Abstract:
A stacker includes a base and a vertical structure supported by the base. A lift unit includes a support surface for engaging and lifting a tray from a stack of trays. The lift unit is mounted to the vertical structure and movable vertically relative to the vertical structure. A lifting mechanism selectively raises and lowers the lift unit relative to the vertical structure. The support surface may be formed on first and second projections configured to engage first and second handle openings of a tray. The stacker facilitates several stacking/destacking methods for more easily converting a stack of trays at a first height to a stack of trays at a second height. For example, the first height may be more convenient or appropriate for use in a bakery, while the second height may be more efficient for loading in a truck.

Description:
BACKGROUND 
       [0001]    Stackable plastic trays are often used for shipping goods, such as bakery items. A common practice in the baking industry is to limit the stack height to 70-90″ for bakery trays leaving a bakery. However, for shipping efficiency, the trailer delivering the loaded bakery trays to the distribution center or retail location should ideally be cubed out to the internal height of the trailer, which may be 100-105″. 
       SUMMARY 
       [0002]    A stacker includes a base and a vertical structure supported by the base. A lift unit includes a support surface for engaging and lifting a tray from a stack of trays. The lift unit is mounted to the vertical structure and movable vertically relative to the vertical structure. A lifting mechanism selectively raises and lowers the lift unit relative to the vertical structure. The support surface may be formed on a first projection configured to engage a first handle opening of a tray. A second projection may be configured to engage a second handle opening in the tray opposite the first handle opening. The stacker facilitates several stacking/destacking methods for more easily converting a stack of trays at a first height to a stack of trays at a second height. For example, the first height may be more convenient or appropriate for use in a bakery, while the second height may be more efficient for loading in a truck. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0003]      FIG. 1  is a perspective view of a stacker according to one embodiment. 
           [0004]      FIG. 2  is a section view through the stacker of  FIG. 1 , looking downward. 
           [0005]      FIG. 3  is similar to the view of  FIG. 2 , with a tray on the lifting unit. 
           [0006]      FIG. 4  is similar to the view of  FIG. 3 , with the lifting unit engaging the tray in a stack of trays. 
           [0007]      FIGS. 5A-F  show a series of six steps for down-stacking half-stacks of trays. 
           [0008]      FIGS. 6A-H  show a series of eight steps for down-stacking from the middle of a stack of trays. 
           [0009]      FIGS. 7A-F  show a series of six steps for up-stacking half-stacks of trays. 
           [0010]      FIGS. 8A-H  show a series of eight steps for up-stacking into the middle of a stack of trays. 
           [0011]      FIG. 9  shows an optional carriage on a stacker according to a second embodiment. 
           [0012]      FIG. 10  is a partially exploded view of the carriage of  FIG. 9 . 
           [0013]      FIG. 11  is a section, side view of a lower portion of the stacker of  FIG. 9  as it is engaging a dolly. 
           [0014]      FIG. 12  is similar to the view of  FIG. 11  with the stacker engaged with the dolly. 
       
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
       [0015]    A stacker  10  according to one example embodiment is shown in  FIG. 1 . The stacker  10  includes a base including a pair of base supports  12  and a vertical structure extending upward from the base, wherein the vertical structure includes a pair of parallel vertical supports  14 . An upper bracket  16  connects upper ends of the vertical supports  14 . A lifting unit  18  is slidably supported on the vertical supports  14  and is slidable vertically relative to the vertical supports  14 . 
         [0016]    A cable  22  is looped over pulleys  24  at the upper bracket  16  and is connected to the lifting unit  18 . The lifting unit  18  includes a pair of rear tip guards  26  extending upward from a rearward portion of the lifting unit  18 . At least one front tip guard  28  extends upward at a frontward portion of the lifting unit  18 . 
         [0017]    The lifting unit  18  can lift a plurality of trays  100  from a stack of trays  100  stacked on a dolly  150 . Each of the plurality of trays  100  includes a pair of opposed side walls  102  having handle openings  104  therethrough. 
         [0018]      FIG. 2  is a section view through the stacker  10  looking downward toward the lifting unit  18 . A lifting mechanism, such as a winch  30 , the cable  22  and the pulleys  24  ( FIG. 1 ), is used to selectively lift and lower the lifting unit  18  relative to the vertical supports  14 . Alternatively, a motor, hydraulics or manually-powered mechanisms could be used to selectively lift and lower the lifting unit  18 . The lifting unit  18  includes a rear portion  32  (such as a metal bar or beam). A fixed arm  34  extends forwardly and perpendicularly from a first side of the rear portion  32 . A first support tab  36  or first projection projects inward from the fixed arm  34 . 
         [0019]    A second, L-shaped arm  38  is pivotably secured to a second side of the rear portion  32 . The L-shaped arm  38  includes a first leg  40  overlapping a portion of the rear portion  32  and a second leg  39  projecting perpendicularly and forwardly from the rear portion  32 . The L-shaped portion  38  is pivotably secured to the rear portion  32  by a pivot pin  42 . A second support tab  44  or second projection projects inward from the second leg  39  of the L-shaped arm  38 . The second support tab  44  and the first support tab  36  project toward one another. The support tabs  36 ,  44  are adjustable on the arms  34 ,  38  to accommodate different size trays  100 . The front tip guard  28 , which is an L-shaped cross-section bracket, is mounted at a forward end of the second leg  39  of the L-shaped arm  38 . The width of the lift unit  18  may also be adjustable (e.g. by adjusting a length of the rear portion  32 ). 
         [0020]    The rear tip guards  26  project upward from the rear portion  32 . The rear portion  32  is secured to a shuttle  29  which is slidably secured to the vertical supports  14 . 
         [0021]      FIG. 3  is a view similar to  FIG. 2  with a tray  100  on the lifting unit  18 . The first support tab  36  and the second support tab  44  are received in the handle openings  104  of the side walls  102  of the tray  100 . Upper surfaces of the first support tab  36  and the second support tab  44  provide support surfaces for engaging the tray  100 . The rear tip guards  26  and the front tip guard  28  hold the tray  100  in place. 
         [0022]      FIG. 4  demonstrates how to engage the lifting unit  18  with one tray  100  in a stack of trays  100 . With the L-shaped arm  38  initially in the open position, the stack of trays  100  (only the top tray  100  is visible) is rolled into position (on a dolly  150 , e.g.  FIG. 1 ). As the target tray  10  impacts the first leg  40  of the L-shaped arm  38 , the L-shaped arm  38  pivots to the secure position. The first support tab  36  is received in one of the handle openings  104  of the tray  100 . As the L-shaped arm  38  pivots inward, the second support tab  44  is also then received in the other handle opening  104 , as shown in  FIG. 3 . Magnets may be mounted in the first leg  40  and the rear portion  32  to help retain the L-shaped arm  38  in this position. Alternatively, a manual latch could selectively secure the L-shaped arm  38  in place. By pulling the L-shaped arm  38  outward, the second support tab  44  is removed from the handle opening  104  and the first leg  40  pushes the target tray  100  (and the entire stack of trays  100  and dolly  150  below it) out of the stacker  10 . Activation of the lifting mechanism causes the lifting unit  18  to lift the target tray  100  upward by the handle openings  104 . 
         [0023]    The ability to lift a plurality of trays  100  off of a dolly  150  ( FIG. 1 ) or a stack of a plurality of trays  100 , or to lower a plurality of trays  100  onto a plurality of trays  100  or a dolly  150  ( FIG. 1 ), can be used in many ways, some of which are described below. 
         [0024]      FIGS. 5A-F  shows a series of six steps  1 - 6  for “down-stacking half-stacks” of trays  100 . In step  1 , a plurality (e.g.  17 ) of trays  100  stacked on a dolly  150  is rolled into the stacker  10 . In step  2 , the stacker  10  lifts about half of the trays  100 . In step  3 , the lower half of the plurality of trays  100  are rolled away on the dolly  150 . In step  4 , another, empty dolly  150  is placed in the stacker  10  below the trays  100 . In step  5 , the stacker  10  lowers the trays  100  onto the dolly  150 . The dolly  150  and trays  100  are then removed from the stacker  10  in step  6 , resulting in two half (approximately) stacks of trays  100  on dollies  150 . Downstacking is useful, for example, if a large number of trays  100  stacked on a dolly  150  are delivered from a truck (for max cube out) but smaller stacks of trays  100  are desired. This downstacking method can easily achieve the smaller stacks of trays  100 . 
         [0025]      FIGS. 6A-H  demonstrate another method for downstacking using the stacker  10 . A large stack of trays  100  is moved into the stacker  10  (step  2 ). A subset of trays  100  is lifted by the stacker  10  (step  3 ). A user then removes the top two trays  100  of the lower subset of trays  100  (steps  4 - 5 ) and places those two trays  100  onto a stack of trays  100  on another dolly  150  (step  6 ). (Optionally more trays  100  could be removed from the lower subset of trays  100 ). The stacker  10  then lowers the upper subset of trays  100  back down onto the remainder of the stack (step  7 ). The resulting stack is then two (or more) trays  100  shorter than it was initially. This can be repeated for more large stacks of trays  100  (e.g. from the truck), until a satisfactorily-sized stack is created with the removed trays  100 . 
         [0026]      FIGS. 7A-F  show a method for upstacking half stacks of trays  100 , for example, to increase the height of stacks of trays  100  for max cube out in the truck. A half stack of trays  100  is moved into the stacker  10  (step  1 ). The trays  100  are lifted from the dolly  150  (step  3 ) and the dolly  150  is removed. Another half stack of trays  100  are moved into the stacker  10  (step  5 ) and the upper half stack of trays  100  is lowered onto the lower half stack of trays  100  and dolly  150 . The resulting large stack of trays  100  provides max cube out in the truck. 
         [0027]      FIGS. 8A-H  show another method for upstacking. In steps  2  and  3 , a plurality of trays  100  are added to an existing half stack on a dolly  150 . When the stack gets too high for a user to add more trays  100  on top, the stacker  10  can be used to permit the user to add trays  100  to the middle of the stack. The stack is placed in the stacker  10  (step  4 ). An upper plurality of trays  100  is lifted from the stack (step  5 ) and the user can add trays  100  to the middle (step  6 ). The upper trays  100  are then lowered onto the stack (step  7 ). The large stack is then removed from the stacker  10  for loading onto the truck (for example). 
         [0028]      FIG. 9  shows an optional carriage  250  for an alternative stacker  210 . The carriage  250  is slidably mounted on the vertical supports  214  and includes the rear portion  232  (which corresponds to the rear portion  32  of the lifting unit  18  of  FIGS. 1-4 ), an upper portion  252  and a pair of outer portions  254  connecting the rear portion  232  to the upper portion  252 . A cable  260  extends from one outer portion  254  to the other. At each end, the cable  260  is biased outwardly by a spring pin  262  (a spring biases the pin (or “brake”) and the cable  260  outward). A plurality of holes  263  are formed in the vertical supports  214  and are sized to receive the spring pins  262 . A pair of side pulleys  264  are connected to the upper portion  254  above the center of the cable  260 . A center pulley  266  (or post) is positioned below the center of the cable  260  between the side pulleys  264  and secured to a center rod  268  slidably mounted to the upper portion  252 . In normal operation, as shown in  FIG. 9 , the lift cable  222  is secured to the rod  268 . The weight of the carriage  250  (and anything being lifted by the stacker  210 ) pulls the center pulley  266  upward, which also pulls the cable  260  upward between the side pulleys  264 . This pulls the spring pins  262  inward, disengaging them from the holes  263  in the vertical supports  214  and the carriage  250  can move freely up and down in the vertical supports  214 . 
         [0029]    If the lift cable  222  breaks or disconnects, there is no force pulling upward on center pulley  266 , and the spring pins  262  are able to pulls ends of the cable  260  outward (thereby forcing center pulley  266  downward) and the spring pins  262  spring outward and engage the vertical supports  214  to brake the carriage  250  (and lifting unit). As soon as the pins align with holes  263  in the vertical supports  214 , the spring pins  262  engage the holes  263  and the carriage  250  is locked in place. After the lift cable  222  is repaired or replaced or reconnected, the carriage  250  returns to normal operation. Other than as shown in  FIGS. 9 and 10 , the stacker  210  may operate the same as the stacker  10  shown in  FIGS. 1-8 . 
         [0030]      FIGS. 11 and 12  show another optional feature for stacker  210  (or stacker  100 ). A dolly retainer is secured to the base of the stacker  210 . The retainer includes a support arm  270  projecting outward from the base toward the dolly bay. A spring  272  is secured at one end to the base or to the support arm  270  adjacent the base. The spring  272  is secured at its other end to a retention arm  276  of an angled bracket  274 . The angled bracket  274  includes the retention arm  276  and a trigger arm  278 , which extend relative to one another at a fixed angle (in this example an acute angle of about 70 to 85 degrees). 
         [0031]    As shown in  FIG. 11 , as the dolly  150  is moved into the dolly bay adjacent the stacker  210 , the deck  152  of the dolly  150  impacts the trigger arm  278 , which overcomes the spring  272  and causes the angled bracket  274  to pivot, first stretching the spring  272  further and then past the peak, such that the spring  272  can retract thereby rotating the retention arm  276  upward behind a lip of the deck  152  of the dolly  150 . This provides enough retention to keep the dolly  150  in place while it is loaded with trays  100  (e.g.  FIG. 1 ); however, the user can intentionally push the dolly  150  (loaded or not) out of the dolly bay and overcome the spring  272  and rotate the angled bracket  274  until the retention arm  276  is out of the way of the lip of the deck  152 , at which time the retention arm  276  is past its peak and the spring  272  is already shortening again (as shown in  FIG. 11 ). 
         [0032]    In accordance with the provisions of the patent statutes and jurisprudence, exemplary configurations described above are considered to represent a preferred embodiment of the invention. However, it should be noted that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.