Patent Publication Number: US-2023157224-A1

Title: Sod harvesting systems and related methods

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present application claims the benefit of priority from U.S. Provisional Application No. 63/281,891 filed Nov. 22, 2021, which is hereby incorporated herein by reference in its entirety. 
    
    
     FIELD 
     The specification relates generally to sod harvesting. 
     BACKGROUND 
     Sod harvesters typically operate by undercutting and chopping sod into slabs, transporting the slabs along a conveyor of the harvester, and transferring the slabs onto a pallet. When a pallet is sufficiently loaded with slabs, the loaded pallet is discharged from the sod harvester and replaced with an empty pallet for continued stacking of slabs. The discharged pallet can be transported to a location where the sod is to be stored, sold, or laid. 
     SUMMARY 
     The following summary is intended to introduce the reader to various aspects of the applicant&#39;s teaching, but not to define any invention. 
     According to some aspects, a method of operating a sod harvester includes: (a) cutting sod slabs from the ground using a cutting assembly; (b) advancing the slabs along a conveyor assembly from the cutting head to a transfer station located along the conveyor assembly; (c) repeatedly transferring the slabs from the transfer station to a pallet station spaced apart from the transfer station using a stacking head to form a loaded pallet at the pallet station; (d) replacing the loaded pallet at the pallet station with an empty pallet; (e) during the replacing step, forming a stack of the slabs at the transfer station using the stacking head; (f) transferring the stack of slabs using the stacking head from the transfer station to the pallet station to deposit the stack onto the empty pallet when received at the pallet station; and (g) repeating (a) to (g) in a continuous sod harvesting process. 
     In some examples, step (c) includes transferring a single layer of one or more slabs during at least some of the trips of the stacking head from the transfer station to the pallet station. 
     In some examples, the replacing step includes discharging the loaded pallet from the pallet station onto the ground and injecting the empty pallet from a pallet loader to the pallet station. 
     In some examples, the discharging step includes lowering the loaded pallet into engagement with the ground. 
     In some examples, forming the stack includes holding a leading slab above the conveyor assembly using the stacking head, advancing a trailing slab along the conveyor assembly under the leading slab, and positioning the leading slab atop the trailing slab. 
     In some examples, forming the stack includes lifting a conveyor supporting the leading slab at the transfer station toward the stacking head and picking up the leading slab off the conveyor using the stacking head. 
     In some examples, picking up the leading slab includes advancing hooks of the stacking head to pierce the leading slab with the hooks. 
     In some examples, forming the stack includes lowering the conveyor away from the leading slab when picked up by the stacking head and advancing the trailing slab along the conveyor under the leading slab. 
     In some examples, forming the stack includes releasing the leading slab onto the trailing slab. 
     In some examples, releasing the leading slab includes withdrawing hooks of the stacking head from the leading slab. 
     In some examples, transferring the stack includes picking up the stack from the transfer station by the stacking head, transporting the stack from the transfer station to the pallet station through translation of the stacking head, and depositing the stack at the pallet station. 
     In some examples, the conveyor is lifted toward the stacking head to raise the stack for pick up by the stacking head. 
     In some examples, picking up the stack includes advancing hooks of the stacking head through both the leading and trailing slabs and depositing the stack includes withdrawing the hooks from both the leading and trailing slabs. 
     In some examples, the stacking head transfers at least one complete slab layer in each trip of the stacking head from the transfer station to the pallet station. 
     In some examples, each pallet has a pallet area over which slabs are stackable, and each slab layer transferred from the transfer station to the pallet station by the stacking head has a slab layer area corresponding in size to the pallet area for stacking at least one complete slab layer over the pallet area during each trip of the stacking head from the transfer station to the pallet station. 
     In some examples, the pallet area is defined by a pallet width and a pallet length, and each of the pallet width and the pallet length is between about 35 inches and 50 inches. 
     In some examples, the slab layer area is defined by a slab layer width and a slab layer length, and each of the slab layer width and the slab layer length is between about 35 inches and 50 inches. 
