Patent Publication Number: US-2023139319-A1

Title: A cargo unloading system and method of operation

Description:
STATEMENT OF CORRESPONDING APPLICATIONS 
     This application is based on the specification filed in relation to New Zealand Patent Application No. 762460, the entire contents of which are incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention relates to systems and methods for use in unloading and/or loading of cargo from a vehicle. 
     BACKGROUND 
     Cargo vehicles, such as semi-trailers, box trucks, vans, train cars, etc. are often used to transport or temporarily store cargo. Depending on the shape, size, quantity, orientation or other characteristics of the cargo, it may be difficult to maximize efficient use of the cargo space of those vehicles. For example, certain cargo units, such as individual items or pallets of items, may be relatively short compared to the height of the semi-trailer, but the nature of the items may prevent them from being stacked on top of one another. As a result, there may be significant amounts of wasted space in the upper portions of the semi-trailer. 
     Systems are known for improving the efficiency of such cargo spaces. For example, the MAXILODA™ trailer cargo double stacking systems provided by Maxiloda Limited (www.maxiloda.co.nz) allow for cargo to be stacked on a second level provided by trolleys supported by rails mounted to the walls of the trailer. However, the unloading and loading of cargo from such vehicles, particularly large vehicles, can be challenging in the absence of a loading bay and associated equipment. This is especially so for cases in which small volumes are being unloaded or loaded at numerous locations. 
     One means of performing this is a forklift, however this is reliant on ownership and maintenance of a forklift (as well having personnel on hand qualified to operate a forklift), which is a significant cost to small businesses. Tail lifts are known which provide a platform on the back of a truck which may be raised and lowered, with a pallet truck used to maneuver pallets relative to the tail lift for loading or unloading. However, such tail lifts only reach the floor of the vehicle (i.e. cannot reach higher levels), and require manual handling of cargo at height which presents a potential health and safety hazard. Further, both of these options are relatively time consuming. 
     The present application is directed to overcoming one or more of the problems discussed above. 
     It is an object of the present invention to address one or more of the foregoing problems or at least to provide the public with a useful choice. 
     All references, including any patents or patent applications cited in this specification are hereby incorporated by reference. No admission is made that any reference constitutes prior art. The discussion of the references states what their authors assert, and the applicants reserve the right to challenge the accuracy and pertinency of the cited documents. It will be clearly understood that, although a number of prior art publications are referred to herein, this reference does not constitute an admission that any of these documents form part of the common general knowledge in the art, in New Zealand or in any other country. 
     Throughout this specification, the word “comprise”, or variations thereof such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps. 
     Further aspects and advantages of the present invention will become apparent from the ensuing description which is given by way of example only. 
     SUMMARY 
     According to one aspect of the present technology there is provided a cargo loading system for use with a cargo storage area of a vehicle, the cargo loading system comprising:
         a mast frame;   a carriage assembly supported by the mast frame, the carriage assembly comprising:
           lifting forks;   a fork lateral control mechanism configured to control lateral movement of the lifting forks across the carriage assembly; and   a carriage pivot control mechanism configured to control pivotal movement of the carriage assembly relative to the mast frame about a first vertical axis;   a fork pivot control mechanism configured to control pivotal movement of the lifting forks relative to the carriage assembly about a second vertical axis, between a first position in which the lifting forks extend away from the carriage assembly and a second position in which the lifting forks extend along the carriage assembly;   
           a carriage vertical control assembly configured to control raising and lowering of the carriage assembly relative to the mast frame;   a mast frame actuating assembly configured to control lateral movement of the mast frame relative to an open end of the cargo storage area of the vehicle.       

     According to one aspect of the present technology there is provided a cargo loading system for use with a cargo storage area of a vehicle, the cargo loading system comprising:
         a mast frame;   a carriage assembly supported by the mast frame, the carriage assembly comprising:
           lifting forks;   a fork lateral control mechanism configured to control lateral movement of the lifting forks across the carriage assembly; and   a fork axial control mechanism configured to control axial movement of the lifting forks between an extended position in which the lifting forks extend from the carriage assembly in a first direction and a retracted position in which the lifting forks extend from the carriage assembly in a second direction opposite to the first direction;   
           a carriage vertical control assembly configured to control raising and lowering of the carriage assembly relative to the mast frame;   a mast frame actuating assembly configured to control movement of the mast frame relative to an open end of the cargo storage area of the vehicle, between a first position adjacent to the open end and a second position away from the open end.       

