Patent Publication Number: US-11660957-B2

Title: Vehicle drive system for a self-propelled trailer

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation-in-part of Ser. No. 16/599,820 filed on Oct. 11, 2019, which claims the benefit of the filing date of Provisional Patent Application No. 62/744,901, filed on Oct. 12, 2018. 
    
    
     FIELD OF THE INVENTION 
     The invention relates to a drive system and, more particularly, to a drive system for a self-propelled trailer. 
     BACKGROUND 
     Workers often find that providing materials for replacement of a building roof is very time consuming, considering the task involves using different mechanical units or manual labor to lift building materials from a truck and position them on a roof. Furthermore, stripping old material from the building roof in order to put on a new roof is also time consuming and a dirty job. Generally, old material is thrown from the roof to the ground around the building and then workers manually pick up debris to deposit it into a disposal container. Even if the material can be thrown directly into a container there remain the problems of getting the disposal container in proximity to the roof and removal from the work site. The most common solution to the disposal problem is to move a dump truck adjacent to the building and to attempt to throw the material directly from the roof into the truck bin. Furthermore, the problem is not limited to roofing material. Any building remodeling generates significant construction trash, and the most convenient method of removing it from the building is to throw it out a window. 
     As a result, it is not always possible to move a large truck into a location adjacent to a building. Fences, lawns, and shrubs can be damaged by any size truck, especially a large transport truck. 
     There is a need for a vehicle having a drive system that facilitates independent movement around the typical landscaped yard surrounding a building and position a storage bin into an extended position near workers and that is study enough to handle large loads. 
     SUMMARY 
     In view of the foregoing, a vehicle drive system is provided and generally includes a hub assembly, a drive assembly and a clutch assembly. The hub assembly having wheel hub upon which a wheel assembly is secured. The drive assembly is configured to selectively transmit a motive force to cause the hub to turn. The drive assembly includes a motor with a rotatable motor output shaft, a transmission assembly connected to the motor and receiving in the rotatable motor output shaft into an input opening therein, and a driveshaft connected to an output from the transmission assembly. The clutch assembly connected to the hub assembly and engagebale to the driveshaft. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The invention is explained in greater detail below with reference to embodiments and the appended drawings of which: 
         FIG.  1    is a front perspective view of a self-propelled tandem axle trailer according to the invention, 
         FIG.  2    is rear perspective view of the self-propelled tandem axle trailer of  FIG.  1   ; 
         FIG.  3    is perspective view of a self-propelled tandem axle trailer according to the invention, showing extension of a front axle to a drivable position; 
         FIG.  4    is another perspective view of the trailer of  FIG.  3   , showing extension and inclination of a storage bin thereof; 
         FIG.  5    is a front perspective view of the trailer of  FIG.  3   , showing further extension and inclination of the storage bin; 
         FIG.  6    is a rear perspective view of the trailer of  FIG.  5   ; 
         FIG.  7    is a close up view of a front wheel of the self-propelled tandem axle trailer according to the invention; 
         FIG.  8    is a bottom perspective view of the self-propelled tandem axle trailer according to the invention; 
         FIG.  9 A  is a bottom perspective view of another embodiment of the self-propelled tandem axle trailer according to the invention; 
         FIG.  9 B  is a bottom view of the self-propelled tandem axle trailer of  FIG.  9 A ; 
         FIG.  10    is a perspective front partial view of an alternative embodiment of a front wheel assembly of the self-propelled tandem axle trailer according to the invention; 
         FIG.  11 A  is a close up, rear view of a suspension, drive and hub assembly of the self-propelled tandem axle trailer according to the invention; 
         FIG.  11 B  is cross-section view of the suspension components of  FIG.  11 A ; 
         FIG.  12 A  is a partially exploded view of components of the drive assembly and hub assembly, including flanged driveshaft, clutch assembly, locking mechanism, and hub; 