     According to some aspects, a method of operating a stacking head of a sod harvester includes: (a) repeatedly transferring sod slabs from a transfer station located along a conveyor assembly of the sod harvester to a pallet station of the sod harvester to form a loaded pallet at the pallet station; (b) during replacement of the loaded pallet with an empty pallet, forming a stack of slabs at the transfer station; and (c) transferring the stack of slabs from the transfer station to the pallet station for deposit on the empty pallet when received at the pallet station, and repeating (a) to (c) in a continuous sod harvesting process. 
     According to some aspects, a sod harvesting system includes: (a) a harvester frame; (b) a cutting assembly mounted to the harvester frame for cutting sod into slabs; (c) a conveyor assembly supported by the harvester frame for transporting the slabs away from the cutting assembly toward a transfer station located along the conveyor assembly; (d) a pallet station supported by the harvester frame and spaced apart from the transfer station, the pallet station operable to hold a pallet for loading with slabs and to discharge the pallet when loaded; (e) a pallet loader supported by the harvester frame for holding a plurality of empty pallets, the pallet loader operable to inject empty pallets one at a time to the pallet station; (f) a stacking head movably mounted to the harvester frame, the stacking head moveable between a pick up position above the conveyor assembly for picking up one or more slabs from the transfer station, and a drop off position above the pallet station for depositing the one or more slabs on a pallet at the pallet station; and (g) a control system configured to control operation of the stacking head to: (i) repeatedly transfer slabs from the transfer station to the pallet station to form a loaded pallet at the pallet station; (ii) during replacement of the loaded pallet with an empty pallet, form a stack of slabs at the transfer station; and (iii) transfer the stack of slabs from the transfer station to the pallet station for deposit on the empty pallet when received at the pallet station, and repeat (i) to (iii) in a continuous sod harvesting process. 
     According to some aspects, a method of operating a stacking head of a sod harvester includes: (a) operating the stacking head in a single layer mode, in which the stacking head transfers a single layer of one or more sod slabs during each trip from a transfer station located along a conveyor assembly of the sod harvester to a pallet station of the sod harvester for deposit of the single layer onto a pallet at the pallet station; and (b) switching operation of the stacking head from the single layer mode to a pre-stacking mode based on operating conditions of the sod harvester, the stacking head configured to form a stack of slabs at the transfer station and transfer the stack to the pallet station when operating in the pre-stacking mode. 
     According to some aspects, a method of operating a sod harvester includes: (a) cutting sod slabs from the ground using a cutting assembly; (b) advancing the slabs along a conveyor assembly from the cutting head to a transfer station located along the conveyor assembly; (c) forming a stack of the slabs at the transfer station using a stacking head; and (d) transferring the stack of slabs using the stacking head from the transfer station to a pallet station to deposit the stack onto a pallet at the pallet station. 
     In some examples, forming the stack includes holding a leading slab above the conveyor assembly using the stacking head, advancing a trailing slab along the conveyor assembly under the leading slab, and positioning the leading slab atop the trailing slab. 
     In some examples, forming the stack includes lifting a conveyor supporting the leading slab at the transfer station toward the stacking head for pick up of the leading slab by the stacking head, lowering the conveyor away from the leading slab held by the stacking head to advance the trailing slab along the conveyor under the leading slab, and releasing the leading slab onto the trailing slab. 
     In some examples, forming the stack includes advancing hooks of the stacking head through the leading slab to pick up the leading slab, and withdrawing the hooks from the leading slab to release the leading slab onto the trailing slab. 
     In some examples, transferring the stack includes advancing the hooks through both the leading and trailing slabs at the transfer station, transporting the stack to the pallet station using the stacking head, and withdrawing the hooks from the leading and trailing slabs at the pallet station. 
     In some examples, each stack includes at least two complete slab layers for stacking on the pallet. 
