US20060153670A1 - Method and apparatus for pallet removal cargo queuing and stowage of stacks of cartons of frozen animal products - Google Patents

Abstract

A method for rapid depalletizing and lifting of stacks of cartons aboard vessels is provided which may include sliding the stacks of cartons from a pallet onto a transport surface at a loading end, moving the stack of cartons along the transport surface to a lifting station having fork channels extending across the lifting station for receiving the blades of a load push lift truck, and lifting the stack of cartons from the lifting station. The transport surface may comprise a plurality of rollers. The stack of cartons may be lifted by cargo slings into the hold of a ship, or lifted from the lifting end on the blades of a load push lift truck. The pallet may be retained on the blades of a load push lift truck while the stack of cartons carried by the pallet is pushed from the pallet by a restraint. The empty pallet may then be carried to and deposited in a pallet accumulation location by the lift truck.

Description

CROSS REFERENCE TO RELATED APPLICATIONS
• The present application is a continuation-in-part of the copending application entitled “Method and Apparatus for Pallet Removal Cargo Queuing and Stowage of Stacks of Cartons of Frozen Animal Products, filed Aug. 4, 2004, Ser. No. 10/910,990, which is a continuation-in-part of the copending application entitled “Method and Apparatus for Loading Stacks of Cartons of Frozen Animal Products onto Vessels Using a Carrier”, filed Oct. 9, 2002, Ser. No. 10/268,182, which is a continuation-in-part of the copending application entitled “Method and Apparatus for Loading Stacks of Cartons of Frozen Animal Products onto Vessels Using a Carrier”, filed Nov. 13, 2000, Ser. No. 09/712,741, which is a continuation-in-part of the copending application entitled “Method and Apparatus for Handling, Transporting, Pallet Removal, and Loading Cartons of Frozen Animal Products Onto Vessels”, filed Apr. 30, 1999, Ser. No. 09/303,792, now abandoned, which is a continuation-in-part of the issued patent entitled “Method and Apparatus for Handling, Transporting and Loading Cartons of Frozen Animal Products Onto Vessels”, issued Nov. 9, 1999, U.S. Pat. No. 5,980,198.
BACKGROUND INFORMATION
• 1. Field of the Invention
• The present invention relates to the field of cargo handling, and in particular, to the rapid depalletizing and loading of cartons of frozen animal products onto a refrigerated vessel or cargo container.
• 2. Background of the Invention
• While there have been significant advances in the methods employed for the loading and unloading of vessels and cargo containers, the loading of refrigerated, cartonized cargo, and in particular, frozen animal products has proved particularly difficult due to several intractable problems. As a result, the transfer of the products from the packers to their loading aboard a vessel or in a container is presently carried out by processes that involve high costs and significant expenditure of manual labor, and which include bottlenecks that slow the process, that may result in product degradation or spoilage, and that result in long loading times for the product onto the vessel or container. It is presently common for the handling of cartons of frozen animal products to proceed as follows.
• A large volume of animal products such as frozen chicken, turkey, beef, pork and seafood products (including livers, hearts, other parts, deboned meat and the like) are frozen and shipped within and exported from the U.S. in relatively shallow, rectangular boxes. For example, chicken thighs, legs or quarters may be shipped in cartons of about 23.5 inches in length by 16.5 inches in width by 4 to 6.25 inches in height (59.7 cm by 41.9 cm by 10.2 to 15.9 cm). A preferred standardized box size for use with the present invention would be 24 inches by 16 inches (61.0 cm by 40.6 cm) with the height of the box varied to hold the particular products to be shipped. A box of such dimensions containing frozen chicken parts may weigh on the order of 30 to 45 pounds (14 to 20 kg).
• As the cartons are generally filled fairly completely with unfrozen animal products, and the animal products are subsequently frozen while in the carton, the cartons of frozen animal products tend to be comparatively resistant to compressive forces. The cartons may also be slightly distorted from their rectangular shape owing to volume changes accompanying freezing and to their handling and stacking. For simplicity, reference will hereafter be made to cartons of frozen chicken, as other animal products may be handled in a similar manner.
• Owing to the size restrictions imposed by standard trucks and trailers, the cartons are normally stacked on 40×48 inch (102×122 cm) pallets in layers of five cartons arranged with two cartons placed on the pallet in an end-to-end relationship beside three cartons placed side to side with their long axes perpendicular to those of the first two cartons. While the exact size of the stack of cartons may vary depending on the exact dimensions of the cartons, stacks of cartons and layers of such stacks will be referred to herein as having the foregoing dimensions or having a wider side of 48 inches (122 cm) and a narrower side of 40 inches (102 cm). These dimensions are, however, approximate, and may vary not only depending on the box dimensions, but also from such factors as bulging of the cartons of frozen chicken and irregularities in the stacking pattern. In general, however, the cartons have a relatively low aspect ratio (length divided by height). For example, a 4″ tall by 16″ long carton would have an aspect ratio of 0.25. This is significantly lower than, for example, the common apple boxes.
• A palletload of cartons generally contains between about 10 to 12 such layers of cartons. A palletload of cartons arranged in this manner would have five cartons per layer. A 12 layer stack of cartons weighing 30 pounds (14 kg) would thus weigh about 1800 pounds (818 kg). Three such stacks of cartons would thus weigh about 5400 pounds (2454 kg, equal to 2.454 metric tons).
• Although it is the general practice to use pallets having dimensions of 40×48 inches (102×122 cm) in the frozen animal products industry, which facilitate loading thereof into enclosed vans or trailers, 48×48 inch pallets (122×122 cm), which hold six rather than five cartons per layer, are sometimes used. In such case, the cartons are generally arranged in layers, each such layer having two rows of three cartons with the three cartons of each row in side-to-side arrangement.
• The stacking pattern for either the 48×48 or 40×48 inch pallets (122×122 cm or 102×122 cm) may be varied, as by rotating it from layer to layer. For the 40×48 inches (102×122 cm) pallets, for example, the two end-to-end cartons may be arranged along one of the long edges of the pallet in one layer and along the other long edge in the next layer.
• Presently, wooden pallets are typically made of three parallel beams arranged with a center beam and two outer beams on either side thereof. Boards or other such support members are nailed, stapled or otherwise fastened to the upper and lower surfaces of the beams transversely to the beams to form the upper and lower surfaces of the pallet. Lift channels extending parallel to the beams are thus formed between the upper and lower transversely-mounted boards. Apertures may be provided in the beams along their lower edges and/or boards may be removed from the lower pallet surface in the area of the apertures (“4-way apertures”) to permit insertion of lift truck blades into the pallet transversely to the beams and lift channels (these are often called “4-way” pallets, as a lift truck can insert the lift blades into the pallet from any of four directions).
• The packer sends the fresh chicken parts in such palletloads to a blast freezer/cold storage warehouse. At the warehouse, the cartons are restacked with spacers between the layers thereof. The spacers allow the circulation of air between the layers of cartons. Once the cartons are so stacked, the palletload of cartons are transferred to a blast freezer, which forces air chilled to about −40° F. (−40° C.) between and around the cartons. The chicken parts should be cooled in the blast freezer to 0° F. (−17.7° C.) and should be held at that temperature. When the freezing process is completed, the cartons are removed from the blast freezer and placed in a rotator. The load of cartons is then rotated 90 degrees onto its side, the spacers are removed, and the load of cartons is then rotated back to an upright position in which it rests once more on the pallet. In order to facilitate transportation and storage of the stacks of cartons, the stacks may be, and typically are, wrapped with a stretchable plastic film to help reduce sliding of the layers of cartons relative to one another. Lift trucks are then used to move the cartons of frozen chicken products and transport them into the cold storage warehouse.
• When the time comes to load a ship, lift trucks are used to remove the palletloads of stacks of cartons of chicken parts from the warehouse, and place them inside dry van trucks or truck trailers for transportation to the dock. The trucks or truck trailers are typically uninsulated and unrefrigerated, and thus can provide a deleterious environment to the frozen product contained therein if they are not soon loaded into a refrigerated ship. At the dock, the cartons are removed from the truck trailer by lift trucks and placed on the dock. Alternatively, if the cold storage warehouse is sufficiently near to the dock, the lift trucks may transport the palletloads of stacks of cartons directly to the dock. In either case, the palletloads of stacks of cartons are subsequently lifted into the hold using the ship's gear, such as by using slings, lifting platforms, lift cages, flying forks or the like to lift the cartons and pallets.
• Many of the ships transporting cartons of frozen chicken internationally are older vessels having ship's gear with a three-ton (metric) rated capacity. This permits them to lift up to three stacks of cartons at a time, depending on the weight of the stacks and of the gear used to lift them. However, other ships may have cranes with capacities of five or more tons. The mass of lift cages, of course, can be substantial, approaching one ton for a lift cage that can be used to lift two stacks of cartons. Thus, with three-ton ship's gear, it would generally only be possible to lift two stacks of cartons into the hold of the vessel at a time.
• In the hold, lift trucks engage the pallets and transport the pallets with their stacks of cartons to locations near where the cartons will be stowed. Stevedores then manually remove the cartons from the pallets and stack the cartons without pallets for shipping. The pallets are then returned to the square of the hatch and are stacked to be hoisted out of the hold and back onto the dock by the ship's gear. The square of the hatch is the volume of space extending vertically downward from the open hatch to the floor of the cargo hold.
• This process is quite inefficient. Delays in bringing a sufficient quantity of product to the dock and in unloading the cartons from the truck can increase the time needed to load the vessel. The space constraints in the vessel limit the number of workers who can be engaged in stowing of the cartons, and thus may create a backup for product arriving at the dock. Excessive delays in loading which result in the cartons being left on the dock or in the truck can allow the product to begin to thaw, which can result in spoilage or otherwise render the product unmarketable. Delay in loading may also result in increased condensation of moisture on the cartons which can complicate the handling process. As the industry is seeking to use less wax on the cartons and to utilize paper-coated boxes, the damaging effect of condensation and internal thawing on the boxes is increased.
• The breakage rate for pallets during this process is fairly high. As many as half of the pallets suffer some breakage, and this can result in splintered wood, which may contain protruding nails, being left at the warehouse, on the dock and in the cargo hold of the vessel. Additional work is thus required to collect the pallets and pallet debris, to extract it from the hold of the ship or remove it from the dock, and to repair or discard the broken pallets. Further, the existence of pallet debris at the warehouse, on the dock, and in particular in the hold of the vessel, presents a risk of injury to workers.
• Inefficient as this method of handling may be, there are a number of constraints that have made it difficult to improve. The main problem encountered is that the holds of the ship are irregular both in the overhead clearance and in the shape of the floor space. Not only does the overhead clearance of the cargo holds vary from ship to ship, and perhaps within a ship from hold to hold, the internal structure of the vessel and of the cooling system within it can result in overhead clearances that vary depending on the location within the hold.