         FIG.  12 B  is a partially exploded view of components of the drive assembly and hub assembly, including a bell housing, hub, and torsion arm; 
         FIG.  13 A  is a top view of an alternative embodiment of a wheel assembly of the self-propelled tandem axle trailer according to the invention; 
         FIG.  13 B  is a bottom view of an alternative embodiment of a wheel assembly of the self-propelled tandem axle trailer according to the invention; 
         FIG.  14    is a partially exploded view of components of the wheel hub assembly depicting the motor, transmission, torsion arm, brake assembly and hub; 
         FIG.  15    is a cross-section view of components of the wheel hub assembly; 
         FIG.  16 A  is close up view of the clutch assembly, depicting the driving and driven clutch elements; 
         FIG.  16 B  is a cross-section view through the engaged clutch elements, depicting the teeth of each of the driving clutch element against the teeth of the driven clutch element; 
         FIG.  17    depicts a close up, cross-section view of the locking mechanism and driveshaft 
         FIG.  18    depicts an exploded view of the locking mechanism elements and bell housing. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENT(S) 
     With respect to  FIGS.  1 - 6   , a trailer  1  according to the invention is shown and ready for towing by a power vehicle, such as a truck with a tow hitch. The trailer  1  generally includes the following major components: a frame  10 , a control system  60 , a storage bin  80 , and an extension device  100 , and a tandem wheel assembly  300 . 
     Now with reference to  FIGS.  1 - 4   , the frame  10  will be discussed. In the shown embodiment, the frame  10  includes a plurality of support beams  12 , a plurality of connecting beams  14 , a front support  16 , a rear support  18 , a trailer connection section  22 . 
     As shown in  FIGS.  2  and  3   , each support beam  12  is an elongated metal support extending along a length of the frame  10 , from a trailing end to a leading end thereof. 
     In the embodiment shown, each support beam  12  is I-shaped and includes a support rail  13  positioned on a lower end and running along a length thereof. 
     Each connection beam  14  runs substantially perpendicular and connecting to the plurality of support beams  12 . The front support  16  is a plate like member connecting the support beams  12  at a front end thereof, while the rear support is another plat like member connecting the support beams  12  at an opposite end thereof. As assembled, the support beams  12 , connection beams  14 , front support  16 , and rear support form a undercarriage chassis  20   
     As shown, in an exemplary embodiment of the invention, the trailer connection section  22  is a trailer hitch  22  positioned and connected to a leading end of the frame  10 , and, in particular, the front support  16 . The trailer hitch  22  includes a connector for connecting with a truck (i.e., ball mount; not shown). 
     According to the invention, the trailer  1  includes a tandem wheel assembly  300 . In an exemplary embodiment of the invention, the tandem wheel assembly  300  is positioned under the undercarriage chassis  20  and generally includes a rear wheel assembly  310 , a front wheel assembly  340 , and an extension assembly  380 . 
     As shown in  FIGS.  8   , the rear wheel assembly  310  includes a pair of rear wheels  312 , a rear wheel frame  314 , a rear steering assembly  320 , and a rear drive assembly  330 . 
     In the embodiment shown, the rear wheel frame  314  includes a rear guide member  315  member having a body  316  and a pair of low friction guides  318  positioned at opposite side ends thereof. Each low friction guide  318  is a u-shaped member secured to the rear wheel frame  314  and is sized and shaped to correspond to receive the support rail  13 . The low friction guide  318  includes low frictions pads  319  are bearing pads known in the art to provide a low friction coefficient between the rear wheel frame  314  and the support rail  13 . In the shown embodiment, the low friction pads  319  line an inside surface of the low friction guide  318 . 
     In the embodiment shown, the rear wheel assembly  310  includes steering capability using a rear steering assembly  320  according to the invention. However, one skilled in the art should appreciate that this rear wheels  312  may be non-steerable. As shown, the rear steering assembly includes a steering bracket  322 , a pair of steering arms  324  connected to the steering bracket  322  and the pair of rear wheels  312 . 