     In some examples, each pallet has a pallet area over which slabs are stackable, and each slab layer in the stack has a slab layer area corresponding in size to the pallet area for stacking at least two complete slab layers over the pallet area during transfer of each stack by the stacking head from the transfer station to the pallet station. 
     In some examples, the pallet area is defined by a pallet width and a pallet length, and each of the pallet width and the pallet length is between about 35 inches and 50 inches. 
     In some examples, the slab layer area is defined by a slab layer width and a slab layer length, and each of the slab layer width and the slab layer length is between about 35 inches and 50 inches. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The drawings included herewith are for illustrating various examples of systems, methods, and apparatuses of the present specification and are not intended to limit the scope of what is taught in any way. In the drawings: 
         FIG.  1    is an elevation view of portions of an example sod harvester; 
         FIG.  1 A  is a perspective view of a portion of the sod harvester of  FIG.  1   ; 
         FIG.  2    is a schematic plan view of portions of the sod harvester of  FIG.  1   , showing a stacking head in a pick up position; 
         FIG.  3    is a schematic plan view like that of  FIG.  2   , but showing the stacking head in a drop off position; 
         FIG.  4    is a perspective view of portions of a pallet station and pallet loader of the sod harvester of  FIG.  1   ; 
         FIG.  5    is an elevation view of the pallet station and pallet loader of  FIG.  4   , showing forks of the pallet station lowered for discharge of a loaded pallet; 
         FIG.  6    is an elevation view like that of  FIG.  5   , but showing the forks raised for engagement with an empty pallet received from the pallet loader; 
         FIG.  7    is a schematic of a stacking head of the sod harvester of  FIG.  1   , showing hooks of the stacking head in a retracted configuration; 
         FIG.  8    is a schematic like that of  FIG.  7   , but showing the hooks in an advanced configuration and holding a single slab layer; 
         FIG.  9    is a schematic like that of  FIG.  8   , but showing the hooks holding a stack of slabs; 
         FIGS.  10 - 14 A  are elevation views like that of  FIGS.  1  and  1 A , showing the sod harvester at different stages of a slab pre-stacking process; 
         FIG.  15    is a schematic plan view of an example pallet for the sod harvester of  FIG.  1   ; 
         FIG.  16    is a schematic plan view of an example slab layer formed by the sod harvester of  FIG.  1   ; and 
         FIG.  17    is a schematic plan view of an example sod slab formed by the sod harvester of  FIG.  1   . 
     
    
    
     DETAILED DESCRIPTION 
     Various systems, apparatuses, or processes will be described below to provide an example of an embodiment of each claimed invention. No embodiment described below limits any claimed invention and any claimed invention may cover systems, processes, or apparatuses that differ from those described below. The claimed inventions are not limited to systems, apparatuses, or processes having all of the features of any one system, apparatus, or process described below or to features common to multiple or all of the systems, apparatuses, or processes described below. It is possible that a system, apparatus, or process described below is not an embodiment of any claimed invention. Any invention disclosed in a system, apparatus, or process described below that is not claimed in this document may be the subject matter of another protective instrument, for example, a continuing patent application, and the applicants, inventors, or owners do not intend to abandon, disclaim, or dedicate to the public any such invention by its disclosure in this document. 
     Sod harvesters operate to cut sod into slabs. The slabs are transported along a conveyor assembly, and a stacking head picks up a layer of slabs and transports the slabs from the conveyor assembly to a pallet. The process is repeated until the pallet is sufficiently loaded with slabs. The loaded pallet is then replaced with an empty pallet for continued stacking of slabs. In some cases, replacement of the loaded pallet with an empty pallet may require slowing of the harvesting process until the empty pallet is in position for receiving slabs. 