     According to one aspect of the present technology there is provided a cargo loading system for use with a cargo storage area of a vehicle, the cargo loading system comprising:
         a mast frame;   a carriage assembly supported by the mast frame, the carriage assembly comprising:
           lifting forks;   
           a fork lateral control mechanism configured to control lateral movement of the lifting forks across the carriage assembly; and   a carriage vertical control assembly configured to control raising and lowering of the carriage assembly relative to the mast frame;   a mast frame actuating assembly configured to control movement of the mast frame relative to an open end of the cargo storage area of the vehicle.       

     In examples, the cargo loading system is configured for use with a vehicle cargo storage system in which a cargo storage area has at least two levels on which cargo may be loaded. In examples, the vehicle cargo storage system may be that described in New Zealand Patent Application No. 752996, the contents of which are hereby incorporated by reference. In use, the system allows for movement of the lifting forks between those levels and ground level, as well as across the cargo storage area. This allows for cargo, especially loaded on pallets, to be moved between these various locations. For completeness: where reference is made to use of the present technology in the unloading of cargo, it should be appreciated that the technology may also be used in the loading of cargo. 
     Mast Frame 
     In examples the mast frame may comprise a primary mast. 
     In examples, the mast frame may comprise a floor assembly comprising a first floor portion and a second floor portion. In examples the first floor portion may be configured to remain stationary in use, and the second floor portion may be configured to move with the primary mast. In examples the first floor portion and the second floor portion may overlap. In examples the second floor portion may comprise a recess portion configured to permit passage of the carriage assembly as it is raised and lowered along the primary mast. 
     In examples, the mast frame may comprise a first mast and a second mast. The mast frame may comprise a crossmember between the first mast and the second mast. In examples, the crossmember may be connected between upper ends of the first mast and the second mast—i.e. producing a substantially “U” shaped frame. 
     In examples, the carriage assembly may span between the first mast and the second mast. In examples, the carriage assembly may be mounted to guides provided on the first mast and the second mast to guide vertical movement of the carriage assembly. For example, the carriage assembly may be mounted to one or more vertical rails on the mast frame using linear bearings. Carriage assembly 
     In examples the carriage assembly may be mounted to the primary mast. In examples the first vertical axis may be provided proximal to the primary mast. 
     In examples, the fork pivot control mechanism may comprise a rotary actuator configured to pivot the forks about the second vertical axis, relative to the carriage assembly. For example, the rotary actuator may comprise a helical hydraulic rotary actuator. 
     In an alternative example, the fork pivot control mechanism may comprise a hinge, and a linear actuator (for example a hydraulic cylinder) actuating a lever arm to pivot the carriage assembly about the hinge. 
     In examples, the carriage assembly may comprise a carriage to which the lifting forks are mounted. The carriage may be mounted to a guide for lateral movement across the carriage assembly. For example, the carriage may be mounted to one or more horizontal rails using linear bearings. In examples, the fork pivot control mechanism may be provided to the carriage. 
     In examples, the carriage assembly may comprise a main carriage arm, wherein the carriage is mounted to the main carriage arm such that movement along a longitudinal axis of the main carriage arm is permitted. In examples, the carriage may comprise a base portion configured to be mounted to the main carriage arm, and a fork arm to which the lifting forks are provided, wherein the fork pivot control mechanism is provided between the base portion and the fork arm. 
     The fork lateral control mechanism provides a means for controlling lateral movement of the forks (i.e. side-shift), for example to allow for selecting between articles of cargo or pallets stored next to each other. In examples, the fork lateral control mechanism may comprise at least one actuator configured to be controlled to drive the carriage laterally across the carriage assembly. In examples the actuator may be a linear actuator, such as a screw based linear actuator (for example, a ball screw drive), or a pressure driven cylinder (for example a hydraulic or pneumatic cylinder). 
     In examples, the forks may be configured to pivot between an upright stored position, and a lowered in use position. Reference to axial movement of a lifting fork should be understood to mean movement in a direction parallel with the longitudinal axis of the fork, i.e. the axis between the ends of the fork along its length. In examples, the fork axial control mechanism may comprise a rack and pinion drive. In such an example, each fork may include a rack configured to engage with a pinion gear. Rotation of the respective pinion gears, for example driven by a motor, may be used to drive the forks between the extended position and the retracted position. 