     As shown in  FIG.  8   , in an exemplary embodiment of the invention, the rear wheel assembly  310  includes a rear drive assembly  330  according to the invention. In an exemplary embodiment of the invention, the rear drive assembly  330  includes a hydraulic motor assembly  332  and a rotor assembly  334 , and an engagement assembly  370  for each rear wheel  312 . 
     In an embodiment of the invention, the hydraulic motor assembly  332  generally includes a motor  332   a , a motor drive mechanism  332   b , and a motor housing  332   c . The motor  332   a  is connected to the control system  60  using hydraulic lines (not shown). The motor  332   a  is attached to the outside of the motor housing  332   c . The motor drive mechanism  332   b  positioned in a motor housing  332   c  is engageable with the hydraulic motor  332   a  and moveable by the engagement assembly  370 . 
     In an embodiment of the invention, the rotor assembly  334  includes a wheel hub  334   a  and a drive shaft  334   b  with a rotor drive mechanism (not shown) engageable with the motor drive mechanism  332   b  by the engagement assembly  370 . The drive shaft  334   b  connected to the wheel hub  334   a.    
     Many of the power system components are not shown for sake of complexity in the drawings, although a discussion is provided for purposes of enabling one skilled in the art to understand how the drive system is assembled and performed. One skilled in art should appreciate that other designs are possible. For instance, the rear drive assembly  330  may include other methods to move the rear wheels  312 , including chains, belts, or a drive shaft and a transmission connected to a combustion or electric engine, so that trailer  1  can be moved around a work site under its own power. 
     As shown in  FIGS.  7  and  8   , the front wheel assembly  340  includes a pair of front wheels  342 , a front wheel frame  344 , a front steering  350  assembly, and a front drive assembly  360 . 
     In the embodiment shown, the front wheel frame  344  is u-shaped member having a body  346  and a pair of low friction guides  348  positioned at opposite side ends thereof. Each low friction guide  348  is a u-shaped member secured to the front wheel frame  344  and is sized and shaped to correspond to receive the support rail  13 . The low friction guide  348  includes low frictions pads  349  that are bearing pads known in the art to provide a low friction coefficient between the front wheel frame  344  and the support rail  13 . In the shown embodiment, the low friction pads  349  line an inside surface of the low friction guide  318 . 
     In the embodiment shown, the front wheel assembly  340  includes steering capability using a front steering assembly  350  according to the invention. However, one skilled in the art should appreciate that this front wheels  342  may be non-steerable. As shown, the front steering assembly includes a steering bracket  352 , a pair of steering arms  354  connected to the steering bracket  352  and the pair of front wheels  342 . 
     As shown in  FIG.  8   , in an exemplary embodiment of the invention, the front wheel assembly  340  includes a front drive assembly  360  according to the invention. However, one skilled in the art should appreciate that these front wheels  342  may be non-driveable, without a drive system. 
     In an exemplary embodiment of the invention, the front drive assembly  360  generally includes a hydraulic motor assembly  362  and a rotor assembly  364 , and an engagement assembly  370  for each front wheel  342 . 
     In an embodiment of the invention, the motor assembly  362  generally includes a motor  362   a , a motor drive mechanism  362   b , and a motor housing  362   c . The motor  362   a  is connected to the control system  60  using hydraulic lines (not shown). The motor  362   a  is attached to the outside of the motor housing  362   c . The motor drive mechanism  362   b  positioned in a motor housing  362   c  is engageable with the hydraulic motor  362   a  and moveable by the engagement assembly  370 . 
     In an embodiment of the invention, the rotor assembly  364  includes a wheel hub  364   a  and a drive shaft  364   b  with a rotor drive mechanism (not shown) engageable with the motor drive mechanism  362   b  by the engagement assembly  370 . The drive shaft  364   b  connected to the wheel hub  364   a.    
     Many of the power system components are not shown for sake of complexity in the drawings, although a discussion is provided for purposes of enabling one skilled in the art to understand how the drive system is assembled and performed. One skilled in art should appreciate that other designs are possible. For instance, the front drive assembly  360  may include other methods to move the front wheels  342 , including chains, belts, or a drive shaft and a transmission connected to a combustion or electric engine, so that trailer  1  can be moved around a work site under its own power. 
     In the shown embodiment, the rear wheel assembly  310  and the front wheel assembly  340  includes an engagement assembly  370 . As shown, each engagement assembly  370  generally includes a main shaft  372 , a first lever assembly  374 , and a second lever assembly  376 . The main shaft  372  is an elongated cylindrical member and connected to the first lever assembly  374  and the second lever assembly  376  at opposite ends thereof. The first lever assembly  374  and the second lever assembly  376  are connected to opposite rear wheels  312  or front wheel  342 , and engage and disengage the motor drive mechanism  332   b ,  362   b , from the rotor drive mechanism (not shown) to rotate the wheel hub  334   a ,  364   a.    
     In an exemplary embodiment of the invention, the extension assembly  380  generally includes a rear end connector  382 , a moveable axle connector  384 , and a moving component  386 . The rear end connector  382  is connected to the rear wheel assembly  310 , while the moveable axle connector  384  is connected to the front wheel assembly  340 . The moving component  386  is a hydraulic actuator positioned and secure to the undercarriage chassis  20  in the shown embodiment. The moving component  386  is capable of extension and contraction. When connected to the front wheel assembly  340 , the front wheels  342  can be positioned between the trailing position A (see  FIGS.  1  and  2   ) and the self-propelled position B (see  FIGS.  5 - 8   ). 
       FIGS.  9 A and  9 B  depict an alternate exemplary embodiment of the invention. The trailer  1 ′ of  FIGS.  9 A and  9 B  generally includes the following major components: a frame  10 , a control system  60 , a storage bin  80 , and an extension device  100 , as discussed previously, and an alternate tandem wheel assembly  300 ′. Though not depicted in  FIG.  9 A  or B, it is contemplated that the trailer  1 ′ would beneficially include a source of power, similar to the example power source depicted in  FIGS.  1 - 6 , and  8   , and may, in exemplary embodiments, be one or more of batteries and/or combustion engines. The power source may power or otherwise enable the powered movement and actions of the various features of the trailer described herein, including power for self-propelled transport, steering, braking, extension and/or retraction of the tandem wheel assembly, and movement of the storage bin, relative to the frame. 
     As shown in  FIG.  9 A , the alternate tandem wheel assembly  300 ′ is positioned under the frame  10 , and generally includes a rear wheel assembly  310 ′, a front wheel assembly  340 ′, and an extension assembly  380 ′. As described previously, the tandem wheel assembly provides for a front wheel assembly that is movably secured to the support rails  13 , such that the front wheel assembly can selectively be positioned in the trailing position A (seen with reference to  FIGS.  1  and  2   ), and the self-propelled position B, depicted in  FIG.  9 A , or any intervening position between them. 
     In any of the trailer embodiments, the front wheel assembly  340 ′ may optionally be secured in either, or both, of the position A or B, by an actuatable locking mechanism, such as a manually or mechanically engaged locking mechanism, for example, locking pins, and the like, that secure the wheel assembly and frame elements so as to prevent unwanted movement relative to each other. Alternatively, the front wheel assembly may be maintained in the desired position through the actuation mechanism, for example, maintaining hydraulic pressure in a hydraulic actuator to secure the front wheel assembly in the desired position, such as when travelling, trailering, or parked and at rest. 
       FIG.  9 A  depicts the rear wheel assembly  310 ′ having a pair of rear wheels  312 , mounted to the hubs of the wheel assembly. Further aspects of a wheel assembly are discussed below. In an embodiment, the rear wheel assembly  310 ′ may be fixedly secured in a position relative to the frame; for example, the rear wheel assembly may be immovably secured to the support rails  13 . The rear wheel assembly may be affixed or secured using techniques known to those skilled in the art. For example, the rear wheel assembly may be mounted to the frame  10  or support rails  13  through the use of one or more fasteners, including for example, mounting posts, bolts and/or nuts, to secure the wheel assembly to the support rails or other frame portion; or alternatively, a portion of the rear wheel assembly may be welded to the support rails  13  or other portion of the frame  10 . 
     Also depicted in  FIG.  9 A  is a front wheel assembly  340 ′, having a pair of wheels  342 , mounted on hubs of the front wheel assembly. In an embodiment, the front wheel assembly is movably mounted upon the frame  10  of the trailer; for example, by the use one or more u-shaped members slidably mounted on the front wheel frame, where the u-shaped member is sized and shaped to receive at least a portion of the support rail  13  of the frame, as depicted in  FIGS.  9  and  10   . The u-shaped member may be provided with low friction guide elements  348 , including low friction pads  349  that serve as bearing pads known in the art to provide a low friction coefficient between the front wheel frame  344 ′ and the support rail  13 . In this manner, the front wheel assembly is movably secured to the frame in a manner that allows the wheel assembly to slide upon the frame support rails, and be alternately positioned in a trailer position A (depicted in  FIG.  1   ), and the self-propelled position B as depicted in  FIG.  9   , or any point in between. As can be seen in the exemplary embodiment of  FIG.  10   , the front wheel assembly  340 ′ is provided with u-shaped members slidably mounted on separate, parallel support rails  13  on the frame  10 , and are positioned such that the u-shaped members prevent twisting movement of the front wheel assembly, relative to the frame, as the spacing provided between the inside dimensions of the opposing u-shaped members is substantially the same, or nearly the same, as the maximum width dimension of the support rails  13 . 
     In an exemplary embodiment of the invention, as depicted in  FIG.  9 A , the extension assembly  380  generally includes a fixed end connector  382 ′ that may be affixed to the frame at or near the rear support plate  18 , though it is contemplated that alternatively, the connector  382 ′ may be secured to the rear wheel assembly, which is itself fixed relative to the frame. The extension assembly  380  further provides a moveable axle connector  384 ′, and a moving component  386 ′. The fixed end connector  382 ′, as depicted in  FIG.  9 A  may be directed through a bracket opening on the rear wheel assembly  310 ′, and affixed to the rear support plate  18  of the frame  10 . The fixed end connector  382 ′ may alternatively be secured to the frame  10  at any point rearward of the front axle when in trailering position A of  FIG.  1   , so as the extension assembly is extended, the forward axle assembly is urged away from the fixation point on the frame. Though not shown, it is contemplated that the extension assembly may be configured in the reverse orientation (not depicted), where an extension assembly is alternatively secured to the frame at a mounting point forward of the front axle when in position B of  FIG.  3   , where extension of the extension assembly urges the front axle rearward into position A for trailering, and retraction of the extension assembly urges the front axle to position B for self-propelled movement of the trailer. 
     In an embodiment, as depicted in  FIG.  9 A , the fixed end connector  382 ′ near the rear of the trailer may be the end portion of a linear actuator of the extension assembly  380 ′, which may fit into a bracket and secured in place against the rear support plate  18  of the frame  10 . The extension assembly  380 ′ further provides for a moveable axle connector  384 ′ on the front wheel assembly  340 ′. In an embodiment, the front wheel assembly  340 ′ may have a bracket that secures to a portion of the linear actuator of the extension assembly  380 ′ and serves as the moveable axle connector  384 ′, as depicted in  FIG.  9 A . The moving component  386 ′ may be any suitable form of linear actuator, for example, a hydraulic actuator positioned and secured to the undercarriage chassis  20 , or frame  10 ′. The moving component  386 ′ is capable of extension and contraction. In an embodiment, the moving component  386 ′ is a double acting hydraulic cylinder. In an embodiment, the front wheel assembly  340 ′ is secured to a portion of the cylinder barrel of the hydraulic cylinder, and the piston rod is secured to the rear of the frame. It is contemplated that where the moving component is a hydraulic cylinder, the positioning of the cylinder components may be mounted in reverse, with the piston rod affixed to the front wheel assembly, and the cylinder barrel secured to frame  10  closer to the rear of the trailer  1 ′, or alternatively, directly connected to the rear wheel assembly  310 ′. It is contemplated, that in any mounting configuration where the linear actuator is connected to the front wheel assembly  340 ′, the front wheel assembly  340 ′ can selectively be positioned between the trailing position A (see  FIGS.  1  and  2   ) and the self-propelled position B (see  FIGS.  9 A  and B), by the action of the linear actuator. 
     Details of the front wheel assembly  340 ′ and rear wheel assembly  310 ′ will now be discussed with reference to  FIGS.  10  and  13 A  and B. For simplicity, the front wheel assembly  340 ′ will be described, though applicable to the features of the rear wheel assembly  310 ′ as well. An isolated front wheel assembly  340 ′ is depicted in  FIG.  10    in front perspective view.  FIG.  13 A  presents a top view of the isolated wheel assembly, with the u-shaped brackets removed for clarity.  FIG.  13 B  presents a bottom view of the isolated wheel assembly. It is anticipated that the depicted wheel assembly in  FIGS.  10  and  13    may be deployed as one or both of the front wheel assembly or rear wheel assembly. 
     For simplicity,  FIG.  10    will be described in the context of being a front wheel assembly  340 ′, though applicable to either front or rear wheel assembly. With reference to  FIG.  10   , the front wheel assembly  340 ′ as shown may be provided with a wheel assembly frame  344 ′, a steering assembly  350 ′, and a pair of hub assemblies  402 . 
     Each hub assembly  402  includes a drive assembly  404 , a suspension assembly  406 , brake assembly  408 , and hub  410  upon which a wheel is to be mounted. The front wheel assembly  340 ′ of  FIG.  10    may provide steering capability, motive and braking force to the trailer  1 ′, as well as serving as a suspension, to isolate or minimize the effects of irregular surface features from the frame while the trailer is in motion. The front wheel assembly  340 ′ of  FIGS.  10 ,  13 A, and  13 B  however features marked differences from those wheel assemblies described previously; for example, each wheel assembly is provided with a single steering actuator, rather than two steering arms as previously described, resulting in a simpler, more cost effective design, where each wheel of the wheel assembly is maintained at a consistent angle, relative to the other wheel of the wheel assembly through the use of a mechanical linkage, such as a tie rod, extended between each hub assembly to ensure each hub assembly&#39;s steering angle consistent with the other. 
     As can be seen with reference to  FIGS.  10  and  13 A  and B, exemplary front wheel assembly  340 ′ in the depicted embodiment may include a pair of hubs configured to accept the mounting of wheels thereupon, with the wheels removed for clarity, a drive assembly, a brake assembly  408 , a wheel assembly frame, a steering assembly, and suspension assembly. The wheel assembly of  FIGS.  10  and  13 A ,B may be deployed as either, or both, of the front and rear wheel assemblies. It is contemplated that one of the wheel assembly embodiment depicted in  FIG.  10    may be combined with a different embodiment of a wheel assembly, for example, the wheel assembly described previously with reference to  FIG.  8   . 
     In an embodiment, the wheel assembly frame  344  may provide support for mounting the other wheel assembly components from, and may be, for example, a truss or beam extended between the aforementioned u-shaped guide elements  348  configured to slide upon the frame rails  13 . 
     The wheel assembly embodiment  340 ′, as can be seen with reference to  FIGS.  13 A and  13 B  provides a steering capability through the action of a steering assembly  350 ′ according to the invention. As depicted, the steering assembly  350 ′ includes a steering bracket  322 ′ which may be affixed to, or otherwise be made as part of the wheel assembly frame, a steering arm  324 ′ (depicted in  FIG.  13   ) extended between the steering bracket  322 ′ and a steering arm mount  412  on a primary hub assembly. The steering assembly further comprises a tie rod  414  extended between steering knuckles  416  on each of the hub assemblies, which may be secured via a balljoint to allow for suspension movement. 
     As was noted previously, either or both of the front and rear wheel assemblies may independently provide steering capabilities to the trailer  1 ′. It is contemplated that the trailer  1 ′ of  FIG.  9 A  may selectively employ rear wheel steering, front wheel steering, or 4-wheel steering. It is contemplated that in order to minimize the turning radius, the extension assembly may be adjusted to be less than fully extended (so that the front wheel assembly is at a point between position A and position B, in order to shorten the wheelbase by moving the front wheel assembly in a direction towards the middle of the trailer, and thereby reduce the turning radius of the trailer, especially when employing round steer mode of four wheel steering. In this circumstance, the center of gravity for the trailer should remain within the dimensions defined by the axles, so as to avoid disrupting the balance of the trailer. 
     Each hub assembly for each of the wheel assemblies for the trailer  1 ′ may have a brake assembly  408  including a brake caliper and brake rotor, as can be seen with reference to  FIG.  10   , by which the rotation of the wheels on the wheel assembly may be selectively slowed, or stopped from rotation. The brake assembly  408  may be actuated hydraulically, electrically, pneumatically, or mechanically. It is contemplated that any of the brake assemblies may be actuated independently, so as to slow or prevent the rotation of any single wheel, or alternatively, the brake assemblies may be actuated in pairs (fronts or rears) together, or further, the brake assemblies may be actuated all together, so as to provide four wheel braking, or prevent rotation of all four wheels simultaneously. It is contemplated that one or more of the brake assemblies may be actuated to secure the trailer  1 ′ in a desired position, acting as a parking brake. In an alternative embodiment, it is contemplated that alternative braking solutions are possible, using, for example, drum brakes as are well understood, or alternatively, using a hydraulic drive system (discussed below), which may provide braking force for the trailer, whether as a supplement to the disk brake system previously described, or as a replacement, such that the hydraulic motor may function as the brake system for the trailer, obviating the need for a disk and caliper brake system, where the hydraulic motor system is employed to provide fluid resistance to the rotation of the wheel and hub, thereby providing braking or locking of the wheel and hub from rotation. 
     Each of the hub assemblies may have a suspension assembly, such as a torsion suspension depicted in  FIGS.  11 A  and B, that allows the independent movement of the wheel hub, relative to the wheel assembly frame, and the trailer it is affixed to, as the trailer traverses uneven ground. 
     In an exemplary embodiment, and with reference to  FIG.  14   , each of the hub assemblies of the trailer may include a drive assembly that is configured to selectively transmit a motive force through the drive assembly to cause the hub  410 , and thus a wheel mounted upon the hub to turn, thereby propelling the trailer  1 ′. As can be seen with reference to the partially exploded view provided by  FIG.  14   , a motor  470  may be provided, which may be a hydraulic motor as depicted, though it is contemplated that the motor may instead be any suitable motor, including electric or pneumatic, which when actuated will result in the rotation of the motor output shaft  472  in a selectable direction. In an embodiment, the drive and direction of rotation of the motor  470  for each of the hub assemblies are independently, selectively reversible, so as to provide adequate maneuverability to the trailer  1 ′ and minimize the turning radius. The rotatable motor output shaft  472  is directed into an input opening in a transmission housing  460 , which may contain a gear reduction system, for example, a planetary gear set which serves to increase the torque output from the motor, while reducing speed of rotation. The output from the transmission housing  460  is directed to a flanged driveshaft  474 , as will be discussed. 
     As shown in  FIG.  12 A , the wheel assembly may be provided with a selectively engageable clutch assembly  500 , providing a mechanism allowing each wheel of a wheel assembly to be driven by the motor, or to allow the hub/wheel to free-wheel independently of any rotation of the driveshaft. While the clutch is engaged, motive forces provided by the motor  470  are directed through the transmission  460 , if any, and then by the driveshaft  474 , whereby the motive forces may be passed through the clutch mechanism  500  to cause the rotation of the hub assembly upon which the wheel is mounted, thereby driving the wheel. While the clutch  500  is disengaged, the wheel and hub assembly may spin freely, independent of the driveshaft  474  and motor  470 , as may be required while the trailer  1 ′ is being towed by a powered vehicle between locations. The clutch mechanism  500  may be of any suitable type for selectively transmitting torque from the motor to the wheel, as is understood by those skilled in the art, and may include friction, centrifugal, diaphragm, positive, hydraulic, electromagnetic, or vacuum clutches, as non-limiting examples. 
