Unitary liftgate

Abstract

The invention is a unitary cantilever liftgate that attaches to the vehicle body instead of the vehicle chassis. The liftgate may be fully assembled and tested prior to installation on the vehicle body. This greatly reduces installation time while improving performance and reliability. Various features such as steps, bumpers and brackets are integrated into the liftgate. Further, the liftgate is preferably configured so that multiple units can be stacked together for shipping and ease of unloading and loading. The stackability of the liftgates simplifies storing as well, by removing the necessity of storing several components separately.

1 . A liftgate assembly, comprising: 
 a unitary frame comprising an opposing pair of side plates and an extension plate extending between the side plates;    a hydraulically driven lift frame pivotally attached to the side plates;    a liftgate platform rotatably attached to the lift frame and supported at one end only; and    impact bumpers attached to the side plates.    
   
   
       2 . The liftgate assembly of  claim 1 , wherein the opposing pair of side plates are adapted to secure the liftgate assembly to an underside of a vehicle body.  
   
   
       3 . The liftgate assembly of  claim 2 , wherein the opposing pair of side plates are bolted to the underside of the vehicle body.  
   
   
       4 . The liftgate assembly of  claim 1 , wherein the side plates in the unitary frame further comprise formed steps.  
   
   
       5 . The liftgate assembly of  claim 1 , further comprising a hydraulic pump mounted on the unitary frame and coupled to the lift frame.  
   
   
       6 . (canceled)  
   
   
       7 . The liftgate assembly of  claim 1 , further comprising brackets attached to the side plates in the unitary frame for mounting vehicle lights.  
   
   
       8 . The liftgate assembly of  claim 1 , wherein the lift frame further includes a lift frame tube configured to function as an underride guard.  
   
   
       9 . The liftgate assembly of  claim 1 , wherein: 
 the liftgate assembly includes at least one upper stacking member and at least one lower stacking member; and    a profile of the lower stacking member is configured to nest with a profile of the upper stacking member.    
   
   
       10 . A vehicle liftgate assembly comprising: 
 a vehicle having a substantially horizontal vehicle bed; and    a liftgate comprising:    a unitary frame, the unitary frame comprising an opposing pair of side plates configured to be secured to an underside of the vehicle bed and an extension plate extending between the side plates;    an actuator driven lift frame pivotally attached to the side plates;    a liftgate platform rotatably attached to the lift frame and supported at one end only; and    impact bumpers attached to the side plates.    
   
   
       11 . The vehicle liftgate assembly of  claim 10 , wherein the side plates are secured to the underside of the vehicle bed by bolts.  
   
   
       12 . The vehicle liftgate assembly of  claim 10 , wherein: 
 the vehicle further includes a vehicle chassis; and    the unitary frame of the liftgate is detached from the vehicle chassis.    
   
   
       13 . The vehicle liftgate assembly of  claim 10 , wherein: 
 the vehicle bed comprises a truck bed floor; and    the unitary frame is mounted substantially below the truck bed floor.    
   
   
       14 . The vehicle liftgate assembly of  claim 13 , wherein the extension plate is mounted in a plane formed by the truck bed floor to provide a bridge from the truck bed to the liftgate platform when the liftgate platform is horizontally extended in the plane of the truck bed floor.  
   
   
       15 - 20 . (canceled)  
   
   
       21 . Method for providing a cantilever liftgate comprising the steps of: 
 (a) providing a unitary frame comprising an opposing pair of side plates and an extension plate extending between the side plates;    (b) pivotally attaching a lift frame to the side plates;    (c) rotatably attaching a liftgate platform to the lift frame so that the platform is supported at one end only; and    (d) attaching impact bumpers to the side plates.    
   
   
       22 . The method of  claim 21 , further comprising the step of shipping the liftgate to a customer.  
   
   
       23 . The method of  claim 21 , further comprising the step of stacking the liftgate on top of another liftgate.  
   
   
       24 . The method of  claim 23 , further comprising the step of packaging and shipping the stacked liftgates together.  
   
   
       25 . The method of  claim 21 , further comprising the step of securing the liftgate to a vehicle body by bolting or welding the unitary frame to the base of a truck bed.  
   
   
       26 . The method of  claim 21 , further comprising the step of attaching a motion limit member to a pivot member of the lift frame to confine a motion of the liftgate platform between a first orientation and a second orientation substantially perpendicular to each other.  
   