     In use, when in the extended position the forks may be used to support a load for vertical and/or lateral movement. In the retracted position, clearance is provided to allow for movement of the carriage and/or mast frame. 
     It should be appreciated that alternative means for controlling axial movement of the forks are contemplated, for example using one or more linear actuators (for example, a ball screw drive) or one or more telescopic pressure driven cylinders. 
     In examples, the carriage assembly may comprise a drag chain between a power source and the carriage, the drag chain configured to deliver power to the fork axial control mechanism. 
     Carriage Pivot Control Mechanism 
     In examples, the carriage pivot control mechanism may comprise a rotary actuator configured to pivot the carriage assembly about the first vertical axis, relative to the mast frame. For example, the rotary actuator may comprise a helical hydraulic rotary actuator. 
     In an alternative example, the carriage pivot control mechanism may comprise a hinge, and a linear actuator (for example a hydraulic cylinder) actuating a lever arm to pivot the carriage assembly about the hinge. 
     Carriage Vertical Control Assembly 
     In examples, the carriage vertical control assembly may be configured to have sufficient travel to lower the lifting forks to ground level (appreciating that some clearance may be provided to allow for common pallet designs), and raise the forks above the height of an upper deck of a multi-deck cargo storage system. 
     In examples, the carriage vertical control assembly may include at least one lifting actuator. For example, the carriage vertical control assembly may comprise at least one hydraulic cylinder with a lift chain connected to the carriage assembly—more particularly a hydraulic cylinder with associated lift chain at either end of the carriage assembly. Other examples of lifting mechanisms include linear actuators (for example, a ball screw drive, lead screw drive, or rack and pinion), or a winch pulling lifting cables that control the carriage assembly height relative to ground. 
     Mast Frame Actuating Assembly 
     In examples in which the mast frame actuating assembly is configured to control lateral movement of the mast frame relative to an open end of the cargo storage area of the vehicle, the mast frame actuating assembly may comprise one or more lateral frame actuators. In examples the lateral frame actuators may comprise one or more hydraulic cylinders, although alternative linear actuators are contemplated such as ball screw drives, lead screw drives, or rack and pinion. 
     In examples, the mast frame actuating assembly may comprise one or more lateral linear guides. In examples, the primary mast may be configured to slide along the one or more lateral linear guides. 
     In examples, the mast frame actuating assembly may be configured to guide movement of the mast frame such that the second position is lower than the first position relative to ground. 
     In examples, the mast frame actuating assembly may comprise a linkage guiding movement of the mast frame through an arc between the first position and the second position. In examples, the linkage may comprise a four-bar linkage. In examples, the four-bar linkage may be configured as a parallel four-bar linkage, such that the mast frame is maintained in a vertical orientation throughout movement between the first position and the second position. 
     In an alternative example, the mast frame actuating assembly may be configured to move the mast frame in a linear motio—i.e. in a horizontal plane between the first position and the second position—for example, using a pantograph linkage or telescoping beams. In such an example, the mast frame may also be lowered and raised to assist in achieving a desired height relative to ground for the lifting forks to unload and load the cargo. 
     In examples, the system may include a vehicle mounted frame to which the mast frame is connected by the mast frame actuating assembly. In such examples, the vehicle mounted frame may be secured to the end of the cargo storage area. In examples, the vehicle mounted frame may be permanently secured to the vehicle—however it is also envisaged that in alternative examples the vehicle mounted frame may be releasably secured to the vehicle. 
     In alternative examples, the mast frame actuating assembly may be secured directly to the vehicle, i.e. without an intermediate vehicle mounted frame. 
     System Control 
     In examples, the various movements of the system described herein may be controlled manually, automatically, or by a combination thereof. 
     In examples in which the mast frame actuating assembly is configured to guide movement of the mast frame through an arc, the carriage vertical control assembly may be controlled to raise the carriage assembly relative to the mast frame during at least a portion of the movement of the mast frame away from the cargo storage area while the forks are in the extended position. It is envisaged that this may be required in certain configurations to ensure that tips of the lifting forks clear the storage space or components thereof. However, it is also envisaged that such control may not be required in other configurations. 