     The present specification discloses aspects of sod harvesting systems and methods that can help maintain a higher harvesting rate during pallet replacement relative to some existing systems. According to some aspects of the present disclosure, during replacement of a loaded pallet with an empty pallet, the stacking head is operated in a pre-stacking mode to form a stack of slabs over the conveyor assembly and deposit the stack onto the empty pallet received at the pallet station. The same stacking head can be used for both forming the stack of slabs and transferring the stack to the pallet. In some examples, after depositing the stack, the stacking head can resume transferring single layers of slabs from the conveyor to the pallet to form another loaded pallet, at which point the pallet replacement and pre-stacking process is repeated. As used herein, the term “loaded” pallet means that the pallet has received a plurality of slab layers sufficient in number to warrant discharge of the pallet from the pallet station (e.g. for replacement with an empty pallet). For further clarity, a “loaded” pallet may be loaded with slabs to only a small percentage of its maximum slab carrying capacity, and may be capable of receiving additional slab layers. 
     Referring to  FIG.  1   , an example sod harvester  100  for harvesting sod is illustrated. The sod harvester  100  includes a harvester frame  102  and a cutting assembly  104  mounted to the harvester frame  102  for cutting sod into slabs  106  ( FIG.  1 A ). In the example illustrated, the cutting assembly  104  has a plurality of cutting heads  104   a  (two cutting heads arranged side-by-side, in the example illustrated) for stripping corresponding sod strips from the ground, and a plurality of corresponding cut-off mechanisms  104   b  (two cut-off mechanisms arranged side-by-side, in the example illustrated) for cross-cutting the sod strips to a desired length to form the slabs  106 . 
     The sod harvester  100  includes a conveyor assembly  108  having a plurality of conveyors supported by the harvester frame  102 . In the example illustrated, the conveyor assembly  108  is operable to receive slabs from the cutting assembly  104 , and to transport the slabs away from the cutting assembly  104  to a transfer station  112  downstream of the cutting assembly  104 . In the example illustrated, the transfer station  112  is located along the conveyor assembly  108 . 
     Referring to  FIG.  2   , in the example illustrated, the conveyor assembly  108  includes a plurality of conveyor sets  114  (two conveyor sets  114 , in the example illustrated) arranged side-by-side and in alignment with corresponding cutting heads and cut-off mechanisms of the cutting assembly  104  for receiving corresponding slabs from the cutting assembly  104 , and transporting the corresponding slabs to the transfer station  112  ( FIG.  3   ). In the example illustrated, each conveyor set  114  includes at least one first conveyor  116   a  and at least one second conveyor  116   b  downstream of the first conveyor  116   a . In the example illustrated, the first conveyor  116   a  is inclined, and the second conveyor  116   b  is generally horizontal. The first conveyor  116   a  is operable to receive slabs  106  from the cutting assembly  104 , and to transport the slabs  106  to the second conveyor  116   b  for presentation of the slabs at the transfer station  112 , which is located on the second conveyors  116   b  in the example illustrated. 
     Referring to  FIG.  2   , in the example illustrated, the sod harvester  100  includes a pallet station  118  supported by the harvester frame  102  ( FIG.  1   ) and spaced laterally apart from (and adjacent a side of) the transfer station  112  ( FIG.  3   ). The pallet station  118  is operable to hold a pallet  120  for loading with slabs, and to discharge the loaded pallet  120  to the ground. 
     Referring to  FIG.  4   , in the example illustrated, the pallet station  118  comprises a forklift  122  having a plurality of forks  124  for holding a corresponding pallet  120  at the pallet station  118 . The forks  124  project rearwardly (relative to the forward travel direction of the sod harvester) and are vertically translatable relative to the harvester frame  102  for raising and lowering the pallet  120  supported by the forks  124 . Referring to  FIG.  5   , the forks  124  are translatable downwardly to lower a corresponding pallet  120  toward the ground incrementally as slab layers are stacked on the pallet  120 . When the pallet  120  is sufficiently loaded with slab layers to form a loaded pallet  120   a , the forklift  122  is operable to lower the loaded pallet  120   a  into engagement with the ground  126  to discharge the loaded pallet  120   a  rearwardly as the harvester  100  moves forward away from the loaded pallet  120   a . Referring to  FIG.  6   , after discharge of the loaded pallet, the forks  124  are translatable upwardly away from the ground for receiving an empty pallet  120   b  (e.g. from a pallet loader as described below) for stacking of slabs on the pallet  120   b.    
     Referring to  FIG.  2   , in the example illustrated, the sod harvester  100  includes a pallet loader  128  supported by the harvester frame adjacent the pallet station  118 . The pallet loader  128  holds a plurality of empty pallets  120   b  and is operable to inject empty pallets  120   b  one by one to the pallet station  118  (e.g. during or after discharge of a loaded pallet from the pallet station  118 ). In the example illustrated, the pallet loader  128  comprises a pallet hopper  130  holding a stack  132  of empty pallets  120   b , and a pallet injector  134  ( FIG.  4   ) operable to transfer a bottom pallet  120   b  from the stack  132  of empty pallets  120   b  to the pallet station  118 . 
     Referring to  FIG.  4   , in the example illustrated, the pallet injector  134  comprises an injector sheet  135  for supporting the bottom empty pallet  120   b  for transfer to the pallet station  118 . The injector sheet  135  is translatable horizontally from a retracted position under the stack  132  and clear of the pallet station  118 , to an advanced position (shown in  FIG.  4   ) extending into the pallet station  118  for injection of the bottom empty pallet  120   b  into the pallet station  118  over the forks  124 . In some examples, the injected pallet  120   b  can be temporarily supported at the pallet station  118  atop the injector sheet  135  (e.g. while the forks  124  are being raised into engagement with the pallet  120   b ) and receive a plurality of initial slab layers prior to engagement by the forks  124 . In other examples, the pallet injector can comprise, for example, a push bar mechanism operable to push the bottom empty pallet  120   b  out from the hopper  130  directly onto the forks  124  when the forks  124  are in (or approaching) vertical alignment with the bottom pallet  120   b.    
     Referring to  FIG.  2   , in the example illustrated, the sod harvester  100  includes a stacking head  136  movably mounted to the harvester frame  102  ( FIG.  1   ). The stacking head  136  is moveable between a pick up position ( FIG.  2   ) above the transfer station  112  for picking up one or more slabs from the transfer station  112 , and a drop off position ( FIG.  3   ) above the pallet station  118  for depositing the one or more slabs onto a pallet  120  at the pallet station  118 . In the example illustrated, the stacking head  136  is translatable between the pick up and drop off positions through a gantry arrangement. In other examples, the stacking head  136  can be translatable between the pick up and drop off positions through a different mechanism, such as, for example, a robotic arm. In the example illustrated, the stacking head  136  is rotatable about a vertical axis to permit stacking of slab layers and/or slab stacks on the pallet at a 90 degree offset from adjacent slab layers and/or slab stacks on the pallet. 
     Referring to  FIG.  7   , in the example illustrated, the stacking head  136  includes a head frame  138  and a plurality of hooks  140  pivotably mounted to the head frame  138 . In the example illustrated, the hooks  140  are pivotable relative to the head frame  138  between advanced and retracted positions. Referring to  FIGS.  8  and  9   , when in the advanced position, the hooks  140  project downwardly from an underside of the head frame  138  for engagement with and holding of one or more slabs  106  through piercing of the slabs  106  with the hooks  140 . Referring to  FIG.  7   , when in the retracted position, the hooks  140  are generally withdrawn relative to the head frame  138  for releasing and depositing the slabs  106  held by the stacking head  136 . 
     Referring to  FIGS.  7  to  9   , in the example illustrated, the stacking head  136  includes a cross-cut assembly  170  for cross cutting each initial slab  106  into a plurality of smaller slabs  106 ′ (e.g. cross cutting each 24-inch by 48-inch slab  106  advanced to the transfer station into three 24-inch by 16-inch slabs  106 ′, or in other examples, into two 24-inch by 24-inch slabs). In the example illustrated, the cross-cut assembly  170  includes a pair of laterally extending blade assemblies  172  fixed to the head frame  138  and spaced apart from each other along the conveyor assembly  108  (when the stacking head is in the pick up position) for cutting each slab  106  into a plurality of smaller slabs  106 ′ when the slabs  106  are brought into engagement with the stacking head  136 . In other examples, the cross-cut assembly  170  may be configured differently (e.g. for cutting each initial slab  106  into two slabs, or into a different number of slabs and/or to different dimensions as required). 
