Patent Publication Number: US-2021178956-A1

Title: Container transfer system

Description:
INCORPORATION BY REFERENCE TO ANY PRIORITY APPLICATION(S) 
     This application claims priority to U.S. Provisional Application No. 62/947384, filed Dec. 12, 2019, of which is incorporated herein by reference. Any and all applications for which a foreign or domestic priority claim is identified in the Application Data Sheet as filed with the present application are hereby incorporated by reference under 37 CFR 1.57. 
    
    
     BACKGROUND 
     Field 
     This disclosure relates to cargo transport, and, in particular, to systems for transferring containers between transport vehicles. 
     Description of the Related Art 
     Traditionally, cargo is transported by one or more vehicles from an origin location to a destination. In some instances, the cargo is loaded on pallets, which are placed into a first transport vehicle by a forklift. In some instances, pallets are not used, and the cargo is loaded directly onto the floor (“floor loaded”) of the first transport vehicle. 
     During transportation, the cargo can be transferred from the first transport vehicle to one or more subsequent transport vehicles. In long haul transfer, the cargo can be transferred, for example, from a train to a truck. As another example, in hub and spoke distribution, cargo can be delivered to a distribution center by a first truck and then divided into one or more second trucks (for example, cross-docked) for delivery to one or more destinations. If the cargo is loaded on pallets, forklifts can facilitate the transfer between transport vehicles. If the cargo is floor loaded, the transfer can be accomplished by manual unloading and loading of cargo. These transfer methods can require additional equipment (such as forklifts) and/or manpower. Additionally, during transfer between transport vehicles, the cargo is exposed to tampering, damage, or loss. 
     SUMMARY 
     A container transfer system installed is described herein. The system may be installed on a vehicle or a rack. The container transfer system may include a conveyance assembly configured to move a container in a substantially horizontal direction along a longitudinal direction of the conveyance assembly. The conveyance assembly may include a frame comprising longitudinal members and transverse members, and a plurality of rollers coupled to the frame, wherein each roller of the plurality of rollers is rotatably coupled to the longitudinal members of the frame by bearings attached to the longitudinal members of the frame. The plurality of rollers comprise may include a first set of drivable rollers configured to be actively driven by a motor coupled to the frame, and a second set of passive rollers. The system may also include a plurality of lift assemblies coupled between chassis rails of the vehicle and the frame of the conveyance assembly, each of the plurality of lift assemblies comprising a lift actuator configured to be actuated to raise and lower the conveyance assembly in a substantially vertical direction. 
     In some embodiments, each of the first set of drivable rollers comprises a sprocket, and a chain is engaged with each of the sprockets and the motor to drive the first set of drivable rollers with the motor. Each of the plurality of lift assemblies can include a bracket comprising a first mounting plate attached to one of the chassis rails of the vehicle and a lift actuator support plate attached to a lower end of the lift actuator, and a frame attachment structure attached to an upper end of the lift actuator, the frame attachment structure further comprising a second mounting plate attached to the frame of the conveyance assembly. The upper end of the lift actuator can be attached to the frame attachment structure with a removable pin configured to be removed to detach the lift actuator from the frame attachment structure. In some embodiments, the frame attachment structure further comprises a rail extending along an axis parallel to an axis of actuation of the lift actuator, the rail slidingly engaged with one or more guides attached to the bracket of the lift assembly. The system the vehicle can include a hydraulic system. The motor can be a hydraulic motor configured to be driven by the hydraulic system of the vehicle. Each of the lift actuators can include a hydraulic ram configured to be driven by the hydraulic system of the vehicle or by an independent power source. The set of drivable rollers may comprise four drivable rollers positioned at a distal end of the conveyance assembly. The plurality of lift assemblies comprises four lift assemblies, each of the four assemblies positioned in one of four corners of the frame of the conveyance assembly. The lift actuator of each of the four lift assemblies can be independently actuated such that longitudinal and transverse tilt of the conveyance assembly can be adjusted to level the conveyance assembly. 
     In some embodiments, the system further comprises a container positioned on the conveyance assembly. The container can include an enclosure configured for receiving cargo, a pair of container rails attached to a bottom surface of the container, and one or more container support surfaces attached to the bottom surface of the container between the pair of rails. The enclosure of the container may include a first door on a first end and a second door on a second end, the second end opposite the first end. The conveyance assembly can be received between the pair of container rails such that container support surfaces rest on the plurality of rollers. The motor can be configured to drive the set of drivable rollers to convey the container along the longitudinal direction. 
     The system may also include one or more locking assemblies configured to engage the container to prevent movement of the container when engaged. Each of the one or more locking assemblies can be attached to one of the chassis rails and comprises an actuator configured to actuate a locking pawl that engages a lug on the container. The actuator can include a hydraulic actuator driven by a hydraulic system of the vehicle or an independent power source. 
     In some embodiments, the vehicle comprises a hydraulic system, the motor comprises a hydraulic motor configured to be driven by the hydraulic system of the vehicle, each of the lift actuators comprises a hydraulic ram configured to be driven by the hydraulic system of the vehicle, and the system comprises hydraulic connectors configured to connect to hydraulic components of a second container transfer system such that the hydraulic components of the second container transfer system can be driven by the hydraulic system of the vehicle. In some embodiments, the second container transfer system is mounted on a rack. The system can include a container configured to be transferred between the container transfer system of the vehicle and the second container transfer system of the rack. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These drawings depict only several embodiments in accordance with the disclosure and are not to be considered limiting of its scope. In the drawings, similar reference numbers or symbols typically identify similar components, unless context dictates otherwise. The drawings may not be to scale. 
         FIG. 1  is a perspective view of an embodiment of a conventional cross-docking site. 
         FIG. 2  is a diagram illustrating a simplified embodiment of a conventional cross-docking process. 
         FIG. 3  is a diagram illustrating a simplified view of an embodiment of container transfer between transport vehicles using the container transfer systems described herein. 
         FIG. 4A  is a perspective view of an embodiment of a container transfer system. 
         FIG. 4B  is a top view of one side of the container transfer system of  FIG. 4A . 
         FIG. 4C  is a side view of the one side of the container transfer system of  FIG. 4B . 
         FIG. 4D  is a detail side view of an end portion of the one side of the container transfer system of  FIG. 4B . 
         FIG. 4E  is a front view of the one side of the container transfer system of  FIG. 4B . 
         FIG. 5A  is a perspective view of a base of a container. 
         FIG. 5B  is a detail perspective view of an engagement structure on the base of  FIG. 5A . 
         FIG. 6A  is a perspective view of a transport vehicle including the container transfer system of  FIG. 4A . 
         FIG. 6B  is a side view of the transport vehicle of  FIG. 6A . 
         FIG. 7A  is a rear view of a transport vehicle and illustrates a locking mechanism for locking a container to the transport vehicle in an unlocked state. 
         FIG. 7B  is a detail view of the locking mechanism of  FIG. 7A  in an unlocked state. 
         FIG. 7C  is a rear view of the transport vehicle and locking mechanism of  FIG. 7A , illustrated in a locked state. 
         FIG. 7D  is a detail view of the locking mechanism of  FIG. 7C  in a locked state. 
         FIG. 8  is a perspective view illustrating an embodiment of a transport vehicle including a container transfer system that can be adjusted so as to be level. 
         FIG. 9  illustrates an embodiment of a semi-trailer including four container transfer systems. 
         FIG. 10  is a perspective view of another embodiment of a container transfer system including lift assemblies and a conveyance assembly. 
         FIG. 11  is a perspective view of an embodiment of one of the lift assemblies of the container transfer system of  FIG. 10 . 
         FIG. 12  is a perspective view of a locking assembly of the container transfer system of  FIG. 10 . 
         FIG. 13A  illustrates a vehicle having the container transfer system of  FIG. 10  installed thereon, according to an embodiment. 
         FIG. 13B  is a top perspective view illustrating the container transfer system of  FIG. 10  installed on a model of the vehicle. 
         FIG. 13C  is a bottom, detail, perspective view illustrating the container transfer system of  FIG. 10  installed on the model of the vehicle. 
         FIG. 14  is a detail view illustrating a portion of the container transfer system of  FIG. 10 , including an embodiment of a locking mechanism and hydraulic connections. 
         FIG. 15  is a bottom perspective view of an embodiment of a container configured for use with the container transfer system of  FIG. 10 . 
         FIG. 16  illustrates an embodiment of a controller configured for use with the container transfer system of  FIG. 10 . 
         FIGS. 17A and 17B  are views illustrating the container transfer system of  FIG. 10  during use, transferring a container between a container transfer system installed on a vehicle and a container transfer system installed on a rack. 
     
    
    
     DETAILED DESCRIPTION 
     Disclosed herein are container transfer systems and related methods. In some embodiments, the container transfer systems are installed directly on transport vehicles and/or racks and are configured to transfer cargo-loaded containers (or unloaded containers) directly between transport vehicles and/or racks. In some embodiments, the container transfer systems are configured to transfer containers without requiring the use of additional equipment (such as forklifts, cranes, hoists, etc.) and/or dedicated facilities (such as docks, facilities, etc.). In some embodiments, the containers transfer systems transfer containers in a substantially horizontally direction. In some embodiments, because the container transfer systems transfer containers directly between transport vehicles, cargo does not need to be unloaded and reloaded. In some embodiments, this simplifies cargo transfer between vehicles and/or eliminates or mitigates tampering, damage, or loss of the cargo. 
     These and other features and advantages of the container transfer systems described herein will become more fully apparent from the following description and appended claims, taken in conjunction with the accompanying drawings. Although the drawings illustrate several specific embodiments, these are provided by way of example only and are not intended to be limiting. The features of any of the embodiments illustrated in drawings or described in text throughout this application can be modified, duplicated, removed, and/or combined with features of any other embodiment illustrated or described herein, or as will be apparent to a person of ordinary skill in the art upon consideration of this disclosure. 
       FIG. 1  is a perspective view of an embodiment of a cross-docking site  10 . The cross-docking site  10  is a location where cargo can be transferred between transport vehicles. In  FIG. 1 , a first transport vehicle  21  and a second transport vehicle  22  are present at the cross-docking site. As illustrated, the first transport vehicle  21  is a larger semi-truck and the second transport vehicle  22  is a smaller delivery truck. However, the cross-docking site  10  can be used to transfer cargo between many different numbers and types of transport vehicles. 
     The cross-docking site  10  includes an elevated platform  15 . To facilitate cargo transfer, the first and second transport vehicles  21 ,  22  are backed to the elevated platform  15  such that doors into the cargo area of each are level with the elevated platform  15 . In general, the cargo area of each transport vehicle  21 ,  22  is an enclosed storage space permanently affixed to the transport vehicle itself or a trailer pulled by the transport vehicle. In some instances, the cargo area may be open, such as a flatbed truck or trailer, for example. In some embodiments, a forklift  25  (or other similar device) located on the elevated platform  15  can then transfer pallets loaded with cargo between the first and second transport vehicles  21 ,  22 . If the cargo is floor loaded into the transport vehicles  21 ,  22 , dock workers may transfer the cargo manually. 
       FIG. 2  is a diagram illustrating a simplified embodiment of a conventional cross-docking process, performed, for example, at cross-docking site  10 . In the illustrated embodiment, the process transfers cargo between the first transport vehicle  21  and four second transport vehicles  22   a - 22   d  (collectively, transport vehicles  22 ), although various modifications of the process are possible. 
     In panel A, the first transport vehicle  21  is backed to the elevated platform  15 . The first transport vehicle  21  has been previously loaded with four unit loads  31 - 34 . For ease of description, each unit load  31 - 34  will be described as including a single pallet loaded with cargo, although, it will be understood that each unit load  31 - 34  may comprise multiple pallets of cargo, quantities of floor loaded cargo, or cargo loaded into one or more other types of shipping containers. The second transport vehicle  22   a  is also backed to the elevated platform  15 . In the illustrated embodiment, the second transport vehicle  22   a  is a delivery truck returned from a delivery and is loaded with an empty pallet. The empty pallet  41  can be unloaded from the second transport vehicle  22   a  by the forklift  25  and stored on the elevated platform  15 . 
     In panel B, the first unit load  31  is transferred to the second transport vehicle  22   a , for example, by the forklift  25 . Transfer of the first unit load  31  includes removing the first unit load  31  from the first transport vehicle  21  and placing the first unit load in the second transport vehicle  22   a . In some instances, transfer of the first unit load  31  can also include storage of the first unit load  31  on the elevated platform  15  or nearby for a period of time. 
     In panel C, the remaining unit loads  32 - 34  are transferred to additional second transport vehicles  22   b - 22   d . Empty pallets  42 - 44  are shown, which have been unloaded from the second transport vehicles  22   b - 22   d . Once loaded, second transport vehicles  22   a - 22   d  depart to deliver unit loads  31 - 34  to their respective destinations. In panel D, empty pallets  41 - 44  are loaded into the first transport vehicle  21  for return to a distribution center where they can be reloaded with cargo. 
     The cross-docking site  10  and process described with reference to  FIGS. 1 and 2  can present several disadvantages. For one, because the cargo must be removed from the first transport vehicle  21  in order to be transferred to the second transport vehicles  22 , it is exposed to tampering, damage, and loss. In some instances, the first and second vehicles  21 ,  22  are not present at the cross-docking site  10  at the same time. In these instances, cargo may be unloaded from the first transport vehicle  21  and stored on the elevated platform  15  (or elsewhere nearby) until the second transport vehicle  22  arrives and can be loaded. Storage of cargo at the cross-docking site  10  increases the exposure of the cargo to tampering, damage, and loss. Additionally, operation of the cross-docking site  10  can be expensive. For instance, the cross-docking site  10  requires a dedicated property, which can be expensive. Further, operation of the cross-docking site  10  can require expensive machinery, such as forklifts  15 , and manpower. Finally, loading and unloading of cargo can take significant time, which can increase cost and decrease shipping speed. Container transfer systems and methods will now be described with reference to  FIGS. 3-9 , which can, in some embodiments, mitigate or resolve one or more of the above-noted disadvantages. 
       FIG. 3  is a diagram illustrating a simplified view of an embodiment of container transfer between transport vehicles  51 ,  52  using the container transfer systems  100  described herein. While not shown in detail in  FIG. 3 , an embodiment of the container transfer system  100  is shown in  FIGS. 4A-4E  below. 