• Another difficulty in loading such cargoes is that the cartons are typically stacked to a uniform height after blast freezing. This is necessary for efficient use of the cold storage warehouse. This uniform height is generally ten or twelve layers of boxes arranged on a lift truck pallet, but it may vary somewhat from this number depending on the size of the cartons. The cartons are unitized by wrapping them with a stretchable plastic film that aids in transportation of the palletloads by lift truck, etc. However, space on refrigerated vessels is at such a premium that the wasted space of such pallets is considered undesirable. Thus, it has been considered necessary to avoid stowing the cartons on the pallets, and thus the practice of manually stowing the cartons in the ship by restacking them without the pallets has persisted. Moreover, since the ceiling height of holds on ships varies, and is seldom equal to the height of the cartons when stacked for warehousing purposes, it has heretofore been considered essential to manually stack the cartons in order to obtain as complete a filling of the vessel as possible.
• Cargo containers do not have the problem of irregular shape, but their packing by means of hand stacking in order to eliminate the use of pallets has been an impediment to their efficient loading in terms of speed and workforce requirements.
• Load push lift trucks have been used to push cargo off the lift truck blades. A load push lift truck has at least two blades extending from its lift mechanism. Load push, side shift lift trucks are known in the art of specialty lift trucks. Such lift trucks are discussed, for example, in U.S. Pat. No. 4,752,179 to Seaberg. Typically, the blades are relatively broad, and may have relatively smooth or polished upper surfaces to facilitate the sliding of the cartons thereon. A push plate associated with the lift mechanism can be extended by means of hydraulic cylinders from a retracted position adjacent the lift mechanism to a position adjacent the ends of the blades. If the stack of cartons is resting on the blades of the lift truck, the push mechanism may also be used to push the cartons off the blades and/or to extract the blades from under cargo as the lift truck moves backward away from the desired position of the stack of cartons. Such a lift truck may include a side-shift mechanism which permits small lateral adjustments in the position of the cargo to facilitate its precise placement. Such load-push lift trucks are known in the art of specialized lift trucks.
SUMMARY OF THE INVENTION
• Parent U.S. Pat. No. 5,980,198 of common ownership and inventorship, which is incorporated herein by this reference, describes the lifting of palletless stacks of cartons into the hold of a ship using cargo slings. Lift trucks, and particularly load push or load push side shift lift trucks may be used for handling of stacks of cartons on pallets and for lifting palletless stacks of cartons.
• One aspect of the invention provides a method for transportation of cartons of frozen products from alongside a refrigerated vessel into the hold of the vessel. In one aspect, palletloads of stacks of cartons may be positioned adjacent a carrier and pushed laterally from the pallet onto the carrier. Despite the weight of the stack of cartons, the stack may be pushed from the pallet in a direction generally parallel to the long axes of the boards forming the upper surface of a wooden pallet. A load push lift truck which is provided with sufficient clearance between the top of the blades and the bottom of the push plate so that the push plate may be extended over the upper surface of the pallet while the blades are inserted into 4-way apertures may be used for this purpose. The carrier may then be lifted into the hold of a ship. The carrier may be provided with fork channels, open channels of sufficient depth and spacing that can receive the blades (the forks) of the lift truck. This permits lifting of the palletless stack of cartons from the carrier for transport to a stowage location. The stack of cartons may be deposited at the storage location by sliding it relative to the long axis of the forks of the lift truck to deposit it in the stowage location. Depending on the configuration of the carrier, a lift truck with multiple sets of blades may be used to load two or more stacks of cartons onto the carrier at a time by use of the load push mechanism.
• In another aspect of the invention, if the carrier is provided with fork channels, a lift truck may pick up the stack of cartons directly once the carrier is landed in the cargo hold of the ship. The load push lift truck may position the push mechanism in its fully retracted position and slides its blades into the fork channels under the stack of cartons. Thereafter, the entire stack of cartons may be transported to its stowage location or to a position near its stowage location, including stowage locations on top of another stack of cartons.
• In another aspect of the invention, a roller deck may be used. The roller deck may be positioned alongside a vessel, and may include a plurality of parallel rollers or sets of wheels mounted along its length. At one end, the loading end, stacks of cartons may be pushed from pallets onto the rollers. At the other end, the slinging end, gaps in the rollers allow cargo slings to be extended across the roller deck for lifting the stacks of cartons into the hold of a vessel and/or lifting of stacks of cartons on the blades of lift trucks. The stacks of cartons may be manually or automatically pushed from the loading end to the slinging end of the roller bed, or the roller bed may be inclined such that the stacks of cartons roll down from the loading end to the slinging end of the roller bed. A spreader bar with multiple hooks along its length that are capable of receiving the ends of the slings may be attached to the ship's gear or other crane and used to pick up multiple stacks of cartons at a time from the slinging end of the roller deck. In such case, the stacks of cartons are landed on a landing pad in the hold of the vessel. The landing pad may include fork channels to allow lift trucks to pick the stacks of cartons up, and to allow the slings to be withdrawn from around the stacks of cartons. Stacks of cartons positioned side by side may be lifted by a single set of slings with each sling in the set extending under both stacks of cartons.
• When the loading of the hold is completed except for the area under the square of the hatch, in another embodiment of the invention, the load push lift truck and other equipment and materials may be removed from the hold. Thereafter, the square of the hatch may be filled by using the ship's gear to lift one or more stacks of cartons from alongside into the square of the hatch using cargo slings disposed about the stack. Multiple stacks of cartons may be lifted at one time if a spreader bar or like apparatus is used.
• Similarly, another aspect of the invention provides for use of one or more load push lift trucks with a roller deck to lift palletless stacks of cartons from the unloading position on the roller deck from either the end or side orientation by inserting the blades of the lift truck into channels running wholly or partially across the unloading position of the roller deck. Such a roller deck may act as a landing pad in the hold of a ship, or may serve as a queuing depalletizer used in conjunction with the loading of containers.
• In another aspect of the invention, the slings may be positioned about the stack of cartons by positioning the carrier or other apparatus having channels extending thereacross beside the ship, depositing stacks of cartons without pallets on such carrier or apparatus, extending two or more slings around each such stack of cartons and lifting the stacks of cartons from the carrier by the slings by passing the eyes on either end of the sling over the hook or other such lifting device attached to the end of the cable of the ship's gear. When positioned in the square of the hatch, one side of each sling may be removed, preferably the side abutting any other stacks of cartons adjacent to such landed stack, and the slings can be pulled under the stack of cartons and between the stack and any adjacent stack by the ship's gear. The slings may thus be returned by the ship's gear to a position alongside the ship for reuse. Of course, in order to speed the loading of the square of the hatch, the slings may be left in place. Some manual restacking of cartons to fill the square of the hatch may be necessary in order to avoid the wasting of space in the cargo hold.
• In yet another aspect of the invention, load push lift trucks and depalletizers may be used to load refrigerated cargo containers.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a partial perspective view of a ship adapted to be loaded with stacks of cartons of frozen animal products.
• FIG. 2 is a front elevation of a typical 4-way wooden pallet.
• FIG. 3 is a side elevation of a typical 4-way wooden pallet.
• FIG. 4 is a perspective view of a carrier according to one embodiment of the invention.
• FIG. 5 is a perspective view of the carrier ofFIG. 4 being loaded with stacks of cartons of frozen animal products by load push lift trucks.
• FIG. 6 is a perspective view of the carrier ofFIG. 4 with a stack of cartons of frozen animal products being removed therefrom by a load push lift truck.
• FIG. 7 is a perspective view of the carrier ofFIG. 4 with cargo slings positioned in the fork channels thereof.
• FIG. 8 is a perspective view of cartons being lifted from the carrier ofFIG. 4 using cargo slings.
• FIG. 9 is a perspective view of cartons of frozen animal products being landed in the square of the hatch of a ship.
• FIG. 10 is a side elevation of an end portion of a cargo sling.
• FIG. 11A is a front elevation of a light-weight carrier according to another embodiment of the invention bearing three stacks of cartons.
• FIG. 11B is a top plan view of the carrier ofFIG. 11A without stacks of cartons loaded thereon.
• FIG. 12 is a side elevation of the carrier ofFIG. 11.
• FIG. 13 is a top plan view of a layer of cartons arranged in a 3-2 pattern, with lifting zones shown in phantom.
• FIG. 14 is a perspective view of a landing pad capable of receiving a single stack of cartons.
• FIG. 15 is a perspective view of a landing pad capable of receiving three stacks of cartons.
• FIG. 16 is a perspective view of a roller deck according to one embodiment of the invention, showing three stacks of cartons being removed at the slinging end and two stacks of cartons being loaded from the side onto the roller deck at the loading end.
• FIG. 17 is a perspective view of a pallet table positioned adjacent one side of a portion of a roller deck.
• FIG. 18 is a perspective view of an end-loading roller deck being loaded by a load push lift truck.
• FIG. 19 is a perspective view of a double-wide, end-loading roller deck being loaded by a load push lift truck.
• FIG. 20 is a perspective view of a depalletizer being loaded with a stack of cartons by a load push lift truck.
• FIG. 20A is a perspective view of a roller depalletizer.
• FIG. 21 is a perspective view of a stack of cargons being removed from the depalletizer ofFIG. 20 by a lift truck.
• FIG. 22 is a perspective view of a roller landing pad.
• FIG. 23 is a perspective view of a landing pad with fork channels for lifting stacks of cartons from either the 40″ or 48″ side of stacks of cartons.
• FIG. 24 is a sectional side view of a push plate for a load push lift truck having a hinged lower gate.
• FIG. 25 is a sectional side view of a push plate for a load push lift truck having a telescoping lower gate.
• FIG. 26 is a perspective view of a stack of cartons being deposited in a stowage location in the hold of a ship by a load push lift truck.
• FIG. 27 is a perspective view of a landing pad.
• FIG. 28 is a perspective view of the lifting portion of load push lift truck with a pallet restraint mounted to the blades.
• FIG. 29 is a perspective view of a lift truck with a clamp-type pallet restraint.
• FIG. 30 is a top plan view of the clamp-type pallet restraint ofFIG. 29 with parts broken away.
DETAILED DESCRIPTION OF EMBODIMENTS OF THE INVENTION
• FIG. 1 depicts aship10 tied up alongside a dock. The ship is provided with ship'sgear12 for loading and unloading theship10. The ship'sgear12 is provided with acable14 that may be extended and retracted using a winch system (not shown). Thedeck16 of theship10 is provided with one or more hatches18. The ship'sgear12 is used to lift cargo from alongside theship10 into thehold20 of theship10. Typically, aship10 has a plurality of such holds20, each of which is accessible by means of ahatch18. Ships used to transport frozen products are typically provided with refrigeration apparatus for maintaining theholds20 at a low temperature.
• FIGS. 2 and 3 are side elevation views of a standard 4-way pallet30, on which a variety of cargo may be stacked. Such pallets are commonly used for holding and transporting stacks of cartons, including stacks of cartons of frozen animal products, such as frozen chicken parts, frozen organ meat, such as liver and kidney, or other frozen animal products. As is known in the art, the 4-way pallet30 comprises acenter beam32, which runs the length of thepallet30, and twoside beams34 which likewise run the length of thepallet30 and which are disposed along opposite edges of thepallet30.
• The upper andlower surfaces36,38 of thepallet30 are formed by a plurality ofboards40 which extend across the width of the pallet and which are fastened to thebeams32,34 by nails, screws or other fasteners.Cutouts42 are provided along of the lower edges of thebeams32,34. Theboards40 which make up thelower surface38 of thepallet30 do not cover the area of thecutouts42. As is well known in the art of cargo handling, a lift truck may lift thepallet30 either by inserting its blades in the closed-top fork channels44 (best shown inFIG. 2) and then using the lifting gear to raise the forks and thepallet30. The pallet may also be lifted by inserting the blades (forks or platens) of a lift truck through the channels (“4-way channels”) formed by thecutouts42 in thebeams32,34 and then raising the blades.
• A lift truck usable according to the present invention may include two relatively flat blades which may conveniently have a width of 4 to 8 inches (10.2 to 20.3 cm), and may include side shift capability. The blades may be smooth and polished, and may have rounded or tapered edges. The load push system should be sufficiently powerful to push a full stack of cartons of frozen chicken parts or the like off of the blades and into a stowage location, such as a position atop another stack of cartons.
• FIG. 4 is a perspective view of acarrier50 according to one embodiment of the present invention. Thecarrier50, which may be made of rectangular steel tubing, steel I-beams and/or steel plate, is preferably welded together, but may be made of other materials, such as aluminum, and may be assembled using bolts or other fasteners, or by other means known in the art. Thecarrier50 is comprised of abase52 and anupright center stop54. As shown inFIG. 4, the center stop54 of the present embodiment includes a lower, generallyrectangular section56 and a generallytriangular lifting section58. Aclevis62 it is mounted through an aperture in aplate60 at the apex of thelifting section58. Theclevis62 is adapted to receive ahook64 attached to the free end of thecable14 of a ship'sgear12 or other such lifting device.
• Therectangular section56 of thecenter stop54 may be of any desired dimensions, but in the present embodiment, is relatively thin and is approximately as tall and wide as a stack of cartons of frozen chicken parts or the like. Thecenter stop54 of the present embodiment may have as great a height as may be conveniently use for the purposes hereof. As will be appreciated by those skilled in the art, an increased height of thecenter stop54 will reduce the degree of tipping of thecarrier30 under asymmetric loads, for example, when only a single stack of cartons mounted on one side only of the carrier is being lifted. Of course, if thecenter stop54 is too tall, such height may make thecarrier50 difficult to transport and store, and may increase the overall weight of thecarrier50.
• Thebase52 of thecarrier50 is generally planar in structure. Thebase52 of thecarrier50 of the present embodiment may be made of steel plate, of steel plate welded to a frame made of rectangular steel tubing or I-beams, or the like, so long as it is sufficiently rigid to bear the weight of stacks of cartons of frozen chicken without undue flexure, and is sufficiently light that the combined weight of the carrier and the cargo is within the load limits of the ship'sgear12. Thecenter stop54 is mounted transversely to the long axis of thebase52 across the middle section thereof, and such mounting should be sufficiently rigid to accommodate asymmetrical loads such as those mentioned above.
• A plurality offork channels66 are formed in the surface of thebase52 for receiving the blades of a lift truck. If lift trucks having two forks are used, then thecarrier50 should be provided with twofork channels66 on each side of thecenter stop54. If fork lifts with more than two forks are used, then a corresponding number offork channels66 should be provided on each side. It should be noted that a three-blade lift truck can lift a stack of cartons arranged in the 2-3 pattern typical for a standard pallet can have its blades spaced apart to lift the stack of cartons from either the 48 inch side or the 40 inch side, although lifting the stack of cartons with two blades from either orientation is more problematic unless the blades are very broad and/or precisely positioned under the load.
• The depth of thechannels66 should be sufficient to allow insertion of the lift truck blades therein beneath a stack of cartons of frozen chicken placed on top of the base52 when the stack of cartons of frozen chicken are supported by theupper surface portions68 of thebase52.
• Thewalls70 of thesling channels66 which face away from the base52 are angled upwardly and inwardly toward the center stop to facilitate the sliding of stacks of cartons of frozen chicken onto thebase52 of thecarrier50 and into contact with thecenter stop54. The outer edges of the base52 function as pallet stops72, as will be explained in greater detail below.
• While thecarrier50 is shown as having two areas for placement of stacks of cartons of frozen chicken, configurations having a greater or lesser number, such as one or three or four such areas, may be designed, as will be appreciated by those skilled in the art.
• In one embodiment of a method according to the present invention, acarrier50 is used to lift depalletized stacks of cartons of frozen animal products. The embodiments of the invention will be described with reference to cartons of frozen chicken parts or frozen chicken for convenience, even though they are applicable to other frozen animal products stored in similar cartons.
• Referring next toFIG. 5, a load push lift truck80 (or side shift, load push lift truck) is used to lift a 4-way pallet30 bearing a stack of cartons offrozen chicken82 by inserting the blades of the lift truck into thecutouts42 of the 4-way pallet30. Thepallet30 and stack ofcartons82 may then be lifted by raising the blades of the lift truck. In the method of the present embodiment, the lift truck carries thepallet30 to a position in which the side of thepallet30 opposite thelift truck80 abuts or is in close proximity to the pallet stop72 of thebase52 of thecarrier50. Thepallet30 and stack82 may then be lowered to the ground and the stack of cartons offrozen chicken82 may then be pushed from thepallet30 in a direction generally parallel to the long axis of theboards40 of thepallet30.
• The direction of sliding of the stack of cartons from such apallet30 may be chosen to reduce abrasion of the lower surfaces of the cartons in the bottom layer of the stack of cartons to acceptable levels consistent with the maintenance of quality standards for the frozen products contained in the cartons. Tearing through of the cartons to expose the frozen animal products is generally considered undesirable. Of course, if the upper surface of thepallet30 is sufficiently smooth, or any edges are sufficiently beveled, the direction of sliding of the stack of cartons relative to thepallet30 may not cause sufficient abrasion to the lower surfaces of the cartons to be of concern. Withstandard pallets30, pushing the stack of cartons offrozen animal products82 may be successfully accomplished without the use of slip sheets or the like.
• Slip sheets present special challenges in the handling of cartons of frozen animal products. First, the cost of the slip sheets is such that it is not generally economical to stow the stacks of cartons with the slip sheets. Further, if the slip sheets are carried into the hold of a ship with the intent that they will not be stowed with the cartons, they must be collected and removed from the ship. Finally, if the cartons are carried into the ship with slip sheets on slings or by carriers, and if they are thereafter lifted by lift trucks and stowed with the cartons, they can block vertical airflow in the hold. As many refrigerated vessels depend on vertical airflow for cooling, this may result in improper cooling of the frozen animal products during shipment, with attendant spoilage.
• In the present embodiment, the bottom of the push plate of the loadpush lift truck80 is provided with sufficient clearance over the forks that the push plate can engage the stack ofcartons82 without engaging the pallet. Four inches (10 cm) of clearance of the push plate over the blades of the lift truck should be sufficient with most standard pallets, but if taller pallets are used, additional clearance may be required.
• According to the present embodiment, stacks ofcartons82 offrozen chicken30 may be pushed off of pallets in this direction without undue damage to the bottom of the bottom layer of the stack ofcartons82. The inclined face of thewalls70 further aid in avoiding damage to the cartons. Should the leading edge of any of the cartons of the stack ofcartons82 droop in thefork channels66 to a level below theupper surface68 of thebase52 of the carrier, the slope of thewalls70 of thefork channels66 will urge the drooping corners back upward to the level of theupper surface68 of thebase52. The stack of cartons may be pushed into engagement or close proximity to the center stop54 of thecarrier50.
• While the simultaneous loading of two stacks of cartons offrozen chicken82 onto thecarrier50 by different lift trucks from opposite directions will reduce the risk of thecarrier50 being pushed along the dock, it should generally be possible for onelift truck80 to load thecarrier50 without sliding it along the dock.
• Of course, once the stack ofcartons82 is properly positioned relative to the carrier, it could be caused to slide onto thecarrier50 by a separate pushing or pulling mechanism that does not require the presence of the lift truck. It should be noted that the pushing mechanism should be configured to push the cartons from the pallet without pushing the pallet at the same time.
• Still referring to the method of this embodiment, once thecarrier50 is loaded, the ship'sgear12 can lift it into the hold of theship10. When thecarrier50 has been landed in the hold, as shown inFIG. 6, a loadpush lift truck80 is then used to lift the stack of cartons off thecarrier50 and to transport the cartons to the storage location. At this stage, either of two approaches may be taken. The loadpush lift truck80 may initially deposit the stack ofcartons82 in their final stowage location, with a view to stevedores subsequently filling the remaining space atop the stack from a lift-truck-deposited stack ofcartons82 nearby, or the lift truck may deposit the stack in a convenient location with a view to the stevedores breaking down the stack into two or more shorter stacks on top of which the loadpush lift truck80 may deposit a full stack ofcartons82, the combined height of the hand-stacked and lift-truck-deposited cartons filling the available vertical space (seeFIG. 26).
• Of course, if the height of the hold space will accommodate two stacks ofcartons82, then thelift truck80 may deposit both such stacks ofcartons82 in their final stowage location. Providing the loadpush lift truck80 with side shift capability allows for greater precision in the placement of the stacks ofcartons82. Such side shift mechanisms shift the carrier and forks of alift truck80 laterally, usually by means of a hydraulic cylinder.
• Twolift trucks80 may be used to remove the stacks ofcartons82 from thecarrier50, so that the carrier may be quickly returned to the dock for further loading. The cycle time of the ship'sgear12 or crane lifting the carrier can be significantly increased if the loading or unloading of thecarrier50 is delayed. If thecarrier50 is designed to carry more than two stacks ofcartons82, of course, more lift trucks may be used simultaneously to unload it, thereby minimizing the time thecarrier50 remains in the hold. Similarly, the time the carrier remains on the dock can be reduced by usingmultiple lift trucks80 in the loading of thecarrier50.
• In order to deposit a stack ofcartons82 on the floor of the cargo hold, the lift truck operator moves thestack82 into the desired position and lowers the blades of the lift truck to the floor. If necessary, the side shift function can be used to position the stack in abutting relation with an adjacent stack or wall. The lift truck operator then simultaneously actuates the load push mechanism and either backs the lift truck away from the location or allows the load push mechanism to push the lift truck back from the stack (assuming the front of the stack is engaged with another stack or with a wall). The process for depositing a stack ofcartons82 on top of another partial or full stack is the same, except the lift truck positions the blades immediately above the full or partial stack on top of which the full stack is to be deposited.
• For stowage in irregular spaces, such as adjacent a sloping wall, in spaces too small for a full stack to be inserted or the like, the lift truck may deposit a full stack of cartons near such stowage location and the stevedores can stow the cartons in such areas by hand.
• With reference toFIG. 9, when substantially all of the cargo hold has been filled, apart from the square of the hatch, the lift truck(s) andcarrier50 are removed from the hold, and the square of the hatch is filled by depositing stacks of cartons lifted by cargo slings directly into the square of the hatch using the ship'sgear12. Some manual stowage of cartons will likely be necessary, of course, as the ceiling height under the closed hatch may not be fillable merely by loading full stacks of cartons one on top of another.
• In another embodiment of the invention, thecarrier50 may be used on the dock to depalletize and provide slings about the stacks ofcartons82 to be deposited directly into the square of the hatch without the use of slip sheets. As shown inFIG. 7, slings90 may be prepositioned in thefork channels66 prior to pushing the stack ofcartons82 onto thecarrier50, or may be drawn through thefork channels66 after loading of the carrier by means of a rod with a hooked end or the like. Thefork channels66 of thecarrier50 provide a convenient means for positioning the slings and provide the ability to add the slings either before or after loading of the carrier. Thecarrier50 may also be used as a depalletizer in a refrigerated warehouse or in other locations, as a loadpush lift truck80 may extend its forks through thefork channels66 and lift the stack ofcartons82 from thecarrier50.
• As shown inFIG. 8, once thecarrier50 is loaded with stacks ofcartons82, as previously described, and once theslings90 are positioned with respect to the stacks ofcartons82, aspreader bar92 mounted on thehook64 at the end of thecable14 of the ship'sgear12 may be used to lift the stacks ofcartons82 into the ship's hold. A plurality ofhooks94 are attached to thespreader bar92 by lengths ofcable96 for engaging the eyes of the cargo slings90 for lifting of the stacks ofcartons82. If theslings90 are properly positioned relative to the stack ofcartons82, the stacks ofcartons82 will swing toward one another into abutting relation after they have been lifted free of thecarrier50 by the ship'sgear12. The stacks ofcartons82 may then be deposited in the square of the hatch directly into their stowage location by the ship's gear, as shown inFIG. 9. While it may appear that the cartons of thestack82 would fall from the bottom of the stack when lifted by slings or the blades of a lift truck, it has been found that they do not tend to do so even when the stack ofcartons82 is not wrapped with the stretch wrap material.
• Of course, the slings used to load the stacks of cartons into the square of the hatch may be left in the cargo hold, and this will facilitate the offloading of the vessel. In such case, the cost of the cargo slings is offset by the lower labor and other costs achieved by the practice of filling the square of the hatch in this manner.
• In another embodiment of the invention, however, as shown inFIG. 9, it has been found that theslings90 may be recovered by lowering thespreader bar92 sufficiently to remove tension from theslings90, unhooking one end of theslings90 from thehooks94 and then drawing theslings90 from about the stacks ofcartons92 by lifting thespreader bar92 using the ship'sgear12. In order to avoid urging the stacks ofcartons82 so deposited out of an abutting relationship with adjacent stacks, the ends98 of the slings which are released may be those which run between the deposited stacks of cartons and the adjacent stacks, as shown inFIG. 9.
• As shown inFIG. 10, the eyes incargo slings90 are frequently made by folding theend portion100 of the web material of which the sling is made back over a portion of theweb material102 in a loop and sewing or otherwise bonding theend portion100 to theportion102. In one embodiment, cargo slings for use in loading the square of the hatch are made of a thinner material to avoid providing an excessively thick overlapping portion, and theedge104 of theend portion104 is securely fastened to theportion102 of thesling90 to reduce the tendency of theedge104 to catch and peel away from theportion102 when thesling90 is drawn between two abutting stacks of cartons. The end of thesling90 may also be cut at a diagonal before looping it back and affixing it to theportion102.
• Of course, thecarrier50 or a modification thereof (e.g., one in which the triangulartop portion58 of thecenter stop54 was removed, or in which the entire center stop54 itself was absent) could be used to depalletize and provide slings around stacks ofcartons82. These slung stacks of cartons could then be lifted into aship10, landed on a landing pad, and stowed by a side shift load push lift truck in the manner described in U.S. Pat. No. 5,980,198 to Coblentz. That is, a landing pad such as that shown inFIGS. 14, 15,27 (or multiples of such a landing pad, as needed, in the event that multiple stacks ofcartons82 are lifted at one time, e.g., as shown inFIG. 8) could be provided in the hold, the slung stacks of cartons could be deposited on the landing pad, the slings could be removed from the stack of cartons by pulling them through the channels in the landing pad, and a load push lift truck could remove the stacks of cartons from the landing pad by inserting its blades into the fork channels of the landing pad and raising the blades. The stack of cartons could then be stowed using the lift truck as hereinbefore described. As with the landing of stacks of cartons in the square of the hatch, one end of each of theslings90 may be removed from thehooks94, and the ship'sgear12 may then pull the slings through the channels formed in the landing pad and return them to dockside for reuse.
• FIG. 11 depicts a lightweight carrier110 that may be connected to a ship's gear by the lift ring112. The carrier110 comprises aspreader bar114 connected to the lift ring112 by two cables116,118. A plurality of hooks120 are mounted into thespreader bar114.
• Referring toFIGS. 11 and 12, the carrier110 further comprises a base122 on which are mounted a plurality of supports124, which are of sufficient height to form channels126 extending across thebase122 under the stacks ofcartons82. The supports124 are of sufficient width and depth to permit the blades of a lift truck to be inserted into the channels126 formed between them.
• As can be seen fromFIGS. 11 and 12, the stacks of cartons are arranged in a three-two carton stacking pattern commonly used for stacking cartons of frozen chicken on a standard 40 by 48 inch (102×122 cm)pallet30 with the 48 inch face of the stacks ofcartons82 being shown inFIG. 11 and the 40 inch face being shown inFIG. 12.
• As shown inFIG. 13, the three-two pattern comprises threecartons128 arranged side-by-side with their long edges abutting one another. Twocartons130 are arranged in end-to-end relation beside the row of the threecartons128.
• Cartons128,130 arranged in this manner (e.g., as the bottom layer of a stack of cartons82) may be lifted from the 40 inch (102 cm) sides of the pattern by inserting two slings or two lift truck blades under them, for example, in the two liftingzones132 shown in phantom inFIG. 13. Three slings or three lift truck blades could be inserted under the cartons of128,130 from the 48 inch (122 cm) side of the three-two pattern ofcartons128,130 by supporting them, for example, in the in the lifting zones133 of which extended transversely to be lifting zones131 and are likewise shown in phantom. When lifting a stack of cartons with the bottom layer stacked in this manner using slings or lift truck forks extending from one of the wider (48 inch-122 cm) sides of the pattern, for security in lifting, three slings or fork platens should be used so that each of the three side-to-side cartons128 is supported by one of the slings or platens.
• Referring again toFIGS. 11 and 12, thebase122 is connected to thespreader bar114 bycables132 which extend from connection points along thespreader bar114 to either side of the base122 (best shown inFIG. 12). The carrier thus provides threeload areas134,136,138, each of which is bounded on either side by two of the four pairs ofcables132. The need for stiffness of thebase122 is thus reduced, as the weight of the three stacks ofcartons82 is supported at four locations along the length of each side of the base122 rather than only in the middle of or at the opposite ends of thebase122. This permits the weight of the base134 to be sufficiently low to allow for the lifting of the three stacks ofcartons82 into the hold of a ship with a three-ton ship'sgear12 or crane. Of course, the inner two of the four pair ofcables132 could be eliminated if a base of sufficient stiffness is provided. Of course, depending on the capacity of the loading crane, abase122 could be fashioned to allow for the loading of two, four or other numbers of stacks of cartons. Further, the depth of the base122 could be extended to allow loading of two stacks of cartons, one behind the other, to provide for the lifting of four stacks of cartons in a 2×2 pattern, or six stacks of cartons in a 3×2 pattern.
• The carrier110 may be loaded by a single load push lift truck making three trips to load the three stacks of cartons in each of the three load. To do so, the lift truck would position each stack ofcartons82 on itspallet30 adjacent to one of theload areas134,136,138 of the carrier110 and use the load push mechanism to push the cartons off thepallet30 and onto the carrier110 in like manner as described above, and in a direction generally parallel to theboards40 comprising the upper surface of thepallet30 so that the lower surface of the cartons is not abraded excessively.
• Of course, if the sum of the thickness of the supports124 and thebase122 is less than the height of apallet30, thepallet30 may be rested on the surface of the dock proximate to or abutting the carrier110 while the stack ofcartons82 is pushed from thepallet30 onto the carrier110. In such case, the stack ofcartons82 could be pushed onto the carrier110 without having to rise over the edge of the supports124. This facilitates the process of pushing stacks ofcartons82 onto the carrier110.
• If the combined height of thebase122 and supports124 is greater than the height of apallet30, the tops of the supports124 could be angled downward for a short distance at their ends to provide an upwardly-inclined ramp extending from a height lower than or equal to the height of a standard pallet. In such case, even if the upper surface of the pallet were lower than the height of the center portion of the upper surface of the supports124, the edge of the stack ofcartons82 would slide up the ramped surface of the supports124 as thestack82 is pushed onto the carrier by the load push mechanism or other mechanism.
• After the stack of cartons has been pushed from thepallet30 onto the carrier, the blades of the lift truck are still extended under thepallet30. The lift truck may then retract the load push mechanism, raise the blades, carry the pallet to a holding location where it deposits thepallet30, and then retrieve another pallet30 (ormultiple pallets30 in the case of a lift truck provided with multiple sets of forks) carrying a stack (or stacks) ofcartons82 for loading onto the carrier.
• To facilitate loading, the carrier may be positioned adjacent astop140, such as the curb commonly found along the edge of a dock, or a backstop could be positioned adjacent the landing area for the carrier. The backstop may be of concrete, steel or other materials, so long as it is of sufficient mass and has sufficient traction on the dock to resist any tendency of the carrier110 to slide backwards when being loaded. The backstop should be capable of engaging the base of the carrier to prevent its sliding and may have a planar vertical surface for resisting the sliding of at least the first layer of cartons in thestack82 off the back of the carrier. This will make it easier for the operator of the lift truck to avoid pushing the cartons beyond the back edge of the carrier and to prevent the carrier from sliding away from the lift truck as the stack of cartons are pushed onto it.
• The speed of loading may be increased by use of a load push lift truck having three pairs of forks and being capable of lifting three stacks ofcartons82 at a time. The stacks ofcartons82 may be positioned with sufficient space between them that the lift truck can pick up three stacks ofcartons82 and push them onto the carrier110 at the same time with the load push mechanism. Alternatively, however, the lifting mechanism of the load push lift truck could be equipped with a side shift mechanism that moves the outer pairs of blades laterally in unison, and may also be provided with a shifter mechanism that permits the two outer pairs of forks to be moved respectively to the right and left away from the center forks. In such case, the lift truck could pick up three stacks ofcartons82 that are positioned side to side, and, if the base has pairs ofcables132 extending between theload areas134,136 and136,138, the shifter mechanism could be used to add the space between thestacks82 needed for the stacks ofcartons82 to clear the middle two pairs ofcables132 that support thebase122 of the carrier. The side shift mechanism could be of assistance in positioning the threestacks82 laterally with respect to the carrier110 so that the clearance between thestacks82 are centered on the middle two pairs ofcables132.
• The carrier110 may then be lifted into thehold20 of aship10 using the ship'sgear12 or other crane. Once in the hold, three-blade lift trucks may be used to unload the carrier by inserting their blades into the channels126 beneath the stacks of cartons and carrying them to stowage locations as described above. For greater efficiency, the lift trucks may be load push lift trucks that can then deposit the stacks ofcartons82 directly into desired stowage locations. Of course, when picking the stack ofcartons82 up from one of the the 48″ side, a three-blade lift truck can provide support to each of the three side-by-side cartons the ends of which abut one another along the 48″ side of the stack. The three-blade lift truck may also be used to lift stacks ofcartons82 from one of the 40″ sides of a stack, provided the carrier or landing pad has fork channels that will accommodate the use of three blades (see, e.g., the landing pad ofFIG. 27).
• It has also been found that using three lift truck blades to lift a stack of cartons in the hold of a ship can be beneficial in the carrying and maneuvering of the stack of cartons into a stowage location. In order to prevent thawing of frozen products during loading, the holds may be maintained at a sub-freezing temperature, and ice can form on the blades of a lift truck. During transportation of the stack ofcartons82 in the hold by a lift truck, the stack of cartons may thus slide laterally relative to the lift truck under such icing conditions. Such shifting has been found to be less likely and less serious when the cartons are supported during transportation by three blades rather than two. Modification of the blades to resist lateral sliding may also present a solution to this problem. Flanges or channels running lengthwise along the blade can provide additional resistance to lateral shifting of stacks of cartons on the blades.
• When two such lift trucks are used in the hold of a ship, invariably one of them is working in greater proximity to the landing zone in which the cartons are deposited. Thus, one of the lift trucks will frequently return for another load before the other. Thus, it may be desirable to carry three or more stacks of cartons into the hold at a time when using two lift trucks in the hold depending on how quickly the lift trucks can stow them. The addition of a third lift truck may improve the cycle time of the carrier110 between the hold and dock, since the carrier may be unloaded more quickly.
• Thebase122 andspreader bar114 may be shortened or lengthened as desired to accommodate greater or lesser numbers of stacks of cartons or to accommodate wider or narrower stacks of cartons in other stack patterns. A base similar to the base122 may also be used in another embodiment of the invention for palletless loading of other cargo carriers or for cargo storage facilities, as described in greater detail below.
• As mentioned above, a carrier110 may also be used to depalletize and provide slings around stacks of cartons. The need for the crane or ship'sgear12 to wait for the lift trucks in the hold of a ship to unload a carrier is not present if stacks ofcartons82 are lifted into the hold using slings and landed on a landing pad as described above, since one end of each of the slings may be unhooked from the associated hook and the slings may be drawn from around the stack ofcartons82 even if the lift trucks have not returned to the landing area to carry the stacks ofcartons82 away.
• FIGS. 14 and 15 depict twosuch landing pads140,142 that are configured to receive up to one stack and three stacks ofcartons82, respectively, at a time. Thelanding pads140,142 of this embodiment comprise arectangular base144 on which are mounted a plurality ofparallel supports148 that can support stacks of cartons. The width and locations of thespacers148 on thebase144 are chosen such that a stack or stacks ofcartons82 landed squarely on thelanding pad140,142 will be supported in a manner to permit lifting of the stack or stacks ofcartons82 by inserting the blades of a lift truck under the stack to be lifted and lifting it from thelanding pad140,142. The stack ofcartons82 may then be carried to a stowage location and deposited as described above, and as shown inFIG. 26.
• Thechannels150 formed between thespacers148 on thelanding pads140,142 must be of sufficient depth that the forks of a lift truck can be inserted under the stack of cartons, and must be of sufficient width to receive such blades. As the blades of a lift truck are generally thicker and wider than cargo slings, such dimensions allow the slings to be pulled through the channels without significant resistance.
• As shown inFIGS. 14 and 15, thelanding pads140,142 are configured for use by three-blade lift trucks for removal of stacks of cartons stacked in a three-two pattern as discussed above. That is, the edges of the base144 perpendicular to the long axis of thespacers148 are, respectively, about one and three times 48 inches (122 cm) in length. Multiple units of the one-stack landing pad140 could be bolted or otherwise fastened or positioned together to form a landing pad of sufficient length to receive multiple stacks ofcartons82 if the dimensions of thebase144 andspacers148 are appropriately chosen.
• Thelanding pad140,142 could be provided with two or more channels extending transversely to thesupports148 andchannels150, so that two-blade lift trucks could be used to unload stacks of cartons from the sides of thelanding pads140,142 having only two channels therein. However, the forks of a two blade lift truck would not typically be of sufficient length to allow their insertion under the center stack of cartons on the three-stack landing pad142 from either of the ends of thelanding pad142, as the forks would have to be 96 inches (244 cm) in length to reach completely under the stack ofcartons82 in the center position. A landing pad configured to receive three or more stacks ofcartons82 and to have the stacks unloaded by two blade lift trucks from the long edge thereof could be made by adjusting the dimensions of thebase144 of the landing pad, the location of the mounting of the supports and the width and thickness of the supports to provide for landing and lifting of stacks ofcartons82 using two slings and two blades, respectively.
• While thecarrier50 or thebase122 of the carrier110 or other such structure may be used to depalletize and provide slings about stacks ofcartons82 at dockside for lifting into the hold of a ship, it is also possible for the crane or ship's gear to be held up waiting for a full load of stacks of cartons to be readied for lifting into the hold of the ship.Multiple carriers50 orbases122 or the like could be used to provide surge capacity for the crane or ship's gear. However, it is more efficient for a crane or ship's gear to return to a single location rather than having to return to multiple locations. In particular, gear used on many ships includes twin booms, one positioned over the hatch and one positioned over the loading area. Winches on each boom take in or let out their cable, as appropriate, to lift or land cargo at specific, chosen locations, so that little effort is required to pick up and deposit cargo at the two chosen locations.
• In another embodiment of the invention, and referring toFIGS. 16-19, surge capacity for picking up one or more stacks of cartons at a time is provided by use of a roller deck that may also provide queuing capacity. The roller decks ofFIGS. 16-19 may be loaded either from the side or from the end, as discussed below. As shown inFIG. 16, aroller deck160 according to this embodiment comprises a base162 on which a plurality ofrollers164 are rotatably mounted. Therollers164 are mounted with their rotational axes transverse to the long edge of the base162, and may be of a length sufficient to extend across the entire width of theroller deck160, or may be segmented or may consist of a plurality of separate wheels rotatably mounted on theroller deck160 with parallel rotational axes. The rollers provide a low-friction transport surface so that stacks of cartons may be moved along the length of theroller deck160. This conveying of the stacks of cartons may be accomplished manually, with the assistance of gravity, or under power. At the lifting (unloading) end166 of the base,channels168 are formed between sections ofrollers164 by spacing therollers164 sufficiently that acargo sling170 or the blades of a lift truck can be inserted into thechannels168 under a stack ofcartons82. The upper portion of the long edge of the base160 could be cut away at the location of such channels to provide additional depth for insertion of the blades of a lift truck.
• If desired, channels could be formed by using segmented rollers spaced to form channels transverse to their rotational axes, aligned portions in which the diameter of the rollers is decreased sufficiently to form useful channels, or, where wheels are used as rollers, the wheels could be omitted in certain areas to form such channels, such that lift truck blades or slings could be extended under the stack of cartons.
• The base160 may be made in several sections, such as alifting section172, aqueuing section174, and aloading section176 for convenient transportation and storage of the apparatus (theloading section176 actually constitutes a queuing section in such case, in addition to thequeuing section174, since a stack of cartons loaded thereon may be conveyed by the rollers to thequeuing section174 and on to the loading section176). Of course, the queuing andloading sections174,176 could be eliminated if queuing is not desired, and thelifting section172 could be loaded directly by the lift trucks However, this embodiment of the invention will be described in connection with a base160 having lifting, queuing andloading sections172,174,176 as it may be advantageous in many circumstances to provide the queuing capacity to reduce the likelihood that either the crane or the loading lift truck will be required to wait for action by the other.
• Thesesections172,174,176 could be aligned and fastened together, as by using bolts or pins, when theroller deck160 is to be used. Multiple loading and liftingsections172,176 could be provided with different patterns of spacing of thechannels168 that could be selected according to the particular needs of the ship and cargo. Thesesections172 could be attached to the other sections as desired, to provide flexibility to the planners based on considerations relating to the cargo, the ship, the available lift truck and other equipment and other factors. Different slinging or lift truck blade spacings could then be used to lift stacks ofcartons82 from theroller deck160, as desired. The width of theroller deck160 should be chosen to accommodate the width of the various stacks of cartons and other articles that may be deposited thereon.
• An end stop180 may be mounted to the base at the liftingend166 of theroller deck160. Thestop180 limits the travel of stacks ofcartons82 or the like along the bed of rollers162 of theroller deck160, thus retaining the stack ofcartons82 on theroller deck160, and allows the repeatable positioning of the stacks of cartons for lifting from theroller deck160 for stowage. Thestop180 should be of sufficient strength, width and height that it can stop the travel of a stack ofcartons82 traveling along theroller deck160 at a normal velocity without causing damage, excessive distortion of the stack (as by one or more layers of cartons sliding relative to other layers) or loss of cartons from the upper layers. The stop may be of a single piece, or may be segmented to allow insertion of the blades of a lift truck under a stack of cartons on the lifting section.
• Theupper surface184 of the roller deck may be level or inclined. If the roller bed is sufficiently inclined, the stacks of cartons can roll from theloading end182 of theroller deck160 to the liftingend166 without the need for any mechanism to urge them toward thestop180. Theroller deck160 may be built with such an incline, may be supported by a plurality of adjustable legs (not shown) along its length, or may have spacers inserted beneath the base162 at positions along its length to support the base162 and upper surface Should any of the stacks ofcartons82 require assistance to reach the liftingend166 of theroller deck160, the incline facilitates the manual pushing of thestack82 to the liftingend166 of the roller deck by a worker or workers. A worker may also be tasked with pushing the stacks of cartons along the rollers162 of alevel roller bed160 having a levelupper surface182, or the rollers could be powered to transport stacks of cartons along theroller deck160.
• Stacks ofcartons82 may be loaded onto theroller deck160 from the side. As shown inFIGS. 16 and 17, a pallet table190 may be provided to facilitate the positioning ofpallets30 bearing stacks ofcartons82 relative theroller deck160 at the appropriate height and in the appropriate plane. The pallet table190 may be bolted or otherwise affixed to theroller deck160, in which case, the vertical distance between theupper surface192 of the pallet table and the adjacentupper surface184 of theroller deck160 should be approximately equal to the thickness of a pallet so that the bottom of a stack of cartons being pushed from thepallet30 onto theroller deck160 will not have to rise in the process of the transfer from thepallet30 to theroller deck160.
• The pallet table190 may be supported byadjustable legs194 which support it at the appropriate height and tilt relative to the surface of the dock and the plane of the adjacentupper surface182 of theroller deck160. Thelegs194 may include ascrew portion196 that may be rotated to adjust the length of theleg194. Anut198 may be affixed to thescrew portion196 of thelegs194 to facilitate adjustment thereof. A plurality ofsuch legs194 may be used to support the base.
• The plane of theupper surface192 of the pallet table190 may either be level with the surface on which it is placed, such as a dock, or leveled with theupper surface184 of theroller deck160 or otherwise. If theupper surface184 of theroller deck160 is tilted with respect to the surface on which it is placed, then thelegs194 may be adjusted to tilt theupper surface192 of the pallet table190 such that it is in a plane parallel to that of theupper surface184 of theroller deck160. Depending on the width of the pallet table, one or more stacks ofcartons82 may be pushed onto theloading section172 of theroller deck160 at a time, as shown inFIG. 16.
• Apallet stop200 may be attached at the rear portion of the pallet table. Apallet30 may be pushed into engagement with the pallet stop200 such that it is proximate to aroller202 rotatably mounted either to theroller deck160 or to the pallet table190. To facilitate loading, the upper surface of theroller202 may be mounted such that it is equal to or higher than the plane of theupper surface184 defined by therollers164 of theloading end182 of theroller deck160.
• Aloading stop206 may be mounted to theroller deck160 along the edge opposite to the pallet table190. The loading stop should be of sufficient height and width to stop stacks of cartons from moving too far across theroller deck160 and to provide indexing for the stacks ofcartons182 to align them with the long axis of the roller deck.
• One ormore stops208,210 may be provided to limit the travel of stacks ofcartons82 along theroller deck160. Many different types of stops may be used. In the present embodiment, two flag stops208,210 are provided. These stops comprise a squaretubular receiver212 mounted to theroller deck160, and aflag stop portion213 comprising asquare tube shaft214 that can be inserted into thereceiver212, aflag portion216 mounted on the shaft for engaging stacks of cartons traveling along theroller deck160 and ahandle218 for removing theflag stop portion213 from engagement with thereceiver212. Theshaft214 may be inserted into the receiver such that theflag portion216 extends transversely over therollers164 of theroller deck160 for stopping movement of stacks ofcartons82 along theroller deck160, and may be removed from thereceiver212, rotated from such orientation and inserted such that the flag portion does not block the progress of stacks ofcartons82 moving along theroller deck160. Other types of stops, such as stops insertable into, or raisable above the upper surface of, theroller deck160 through gaps between adjacent rollers, roller brakes that stop rotation of one or more rollers at desired stop locations and the like may also be used. Alternatively, sections ofrollers164 could be selectively powered to rotate and move the stacks ofcartons82 along theroller bed160 to desired locations.
• While thestops200,206 may be used to restrain the pallet against movement toward theroller deck160 during loading of theroller deck160, the lift truck may also carry restraints, as described below, to retain the pallet on the forks of the lift truck and restrain motion of the pallet toward theroller deck160.
• If theupper surface192 of the pallet table is tilted relative to the plane of the surface on which the pallet table190 is positioned, awheel ramp218 may be positioned proximate to the higher side of the pallet table190 such that a wheel of thelift truck220 can be driven onto it to tilt the lift truck by an angle to level the forks of the lift truck with the pallet table190.
• Theroller deck160 of the present embodiment may be used as follows. load push lift truck carrying one or more stacks ofcartons82 onpallets30 raises thepallets30 above the level of theupper surface192 of the pallet table190, positions the stacks of cartons above the pallet table190 and lowers thepallets30 onto theupper surface192 of the table190. The operator of thelift truck220 then engages theload push mechanism222 of the lift truck to push thepush plate224 forward relative to the pallet table and slide the stacks ofcartons82 over theroller202 and onto the roller deck. The stacks ofcartons82 may be pushed into engagement with theload stop206 to align them with the long axis of theroller deck160. The stacks of cartons then move or are moved along the roller deck to a position intermediate theends166,182 of theroller deck160 where they may be held by theflag stop210 and queued for moving to the liftingend166 of the roller deck.
• Cargo slings170 may be placed in thechannels168 prior to movement of stacks ofcartons82 into position above them, or may be pushed or pulled through thechannels168 between the rollers by a hooked rod or the like. Once the desired number of stacks ofcartons82 are moved into position, with theendmost stack82 abutting theend stop180, the ends of the cargo slings170 may be attached to the cargo hooks230 of aspreader bar232. Thespreader bar232 can then lift the stacks of cartons off theroller deck160 and carry them into the hold of a ship. Alternatively, the stacks of cartons could be removed from the roller deck by a lift truck, that would insert its blades into thechannels168 and lift the stack or stacks ofcartons82 from the roller deck.
• Further, the roller deck could be modified in the lifting zone by segmenting the rollers such that a plurality of axially aligned rollers extend across theroller deck160, and providing space between such rollers to form channels therebetween for slings or lift truck blades extending transversely of the rotational axes of therollers164. Rollers could also be formed with reduced diameters at selected locations to form such channels, or, if the rollers comprise a plurality of wheels, such wheels could be spaced or omitted to form such channels. Such channels may be in addition to or in lieu of thechannels168 into which slings or lift truck blades may be extended. In order to facilitate use of the channels extending transversely to the rotational axis of therollers164, thebackstop180 may be eliminated or modified so that it did not interfere with the inserting of the slings or lift truck blades into the channels or the lifting of the stack of cartons from theroller bed160. Flag stops, or a series of upstanding stops could be used for this purpose. Such aroller bed160 could be used in the hold of a ship or elsewhere to provide a landing pad with queuing. In such case, channels parallel and perpendicular to the rollers could be provided that would allow the landing of multiple stacks ofcartons82 on theroller deck160 at one end, and the lifting of such stacks of cartons at that end or at the other end. In the latter case, the stacks of cartons could be rolled along thebed160 to the other end to make room for the landing of more stacks ofcartons82 on the one end.
• Theroller deck160 can be made in various lengths.Longer roller decks160 can provide queuing of stacks of cartons to reduce delays of the ship's gear or other crane mechanism in waiting for a complete load to be presented. In the present embodiment, moreover, theroller deck160 may be loaded with two stacks ofcartons82 at a time, while the spreader bar is adapted to carry three stacks ofcartons82 at a time. Thus, with its third load, thelift truck220 would have deposited two loads for the crane or ship's gear to carry into the hold of the ship. Theroller deck160 may also be used as a queuing landing pad for use in the hold of a ship. In such case, channels could be provided in theloading area176 in like manner to thechannels168 provided in thelifting section172
• It should be noted that the normal three-two stacking pattern of cartons on a 40″×48″ (102 cm×122 cm) and the orientation of the boards forming the top of the pallet may result in theslings90 passing under the stack of cartons in the 40″ (102 cm) direction. In such case, threeslings90 would be needed perstack82, as the three side-by-side cartons of a layer should each be supported by a separate sling. When slinging under the 48″ (122 cm) width of thestack82, only two slings are needed.
• End loading of aroller deck160 can be accomplished by positioning the pallet table190 adjacent the end of theroller deck160, as shown inFIGS. 18 and 19. Referring toFIG. 19, the pallet table190 may be made to accommodate two pallets at a time to be received from a double-wide loadpush lift truck220. The double-wide roller deck160 can be made as a double-wide unit, or may comprise two single-wide units that are positioned side by side. Theslings90 used to lift two stacks of cartons at a time, of course, would be longer than required for lifting a single stack of cartons at a time. The stretch-wrapping of the stacks ofcartons82 can facilitate the lifting of two stacks ofcartons82 at a time by a single pair (or set of three) cargo slings90.
• As mentioned above, despite the weight of the stacks ofcartons82, thebase52,122 may be used to depalletize them without the need for use of a slipsheet. Stacks ofcartons82 could be lifted into the hold of a ship from thebase50,122 or from depalletizer platforms having similar channels for slings and/or lift truck forks. Referring toFIGS. 20, 20A and21,such depalletizer platforms240 may include a base242 having a plurality ofsupports244 similar in function to thesupports124,148 of the carrier110 andlanding pads140,142. Abackstop246 may be provided to assist the operator of alift truck220 to position stacks of cartons on the upper surfaces of thesupports244 of thedepalletizer platform240. Theplatform240 could also be positioned adjacent a curb or free-standing backstop, as described in connection with the carrier110 ofFIG. 11 to facilitate loading and to resist sliding of thedepalletizer platform240. Thebase242 of thedepalletizer platform240 may also include apallet apron248 of sufficient size that the wheels of a lift truck carrying a loadedpallet30 would be driven onto a portion of theapron248 when apallet30 is moved into abutment with the outermost of thespacers244. The weight of thelift truck220 bearing on theapron248 should control any tendency of thedepalletizer240 to slide away from thelift truck220 as the stack ofcartons82 is pushed from thepallet30 onto thedepalletizer240. The outward-facing edge (the edge remote from the backstop246) of thesupports244 may be beveled to facilitate pushing of the stack ofcartons82 onto thesupports244. Thelift truck220 may then retract the load push mechanism, lift the empty pallet on the blades of thelift truck220 and take the empty pallet to a holding or stowage location.
• While thestops200,206 provide an effective means for restraining the pallet against motion when the stack ofcartons82 is pushed onto theroller deck160, other types of restraints could be used. For example, as shown inFIGS. 28 and 29, restraints can be mounted on the lift truck. Referring toFIG. 28, therestraint300 comprises a metal bar of generally triangular cross section mounted on theblades302 of a lift truck. The rear surface of the restraint of this embodiment extends vertically upward from the blade. The forward surface of the restraint slopes upward and rearward relative to the blade to facilitate insertion of theblade302 and restraint into a 4-way channel of a standard pallet. The restraint is mounted on theblade302 toward its rear, such that when the restraint is inserted into a 4-way channel of apallet38, and theblade302 of the lift truck is raised, the back of therestraint300 can engage the upper portion of the inner surface of theside beam34 of thepallet38 to restrain the pallet against movement off of theblade302. The pallet can be released by lowering theblade302 andpallet38 onto a surface. The blade can then be withdrawn from the 4-way channel42 of thepallet38.
• Apallet stop304 may also be mounted on theblade302. Thepallet stop304 in the present embodiment is of rectangular cross section and may have a length greater than the width of the 4-way channel in theside beam34 of the pallet and a height above theblade302 that is greater than the height of the 4-way channel so that the pallet stop may engage theside beam34 of thepallet38 when theblade302 of the lift truck is inserted into the 4-way channel of thepallet38. The pallet stop is positioned such that its forward surface is forward of the forward surface of thepush plate224 when thepush plate224 is fully retracted, and prevents theblade302 from being pushed so far into the 4-way channel of thepallet38 that the back edge of the pallet38 (the leftmost edge as shown inFIG. 28) is forward of the front surface of thepush plate224 when thepush plate224 is fully retracted. Therestraint300 and pallet stop304 may be mounted to theblades302 of the lift truck and may be attached by a variety of means including bolts or clamps, or by welding. Of course, there must be sufficient clearance between the upper surface of theblades302 of the lift truck and the lower edge of thepush plate224 so that the push plate can be extended over the top of thepallet38.
• In another embodiment, and referring toFIGS. 29 and 30, a retainingapparatus310 is mounted on alift truck220. Thisrestraint310 comprises ahousing312 extending transversely relative to theblades302 of thelift truck220. The forward surface of thehousing312 serves as a pallet stop in a manner similar to the pallet stop304 shown inFIG. 28.Grippers314 are slidably mounted in each end of thehousing312 and are extendable and retractable relative to thehousing312 by a hydraulic cylinder. According to this embodiment, the pallet-engagingportion316 of thegrippers314 is L-shaped, with thedistal end portion318 of the gripper of the pallet-engagingportion316 forming a right angle with thelateral portion320 of thepallet engaging portion316.
• Therestraint310 may be operated by the driver of the lift truck to extend and retract thegrippers314, as by ahydraulic cylinder322 mounted in thehousing312. The horizontal distance between the forward surface of the housing and thedistal end318 of the pallet-engagingportion316 of thegrippers314 should be greater than the thickness of the side beams34 of apallet38 when the grippers are in their extended position. The distance between the distal ends318 of thegrippers314 in the extend position should be greater than the length of theside beam34 of apallet38 and less than the length of theside beam34 when thegrippers314 are retracted. The distal ends318 of the pallet-engagingportion316 of thegrippers314 can thus be inserted into thefork channels44 of apallet38 to restrain thepallet38 from moving off theblades302 of the lift truck when a stack ofcartons82 is pushed from thepallet38.
• In the embodiment depicted inFIGS. 20 and 21, the depalletizer is configured to hold a stack ofcartons82 with a width of 48″ (122 cm), the width extending parallel to thebackstop246, and a depth of 40″ (102 cm). However, it could be configured to receive stacks of other sizes or orientations as desired.
• In use, a load push lift truck positions a palletized stack ofcartons82 with the far edge of thepallet30 adjacent the outermost of thesupports244. The load push mechanism is then engaged, pushing the stack ofcartons82 from thepallet30 onto the upper surfaces of thesupports244. Slings can be positioned in thetransverse channels250 orlongitudinal channels252 to lift the stack ofcartons82 from the depalletizer. However, thestack82 may also be removed from the depalletizer by the blades of a lift truck inserted into the transverse orlongitudinal channels250,252 formed between thespacers244. For lifting a 40″×48″ (102 cm×122 cm) stack ofcartons82 from the front of thedepalletizer240, with the 48 inch (122 cm) edge being the front edge of thestack82, a three-blade lift truck may be used with the transverse spacing of its blades adjusted such that each one supports a separate one of the three side-to-side cartons in the bottom layer of the stack ofcartons82. A two- or three-blade lift truck220 may be used to lift the stack ofcartons82 from thedepalletizer240 by inserting its blades into thetransverse channels250.
• Thedepalletizer platform240 could be configured with a depth of 48 inches (122 cm) and a width of 40 inches (102 cm) if desired, and if thepallet30 is provided with a smooth upper surface, such as a plastic, plywood or metallic surface that permits pushing the stack ofcartons82 off thepallet30 in a direction parallel to the 48″ (102 cm) edge of thepallet30. Thedepalletizer platform240 could also be sufficiently wide to accept multiple stacks ofcartons82 at a time. As shown inFIG. 20A, rollers245 (or a plurality of wheels) could be used in a platform in place of thesupports244 to facilitate loading, withchannels251 being formed between rollers by segmenting each of the rollers into a plurality of segments and providing space between segments that can receive theblades290 of alift truck220, by using wheels as rollers, and omitting and/or spacing the wheels apart in the areas where channels are desired, and so forth. An upstanding plate or series ofplates253 may be attached to the base242 to provide a pallet stop against which a pallet to be unloaded may be placed.
• In one embodiment of the invention, adepalletizer platform240 is used for the loading of a shipping container or the like. The interior width of refrigerated shipping containers varies. Containers with interior widths of from a little more than 88 inches (224 cm) to more than 90 inches (229 cm) may be found. Such containers may be loaded by depositing pairs of stacks (or rows of stacks) ofcartons82 in their interior side by side with the 40 inch (102 cm) side of thestack82 being oriented perpendicular to the side wall of the container (“40+40 loading”). The remainder of the width may be hand stacked in the remaining space between thestacks82 or between astack82 and the wall of the container. Thestacks82 could also be positioned with one stack (or row of stacks) having its 48 inch (122 cm) side and one stack82 (or row of stacks) with its 40 inch (102 cm) side perpendicular to the side walls of the container (“48×40 loading”).
• As mentioned above, load push lift trucks that are used to push stacks ofcartons82 from the pallets onto a carrier110 ordepalletizer platform240 must have push mechanisms with sufficient clearance over the blades so that the push mechanism does not engage both the stack ofcartons82 and the upper portion of thepallet30. The lift trucks that lift the stacks ofcartons82 from alanding pad140,142,carrier50,110 ordepalletizer240 have the bottom layer of the stack ofcartons82 resting on the blades of thelift truck220. As such, if the push plate of the lift truck has a clearance of, for example, 4 inches (10 cm) over the blades, the push plate may not engage the bottom layer of the stack of cartons. This may be particularly important in the event that the stack of cartons are not wrapped with plastic wrap or the like. Thus, the lift trucks used in the hold of a ship may have load push mechanisms with lower edges having less clearance over the blades.
• In another embodiment of the invention, the loading of a container can be accomplished using adepalletizer platform240 and one ormore lift trucks220. For 40+40 loading, a single, two blade load push lift truck could be used as follows. Thelift truck220 positions a palletload ofcartons82 on thedepalletizer240 and uses its load push mechanism to push the stack ofcartons82 onto thesupports244 of thedepalletizer240. Thelift truck220 may then retract the load push mechanism and deposit thepallet30 in a holding area. Theblades272 of the lift truck can then be inserted in thetransverse channels250 of thedepalletizer platform240, and the stack ofcartons82 may be lifted from the depalletizer and carried to a stowage location in a container or the like. The stack ofcartons82 may then be deposited in the stowage location using the load push mechanism of the lift truck.
• For 48+40 loading, a two-blade and a three-blade lift truck could be used. The lift truck with three blades would insert its blades into thelongitudinal channels252 of thedepalletizer240, and lift and carry the stack ofcartons82 to its stowage location. The two blade lift truck could then use thetransverse channels250 to insert its blades under a stack ofcartons82 and to lift and carry it into a container or the like. The load push mechanism could then be used to deposit the stack ofcartons82 in the desired stowage location. A container could thus have two parallel rows of 40 inch (102 cm) and 48 inch (122 cm) width, respectively. If the stacks ofcartons82 are of such height that they can be stacked on top of one another within the container, then a second stack ofcartons82 may be brought into the container by thelift truck220 and deposited on top of a first such stack by the load push lift truck. If the stacks ofcartons82 are of such height that their combined height exceeds the interior height of the container, layers of cartons may be removed from stacks ofcartons82 that have been deposited in their stowage location and may be hand stowed to fill in other space in the container. After removal of sufficient layers of cartons from thestack82, a full stack can be deposited on top of the remaining layers in order to take advantage of the headspace in the container.
• According to another embodiment of the invention, the backstop of thedepalletizer240 may be taller than a stack of cartons to facilitate placing of one stack on top of another. In such case, the lift truck may position the pallet carrying a second stack ofcartons82 at approximately the level of the top layer of cartons in a first stack that is resting on thedepalletizer240. The load push mechanism may then be used to push the stack ofcartons82 off the pallet and onto the top of the first stack ofcartons82. If desired, one or more layers of cartons could be removed from the first stack ofcartons82 so that the combined height of the first and second stacks ofcartons82 are of the desired final height, such as the maximum height of a stack of cartons that can be loaded into a cargo container.
• In accordance with another embodiment of the invention, a load push mechanism is modified to include agate section282 on the lower edge of thepush plate280. Thegate section282 may be hydraulically activated, and may be of a type that does not interfere with the operation of the load push mechanism. For example, as shown inFIGS. 24 and 25, a hingedgate284 or atelescoping gate286 may be movable by one or morehydraulic cylinders288 between positions in which thelower edge298 of thegate284,286 is proximate to theblades290 of thelift truck220.
• Thegate284, as shown inFIG. 24, is pivotably mounted to thepush plate280 by ahinge296. Thehydraulic cylinder288 is pivotably connected at its ends between thegate284 and thepush plate280 such that, in its fully extended position, the push plate is pivoted to a position in which it is parallel to the face of thepush plate280. When thehydraulic cylinder288 is retracted, thegate284 is raised to provide maximum clearance between the upper surface of theblades290 of thelift truck220 and thepush plate280. Thus, thegate260 can be lowered to engage the bottom layer of a stack ofcartons82 being carried on theforks290 of alift truck220, for example, for depositing in a stowage location, or it can be raised to provide clearance so that the push plate may be extended to push a stack ofcartons82 from a pallet, for example, onto a depalletizer such ascarrier50,110,roller deck160 ordepalletizer260 with theforks290 in the 4-way fork channels.
• Thegate284 operates in a similar manner, except that it is slidably mounted in and telescopes into the lower portion of thepush plate280. Thegate286 is operated by one or more hydraulic cylinders, oneend288 of which is mounted to thepush plate280 and the other end of which is connected to thegate286. Thehydraulic cylinder288 may be operated to move thegate286 vertically toward and away from theblades290 of thelift truck220.Multiple gates284,286 may be used along the bottom edge of thepush plate280 if desired.
• Where it is desired to use a loadpush lift truck220 for pushing stacks ofcartons82 frompallets30, the gate may be moved to its retracted position. When a stack of cartons is carried directly on theblades290 of thelift truck220, the gate may be lowered to ensure that the push plate is able to engage the bottom layer of the stack ofcartons82.
• Of course, other methods may be used to provide variable clearance over theblades290 of a load push lift truck. For example, thewhole push plate280 could be vertically movable with respect to the load push mechanism, or the load push mechanism itself could be vertically movable relative to the lift mechanism, or the blades of the lift truck could be lowerable (including by replacement of the blades) relative to thepush plate280. In any case, the variable clearance over the blades of a lift truck may permit the lift truck to be used both for depalletizing stacks ofcartons82 as well as for depositing the stacks of cartons in stowage locations. For lift trucks dedicated to depalletizing or stowage of stacks ofcartons82, an appropriate, fixed clearance of thepush plate280 over theblades290 may be chosen.
• The low profile of the cartons normally used for frozen animal products present challenges if sufficient clearance is not provided. In the case of pushing stacks of cartons from a pallet, too little clearance may result in thepush plate280 engaging the pallet rather than the stack ofcartons82. Too great a clearance, of course, may result in engagement of the push plate with the second layer of cartons in thestack82, but not the first layer. This can result in sliding of the second and other layers of the stack ofcartons82 relative to the first layer.
• While the present invention has been described with reference to various embodiments, it will be apparent to those skilled in the art that modifications may be made within the scope of the invention.