   
       27 . A liftgate, comprising: 
 a unitary frame including an opposing pair of side plates and an extension plate extending there between, each of the side plates having an upper edge adapted for attaching to an underside of a body;    a lift frame pivotally attached to the side plates of the unitary frame and having a pivot member;    a platform having a first side rotatably attached to the pivot member of the lift frame, the platform being supported at the first side only;    a motion limiting stop attached to the lift frame adjacent the pivot member and configured to limit a motion of the platform; and    impact bumpers attached to the side plates.    
   
   
       28 . The liftgate of  claim 27 , wherein the upper edge of each side plate in the unitary frame is adapted for attaching to the underside of a vehicle body.  
   
   
       29 . The liftgate of  claim 27 , further comprising a plurality of bolts for bolting the upper edges of the side plates in the unitary frame to the underside of the body.  
   
   
       30 . The liftgate of  claim 27 , wherein the side plates in the unitary frame further comprise formed steps.  
   
   
       31 . The liftgate of  claim 27 , further comprising a hydraulic pump mounted on the unitary frame and coupled to the lift frame.  
   
   
       32 . The liftgate of  claim 27 , further comprising impact bumpers attached to the unitary frame.  
   
   
       33 . The liftgate of  claim 27 , further comprising brackets attached to the side plates in the unitary frame for mounting vehicle lights.  
   
   
       34 . The liftgate of  claim 27 , wherein the lift frame further includes a lift frame tube configured to function as an underride guard.  
   
   
       35 . The liftgate of  claim 27 , wherein the unitary frame further includes at least one upper stacking member on an upper edge of each of the side plates and at least one lower stacking member on a lower edge of each of the side plates, a profile of the lower stacking member being configured to nest with a profile of the upper stacking member.  
   
   
       36 . A vehicle body assembly including a vehicle body and a cantilever liftgate, the cantilever liftgate comprising: 
 a unitary frame comprising an opposing pair of side plates and an extension plate extending there between, the side plates having upper edges configured to be attached to an underside of the vehicle body;    an actuator driven lift frame pivotally attached to the side plates;    a liftgate platform rotatably attached to the actuator driven lift frame; and    impact bumpers attached to the side plates.    
   
   
       37 . The vehicle body assembly of  claim 36 , wherein the upper edges of the side plates are securely attached to the vehicle body by bolts.  
   
   
       38 . The vehicle body assembly of  claim 36 , wherein the lift frame is configured to be attached to the unitary frame prior to the upper edges of the side plates being attached to the vehicle body.  
   
   
       39 . The vehicle body assembly of  claim 36 , the cantilever liftgate further comprising a motion limiting stop attached to the lift frame and configured to limit a rotational motion of the liftgate platform.  
   
   
       40 . The vehicle body assembly of  claim 36 , wherein the extension plate is substantially coplanar with a floor of the vehicle body.  
   
   
       41 - 45 . (canceled)  
   
   
       46 . A method for providing a cantilever liftgate, comprising the steps of: 
 (a) providing a unitary frame comprising an opposing pair of side plates and an extension plate extending between the side plates;    (b) pivotally attaching a lift frame to the side plates;    (c) rotatably attaching a liftgate platform to a pivot member of the lift frame so that the platform is supported at one end only;    (d) attaching a motion limit member to the pivot member of the lift frame; and    (e) attaching impact bumpers to the side plates.    
   
   
       47 . The method of  claim 46 , further comprising, after steps (a), (b), (c), and (d) have been completed, the step of securing the unitary frame to an underside of a vehicle body.  
   
   
       48 . The method of  claim 47 , wherein the step of securing the unitary frame to an underside of a vehicle body includes bolting or welding the unitary frame to a base of the truck bed.  
   
   
       49 . The method of  claim 46 , further comprising, after steps (a), (b), (c), and (d) have been completed, the step of stacking the liftgate on top of another liftgate.  
   
   
       50 . The method of  claim 49 , further comprising the step of packaging and shipping the stacked liftgates together.  
   
   
       51 . The method of  claim 46 , wherein the step of attaching a motion limit member to the pivot member of the lift frame includes confining a motion of the liftgate platform between a first orientation and a second orientation substantially perpendicular to each other.