     The above and other features will become apparent from the following description and the attached drawings. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Further aspects of the present invention will become apparent from the ensuing description which is given by way of example only and with reference to the accompanying drawings in which: 
         FIG.  1 - 1    is a side view of an exemplary first cargo storage system installed in a cargo storage area of a cargo vehicle; 
         FIG.  1 - 2    is a perspective view of the first cargo storage system; 
         FIG.  2 - 1    is a side view of an exemplary second cargo storage system installed in a cargo storage area of a cargo vehicle; 
         FIG.  2 - 2    is a perspective view of the second cargo storage system; 
         FIG.  3 - 1    is a first perspective view of a support platform comprising a plurality of the support beams; 
         FIG.  3 - 2    is a second perspective view of the support platform; 
         FIG.  4    is a perspective view of a first exemplary cargo loading system; 
         FIG.  5 - 1    is a perspective view of an exemplary lifting fork carriage assembly of the first cargo loading system, having lifting forks extended; 
         FIG.  5 - 2    is a perspective view of the exemplary lifting fork carriage assembly having lifting forks retracted; 
         FIG.  6 - 1    is a perspective view of the first cargo loading system with the lifting fork carriage assembly in a raised position; 
         FIG.  6 - 2    is a perspective view of the first cargo loading system with the lifting fork carriage assembly in a lowered position; 
         FIG.  7 - 1  to  7 - 3    are side views of the first cargo loading system in various stages of operation; 
         FIG.  8    is a perspective view of a second exemplary cargo loading system; 
         FIGS.  9 - 1  to  9 - 5    are views of an exemplary lifting fork carriage assembly of the second cargo loading system; 
         FIG.  10    is a perspective view of an exemplary lifting mechanism of the second cargo loading system; 
         FIG.  11 - 1    is a perspective view of a floor assembly of the second cargo loading system in an expanded condition; 
         FIG.  11 - 2    is a perspective view of a floor assembly of the second cargo loading system in a contracted condition; 
       system; 
         FIG.  12 - 1    is a perspective view of the second cargo loading system in an exemplary stage of operation; and 
         FIG.  12 - 2    is a perspective view of the second cargo loading system in another exemplary stage of operation. 
     
    
    
     DETAILED DESCRIPTION 
     Cargo Storage Systems 
       FIG.  1 - 1    illustrates a first cargo storage system  100  installed in a cargo storage area  102  of a cargo vehicle (not illustrated), with which aspects of the present technology may be used. The cargo storage area  102  is defined by side walls  104 , floor  106 , ceiling  108 , a forward end wall  110 , and a rearward end  112  which is shown in an open condition, but may be closed (for example by a door or doors). Referring to  FIG.  1 - 2   , the first cargo storage system  100  comprises a first pair  150  of rails, comprising first load rail  152 - 1  and second load rail  152 - 2  (referred to herein as load rails  152 ), each rail  152  having a first end  154  and a second end  156 . The load rails  152  have enclosed tracks to receive track guides of support beams, as will be described further below. In the exemplary embodiment illustrated, entry into the enclosed track from the first end  154  and/or second end  156  of each load rail  152  is blocked (for example by end caps). Instead, each of the load rails  152  comprises a drop in beam opening  158  on an upper side of the load rail  152 , leading into the enclosed track in order to allow support beams to be introduced to, and retrieved from, the load rails  152 . In the exemplary embodiment illustrated, the drop in beam openings  158  are provided proximate to, but offset from, the first ends  154  of the load rails  152 . This allows a user to stand on the floor  106  of the cargo storage area  102  between the load rails  152  while inserting the support beams into, or retrieving them from, the drop in beam openings  158 —while also maximizing the useful length of the load rails  152  in use, as will become more evident from the description below. 
       FIG.  2 - 1    illustrates a second cargo storage system  200  installed in a cargo storage area  102  substantially as described above with reference to  FIG.  1 - 2   . Referring to  FIG.  2 - 2   , the second cargo storage system  200  comprises a first pair  150  of rails comprising first load rail  152 - 1  and second load rail  152 - 2 , substantially as described above with reference to  FIG.  1 - 1    and  FIG.  1 - 2   . The second cargo storage system  200  further comprises a second pair  202  of rails, comprising first storage rail  204 - 1  and second storage rail  204 - 2  (referred to herein as storage rails  204 ), each storage rail  204  having a first end  206  and a second end  208 . Similar to the load rails  152 , the storage rails  204  have enclosed tracks to receive track guides of support beams. In the exemplary embodiment illustrated, entry into the enclosed track from the second end  208  of each storage rail  204  is blocked (for example by end caps). 
     The storage rails  204  are provided above the load rails  152 , at a height proximate the ceiling  108  of the cargo storage area  102 . The second cargo storage system  200  comprises a third pair  210  of rails, comprising first transition rail  212 - 1  and second transition rail  212 - 2  (referred to herein as transition rails  212 ). The transition rails  212  also have enclosed tracks to receive track guides of support beams, and facilitate the transfer of support beams between the load rails  152  and the storage rails  204 . In the embodiment illustrated, the transition rails  212  follow a nonvertical path between the first ends  206  of the storage rails  204  and points offset from the first ends  154  of the load rails  152  at which a junction is formed across which the support beams can be transferred. In the embodiment illustrated, the transition rails  212  enter the junctions at an acute angle relative to the portions of the load rails  152  extending from the junctions towards the second ends  156 . 
     In the embodiment illustrated, each transition rail  212  comprises a safety station  214  configured to present a tortuous section to a support beam passing through it, particularly to interrupt or at least slow unrestrained descent of a support beam from the storage rails  204  to the load rails  152 . In this embodiment, the enclosed track through the safety station  214  has a reverse curvature. 
     In exemplary embodiments, each of the load rails  152  may comprise a drop in beam opening  158  on an upper side of the load rail  152 . In exemplary embodiments the drop in beam openings  158  may be provided between the junctions and the first ends  154  of the load rails  152 —although it is expressly noted that alternative locations are contemplated, for example in the safety stations  214 . 
     In some use cases, it may be beneficial to permanently retain the support beams within the system  200 . However, the ability to easily remove beams from the system  200  on demand is envisaged as providing benefits in other cases. For example, the support beams may contribute a significant proportion of the total mass of the system  200 . Being able to remove the beams to increase the load capacity of the cargo vehicle may be valuable, especially if the vehicle is to be used in this configuration (i.e. without support beams, or with a lower number of beams) for an extended period of time. Further, the stored support beams may occupy volume, or limit the height, of the cargo storage area—removal of the support beams where otherwise not required may assist with recovering this space. The beams may be stored at a vehicle depot, or potentially used in another vehicle that has the system  200  fitted. For entities operating a number of cargo vehicles with the system  100  and/or system  200  fitted, this may allow for distribution of the support beams on a case by case basis—potentially reducing the total number of support beams required by that entity (with associated benefits in terms of costs and storage space required). 
       FIG.  3 - 1    illustrates a support platform  300  provided by a plurality of support beams  302  mounted on load rails  152 , secured relative to each other using spacer beams  304 . In use, cargo may be loaded (whether directly, or via pallets) onto the support platform  300 ).  FIG.  3 - 2    illustrates one of the support beams  304  released from the neighboring support beam  304  and the remaining support platform  300 , allowing for independent movement along the load rails  152 . 
     First Exemplary Cargo Loading System 
       FIG.  4    illustrates a cargo loading system  400  according to one aspect of the present technology. The system  400  includes a vehicle mounted frame  410  configured to be secured to the cargo storage area  102  at the rearward end  112 . The vehicle mounted frame  410  includes a first upright member  412 - 1  and a second upright member  412 - 2 , in use disposed to either side of the opening of the cargo storage area  102 . In this example, the vehicle mounted frame  410  further includes an upper crossmember  414  and a lower crossmember  416  connecting the first upright member  412 - 1  and the second upright member  412 - 2 . 
     The system  400  further includes a mast frame  420 , having a first mast  422 - 1  and a second mast  422 - 2 , and a mast plate  424  connecting the first mast  422 - 1  and a second mast  422 - 2 . A mast frame actuating assembly in the form of a planar four-bar linkage (referred to herein as linkage  430 ) is provided between the vehicle mounted frame  410  and the mast frame  420 . The linkage  430  includes upper pivot arms  432 - 1  and  432 - 2 , and lower pivot arms  434 - 1  and  434 - 2 . Movement of the linkage  430  is controlled by first linkage hydraulic cylinder  436 - 1  and second linkage hydraulic cylinder  436 - 2 , connected between the upright members  412  of the vehicle mounted frame  410  and the upper pivot arms  432 . 
     A carriage assembly  500  is supported by the mast frame  420 , including first lifting fork  502 - 1  and second lifting fork  502 - 2  (referred to herein as lifting forks  502 ). Referring to  FIG.  5 - 1    and  FIG.  5 - 2   , the carriage assembly  500  includes a carriage assembly frame  504  and a lifting fork carriage  506 . The lifting fork carriage  506  is mounted to carriage rails  508  using linear bearings (not shown), which guide lateral movement of the lifting fork carriage  506  laterally across the carriage assembly  500  (i.e. along the carriage assembly frame  504  between first mast  422 - 1  and second mast  422 - 2 ). 
     A fork lateral control mechanism  510  is provided to control lateral movement of the lifting fork carriage  506 . In this example, the fork lateral control mechanism  510  includes a linear actuator in the form of a ball screw nut  512  (not illustrated, but secured to the lifting fork carriage  506 ) mounted to a threaded shaft  514  which is driven by a first carriage hydraulic motor  516 . 
       FIG.  5 - 1    shows the lifting forks  502  in an extended position, i.e. projecting in a direction towards the vehicle mounted frame  410 .  FIG.  5 - 2    shows the lifting forks  502  in a retracted position, i.e. projecting in a direction away from the vehicle mounted frame  410 . The first lifting fork  502 - 1  and second lifting fork  502 - 2  include a first axial rail  518 - 1  and a second axial rail  518 - 2  respectively. The first axial rail  518 - 1  and second axial rail  518 - 2  are provided on first fork linear bearing  520 - 1  and second fork linear bearing  520 - 2  respectively. In this example, a fork axial control mechanism is provided in the form of a pinion drive including a first fork rack  522 - 1  provided on the first lifting fork  502 - 1  and a second fork rack  522 - 2  provided on the second lifting fork  502 - 2 , a first pinion gear  524 - 1  engaging the first fork rack  522 - 1  and a second pinion gear  524 - 2  engaging the second fork rack  522 - 2 , and a second carriage hydraulic motor  526  driving the first pinion gear  524 - 1  and second pinion gear  524 - 2 . It will be appreciated that one of the first pinion gear  524 - 1  or the second pinion gear  524 - 2  may be driven directly by the second carriage hydraulic motor  526 , and also engage the other pinion gear to drive axial movement of the associated lifting fork. In this example, a drag chain  528  is provided to support hydraulic hoses connecting to the second carriage hydraulic motor  526  as the carriage  506  moves between a range of positions across the carriage assembly  500 . 
     Referring to  FIG.  6 - 1    and  FIG.  6 - 2   , the cargo loading system  400  includes a carriage vertical control assembly configured to control raising and lowering of the carriage assembly  500  relative to the mast frame  430 , e.g. a raised position as shown in  FIG.  6 - 1   , and a lowered position as shown in  FIG.  6 - 2   . In examples the cargo loading system  400  may be configured such a portion of the carriage assembly  500  (e.g. the lifting forks  502 ) may be lowered beyond the mast frame  430 — i.e. there is ground clearance below the mast frame  430 . 
     In this example, the carriage vertical control assembly includes a first lifting mechanism  600 - 1  in the first mast  412 - 1 , and a second lifting mechanism  600 - 2  in the second mast  412 - 2 . Referring to  FIG.  6 - 3   , each lifting mechanism  600  includes a lifting hydraulic cylinder  602  and an associated lift chain  604  connected to a carriage assembly mounting bracket  606 . The carriage assembly mounting bracket  606  has carriage linear bearings  608  connected to a mast rail  510 , the mast rail  510  extending along the mast  412 . As well as guiding vertical movement of the carriage assembly  500 , this connection also assists with tying the masts  412 - 1  and  412 - 2  together. In use, the lifting hydraulic cylinders  602  are raised and lowered to control the height of the carriage assembly  500 , with the lift chains  604  increasing the effective travel of the hydraulic cylinders  602 . 
     It is envisaged that when not in use (including during movement of the vehicle proper) the cargo loading system  400  may be closed with the carriage assembly  500  lowered and the lifting forks  502  extended into a stowing space of the vehicle, as generally illustrated in  FIG.  6 - 2   . When used to unload cargo stored in the storage space, the lifting forks  512  may be retracted, the carriage assembly  500  raised to the desired height, the carriage  506  moved laterally into the desired position, and the lifting forks  512  extended. 
     The carriage assembly  500  may then be raised to take the load of the cargo, and the mast frame  420  moved away from the vehicle mounted frame  410  through an arc as shown in  FIG.  7 - 1   . In examples, the cargo loading system  400  may be configured such that the height of the carriage assembly  500  relative to the mast frame  420  may be maintained through the movement of the mast frame  420 . In alternative examples, where the lifting forks  502  may not have sufficient clearance, the carriage assembly  500  may be raised during this movement. 
     The loaded carriage assembly  500  may then be lowered (as illustrated by  FIG.  7 - 2   ) to deposit the cargo at ground level, at which time the lifting forks  502  may be retracted (as illustrated by  FIG.  7 - 3   ) to clear the cargo. 
     It will be appreciated that loading of cargo may be performed using a reversed order of operations, i.e. the cargo may be positioned at ground level and lifted to the cargo storage area using the cargo loading system  400 . 
     Second Exemplary Cargo Loading System 
       FIG.  8    illustrates a cargo loading system  800  according to another aspect of the present technology. The system  800  includes a vehicle mounted mast frame  810  configured to be secured to the cargo storage area  102  at the rearward end  112 . The vehicle mounted mast frame  810  includes a first upright member in the form of primary mast  812 - 1  and a second upright member  812 - 2 . In use, the second upright member  812 - 2  remains in a fixed position relative to the cargo storage area  102 . In this example, the vehicle mounted mast frame  810  further includes an upper crossmember assembly  814  and a lower crossmember assembly  816  connecting the primary mast  812 - 1  and the second upright member  812 - 2 . 
     A carriage assembly  900  is supported by the primary mast  812 - 1 , the carriage assembly  900  including a carriage assembly mounting bracket  902  having carriage linear bearings  904  connected to mast rails  850 , with the mast rails  850  extending along the length of the primary mast  812 - 1 . 
     A carriage assembly main arm  906  of the carriage assembly  900  is pivotally mounted to the carriage assembly mounting bracket  902  by a first helical hydraulic rotary actuator  908 . The first helical hydraulic rotary actuator  908  may be controlled to pivot the carriage assembly main arm  906  about a first vertical axis through 90 degrees between a perpendicular position as shown in  FIG.  8    (i.e. perpendicular relative to upper crossmember assembly  814  and/or lower crossmember assembly  816 ), and a parallel position as shown in  FIG.  10    (i.e. parallel to upper crossmember assembly  814  and/or lower crossmember assembly  816 ). 
     The carriage assembly  900  further comprises a lifting fork carriage base  910 . The lifting fork carriage base  910  is mounted to carriage rails  912  (as shown in  FIG.  9 - 3   ) extending along carriage assembly main arm  906  using linear bearings  914  (as shown in  FIG.  9 - 3   ), which guide lateral movement of the lifting fork carriage base  910  along carriage assembly main arm  906 . A fork lateral control mechanism  916  is provided to control lateral movement of the lifting fork carriage base  910 , as shown in  FIG.  9 - 3   . In this example, the fork lateral control mechanism  916  includes a linear actuator in the form of a carriage hydraulic motor  918  driving a pinion gear engaging with a rack  920  extending along the carriage assembly main arm  906 . 
     The carriage assembly  900  further comprises a lifting fork arm  930  pivotally mounted to the lifting fork carriage base  910  by a second helical hydraulic rotary actuator  932 . The second helical hydraulic rotary actuator  932  may be controlled to pivot the lifting fork arm  930  through 90 degrees between a perpendicular position as shown in  FIG.  9 - 4    (i.e. perpendicular relative to carriage assembly main arm  906 ), and a parallel position as shown in  FIG.  9 - 5    (i.e. parallel to carriage assembly main arm  906 ). 
     A first lifting fork  934 - 1  and second lifting fork  934 - 2  (referred to herein as lifting forks  934 ) are provided to lifting fork arm  930 . The lifting forks  934  are pivotally connected to the lifting fork arm  930 , and moveable between a lowered in-use position as shown in  FIG.  9 - 1   , and a raised stored position as shown in  FIG.  9 - 2   . 
     Referring to  FIG.  10   , the cargo loading system  800  includes a carriage vertical control assembly in the form of lifting mechanism  870 , configured to control raising and lowering of the carriage assembly  900  relative to the primary mast  812 - 1 , e.g. a raised position as shown in  FIG.  12 - 1   , and a lowered position as shown in  FIG.  8   . In this example, the lifting mechanism  870  is provided in the primary mast  812 - 1 . The lifting mechanism  870  includes a lifting hydraulic cylinder  872  and lifting pulley  872 , with associated lift chain  874  trained over the lifting pulley  872  and connected to the carriage assembly mounting bracket  902 . Hydraulic line  878  and electrical line  880  also run over the same lifting pulley  874 , allowing connection between the mast frame  810  and carriage assembly  900 . 
     In this example, the upper crossmember assembly  814  and lower crossmember assembly  816  are provided in sliding sections, with lateral frame actuators in the form of upper hydraulic cylinder  882  and lower hydraulic cylinder  884  therebetween to control relative movement across the open end of the cargo storage area  102 . 
     Referring to  FIG.  11 - 1    and  FIG.  11 - 2   , the lower crossmember assembly  816  includes a floor assembly  1000 . The floor assembly  1000  has a first base portion  1002 , and a first stationary floor portion  1004  adjacent the second upright member  812 - 2 . A lower linear rail  1006  extends along the base portion  1002 —i.e. across the open end of the cargo storage area  102 . A second base portion  1008  is mounted to the lower linear rail  1006  (for example, using linear bearings), and has a second floor portion  1010 . In use, the second floor portion  1008  slides over the first stationary floor portion  1004  to present a complete floor at the open end of the cargo storage area  102 . A gap  1012  is provided between the second floor portion  1010  and the primary mast  812 - 1  to permit passage of the carriage assembly  900  along the primary mast  812 - 1 . 
     In use, the lifting forks  934  may be moved through a range of motions in order to load and unload cargo (for example, loaded onto pallets) relative to the cargo storage area  102 . The lateral movement of the primary mast  812 - 1  enables positioning across the width of the cargo storage area  102 , while vertical movement of the carriage assembly  900  along the primary mast  812 - 1  enables movement of the lifting forks  934  between an upper level and ground level (and positions therebetween). Linear movement of the lifting forks  934  along the carriage assembly main arm  906  allows the forks  934  to be inserted into, and extracted from, the cargo storage area  102 . Pivotal movement of the lifting fork arm  930  assists with ground loading/unloading (in conjunction with the lateral movement of the primary mast  812 - 1 ). 
     The cargo loading system  800  may be stored in different positions, depending on the current use of the vehicle. For example, during transit it is envisaged that the forks  934  may be folded up, and the carriage assembly  900  pivoted to be parallel to, and resting on, the floor assembly  100 . In this position, the weight of the carriage assembly  900  is supported to reduce the likelihood of creep of the hydraulic lifting mechanism  870  during transport. In another example, when access to the cargo storage area  102  is required, without use of the cargo loading system  800 , the carriage assembly  900  may be lowered below the floor assembly  1000  and pivoted to be parallel to the floor assembly  1000  (i.e. such that the forks  934  project below the floor assembly  1000 ).The various steps or acts in a method or process described in connection with the present disclosure may be performed in the order described, or may be performed in another order. Additionally, one or more process or method steps may be omitted or one or more process or method steps may be added to the methods and processes. An additional step, block, or action may be added in the beginning, end, or intervening existing elements of the methods and processes. 
     Reference throughout this specification to “one example” or “an example” (or the like) means that a particular feature, structure, or characteristic described in connection with the example is included in at least one embodiment of the disclosure. Thus, appearances of the phrases “in one example” or “in an example” or the like in various places throughout this specification are not necessarily all referring to the same embodiment. 
     Furthermore, the described features, structures, or characteristics may be combined in any suitable manner in at least one embodiment. In the foregoing description, numerous specific details are provided to give a thorough understanding of the exemplary embodiments. One skilled in the relevant art may well recognize, however, that embodiments of the disclosure can be practiced without at least one of the specific details thereof, or can be practiced with other methods, components, materials, et cetera. In other instances, well-known structures, materials, or operations are not shown or described in detail to avoid obscuring aspects of the invention. 
     The illustrated examples of the disclosure will be best understood by reference to the figures. The foregoing description is intended only by way of example and simply illustrates certain selected exemplary embodiments of the disclosure. 
     Throughout this specification, the word “comprise” or “include”, or variations thereof such as “comprises”, “includes”, “comprising” or “including” will be understood to imply the inclusion of a stated element, integer or step, or group of elements integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps, that is to say, in the sense of “including, but not limited to”.