Claims (14)

1. A queuing depalletizer for palletized stacks of cartons of frozen animal products comprising:

an elongated transport surface having a loading station at a loading end and an lifting station at a lifting end, the elongated transport surface having a first axis extending from the loading end to the lifting end;

a pallet restraint for limiting movement of a pallet toward the loading end of the transport surface when a stack of cartons is pushed from the pallet onto the loading station;

a stop adjacent the lifting end of the transport surface for stopping movement of stacks of cartons along the transport surface at the lifting end of the transport surface; and

a plurality of spaced channels formed in the transport surface at the lifting station for receiving lifting apparatus.

2. The queuing depalletizer ofclaim 1 wherein the elongated transport surface comprises a plurality of rollers rotatably mounted to a frame with their axes of rotation extending perpendicularly to the first axis of the transport surface.

3. The queuing depalletizer ofclaim 1 wherein the elongated transport surface comprises a plurality of wheels rotatably mounted to a frame with their axes of rotation extending perpendicularly to the first axis of the transport surface.

4. The queuing depalletizer ofclaim 1 wherein the spaced channels are of sufficient depth to receive cargo slings positioned therein while permitting stacks of cartons to be moved along the transport surface over the channels.

5. The queuing depalletizer ofclaim 1 wherein the spaced channels are of sufficient depth to receive the blades of a lift truck positioned therein while permitting stacks of cartons to be moved along the transport surface over the channels.

6. The queuing depalletizer ofclaim 2 wherein the transport surface is of sufficient length to accommodate at least three stacks of cartons of frozen animal products.

7. A depalletizer for palletized stacks of cartons of frozen animal products comprising:

a support surface for receiving a stack of cartons of frozen animal products pushed from a pallet;

a pallet restraint for limiting movement of a pallet when a stack of cartons is pushed from the pallet onto the loading station;

a plurality of channels formed in the support surface of sufficient length and width to receive lifting apparatus for lifting a stack of cartons from the support surface;

8. The depalletizer ofclaim 7 wherein the pallet restraint comprises a back stop for limiting the travel of a stack of cartons being pushed from a pallet onto the support surface.

9. The depalletizer ofclaim 8 wherein the back stop extends to a height above the support surface greater than the height of a stack of cartons.

10. The depalletizer ofclaim 7 wherein the support surface is elongated and includes a loading position adjacent one end and a lifting position adjacent the other end, the channels being positioned at the other end of the support surface, and wherein the support surface comprising a plurality of rollers rotatably mounted to a frame for conveying stacks of cartons of frozen animal products from the receiving position to the lifting position.

11. The depalletizer ofclaim 1 wherein the lifting station of the elongated transport surface compises a plurality of rollers for supporting a stack of cartons in the lifting position and wherein the spaced channels are positioned in gaps between the rollers.

12. The depalletizer of claim26 wherein the elongated support surface is inclined between the loading station and the lifting station, and wherein the incline is sufficient that a stack of cartons of frozen animal products can move under the influence of gravity from the loading station to the lifting station.

13. The depalletizer ofclaim 1 wherein the pallet restraint is mounted to the depalletizer adjacent the loading end.

14. The depalletizer ofclaim 1 wherein the pallet restraint is mounted on a lift truck.

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