     As shown in panel A of  FIG. 3 , a first transport vehicle  51  is loaded with four containers  61 - 64 . Each container  61 - 64  can hold cargo. In some embodiments, the containers  61 - 64  can be fully enclosed and secured. The containers  61 - 64  are not permanently attached to the first transport vehicle  51 , but rather are supported on a container transfer system  100  of the first transport vehicle  51 . A second transport vehicle  52  is also illustrated. The second transport vehicle  52  also includes a container transfer system  100 . As illustrated in panel A, the container transfer system  100  of the second transport vehicle  52  is empty (that is, no container is supported on the container transfer system  100 , as illustrated by the dashed box). To transfer a container  61  from the first transport vehicle  51  to the second transport vehicle  52 , the first and second transport vehicles  51 ,  52  are backed together, such that the container transfer systems  100  are aligned. In some embodiments, the container transfer systems  100  include features to level and align the two systems. In some embodiments, the first and second vehicles  51 ,  52  can be backed together in any location, as long as the location allows sufficient space for the maneuvering of the first and second transport vehicles  51 ,  52 . Thus, in some embodiments, transfer of cargo is not limited to occurring only at cross-docking sites and does not require a dedicated cross-docking property. 
     As illustrated in panel B, the container transfer systems  100  are activated to transfer the container  61  from the first transport vehicle  51  to the second transport vehicle  52 . As illustrated, in some embodiments, the transfer of container  61  proceeds in a substantially horizontal direction. In some embodiments, the transfer does not require external machinery, such as forklifts, cranes, hoists, etc. Further, in some embodiments, the container  61  remains closed during transfer, and thus, the cargo is not exposed to tampering, damage, or loss. 
     Once loaded with container  61 , the second transport vehicle  52  can depart to deliver its cargo to its destination, as shown in panel C. As shown in panel D, an additional second transport vehicle  52  can be backed to the first transport vehicle  51  to receive transfer of container  62 . This process can be repeated until all of containers  61 - 64  are transferred. 
     The transfer process illustrated in  FIG. 3  is provides one example, among many, that illustrates the use of the container transfer systems  100  described herein. Numerous modifications of the process are possible. For example, the number of containers each transport vehicle can be configured to hold can be varied. In some embodiments, each transport vehicle can hold one, two, three, four, five, six, or more containers. As another example, the number of containers transferred between each transport vehicle can be varied. While  FIG. 1  illustrates transfer of a single container at a time, in some embodiments, one, two, three, four, five, six, or more containers can be transferred together. As yet another example, in some embodiments, the container transfer systems  100  can be installed on other types of transport vehicles. For example, a container transfer system  100  can be installed on a rail car, a trailer, or in the cargo hold of an airplane or ship, among others. As yet another example, in some embodiments, the container transfer systems  100  can be installed on a holding rack, such that a container can be transferred from a transport vehicle to the holding rack and again from the holding rack to a transport vehicle. In the illustrated embodiment, containers are transferred from end to end. In some embodiments, however, containers can be transferred from side to side. 
     The container transfer systems  100  described herein can be used with many types and sizes of containers. The size, shape, and capacity of the containers can vary without limit and may depend upon the types of items to be transferred. In some instances, this may be cargo containers. In other instances, this may be different types of platforms (e.g., pallets, truck beds, etc.). For example, a single commercial truck may use the container transfer system  100  to shift between being a flatbed truck, to a dump truck, to a cement mixer, etc. As another example, in the case of agricultural equipment, one truck may be used for a variety of implements and accessories. In some embodiments, the cargo containers may be configured to comply with federal size constraints (for example, maximum lengths and widths for use on public roads). In some embodiments, the containers can be fully enclosed. In some embodiments, the containers can be securable (for example, lockable). In some embodiments, the containers can be open, for example, comprising open tops, ends, or sides. 
     In some embodiments, the container transfer systems  100  described herein provide one or more advantages. For example, in some embodiments, the container transfer systems  100 : allow direct transfer of containers of cargo between transport vehicles, allow transfer of cargo at any location, do not require additional equipment or manpower to transfer containers, and/or do not expose (or reduce exposure of) the cargo to tampering, damage, or loss. In some embodiments, the container transfer systems  100  are fully operable by a single person, such as the driver. In some embodiments, the container transfer systems are controllable from within the cab of the transport vehicle. The container transfer system can include a controller allowing a user to manipulate the container transfer system  100 , for example, to manually control the height and angle of the system as well as to drive the chain drives. In some embodiments, the system may be automated, and may include laser and proximity sensors that provide inputs to a computerized control system. A detailed embodiment of a container transfer system  100  will now be described with reference to  FIGS. 4A-4E . 
       FIG. 4A  is a perspective view of an embodiment of a container transfer system  100 . Although shown alone in  FIG. 4A , the container transfer system  100  is configured to be mounted to the frame of a truck, trailer, other transport vehicle, or rack as described below (see  FIGS. 6A-6B , for example). In the illustrated embodiment, the container transfer system  100  includes two separate assemblies  101   a ,  101   b . As will become apparent from the following description, each assembly  101   a ,  101   b  is configured to (1) convey a container backwards or forwards along its length (referred to herein as the horizontal direction) and (2) move up and down vertically. 
     In the illustrated embodiment, each assembly  101   a ,  101   b  includes one conveyance mechanism  120   a ,  120   b . As will be described below, the conveyance mechanism  120   a ,  120   b  is configured to convey a container backwards and forwards in the horizontal direction. 
     Each assembly  101   a ,  101   b  also desirably includes two lift mechanisms  140   a ,  140   b . For each assembly  101   a ,  101   b , the two lift mechanisms  140   a ,  140   b  support the conveyance mechanism  120   a ,  120   b . In the illustrated embodiment, for each assembly  101   a ,  101   b , a first lift mechanism  140   a ,  140   b  is positioned at substantially a first end of the conveyance mechanism  120   a ,  120   b , and a second lift mechanism  140   a ,  140   b  is positioned substantially at a second end of the conveyance mechanism  120   a ,  120   b . Although the lift mechanisms  140   a ,  140   b  are shown positioned substantially at the ends of the conveyance mechanisms  120   a ,  120   b , this need not be the case in all embodiments. For example, in some embodiments, the lift mechanisms  140   a ,  140   b  can be positioned spaced inward from the ends of the conveyance mechanisms  120   a ,  120   b . In some embodiments, for each assembly  101   a ,  101   b , the lift mechanism  140   a ,  140   b  are substantially similar to each other. In some embodiments, the lift mechanisms  140   a ,  140   b  on one end of the conveyance mechanisms  120   a ,  120   b  can be arranged in a mirrored configuration to the lift mechanisms  140   a ,  140   b  on the opposite end of the conveyance mechanisms  120   a ,  120   b . In some embodiments, each assembly  101   a ,  101   b  includes more than two (for example, three, four, five, or more) lift mechanisms  140   a ,  140   b  for each conveyance mechanism  120   a ,  120   b.    
     As will be described below, the lift mechanisms  140   a ,  140   b  are configured to raise and lower the conveyance mechanisms  120   a ,  120   b  in the vertical direction, as well as adjust the angle of the conveyance mechanisms  120   a ,  120   b  relative to horizontal. In some embodiments, each lift mechanism  140   a ,  140   b  is independently controllable so as to allow for independent adjustment of the height of each conveyance mechanism  120   a ,  120   b  as well as independent adjustment of the angle of each. 
