Abstract:
The present invention generally relates to work platforms, and, more particularly, to a work platform for use with a lift truck to elevate personnel safely and conveniently.

Description:
TECHNICAL BACKGROUND 
     The present invention generally relates to work platforms, and, more particularly, to a work platform for use with a lift truck to elevate personnel safely and conveniently. 
     BACKGROUND OF THE INVENTION 
     Generally a work platform is a portable enclosure for elevating personnel to a desired location. Typically work platforms may be transported, elevated or lowered by the tines of a fork truck or lift truck. The safety of personnel enclosed in the work platform is of the utmost concern. Some safety features on work platforms may include kick-plates, high handrails, mid-rails and a vertically extending guard barrier adjacent to the lift truck to prevent a worker from becoming entangled in components of the lifting mechanism of the lift truck. Additional safety features may include safety chains or straps, pin-style tine locks, and fork pockets to secure the work platform to the lift truck. 
     Typically, fork pockets positioned on the bottom side of a work platform do not protect against the work platform sliding off of the tines of a lift truck. Safety chains or straps and pin-style tine locks may be connected to the lift truck to prevent the work platform from being inadvertently pushed off of the tines of the lift truck by an overhead structure when the work platform is elevated. Some state safety regulations may require separating a work platform from a lift truck when not in operation. Unimpeded inspection of a work platform may be easier if the work platform is separated from a lift truck. However, consistent separation and reattachment of a work platform from a lift truck may increase the risk of failing to reattach safety chains or straps and pin-style tine locks. Busy operators and personnel may not always remember to reattach safety chains or pin-style tine locks. 
     SUMMARY OF THE INVENTION 
     The present invention provides an adjustable guard barrier that is capable of releasably moving an adjustable barrier upon impact. The adjustable barrier may be pivotally raised or lowered. 
     One embodiment of the present invention is a work platform for use with a lift truck, the work platform including, a base, a guard rail supported by the base, and a guard barrier rigidly coupled to the base, the base, the guard rail and the guard barrier defining an enclosure, and an adjustable barrier operably coupled to the guard barrier, the adjustable barrier extending above the guard barrier and configured to pivot between a substantially vertical position and a substantially horizontal position. 
     Another embodiment of the present invention is a work platform for use with a lift truck, the work platform including, a base, at least one guard rail supported by the base, and a guard barrier, the base, the guard rail and the guard barrier defining an enclosure, an adjustable barrier operably coupled to the guard barrier, and means for movement of the adjustable barrier upon contacting an overhead structure. 
     A further embodiment of the present invention is a work platform for use with a lift truck, the work platform including, a base, a guard barrier rigidly coupled to the base, an adjustable guard barrier coupled to the guard barrier, a plurality of side fences rigidly coupled to the base, and an adjustable support coupled to the guard barrier and the adjustable barrier, the adjustable support configured to allow the adjustable barrier to pivot downward when the adjustable barrier contacts an overhead structure. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a perspective view of one embodiment of a work platform of the present invention in association with a lift truck. 
         FIG. 2  is a perspective view of the work platform shown in of  FIG. 1 . 
         FIG. 3  is a partial, perspective view, of a portion of the adjustable barrier and guard barrier of the work platform shown in the previous figures. 
         FIG. 4  is a profile view of the work platform and lift truck shown in  FIG. 1  with the work platform shown in an elevated position in which the adjustable barrier of the work platform comes into contact with an overhead structure during rearward movement of the lift truck. 
         FIG. 5  is a profile view of the work platform and lift truck shown in  FIG. 4  with the work platform shown in an elevated position in which the adjustable barrier is collapsed by contacting overhead structure during rearward movement of the lift truck. 
     