     Referring to  FIG.  1   , in the example illustrated, the conveyor assembly  108  includes a slab lift  142  for lifting slabs  106  at the transfer station  112  toward the stacking head  136  for transfer thereto. In the example illustrated, the slab lift  142  is in the form of a scissor-style lift supported by the harvester frame  102  and operable to lift and lower the second (horizontal) conveyors  116   b  toward and away from the stacking head  136 . When lowered, the input end of each second conveyor  116   b  is in generally vertical alignment with the output end of each corresponding first conveyor  116   a  for receiving slabs  106  from the first conveyor  116   a . Referring to  FIG.  14   , when lifted, each second conveyor  116   b  is raised toward the stacking head  136  to an elevation above the output end of the first conveyor  116   a  for presenting the slabs  106  to the stacking head  136  (for pick up of the slabs  106  by the stacking head  136  through actuation of the hooks  140 ). In other examples, the second conveyors  116   b  may be vertically fixed relative to the harvester frame  102 , and the stacking head  136  may be vertically translatable relative to the harvester frame  102  toward and away from the second conveyors  116   b  for pick up of the slabs  106  at the transfer station  112 . 
     In the example illustrated, the sod harvester  100  includes a control system having one or more controllers and a plurality of sensors in communication with the controllers for controlling and coordinating operation of the sod harvester  100  (including the cutting assembly  104 , conveyor assembly  108 , pallet station  118 , pallet loader  128 , stacking head  136 , and other system components) to perform a continuous sod harvesting process as described herein. 
     Referring to  FIGS.  1  and  1 A , the sod harvesting process includes cutting sod slabs  106  from the ground using the cutting assembly  104 . In the example illustrated, each slab  106  is cut to a width of approximately 24 inches and an initial length of approximately 48 inches. Referring to  FIGS.  2  and  3   , the slabs are advanced along the conveyor assembly  108  from the cutting assembly  104  to the transfer station  112 . The slabs  106  at the transfer station  112  are picked up by the stacking head  136 , transported to the pallet station  118 , and deposited onto a pallet  120  at the pallet station  118 . In the example illustrated, as the slabs are brought into engagement with the stacking head  136  (e.g. through lifting of the conveyors), each slab is cross cut into a plurality of smaller slabs  106 ′ ( FIG.  8   ; e.g. into three 24-inch by 16-inch slabs) through engagement with the cross-cut assembly  170  of the stacking head  136 . The slab transfer process is continuously repeated for slabs advanced to the transfer station  112  to form a loaded pallet (see e.g. pallet  120   a  in  FIG.  6   ) at the pallet station  118 . 
     In some examples, during formation of the loaded pallet, the stacking head  136  can be operated in a single layer mode to transfer only a single layer of slabs  106  during each trip (or at least some trips) of the stacking head  136  from the transfer station  112  to the pallet station  118 . Operating the stacking head in a single layer mode can be more efficient in some cases (e.g. outside of pallet replacement). In some examples, the stacking head  136  can transfer a stack of slabs  106  (i.e. two or more layers of slabs) during each trip of the stacking head  136  from the transfer station  112  to the pallet station  118 , and/or may switch between transferring single layers and stacks of slabs  106  as may be suitable depending on operating conditions of the sod harvester  100 . 
     Referring to  FIGS.  5  and  6   , after formation, the loaded pallet  120   a  is replaced with an empty pallet  120   b . In the example illustrated, replacement of the loaded pallet  120   a  with the empty pallet  120   b  includes discharging the loaded pallet  120   a  from the pallet station  118  by lowering the forks  124  to bring the loaded pallet  120   a  into engagement with the ground  126 , and moving the sod harvester  100  forward away from the loaded pallet  120   a  until the forks  124  are clear of the loaded pallet  120   a . After the loaded pallet  120   a  is vertically clear of the pallet loader  128 , an empty pallet  120   b  can be injected into the pallet station  118  from the stack  132  of empty pallets. After discharge of the loaded pallet  120   a , the forks  124  are raised away from the ground for receiving the empty pallet  120   b . In some examples, the empty pallet  120   b  can be received at the pallet station  118  for loading of initial layers of slabs prior to engagement by the forks  124  (e.g. while temporarily supported atop the injector sheet  135  ( FIG.  4   )). 
     During replacement of the loaded pallet  120   a  with the empty pallet  120   b , the stacking head  136  is operated in a pre-stacking mode to form a stack  148  ( FIG.  14   ) of the slabs  106  at the transfer station  112 . This can help reduce idle time of the stacking head  136  and slowdown of the harvesting process (e.g. to avoid excessive accumulation of slabs  106  on the conveyor assembly  108 ) during pallet replacement. 
     Referring to  FIGS.  10  and  10 A , in the example illustrated, forming the stack  148  includes advancing leading slabs  106   a  along the conveyor assembly  108  to the transfer station  112 . Referring to  FIGS.  11  and  11 A , the second conveyors  116   b  supporting the leading slabs  106   a  at the transfer station  112  are lifted (e.g. through operation of the lift  142 ) toward the stacking head  136  for engagement of the leading slabs  106   a  by the stacking head  136 . When lifted by the second conveyors  116   b  to the stacking head  136 , the leading slabs  106   a  are brought into engagement with the cross-cut assembly  170  and cross-cut into a plurality of smaller trailing slabs  106   a ′ ( FIG.  9   ). After the second conveyors  116   b  are lifted, the stacking head  136  picks up the leading slabs  106   a  (e.g. by advancing the hooks  140  ( FIG.  8   )). 
     Referring to  FIGS.  12  and  12 A , the second conveyors  116   b  are then lowered away from the leading slabs  106   a  held by the stacking head  136 . Referring to  FIGS.  13  and  13 A , after the second conveyors  116   b  are lowered, trailing slabs  106   b  are advanced along the conveyor assembly  108  to the transfer station  112  under the leading slabs  106   a . The stacking head  136  can then release the leading slabs  106   a  to drop the leading slabs  106   a  onto the trailing slabs  106   b  (e.g. by withdrawing the hooks  140  ( FIG.  8   )) to form the stack  148 . 
     In other examples, the second conveyors  116   b  can be lifted toward the stacking head  136  to raise the trailing slabs  106   b  toward an underside of the leading slabs  106   a  held by the stacking head  136 . During or after raising of the trailing slabs  106   b , the stacking head  136  can release the leading slabs  106   a  onto the trailing slabs  106   b  to form the stack  148 . 
     Referring also to  FIGS.  2  and  3   , the stacking head  136  transfers the stack  148  to the pallet station  118  for deposit onto the empty pallet  120   b  (when received at the pallet station  118 ). In the example illustrated, the second conveyors  116   b  are lifted to raise the stack  148  toward the stacking head  136 , and the stack  148  is picked up by the stacking head  136  (e.g. by advancing the hooks  140  ( FIG.  9   ) through both the leading and trailing slabs  106   a ,  106   b , which can comprise a plurality of smaller slabs  106   a ′,  106   b ′ as shown in  FIG.  8   ). When the trailing slabs  106   b  are lifted to the stacking head  136  (either alone or as part of the stack  148 ), the trailing slabs  106   b  are brought into engagement with the cross-cut assembly  170  and cross-cut into a plurality of smaller trailing slabs  106   b ′ ( FIG.  9   ). 
     After the stack  148  is picked up, the second conveyor  116   b  can be lowered for receiving subsequent slabs. Transferring the stack  148  further includes translating the stacking head  136  while holding the stack  148  from the pick up position ( FIG.  2   ) to the drop off position ( FIG.  3   ), and releasing the stack  148  (e.g. by withdrawing the hooks  140  ( FIG.  9   )) onto the empty pallet  120   b  (when received at the pallet station  118 ). After depositing the stack  148  at the pallet station  118 , the stacking head  136  can be switched back to operate in the single layer stacking mode, or can continue operating in the pre-stacking mode and/or switch between single layer and pre-stacking modes based on operating conditions. The stacking and pallet replacement process is then repeated. 
     Referring to  FIGS.  15  and  16   , in the example illustrated, each pallet  120  has a pallet area  150  over which the slabs  106  are stackable. In the example illustrated, the pallet area  150  extends over the entire pallet  120 , and the pallet area  150  is circumscribed and defined by a peripheral edge of the pallet  120 . The pallet area  150  is defined by a pallet width  152  and a pallet length  154  extending perpendicular to the pallet width  152 . Each of the pallet width  152  and the pallet length  154  can be between about, for example, 35 inches and 50 inches. In the example illustrated, the pallets  120  are standard North American pallets, and each of the pallet width  152  and the pallet length  154  is about 48 inches. 
     In the example illustrated, the stacking head  136  ( FIG.  14   ) is configured to stack and transfer slab layers  156  having a slab layer area  158  corresponding in size (e.g. approximately equal to) to the pallet area  150 . This can allow for stacking of at least one complete slab layer  156  over the pallet area  150  during each trip of the stacking head  136  ( FIG.  14   ) from the transfer station to the pallet station (and at least two complete slab layers  156  over the pallet area  150  during transfer of each slab stack  148  ( FIG.  14   ) by the stacking head from the transfer station to the pallet station). The slab layer area  158  is defined by a slab layer width  160  and a slab layer length  162 . Each of the slab layer width  160  and the slab layer length  162  can be, for example, between 35 and 50 inches, for stacking of at least one complete slab layer over the pallet area  150  during each trip of the stacking head from the transfer station to the pallet station. In the example illustrated, the slab layer width  160  and the slab layer length  162  are generally equal to each other, and each of the slab layer width  160  and the slab layer length  162  is about 48 inches for stacking over a 48-inch by 48-inch pallet area. 
     In the example illustrated, each slab layer  156  is defined by two of the initial slabs  106  positioned side by side (and optionally cross cut into a plurality of smaller slabs  106 ′) to form the slab layer area  158 . Referring to  FIG.  17   , in the example illustrated, each slab  106  has a slab width  164  and an initial slab length  166 . The slab length  166  can be between, for example, 44 and 52 inches and the slab width  164  can be between, for example, 22 and 26 inches. In the example illustrated, the slab length  166  is about 48 inches and the slab width  164  is about 24 inches to provide a slab layer area  158  of about 48 inches by 48 inches. 
     In other examples, each slab layer can be defined by a different number of initial slabs positioned side by side. For example, in some examples, each slab layer can be defined by three initial slabs positioned side by side to form the slab layer area. In such examples, each initial slab can have a slab width of between about, for example, 14 and 18 inches (e.g. about 16 inches), and an initial slab length of between about, for example, 44 and 52 inches (e.g. about 48 inches, for forming two smaller 16-inch by 24-inch slabs, or three smaller 16-inch by 16-inch slabs when subsequently cross cut by the stacking head). 
     In other examples, the pallets can have different dimensions. In some examples, the pallets can be CHEP pallets having a pallet area of about, for example, 1200 mm by 1000 mm (about 47 inches by 37 inches), and the slab layer area can correspond in size to this pallet area. 
     In other examples, the pallets can have a pallet area of about, for example, 46 inches by 46 inches, and the slab layer area can correspond in size to this pallet area. In such examples, the initial slab length can be between about, for example, 42 inches and 50 inches (e.g. about 46 inches). The slab width can be between, for example, 22 and 26 inches (e.g. about 24 inches) for two slabs side by side, or between about, for example, 14 and 18 inches (e.g. about 16 inches) for three slabs side by side.