     While each lift mechanism desirably  140   a ,  140   b  supports an end of a conveyance mechanism  120   a ,  120   b , each lift mechanism  140   a ,  140   b  is desirably supported by a mounting frame  160   a ,  160   b . The mounting frames  160   a ,  160   b  are configured to be mounting points for installing each assembly  101   a ,  101   b . For example, in some embodiments, the mounting frames  160   a ,  160   b  are configured to mount to the frame of a transport vehicle, a rail car, a cargo bay of a boat or airplane, a storage rack, etc. The mounting frames  160   a ,  160   b  provide a base for the container transfer system  100 . The mounting frames  160   a ,  160   b  are configured to provide the structural strength required to carry the weight of the container transfer system as well as any container and load that can be placed thereon. The embodiments of the mounting frames  160   a ,  160   b  shown in the figures are provided by way of example only and, in some embodiments, can be varied to conform to the transport vehicle (or other object) to which the container transfer system  100  is to be mounted. 
     As shown in  FIG. 4A , the assemblies  101   a ,  101   b  can be positioned in a substantially parallel arrangement. In some embodiments, the assemblies  101   a ,  101   b  are substantially mirror images of each other. That is, the assembly  101   b  can include substantially the same components as the assembly  101   a , although in the reversed configuration. Thus, for ease of description, the following discussion of  FIGS. 4B-4E  will describe the components of the assembly  101   a  of the container transfer system  100 , with the understanding that the assembly  101   b  includes similar features. 
       FIG. 4B  is a top view of the assembly  101   a , and  FIG. 4C  is a side view of the assembly  101   a .  FIG. 4D  is a detail side view of an end portion the assembly  101   a , and  FIG. 4E  is a front view of the assembly  101   a . For simplicity, the components of the assembly  101   a  numbered in  FIGS. 4B-4E  do not include reference characters “a” and “b,” which have been used previously herein (for example, in  FIG. 4A ) to refer to the components of the assemblies  101   a ,  101   b , respectively. 
     As shown in  FIGS. 4A-4E , the assembly  101   a  includes the conveyance mechanism  120 . In the illustrated embodiment, the conveyance mechanism  120  includes a conveyor chain  121 . The conveyor chain  121  may be formed as a continuous loop of chain mounted on sprockets  123 . The sprockets  123  are partially seen in  FIGS. 4B and 4D , and one of the sprockets  123  is visible in the cutaway portion of  FIGS. 4C and 4D . In the illustrated embodiment, the assembly  101   a  includes six sprockets  123 , although other numbers of sprockets  123  possible. One sprocket  123  is positioned at each end of the conveyance mechanism  120  and the remaining sprockets  123  are spaced evenly between the two end sprockets  123 . In some embodiments, the sprockets  123  are not evenly spaced. In some embodiment, a sprocket  123  is positioned every few feet along the length of the conveyance mechanism  120 . For example, a sprocket  123  can be positioned every 3 feet, every 2.5 feet, every 2 feet, every 1.5 feet, every 1 foot, or every six inches along the conveyance mechanism  120 , as well as at greater or smaller spacings or spacings in between the listed values. 
     The sprockets  123  are rotatably supported on axles  124  that are mounted to a drive tray  125 . In some embodiments, the drive tray  125  comprises a U-shape or a squared U-shape channel. In some embodiments, the sprockets  123  and are positioned substantially within the channel of the drive tray  125 . In some embodiments, a top portion of the sprockets  123  extends about the drive tray  125 , such that the top run of the conveyor chain  121  is positioned above the drive tray  123 . The lower run of the conveyor chain  121  may be positioned within the drive tray  125 . 
     A motor  126  is attached to one of the axles  124  and configured to drive on of the sprockets  123 . The motor  126  drives one of the sprockets  123 , which in turn, advances the conveyor chain  121 . The motor  126  may be configured to operate in both directions (in other words, clockwise and counterclockwise) such that the conveyor chain  121  can be moved in both forward and backward directions. As will be described with reference to  FIGS. 5A and 5B , a container can include engagement features that engage the conveyor chain  121 , such that a container resting on the conveyor chain  121  moves with the conveyor chain  121 . Thus, the conveyance mechanism  120  is configured to convey a container back and forth in a horizontal direction along the length of the conveyance mechanism  120 . 
     In the illustrated embodiment, the motor  126  is connected to one of the middle axles  126 , although this need not be the case in all embodiments. In the illustrated embodiment, the motor  126  is positioned on the inside of the assembly  101   a  (see  FIG. 4A ); again, this need not be the case in all embodiments. In some embodiments, the motor  126  is an electric motor. The motor  126  can be powered by the electrical system of the transport vehicle to which the container transfer system  100  is attached. Alternatively, the motor  126  can be separately powered, for example, by batteries or an external power source. The motor  126  can be connected to a user interface that allows an operator to control the motor  126 . Although only a single motor  126  is illustrated from the assembly  101   a , in some embodiments, more than one motor  126  can be included. 
     As shown in  FIG. 4A , each assembly  101   a ,  101   b  includes its own motor  126   a ,  126   b . In some embodiments, the motors  126   a ,  126   b  are synchronized such that the conveyor chains  121   a ,  121   b  are driven together, at the same speed, and in the same direction. In some embodiments, each motor  126   a ,  126   b  can be independently controlled. In some embodiments, a single motor  126  is connected via one or more drive shafts to a sprocket  123  on each of the assemblies  101   a ,  101   b  such that a single motor  126  drives the conveyor chains  121   a ,  121   b  of the assemblies  101   a ,  101   b.    
     The conveyance mechanism  120  shown in the figures and described herein is provided by way of example only. In other embodiments, other types of systems can be used. For example, in some embodiments, a rotating acme or lead screw can replace the sprockets and conveyor chain in order to produce linear motion. In other embodiments, the conveyor chain can be replaced by a belt. 
     As noted previously, the conveyance mechanism  120  is supported by two lift mechanisms  140  and the lift mechanisms  140  are configured to raise and lower the conveyance mechanism  120  in the vertical direction. In the illustrated embodiment, each lift mechanism  140  includes an air spring  141 . As illustrated, the air springs  141  are mounted substantially below each end of the conveyance mechanism  121 . In some embodiments, the air springs  141  are coupled to the drive tray  125  with a tongued bracket  143  mounted in a groove of the drive tray  125  in a tongue-in-groove configuration (see cutaway portion of  FIG. 4D ). In some embodiment, the tongue and groove can be reversed: the groove can be included on the bracket  143  and the tongue on the drive tray  125 . The tongue-in-groove configuration can be configured to allow some relative horizontal motion between the drive tray  125  and the air spring  141 , while constraining their vertical motion together. In some embodiments, the bracket  143  is rigidly attached to the drive tray  125 . 
     The air spring  141  can be pneumatically connected to a compressor (not shown) configured to supply pressurized air to the air spring  141 . By adding air to the air spring  141  the height of the air spring  141  can be increased. As the height of the air spring  141  is increased, the conveyance mechanism  120  is raised vertically. Conversely, removing air from the air spring  141  (for example, by bleeding through a valve (not shown)) the height of the air spring  141  can be reduced, lowering the conveyance mechanism  120 . In some embodiments, hydraulic elements can be used in place of (or in addition to) pneumatic elements. 
     Many transport vehicles onto which the container transfer system  100  can be installed include suitable compressed air systems for supplying air to the air springs  141 . For example, a tractor having an air-ride suspension system is already equipped with suitable compressor technology to accommodate the lift mechanism  140 . In some embodiments, a separate compressor or other source of pressurized air can be provided to provide air to the air springs  141 . 
     In some embodiments, the air spring  141  of each lift mechanism  140  is individually adjustable. By adjusting the height of each air spring  141  on the four corners of the container transfer system  100 , the height and angle of each conveyance mechanism  120  can be independently controlled an adjusted. In some embodiments, this can allow a load (for example, a container) to be tilted, raised, or lowered in any direction, and allow two container transfer systems  100  to be aligned as shown in  FIG. 8 . 
     Although an air spring  141  is shown in the figures and described herein, other mechanisms (for example, hydraulic rams) can be used in some embodiments. The air springs  141  can be controlled by a user interface that allows an operator to adjust the height of the lift mechanisms  140 . 
     In the illustrated embodiment, each lift mechanism  140  also includes a telescoping strut  144 . The telescoping strut  144  is configured such that its length is adjustable to adapt to the height of the air spring  141  and the conveyance mechanism  120 . The telescoping strut  144  is biased toward an extended configuration. The telescoping strut  144  is connected at its upper end a stabilizer slide  145 . The stabilizer slide  145  is configured to slidingly engage with the drive tray  125  of the conveyance mechanism  120 . In some embodiments, the stabilizer slide  145  comprises a U-shaped bracket and the drive tray  125  is slidingly nested in the stabilizer slide  145 . In some embodiments, the stabilizer slide  145  includes replaceable glide pads. In some embodiments, the glide pads may comprise Teflon. In some embodiments, the glide pads may include bearings or rollers. In some embodiments, the replaceable glide pads are positioned between the stabilizer slide  145  and the drive tray  125  to provide a smooth bearing surface at the junction between the drive tray  125  and the stabilizer slides  145 . Thus, the upper end of telescoping strut  144  is slidingly engaged with the drive tray  125  in order to adapt to changes in the height of the air spring  141  and provide additional support for the conveyance mechanism  120 . In some embodiments, the sliding engagement between the stabilizer slide  145  and the drive tray  125  allows the lift mechanism to account for varying angles of the conveyance mechanism  120  (for example, where one end of the conveyance mechanism  120  is lifted higher than the other). In some embodiments, the telescoping strut  144  is rigidly attached to the drive tray  125 . 
     In the illustrated embodiment, each lift mechanism  140  includes a telescoping stabilizer bar  147 . In some embodiments, the stabilizer bar  147  comprises a pivoting tie rod that diagonally connects the bracket  143  of the air spring  141  to the telescoping strut  144 . In some embodiments, the stabilizer bar  147  provides additional support to the load and further couples the motion of the air spring  141  to that of the telescoping strut  144  and stabilizer slide  145 . In some embodiments, the telescoping stabilizer bar  147  further accommodates for uneven independent adjustment of the air springs  141 . 
     Each lift mechanism  140  is attached to a mounting frame  142 . In some embodiments, each mounting frame  142  comprises a rigid support frame, for example, made from welded square or round tubing. In the illustrated embodiment, each mounting frame  142  is shaped as a right triangular prism, although other shapes are possible. As noted previously, the shape of the mounting frame  142  can be varied to fit the application of the container transfer system  100 . 
     The chain drives  121  of the container transfer system  100  are configured to interface with containers, such that the container transfer system  100  can convey containers back and forth in a horizontal direction without requiring the use of external machinery, such as forklifts, cranes, hoists, etc. The height of the container transfer system  100  can be adjusted by the lift mechanisms  140  in order to match the height of another container transfer system  100  to which the container can be conveyed as shown in  FIG. 3 . 
       FIG. 5A  is a perspective view of a base  200  for a container that can be used with the container transfer systems  100  described herein. The base  200  is configured to support the container. Although not shown, in some embodiments, the container is a rectangular enclosure, although other shapes are possible. As noted previously, in some embodiments, the container is fully enclosed and lockable, while, in other embodiments, the container remains open (for example, having an open top, sides, and/or end). In some embodiments, a flat platform may be mounted on the base  200  to form a flatbed. 
     As shown in  FIG. 5A , the base  200  can comprise a frame of transverse supports  210  supported by longitudinal supports  220 . In the illustrated embodiment, the transverse supports comprise square tubing, although other configurations are possible. In the illustrated embodiment, the longitudinal supports  220  comprise channel beams, although, again, other configurations are possible. The number and arrangement of transverse supports  210  and longitudinal supports  220  can be varied from the example embodiment shown in  FIG. 5 . 
     As also shown in  FIG. 5A , and in the detail view of  FIG. 5B , the base  200  also includes engagement structures  230 . In the illustrated embodiment, the engagement structures  230  are drive trains that extend longitudinally along the bottom of the base  200 . The two engagement structures  230  are spaced apart in a configuration that matches that of the two assemblies  101   a ,  101   b  of the container transfer system  100  of  FIG. 4A . Thus, when the base  200  is placed on the container transfer system  100 , the two engagement structures  230  rest on the conveyance mechanism  120   a ,  120   b . In the illustrated embodiment, the engagement structures  230  include a toothed configuration as shown in  FIG. 5B . The toothed configuration is configured to engage the conveyor chains  121   a ,  121   b . Thus, motion of the conveyor chains  121   a ,  121   b  is imparted to the base  200 . In some embodiments, the engagement structures  230  may comprise other forms that correspond to features on the conveyance mechanisms  120   a ,  120   b.    
     In some embodiments, the base  200  is made from modular components such that the size and configuration of the base  200  can be modified and adjusted to match the size and shape of a particular container with which it will be used. 
       FIG. 6A  is a perspective view of a transport vehicle  300  including the container transfer system  100  of  FIG. 4A .  FIG. 6B  is a side view of the transport vehicle  300  of  FIG. 6A . In the illustrated embodiment, the transport vehicle  300  is a delivery truck and is configured to receive one container thereon (for example, similar to the second transport vehicle  52  shown in  FIG. 3 ). The mounting frames  142  are mounted to frame members  310  of the transport vehicle  300 . As will be described below with reference to  FIGS. 7A-7D , in some embodiments, when the container transfer system  100  is conveying a container, the base  200  of the container is lifted above (not-contacting) the frame members  310  of the transport vehicle  300 . In some embodiments, once the container is positioned on the container transfer system  100 , the lift mechanisms  140  can lower the container so that it rests on the frame members  310 . In some embodiments, the longitudinal supports  220  of the base  200  rest on the frame members  310  of the transport vehicle  300 . In some embodiments, the container can then be locked to the frame members  310  to ensure stability during transport. 
       FIGS. 7A and 7C  are rear views of the transport vehicle  300  and illustrate a locking mechanism  350  for locking the base  200  to the transport vehicle  300  in unlocked state and locked states, respectively. In  FIGS. 7A and 7C , the container transfer system  100  is omitted for clarity.  FIGS. 7B and 7D  are detail views of the locking mechanism  350  in unlocked and locked states, respectively. 
     As illustrated in  FIG. 7A , the base  200  is lifted by the lift mechanisms  140  of the container transfer system  100  such that the longitudinal supports  220  are positioned a distance H above the frame members  310  of the vehicle  300 . In some embodiments, the container transfer system  100  can position the base  200  in this position when the container is being conveyed back and forth. In this position, the weight of the container is supported by the container transfer system  100 . Further, in this position, in some embodiments, the container is not locked to the vehicle  300 . As shown in  FIG. 7B , a locking pin  351  of the locking system  300  is not engaged with the longitudinal support  220  of the base  200 . 
       FIGS. 7C and 7D  illustrate an example of the locked configuration. As shown, the base  200  has been lowered such that that longitudinal supports  220  rest on the frame members  310 . In some embodiments, the container transfer system  100  may place the container in this position during transport. In some embodiments, at least a portion of the weight of the container is supported on the frame members  310  of the vehicle  300  in this position. In some embodiments, the longitudinal supports  220  of the base  200  include angled guide members  221  that extend downwardly to guide the longitudinal supports  220  onto the frame members  310  as the container transfer system  100  lowers the container. As shown in  FIG. 7D , once lowered, the locking pin  351  engages with the longitudinal supports  220  of the base  200  to lock the base into position on the frame members  310 . In some embodiments, the locking pin  351  includes a portion that extends through an opening in the angled guide members  221 . In some embodiments, the locking pin  351  includes a portion  352  that locks over a projection  223  on the longitudinal supports  220 . In some embodiments, other methods for securing the container to the transport vehicle  300  are possible. 
       FIG. 8  is a perspective view illustrating an embodiment of a transport vehicle  300  including a container transfer system  100  and illustrates that each corner of the container transfer system  100  can be independently adjusted. As previously described, a lift mechanism  140  can be included in each corner of the container transfer system  100 . This allows each corner to be raised or lowered individually. This control can allow the transfer system  100  to be aligned with another container transfer system  100  of another transport vehicle  300  regardless of uneven ground condition or a height difference between the two vehicles. This control can also allow a container placed on the container transfer system  100  to be leveled. 
       FIG. 9  illustrates an embodiment of a semi-trailer  400  including four container transfer systems  100   a - 100   d . In some embodiments, this configuration allows the semi-trailer  400  to hold four containers (for example, similar to the transport vehicle  51  of  FIG. 3 ). In some embodiments, the container transfer systems  100   a - 100   d  are independently operable. In some embodiments, the container transfer systems  100   a - 100   d  operate together. In some embodiments, the semi-trailer  400  can include other numbers of container transfer systems, for example, one, two, three, five, six or more. 
       FIG. 10  is a perspective view of another embodiment of a container transfer system  500 . As will be described below, the container transfer system  500  can be configured to transfer moveable containers (such as the container  700  shown in  FIG. 15 ) between two vehicles that each include the container transfer system  500  and/or between a vehicle including the container transfer system  500  and a compatible rack (for example, as shown in  FIGS. 17A and 17B ). The container transfer system  500  may provide any or all of the advantages described above as well as others. Examples of a vehicle  600  including the container transfer system  500  are shown in  FIGS. 13A-14 and 17A-17B , which are described below. In some embodiments, the container transfer system  500  can be considered a horizontal transfer system, as it can be configured to transfer containers in a horizontal or substantially horizontal direction. The container transfer system  500  can transfer loaded or unloaded containers without having to open, load, and unload the containers, providing the benefits described above. 
     In the illustrated embodiment of  FIG. 10 , the container transfer system  500  comprises a conveyance assembly  502 , a plurality of lift assemblies  504 , and one or more locking assemblies  506 . The conveyance assembly  502  is configured to move containers (such as the container  700  of  FIG. 15 ) in a horizontal or substantially horizontal direction. The conveyance assembly  502  can be mounted to (e.g., on top of) the plurality of lift assemblies  504 . Further, the plurality of lift assemblies  504  can be mounted to a vehicle or storage rack. For example, as shown in  FIGS. 13A-14 , the plurality of lift assemblies  504  can be mounted to a chassis of a vehicle  600 , such as a transport truck. 
     The plurality of lift assemblies  504  are configured to move the conveyance assembly  502  in a substantially vertical direction. That is the plurality of lift assemblies  504  can be configured to raise and lower the conveyance assembly  502 . In some instances, raising and lowering the conveyance assembly  502  can be useful to vertically align a height of the container transfer system  500  with a height of another container transfer system  500  such that a container supported thereon can be vertically transferred between the two. In some embodiments, the lift assemblies  504  can be configured to lower the conveyance assembly  502  such that it rests substantially on top of the chassis of the vehicle. This may be an advantageous position during movement (e.g., driving) of the vehicle as it can increase the stability of any containers loaded onto the container transport system  500  and direct the loads associated with the containers down onto the chassis of the vehicle. 
     In the illustrated embodiment, the container transfer system  500  includes four lift assemblies  504  positioned generally in the four corners of the conveyance assembly  502 . This may be advantageous as, not only does it allow the conveyance assembly  502  to be raised and lowered, it also allows the conveyance assembly  502  be leveled in both longitudinal and transverse directions (e.g., for tilt control). This also may facilitate alignment of two container transfer systems  500  such that containers can be transferred therebetween. 
     The container transfer system  500  of  FIG. 10  also includes one or more locking assemblies  506 . The locking assemblies  506  can be configured to lock a container in place once it has been loaded onto the container transfer system  500 . For example, the locking assemblies  506  can, when engaged, be configured to prevent a container from moving forward or backwards along the longitudinal direction of the conveyance mechanism  502 . An example locking assembly  506  is shown in  FIG. 12 , which is described in more detail below. 
     With continued reference to  FIG. 10 , the illustrated embodiment of the conveyance assembly  502  will now be described in more detail. As illustrated, the conveyance assembly comprises a frame  508  and rollers  510 . The frame  508  is configured to provide structural support for the container transfer system  500  as well as to support additional components of the conveyance assembly  502 . In the illustrated embodiment, the frame  508  comprises longitudinal members  518  and transverse members  520 . Other configurations for the frame  508  may also be possible. 
     The rollers  510  are mounted to and supported by the frame  508 . For example, in the illustrated embodiment, the rollers  510  are supported by bearings  512  which are mounted to the longitudinal members  518  of the frame  508 . The bearings  512  can be configured to allow the rollers  510  to rotate to allow movement or conveyance of containers along the longitudinal direction of the conveyance assembly  502 . 
     In the illustrated embodiment of  FIG. 10 , the rollers  510  comprise a set of drivable rollers  510   a  (or active rollers) and a set of passive rollers  510   b  (or idler rollers). As will be described in more detail below, the drivable rollers  510   a  can be actively driven or rotated to cause a container positioned thereon to be conveyed along the longitudinal direction of the conveyance assembly  502 . The passive rollers  510   b  are not actively driven. That is, the passive rollers  510 b are configured to rotate freely. Thus, as the active rollers  510   a  drive movement of a container along the conveyance assembly  502 , the passive rollers  510   b  allow the container to continue to move along the conveyance assembly  502 . 
     In the illustrated embodiment, the conveyance assembly  502  includes four drivable rollers  510   a , which are positioned on one end (e.g., the distal most end) of the conveyance assembly  502 . Other numbers and positions for the drivable rollers  510   a  are also possible. As shown in  FIG. 10 , in some embodiments, the drivable rollers  510   a  can be split (for example, in the middle) to allow for placement of a sprocket  514 . A chain or other similar mechanism (e.g., a belt) can be mounted on the sprockets  514  of the drivable rollers  510   a  and connected to a motor  516 . The motor  516  can drive rotation of the chain, causing corresponding rotation of the sprockets  514  and driving the rotation of the drivable rollers  510   a . The motor  516  can be supported by the frame  508 . In some embodiments, the motor  516  can be a hydraulic motor, connected to and driven by a hydraulic system of the vehicle to which the container transfer system  500  is mounted or by an independent power source. In other embodiments, other types of motors (e.g., electric or others) can be used. Further, while the illustrated embodiment includes drivable rollers  510   a  that are split in the middle to accommodate the sprockets  514 , other positions for the sprockets  514  are also possible. For example, the sprockets  514  could be positioned on ends of the drivable rollers  510   a.    
     As shown in  FIG. 10 , the lift assemblies  504  can comprise a lift actuator  522 , brackets  524 , as well as other features shown in the detailed view of  FIG. 11 . Before turning to  FIG. 11 , however, several features of the lift assemblies  504  will be described briefly with reference to  FIG. 10 . For example, the lift assemblies  504  can include brackets  524  that include first mounting plates  526  and lift actuator support plates  528 . The first mounting plates  526  can be configured to attach the lift assemblies  504  to, for example, the chassis of a vehicle as will be described in more detail in  FIGS. 13A-13C . The brackets  524  can extend between the first mounting plates  526  and the lift actuator support plates  528 . The lift actuators  522  can be mounted on the lift actuator support plates  528 . For example, a bottom portion of the lift actuators  522  can be attached to the lift actuator support plates  528 . A top portion of the lift actuators  522  can be attached to the frame  508  of the conveyance assembly  502 , such that with the lift actuators  522  are actuated, the lift actuators  522  can raise or lower the conveyance assembly  502 . 
       FIG. 11  is a perspective view of an embodiment of one of the lift assemblies  504  of the container transfer system  500  of  FIG. 10  and illustrates additional details thereof. As shown in  FIG. 11 , the illustrated embodiment of the lift assembly  504  can include the lift actuator  522  and the bracket  524  (which as described above can include the first mounting plate  526  and the lift actuator support plate  528 ). The lift actuator  522  can be a linear actuator. In some embodiments, the lift actuator  522  is hydraulic. For example, the lift actuator  522  may comprise a hydraulic ram. When both the motor  516  of the conveyance assembly  520  and the lift actuator  522  of the lift assemblies  504  are hydraulic, the container transfer system  500  can advantageously be driven by a hydraulic system of the vehicle to which the container transfer system  500  is mounted or an independent power source. In other embodiments, other types of linear actuators can be used in place of a hydraulic ram. 
     As mentioned above, the lift actuator  522  is supported by the lift actuator support plate  528  of the bracket  524  which can be mounted to the chassis of a vehicle (see, for example,  FIG. 13C ). The lift actuator  522  can also be attached to the frame  508  of the conveyance assembly  502 . For example, as shown in  FIG. 11 , a top portion of the lift actuator  522  is connected to a frame attachment structure  530  that is configured to attach to the frame  508  of the conveyance assembly  502 . In the illustrated embodiment, for example, the frame attachment structure  530  comprises bracket  532 , and a second mounting plate  534 . The bracket  532  can be configured to attach to the lift actuator  522  and the second mounting plate  534  can be configured to attach to the frame  508  of the conveyance assembly  502 . In the illustrated embodiment, the bracket  532  is configured to attach to the lift actuator  522  using a pin  540 . The pin  540  can be removed to detach the lift actuator  522  from the conveyance assembly  502  which may facilitate replacement of the lift actuator  522  in the event that a repair is needed. 
       FIG. 11  also illustrates the that bracket  532  of the frame attachment structure  530  can be attached to a rail  536 . The rail  536  can be a linear rail. The rail  536  can be engaged with guides  538  such that the motion between the rail  536  and the guides  538  is constrained such that motion is only permitted along the longitudinal axis of the rail  536 . The longitudinal axis of the rail  536  can be aligned with (for example, parallel to) the longitudinal axis or axis of actuation of the lift actuator  522 . The guides  538  can be attached to the bracket  524 , which as described previously, can be mounted to the chassis of the vehicle via the first mounting plate  526 . 
     Motion of the lift assembly  504  will now be described with reference to the embodiment of  FIG. 11 . The bracket  524  is fixedly attached to the chassis of a vehicle (see  FIG. 13C ) via the first mounting plate  526 . The lift actuator  522  is fixedly attached to the bracket  524  via the lift actuator support plate  528 . The lift actuator  522  is also attached to the frame  508  of the conveyance assembly  502  via the frame attachment structure  530  which is connected to the lift actuator  522  through bracket  524 . As the actuator  522  is actuated, the lift actuator  522  can extend, causing the lift actuator  522  to lift the frame attachment structure  530  and correspondingly, to lift the conveyance assembly  502 . At the same time, the rail  536  slides along the guides  538 , which serve to ensure that motion is constrained along the axis of actuation of the lift actuator  522 . In this way, the lift assemblies  504  can raise and lower the conveyance assembly  502  relative to the chassis of the vehicle. 
     Further, each of the lift assemblies  504  can be independently operable and adjustable such that the longitudinal and transverse tilt of the conveyance assembly  502  can adjusted and leveled. 
       FIG. 12  is a perspective view of the locking assembly  506  of the container transfer system  500  of  FIG. 10 . In the illustrated embodiment, the locking assembly  506  comprises a bracket  542  including an attachment plate  544 . In some embodiments, the attachment plate  544  is configured to attach the locking assembly  506  to the chassis of the vehicle (as best seen in  FIG. 14 ). The bracket  542  of the locking assembly  506  also supports an actuator  546  which includes a locking pawl  548 . The actuator  546  can be configured to raise and lower the locking pawl  548 . In the lowered position (for example, as shown in  FIG. 12 ), the locking pawl  548  can engage with a lug  550 . The lug  550  can be attached to a container, such as the container  700  of  FIG. 15 . When the locking pawl  548  engages the lug  550 , motion of the container  700  can be constrained, locking the container in place. When the locking pawl  548  is in the raised position, it does not engage the lug  550 , allowing for motion of the container. For example, when the locking pawl  548  is not engaged with the lug  550 , the conveyance assembly  502  can move the container forward and/or backwards along the longitudinal axis of the conveyance assembly  502 . 
     In some embodiments, the actuator  546  can be a hydraulic actuator, such as a hydraulic ram. The hydraulic actuator  546  can be connected to a hydraulic system of the vehicle (or an independent power source) which can be controlled to actuate the actuator  546 . Other types of actuators, for example, electric linear actuators can also be used. In some embodiments, locking assembly  506  can be replaced with a mechanical locking assembly, such as that described above with reference to  FIGS. 7A-7D . 
       FIG. 13A  illustrates a vehicle  600  having the container transfer system  500  of  FIG. 10  installed thereon, according to an embodiment. In the illustrated embodiment, the vehicle  600  comprises a truck, such as a transport truck, although other types of vehicles can also be used. As shown, in the illustrated embodiment, the container transfer system  500  is positioned over the chassis of the vehicle  600  such that the conveyance assembly  502  is generally positioned between the wheels of the vehicle. Because it is difficult to see how the container transfer system  500  is attached to the vehicle  600  in  FIG. 13A ,  FIGS. 13B and 13C  illustrate the vehicle as a simplified model to better illustrate the interactions between the container transfer system  500  and the vehicle  600 . 
       FIG. 13B  is a top perspective view illustrating the container transfer system  500  of  FIG. 10  installed on a model of the vehicle  600 . As better seen in  FIG. 13B , the vehicle  600  comprises a chassis including chassis rails  602 . The container transport system  500  is positioned on the vehicle  600  such that it can be supported by the chassis rails  602 . The lift assemblies  504  can be attached to the chassis rails  602  as better seen in  FIG. 13C . 
       FIG. 13C  is a bottom, detail, perspective view illustrating the container transfer system  500  of  FIG. 10  installed on the model of the vehicle  600 . In this view, one can see how the lift assemblies  504  can be attached to the chassis rails  602 , according to the illustrated embodiment. As shown, the first mounting plates  526  of the brackets  524  of the lift assemblies  504  can be attached to inner surfaces of the chassis rails  602 . Further, the frame  508  of the conveyance assembly  502  can rest on or substantially on the chassis rails  602  when the lift actuators  522  are in the lowered position. When actuated, the lift actuators  522  can raise the conveyance assembly  502  off the chassis rails  602  to a position above the chassis rails  602 . 
       FIG. 14  is a detail view illustrating a portion of the container transfer system  500  of  FIG. 10 , including an embodiment of a locking assembly  506  and hydraulic connections  552 . In this view, the connection between the attachment plate  544  of the bracket  542  of the locking assembly  506  and the chassis rail  602  of the chassis of the vehicle  600  can be seen. As shown, in the illustrated embodiment, the locking assembly  506  is attached to the outer surface of the chassis rail  602 . Other placements for the locking assembly  506  are also possible. 
       FIG. 14  also illustrates how, in the illustrated embodiment, the locking assembly  506  can engage with a container  700 . As better seen in  FIG. 15 , the container  700  can include container rails  702  on a bottom surface thereof. When the container  700  is positioned on the container transport system  500 , the container rails  702  are positioned in proximity the locking assembly  506 . The container rails  702  can include the lug  550  (not visible in  FIG. 14 ), which can engage with the locking pawl  548  to secure the container  700  relative to the container transport system  500  and chassis of the vehicle  600 . 
       FIG. 14  also illustrates that the container transfer system  500  can include hydraulic connections  552  for connecting to corresponding hydraulic connections of another container transfer system  500 . In the illustrated embodiment, these hydraulic connections  552  are positioned on the bumper  606  of the vehicle  600 , although other locations for the hydraulic connections  552  are also possible. As described previously, the container transfer system  500  of the vehicle  600  can be powered or actuated using a hydraulic system on the vehicle  600 . The hydraulic system of the vehicle can drive the conveyance assembly  502 , lift assemblies  504 , and locking assemblies  506 . In some embodiments, it may be desirable to move a container  700  from the vehicle  600  to another container transfer system  500  on a rack. Such a container transfer system  500  on the rack may not include a hydraulic system to power the hydraulic components thereof. Accordingly, the hydraulic system of the vehicle  600  can be connected to the hydraulic components of the container transfer system  500  of the rack using the hydraulic connections  552  as shown in  FIG. 14 . This can allow the hydraulic system of the vehicle to also power the hydraulic components of the container transfer system  500  of the rack. 
       FIG. 15  is a bottom perspective view of an embodiment of a container  700  configured for use with the container transfer system  500  of  FIG. 10 . As described previously, container rails  702  can be positioned on a bottom surface of the container  700 . When the container  700  is positioned on the container transfer system  500 , the container transfer system  500  may be received between the container rails  702 . The container rails  702  may serve to facilitate alignment between the container  700  and the container transfer system  500 . The container  700  may also include container support surfaces  704  on a bottom surface thereof. In some embodiments, the container support surfaces  704  can be configured to provide a flat surface for engaging with the rollers  510  of the container  700 . That is, the container support surfaces  704  of the container  700  may ride on the rollers  510  of the container transfer system  500  during conveyance of the container  700  by the conveyance assembly  502 . 
     As shown in  FIG. 15 , the container  700  may generally comprise an enclosure for receiving and securing cargo. The container  700  may include a door  706  as shown. Further, in  FIG. 15 , one of the side walls of the container is removed to show that the container  700  may also include a second door  706  on the opposite side of the container. This may allow the contents of the container  700  to be access from either side, which may be particularly advantageous as the accessible end of the container  700  may change as the container  700  is transferred between two vehicles. 
       FIG. 16  illustrates an embodiment of a controller  800  configured for use with the container transfer system of  FIG. 10 . The controller  800  may be configured to control operation of the conveyance assembly  502 , lift assemblies  504 , and/or locking assemblies  506 . In some embodiments, the controller  800  is configured to provide simplified or “one-touch” transfer control, allowing an operator simply transfer a container  700  between two transfer system  500  without having to specifically level and align the two container transfer systems  500 . For example, upon selecting the option to transfer a container  700 , one container transfer system  500  may automatically adjust the lift assemblies  504  to level with a second container transfer system  500 . The system may then disengage the locking assemblies  506  and activate the conveyance assembly  502  to move the container  700  from the first container transfer system  500  to the second container transfer system  500 . In other embodiments, the controller  800  may be used to control each of these functions individually. 
       FIGS. 17A and 17B  are views illustrating the container transfer system  500  of  FIG. 10  during use, transferring a container  700  between the container transfer system  500  installed on a vehicle and a container transfer system  500  installed on a rack. As shown in  FIG. 17A , the vehicle  700  may be backed to the rack such that the two container transfer systems  500  are longitudinally aligned. The hydraulic system of the vehicle  600  may be connected to the hydraulic components of the container transfer system  500  of the rack using the hydraulic connections  552 . As shown in  FIG. 17B , the lift assemblies  504  of the container transfer system  500  of the vehicle  600  can be actuated to level the conveyance assembly  502  of the container transfer system  500  of the vehicle  600  with the container transfer system  500  of the rack. The locking assemblies  506  can be released and the container  700  can be transferred to the rack using the conveyance assemblies  502 . 
     The foregoing description details certain embodiments of the systems, devices, and methods disclosed herein. It will be appreciated, however, that no matter how detailed the foregoing appears in text, the systems, devices, and methods can be practiced in many ways. As is also stated above, it should be noted that the use of particular terminology when describing certain features or aspects of the invention should not be taken to imply that the terminology is being re-defined herein to be restricted to including any specific characteristics of the features or aspects of the technology with which that terminology is associated. 
     It will be appreciated by those skilled in the art that various modifications and changes can be made without departing from the scope of the described technology. Such modifications and changes are intended to fall within the scope of the embodiments. It will also be appreciated by those of skill in the art that parts included in one embodiment are interchangeable with other embodiments; one or more parts from a depicted embodiment can be included with other depicted embodiments in any combination. For example, any of the various components described herein and/or depicted in the figures can be combined, interchanged or excluded from other embodiments. 
     The above description discloses several methods and materials of the present invention. This invention is susceptible to modifications in the methods and materials, as well as alterations in the fabrication methods and equipment. Such modifications will become apparent to those skilled in the art from a consideration of this disclosure or practice of the invention disclosed herein. Consequently, it is not intended that this invention be limited to the specific embodiments disclosed herein, but that it cover all modifications and alternatives coming within the true scope and spirit of the invention as embodied in the attached claims. Applicant reserves the right to submit claims directed to combinations and sub-combinations of the disclosed inventions that are believed to be novel and non-obvious. Inventions embodied in other combinations and sub-combinations of features, functions, elements and/or properties can be claimed through amendment of those claims or presentation of new claims in the present application or in a related application. Such amended or new claims, whether they are directed to the same invention or a different invention and whether they are different, broader, narrower or equal in scope to the original claims, are to be considered within the subject matter of the inventions described herein.