein said lip plate is substantially parallel to said header plate when in said pendant position.  
   
   
       41 . The dock leveler of  claim 40 , and wherein said longitudinal outer ends of said beams are recessed a slight distance from said outer longitudinal end of said deck.