    
    
     DETAILED DESCRIPTION 
     The embodiments described below are merely exemplary and are not intended to limit the invention to the precise forms disclosed. Instead, the embodiments were selected for description to enable one of ordinary skill in the art to practice the invention. 
     Referring now to  FIG. 1 , a work platform  10  including base  14 , guard rails  16 , guard barrier  18 , adjustable barrier  20 , and door  44  is shown. The adjustable barrier includes a first structure  40  that extends around and surrounds a second structure  42 . The second structure  42 , in the illustrated embodiment, extends between the first structure  40 . In the illustrated embodiment, the second structure  42  may include, but is not limited to, a screen that is coupled with the first structure  40 . Work platform  10  is configured to be lifted by a lift truck or fork truck  9 . Safety straps  17  may be used with pin style tin locks or any other suitable fasteners to secure work platform  10  to lifting mechanism  11  of lift truck  9 . Base  14 , guard rails  16 , guard barrier  18 , and door  44  cooperate to define enclosure  24 . Guard barrier  18  is rigidly coupled to base  14 . Adjustable barrier  20  is pivotally coupled to guard barrier  18  and extends upward to prevent a worker in enclosure  24  from becoming injured by moving parts of lifting mechanism  11  of lift truck  9 . Door  44  is illustratively coupled to guard rails  16  at the ends opposite from guard barrier  18  and adjustable barrier  20 . Door  44  illustratively pivots about one guard rail  16  from an open configuration ( FIG. 1 ) that exposes access opening  46  into enclosure  24  between both guard rails  16  and a closed configuration ( FIG. 2 ) that closes or blocks the access opening  46  into enclosure  24  between guard rails  16 . As illustrated by  FIG. 1 , in this embodiment enclosure  24  is generally rectangularly shaped, however enclosure  24  may be of any suitable shape. 
     Work platform  10  also includes adjustable supports  22 . Adjustable supports  22  couple guard barrier  18  to adjustable barrier  20 . Adjustable supports  22  allow adjustable barrier  20  to pivot in relation to guard barrier  18 . As illustrated in  FIGS. 1 and 2 , adjustable barrier  20  may pivotal relative to guard barrier  18  to a range of positions from a substantially vertical position, as shown in  FIG. 1 , to a substantially horizontal position, as shown in  FIG. 2 . 
     Referring now to  FIG. 3 , a partial view of adjustable supports  22  is shown. Adjustable supports  22  include hinges  26  and hinge bolts  30 . Hinges  26  couple to adjustable barrier  20  and guard barrier  18  to allow rotational movement relative to each other. In this embodiment, adjustable barrier  20  is held in the vertical position, as shown in  FIG. 1 , by tightening hinge bolts  30  to create a sufficient amount of friction in hinges  26  to hold adjustable barrier  20  in the vertical position. In the illustrated embodiment, adjustable supports  22  include friction fit hinges, however, in other embodiments (not shown), any suitable adjustable support such as a shear pin assembly may be used for adjustable supports  22 . 
     Referring now to  FIGS. 4 and 5 , work platform  10  is shown in use. In  FIG. 4 , work platform  10  is shown positioned on the tines of lift truck  9  in an elevated position. In this embodiment, lift truck  9  is moving rearward. The first structure  40  of adjustable barrier  20  of work platform  10  is shown contacting I-beam  32  of overhead structure  34 . Upon impact, adjustable barrier  20  pivots downward  30  in relation to guard barrier  18 . In  FIG. 5 , as lift truck  9  continues to move rearward, adjustable barrier  20  is pivoted or folded down to allow work platform  10  to pass under I-beam  32 . Pivotal movement of adjustable barrier  18  may prevent work platform  10  from being pushed off of the tines of lift truck  9  that are supporting work platform  10 . Adjustable supports  22  may be adjusted so that sufficient force is provided to maintain adjustable barrier  20  in the vertical position until adjustable barrier  20  contacts an overhead structure. The force required to move adjustable barrier  20  from the vertical position is less than the force required to push work platform  10  off of the tines of lift truck  9 . 
     Adjustable barrier  20  may perform multiple functions for work platform  10 . If adjustable barrier  20  is in the substantially horizontal position, as shown in  FIG. 2 , a first side  28  of adjustable barrier  20  may serve as a shelf, as illustrated by  FIG. 2 . An operator on work platform  10  may position adjustable barrier  20  in the horizontal position to form shelf  28 . When adjustable barrier  20  is in the horizontal position, a worker on work platform  10  should be positioned a sufficient distance from lifting mechanism  11  of lift truck  9  to prevent injury. Also when adjustable barrier  20  is in the substantially horizontal position, work platform  10  may require less storage space when compared to a work platform lacking an adjustable barrier of similar height. 
     While this invention has been described as having an exemplary design, the present invention may be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains.