Abstract:
A carriage has a pivot frame which receives individual pallets. When full, a latch is released and the frame is pivoted on a base by springs into a position parallel to inclined roller tracks. An operator pushes the carriage along the tracks to an unload station, where a stack of pallets is engaged by ramps leading to elevated roller tracks. Forward movement discharges the stack to the elevated tracks, and the carriage is drawn back to the starting position, where a latch is released to allow the pivot frame to return to its original orientation against the resistance of an air cylinder. A foot latch retains the carriage within the unload station during loading.

Description:
CROSS REFERENCES TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT AS TO RIGHTS TO INVENTIONS MADE UNDER FEDERALLY SPONSORED RESEARCH AND DEVELOPMENT 
     Not applicable. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to conveyors in general, and more particularly to apparatus for accumulating and transporting empty pallets for engagement by a lift apparatus. 
     A distribution center receives quantity loads of product, breaks those loads down into smaller aggregations, and distributes the products to a retailer or consumer. Often the bulk product is shipped and stored on a unit-sized pallet. Such pallets are received in racking systems which may extend several stories vertically above the ground floor. Goods on pallets are loaded by lift trucks into rack supply lanes where they advance to a picking face where operators select the quantities required for each destination. When the contents of a particular pallet are exhausted, the operator must extract the empty pallet from the supply lane, move it to a neighboring return lane, and arrange the pallet with other empty pallets in a stack assembled at the exterior face of the rack system where it can be accessed and removed by a lift truck. 
     A standard wooden pallet (48″×40″×6″) may weigh 33 to 48 lbs. The continual lifting and stacking of these pallets places a burden on the distribution center workers which would desirably be alleviated. Moreover, because distribution center rack systems often extend multiple stories above the ground floor over which the lift trucks move, it is desirable that workers not be required to approach too closely to a sheer drop. Another consideration is that in the vast expanse of many distribution centers it is desirable to keep construction and operation costs to a minimum. Although various robotic, pneumatic, or hydraulic conveyors are known, a pallet conveyor system which did not require any power source would eliminate not only construction and equipment costs, but would reduce the maintenance and operation costs of the facility. 
     SUMMARY OF THE INVENTION 
     The pallet conveyor of the present invention provides a manually operated and ergonomic apparatus for moving individual pallets from the picking face of a rack system within a distribution center to a stack ready for removal at the exterior face of the rack system by a life truck. A carriage has a base which is mounted to two downwardly inclined roller tracks for movement in a machine direction from a load station, where individual pallets are entered into the carriage, and an unload station, where a stack of pallets is presented on a horizontal surface for removal by a lift truck&#39;s tines. The carriage has a pivot frame mounted to the base to pivot about a cross-machine direction axis. The pivot frame has two side members which connect an inlet member to two inwardly extending pallet flanges 90 degrees away. A handle protrudes from the inlet member and has an inlet edge. Each pallet is slid over the inlet member to fall into the pivot frame along the inlet member. It may then be pivoted to lie parallel to the pallet flanges. Repeating this process, the pivot frame is filled with an array of on-edge pallets. Once full, a latch is released allowing a spring to rotate the pivot frame so that the pallet flanges and the overlying pallets extend parallel to the base. An operator needs to release a foot pedal (or other release mechanism) to allow the operator to move the stack of pallets along the track. A second latch is engaged to retain the pivot frame in this orientation while the operator pushes the carriage along the roller tracks until two inlet ramps at the unload station engage the pallet stack as the forward motion of the carriage drives the stack up onto the unload roller tracks. The pallet load being thus removed from the carriage, the operator then withdraws the carriage and walks it back to the load station, where the second latch is released and the pivot frame is returned to its original condition by the operator pressing down on the handle against the resistance of an air cylinder. A foot latch retains the carriage within the unload station during loading. 
     It is an object of the present invention to provide a manually operated conveyor which allows a single operator to stack and transport a number of pallets with minimal lifting. 
     It is a further object of the present invention to provide an apparatus to assist an operator in stacking and transporting pallets from one face to another of a rack system. 
     Further objects, features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded isometric view of the pallet conveyor of the present invention. 
         FIG. 2  is a side elevational view of the pallet conveyor of  FIG. 1  showing pallets being loaded at a load station, and a stack of pallets being removed by a lift truck at an unload station. 
         FIG. 3  is a side elevational view of the pallet conveyor of  FIG. 2  as a load of pallets is being transferred to the unload station. 
         FIG. 4  is a side elevational view of the pallet conveyor of  FIG. 3  as the pallets are offloaded from the carriage at the unload station. 
         FIG. 5  is a fragmentary cross-sectional view of the pallet conveyor carriage of  FIG. 4  showing the cable actuation mechanism of the rear and front latches. 
         FIG. 6  is a side cross-sectional view of the carriage and track of the device of  FIG. 4 , shown untilted for clarity. 
         FIG. 7  is a side cross-sectional view of the device of  FIG. 2 , shown in the load position, and shown untilted for clarity. 
         FIG. 8  is front elevational view of the carriage of an alternative embodiment pallet conveyor of this invention employing torsion springs. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring more particularly to  FIGS. 1-8 , wherein like numbers refer to similar parts, a manual pallet conveyor  20  of this invention is shown in  FIG. 1 . As shown in  FIG. 2 , the conveyor  20  is mounted within a conventional rack  22  such as is commonly used in a product distribution center. The rack  22  has vertical members  24  which extend upwardly above a floor  26  where operators move along an aisle  36  adjacent the rack extracting products from a pick face  28 . The rack  22  will typically have multiple vertical levels spaced above a main floor  30  where lift trucks  32 , as shown in  FIG. 2 , move between the rack  22  and other locations, bringing pallets  34  to the loading face  38  of the rack. The pallets  34  carrying product to be distributed are inserted into the racks  22  on roller tracks (not shown) which are inclined from the loading face  38  to the pick face  28 . When the product on a pallet has been depleted, the operator extracts the empty pallet  34  from a rack bay containing product, and brings it to a return bay  40  for assembly into a vertical stack of pallets and removal from the rack. Each return bay  40  is outfitted with a conveyor  20 . The proportion of return bays  40  to product bays will depend on the dynamics of the particular distribution center, but the product bays will outnumber the return bays. 
     As shown in  FIG. 2 , the conveyor  20  has two parallel roller tracks  42  which are mounted to the rack  22  within a return bay  40 . The tracks  42  are preferably inclined from the pick face  34  to the loading face  38  at an angle of about 1-5 degrees with respect to the horizontal. The tracks  42  may be mounted to the rack above the level of the aisle floor  26 , for example 16-26 inches, to facilitate convenient loading of empty pallets into the conveyor  20 . Tread plates  43  are positioned between the roller tracks  42  to enable an operator to walk along the return bay  40 . 
     As shown in  FIG. 1 , the conveyor has a carriage  44  which moves in a machine direction along the tracks  42  from a load station  46  opening on the pick face of the rack to an unload station  48  at the load face of the rack. The carriage  44  has a base  50  with a planar lower wall  52  which rides on the rotatable rollers  54  of the roller tracks  42 . As shown in  FIG. 1 , the rollers  54  of the roller tracks  42  are mounted between an inside C-channel  56  and an outside C-channel  58 . The outside C-channel  58  has an outwardly projecting flange  60 . Two follower brackets  62  are mounted beneath the carriage base  50  lower wall  52  on each side of the carriage. The follower brackets  62  extend beneath the outwardly projecting flanges  60  of the roller tracks  42  and retain the carriage  44  on the tracks. The follower brackets  62  may have plastic bumpers  64  to position the carriage in the cross machine direction with respect to the roller tracks  42 . 
     The base lower wall  52  has two upwardly extending side members  66  which extend in the machine direction, and a front member  68  which extends upwardly in the front of the base  50  and a rear member  70  which extends upwardly at the rear of the base. A foot release latch  72 , shown in  FIGS. 1 and 2 , is pivotally mounted to one of the roller tracks  42  upstream of the carriage. The foot release latch  72  is pinned to the track  42  and has a projection  74  which extends frontwardly to engage the rear member  70  of the base  50  and thereby restrain the carriage from moving in the machine direction towards the unload station. The foot release latch  72  has a sidewardly projecting foot pedal  76 , which, when trod upon by an operator, releases the carriage so that it may be advanced towards the unload station. 
     A pivot frame  78  is mounted to the base  50  of the carriage  44  about a pivot axis which extends in the cross machine direction through two bolts  80  which extend through two mounting arms  82  extending downwardly from the pivot frame. The bolts  80  extend through the base side members  66 . The pivot frame  78  is comprised of two generally triangular side members  84  which are joined by a rear member  86  which spaces the side members in the cross machine direction and parallel to one another a sufficient width to receive a plurality of pallets between the side members. Each side member has a pallet support flange  88  extending in the machine direction and in the cross machine direction. Each pallet support flange  88  has an upper surface  89  which is positioned to engage the lowermost pallet in a stack of pallets to be transported. The pallet support flanges are connected by an entry lip  91  which extends in the cross machine direction and extends frontwardly from the rear member  86 . A first gap  90  is defined between the pallet support flanges  88 . The gap  90  opens downwardly and towards the unload station. The rear member  86  has an interior surface  87  which is approximately perpendicular to the upper surfaces of the pallet support flanges  88 , thus a 90 degree angle is defined between the rear member  86  and the pallet support flanges  88 . 
     The mounting arms  82  may be formed as parts of the side members so as to extend downwardly from the triangular side members. Although the pivot frame may be formed as a weldment, it may be assembled with fasteners from sheet metal parts, allowing the pivot frame to be knocked down for compact shipping prior to installation. 
     As best shown in  FIG. 7 , the rear member  86  has an upper inlet edge  92 . The pivot frame  78  defines an interior  94  which can receive pallets therein. The pivot frame  78  is pivotable on the bolts  80  between a first position where the rear member  86  is tilted towards the load station and the pallet flanges extend generally upwardly, and a second position in which the rear member  86  is generally perpendicular to the roller tracks  42  and the pallet flanges are parallel or approximately parallel to the roller tracks. In the first position, the rear member interior surface  87  is disposed at an angle of from 20 to 45 degrees with respect to the plane of the base lower wall  52 , and is preferably about 30 degrees. 
     A ledge  96  projects rearwardly of the rear member  86 , and extends from the rear member upper edge  92  at an angle greater than 180 degrees from the interior surface  87  of the rear member  86 . This angle may be between 215 to 240 degrees, measured from the surface  87 . The ledge  96  may be formed from the same sheet metal element as the rear member  86 . The ledge  96  is terminated by semicylindrical housing  98  which receives a rotatable handle  100 , shown in  FIG. 1 . 
     The handle  100  comprises a shaft  102  which extends in the cross machine direction and which is supported by three cylindrical bearings  104  which are fixed to the housing  98 , one in the center of the housing and one at each end of the housing. The ends of the handle  100  are provided with handle extensions  101  which project radially outwardly to assist in rotating the handle within the bearings  104 . The handle  100  may be provided with two resilient handgrips  106 , for example formed of rubber or polyurethane, which are accessible through clearance openings  108  in the housing  98 . Thus an operator may engage the carriage with both hands on the handle  100  for applying force to the carriage  44  to move it towards or away from the unload station  48 . The housing  98  projects beyond the handle  100  such that a pallet may be loaded across the housing, as shown in  FIG. 2 , without interfering with the handle. 
     The handle  100  provides the points of engagement between the operator and the carriage so that the operator may carry out all multiple operations necessary to control the conveyor  20 . In addition to providing a position for applying force to move the carriage in the machine direction, the handle  100  is also connected by cable linkages to two latches which selectively retain the pivot frame  78  in the first position for loading, or the second position for transport. 
     As shown in  FIG. 5 , the front latch assembly  110  releasably retains the pivot frame in the second position for transport. The front latch assembly  110  has a latch member  112  which is pivotably mounted about a pivot axle  114  to one of the base side members  66 . A restoring spring  116  extends between the latch member and the base lower wall  52 , and urges the latch member  112  into engagement with a slot  118  formed in a bracket  120  which projects downwardly from an overlying pallet support flange  88 . An actuation cable  122  extends from the latch member  112  through a cable fitting  124  fixed to the base side member  66  and from there to an eyelet  126  which extends from the handle shaft  102  through one of the clearance openings  108  in the handle housing. As shown in  FIG. 5 , the latch member  112  has an inclined upper cam surface  128  such that when the pivot frame is urged frontwardly into the second position, the latch member will be driven into engagement with the slot  118  in the bracket  120 , and the pivot frame will thereby be retained in the second position. When it is desired to release the front latch assembly  110 , the handle shaft  102  is rotated by the operator, thus retracting the latch member  112  and freeing the pivot frame from engagement with the latch. 
     A rear latch assembly  130 , shown in  FIG. 5 , has a similar construction, with a latch member  132  which is pivotably mounted about a pivot axle  134  to one of the base side members  66 . A restoring spring  136  extends between the latch member and the base lower wall  52 , and urges the latch member  132  into engagement with a slot  138  formed in a bracket  140  which projects from the pivot frame rear member  70 , as shown in  FIG. 1 . An actuation cable  142  extends from the latch member  132  through a cable fitting  144  fixed to the base side member  66  and from there to the eyelet  126  which extends from the handle shaft  102  through one of the clearance openings  108  in the handle housing. Separate cables may be used for each latch assembly, or, as shown, the two cables may be joined at a splitter  146  to a single cable which connects to the eyelet  126 . Hence rotation of the handle causes both the front latch assembly and the rear latch assembly to be simultaneously operated. 
     As shown in  FIG. 6 , four resilient bumpers  148  are mounted to the base  50  to absorb the impact when the pivot frame is latched into the first or the second position. As shown in  FIG. 4 , to further reduce the impact of the change in position of the pivot frame and to serve as a shock absorber an air cylinder  150  extends between the base  50  and a cylinder bracket  152  which projects rearwardly of the rear member  70  of the pivot frame. 
     As shown in  FIGS. 1 and 2 , the pivot frame  78  is biased to the second transport position by two extension springs  154 . The springs  154  extend between spring brackets  156  fixed to the front of the base side members  66 , and spring brackets  158  which extend downwardly from the pivot frame pallet support flanges  88 . The springs  154  are preferably provided with axially extending cables  155  (shown in  FIG. 7  only), which are secured to the pivot frame and the base. The cables  155  then retain portions of the springs should a spring break. 
     As shown in  FIG. 2 , the unload station comprises two horizontal segments of roller track which define receiving members  160  for supporting a stack  162  of pallets  34 . The receiving members  160  have rollers which define an approximately horizontal pallet support surface  163  which is above the level of the pallet support flanges  88  of the pivot frame  78  when the carriage is fully engaged in the unload station as shown in  FIG. 4 . As shown in  FIG. 1 , the receiving members  160  are spaced inwardly of the tracks  42  in the cross-machine direction. They are spaced inwardly sufficiently that they do not interfere with the pallet support flanges  88 . An inlet ramp  164  is mounted to the rear of each receiving member  160 , the ramps extend from a position below the upper surfaces  89  of the pallet support flanges, to a position above the upper surfaces. As shown in  FIG. 2 , a clearance opening  166  is provided below each inlet ramp  164 . The cut-out portions of the receiving members  160  allow the base  50  of the carriage to progress beneath the receiving members. Each receiving member  160  is terminated by a load stop member  168 , shown in  FIG. 1 , which has a projection which engages with the lower edge of a pallet stack and retains the stack on the receiving members. 
     The conveyor  20  makes it possible for an operator to assemble a vertical stack of pallets without electrical, pneumatic, or hydraulic assistance, and without having to directly lift the individual pallets onto a vertical stack. With the carriage retained at the load station by engagement with the foot release latch  72 , and the pivot frame retained in the first position for loading by the rear latch assembly  130 , the operator brings an empty pallet  34  along the aisle  36  to the floor  26  at the foot of the load station  46 . The operator may be able to drag or skid the pallet  34  to this position. The pallet  34  is then leaned up against the handle housing  98  in the position A indicated in  FIG. 2 . With a portion of the weight of the pallet supported on the handle housing  98 , the operator slides the pallet upwardly until the pallet&#39;s center of mass passes over the ledge  96  at which point the weight of the pallet causes it to pivot and be supported on the ledge. After this point the operator need no longer lift the pallet, but is instead urging the pallet frontwardly in the machine direction. When the pallet&#39;s center of mass passes beyond the upper inlet edge  92  of the rear member of the pivot frame  78 , the pallet will pivot again and descend into the pivot frame interior, until the pallet engages the entry lip  91  which is substantially coplanar with the pallet support flanges  88 , as indicated by position B in  FIG. 2 . With the pallet extending along the interior surface  87  of the pivot frame rear member, the upper edge of the pallet extends above the handle housing where it is readily accessible to the operator who gives it a strong push to cause the pallet to pivot from lying along the interior surface of the rear member to lying along the oppositely inclined pallet support flanges  88 , as indicated by the position C in  FIG. 2 . Subsequent pallets are introduced into the pivot frame interior in a similar manner, although these pallets in position B will engage against the underlying pallets of the stack rather than the pallet support flanges. 
     When enough pallets have been received within the carriage to form a stack of the desired height, the operator engages the handle  100  and rotates it to release the rear latch assembly  130 . Once the rear latch member  132  disengages from the pivot frame  78  bracket  140 , the extension springs  154  act to rotate the pivot frame about the bolts  80  into the second position where the pallets in the stack are substantially parallel to the lower wall  52  of the carriage base  50 . The air cylinder  150  serves to slow the transition from the first position to the second position, reducing the impact on the pallets when the pivot frame swings into the second position. 
     The operator then steps on the foot pedal  76  of the foot release latch  72 , to disengage the projection  74  from the rear wall  70  of the carriage base  50 . As the roller tracks  42  are inclined towards the unload station, the unrestrained carriage will tend towards the unload station. With the carriage unrestrained in the load station, the operator steps up on to the tread plates  43  within the return bay  40  and pushes on the handle to assist the loaded carriage along its path towards the unload station as shown in  FIG. 3 . 
     As the carriage  44  approaches the receiving members  160 , the pallet stack engages the inlet ramps  164 . The interior surface  87  of the rear member  86  bears on the pallet stack, and, as the operator pushes the carriage forward, the rear member engages the stack and urges it up on to the top surface of the receiving members  160  until the front edge of lowermost pallet of the stack encounters the load stop members  168 . At which point the center of mass of the pallet stack is disposed over the receiving members  160  and the pallet stack is nearly entirely supported on the receiving members  160 . The carriage  44  is also prevented from advancing too far and driving the pallet stack beyond the receiving members  160  by engagement of the carriage base front member  68  against the edges of the pallet receiving members at the clearance openings  166  as shown in  FIG. 4 . 
     Once the pallet stack has been transferred to the receiving members  160  at the unload station  48 , the operator withdraws the carriage  44  from beneath the receiving members by walking back the carriage toward the load station. During its return trip, the pivot frame may be retained in the latched second position. 
     The pallet stack  162 , supported on the receiving members, is then readily engaged by the lift truck  32  tines  186 , removed from the rack  22 , and transported elsewhere. 
     When the carriage  44  is once again within the load station, the foot release latch  72  is again engaged with the base  50 , holding the carriage in place in the machine direction. The operator then rotates the handle  100  to release the front latch assembly  110  and presses down on the handle to pivot the pivot frame until it latches with the rear latch assembly  130 . Again, the air cylinder  150  cushions the shock of the pivot frame engaging the base. It will be observed that the bracket  140 , with which the rear latch engages, controls the maximum angle at which the pivot frame  78  can be inclined. A similar unslotted bracket  170  is located on the opposite side of the pivot frame rear member. Once the pivot frame  78  is returned to the first position, it may be loaded again with additional pallets. The first stack  162  need not be immediately removed from the unload station  48 , as the unload station does not need to be cleared until the carriage is filled with a new stack. 
     An alternative embodiment carriage  172  is shown in  FIG. 6  which employs torsion springs  174  instead of extension springs to urge the pivot frame  176  into the second, transport, position. The torsion springs  174  may be mounted on a shaft  178 , with each spring extending between a torsion spring block  182  connected to the carriage base  180 , and the pivot frame  176 . 
     It is understood that the invention is not limited to the particular construction and arrangement of parts herein illustrated and described, but embraces all such modified forms thereof as come within the scope of the following claims.