     As can be seen with reference to  FIGS.  15 ,  16 A and  16 B , the clutch assembly  500  will be engaged or disengaged with the lateral shifting of the flanged driveshaft  474 . While the driveshaft is in the first position, the teeth of the driving clutch element  502  will be engaged with the receiving elements (such as teeth) of the driven clutch element  504 , in order to positively transmit the rotation of the flanged driveshaft  474  through the clutch  500  elements and to the wheel hub  410 . While the flanged driveshaft  474  is in the second position, the teeth of the driving clutch element  502  will not be engaged with the receiving elements of the driven clutch element  504 , as the lateral shift of the driveshaft  474  is enough to separate the driving clutch element  502  from the driven clutch element  504 . Thus, so long as the driveshaft  474  remains in the second position, the driveshaft  474  may be caused to rotate by the motor, and the driving clutch element  502  will also rotate, yet there as there is no contact between the driving clutch element  502  and the driven clutch element  504 , then the driven clutch element  504 , wheel hub  410  and wheel will remain isolated from movement of the driveshaft and motor, if any; moreover, while the trailer  1 ′ is being towed, the driven clutch element  504 , wheel hub  410  and wheel will be free to turn, without affecting the driveshaft  474  and motor  470 . 
     To actuate the lateral movement of the flanged driveshaft  474  in order to engage and disengage the clutch, the wheel hub assembly may be provided with a locking mechanism  600 , which may be any suitable actuation, including manual, electric, hydraulic, or pneumatic operation. In the exemplary embodiment depicted in  FIG.  15   , and in greater detail in  FIG.  17   , the locking mechanism  600  provides a hydraulic actuator, and comprises at least one of each of a pushing member  602  and one or more seals  604  configured to slidingly reciprocate within a pushing member receptacle  603 , an urging member  606 , a roller  608 , and a pivot pin  610 , which may be fitted within the confines of the pushing member receptacle. The seals  604  may be O-rings that are mounted on the body of the pushing member, and may partially resided within O-ring grooves on the pushing member. An exploded view of the components of the locking mechanism  600  is depicted in  FIG.  18   , depicting the locking mechanism as a cartridge component that may be fitted into the bell housing  476 . As depicted, the pushing member receptacle  603  may be a hollow body, that is configured to slidably accept the pushing member therein, and acts similar to a hydraulic cylinder barrel, in that it is configured to contain hydraulic pressure acting upon the pushing member  602 , which acts as a hydraulic cylinder. The pushing member receptacle may be provided with a fixed seal  605 , which may be a gland seal or mechanical seal, such as an O-ring, positioned in the pushing member receptacle below the seals on the pushing member, where the fixed seal receives the elongate body portion of the pushing member therethrough, and serves to prevent leakage of hydraulic fluid below the fixed seal. The urging member  606  is secured at one end over a pivot pin  610 , and is free to move laterally at the other end. The urging member  606  is normally biased in a direction away from the motor (to the left as depicted in  FIG.  15   ), which may be accomplished using any suitable method, for example, with a spring pushing against the urging member, normally biasing to the left in  FIG.  15   . When the pushing member  602  is subjected to hydraulic pressure, such as may be applied through the first hydraulic port  612 , the pressure above the pushing member seal  604  is increased, and causes the pushing member  602  to be advanced towards the driveshaft  474  (in a downward direction), whereupon the lower portion of the pushing member  602  encounters the roller  608 , which is secured to the urging member  606 , typically near the mid-point of the urging member. Further advancement of the pushing member  602  causes the roller  608 , to be displaced, depicted in a direction to the right in  FIGS.  15  and  17   , whereupon the urging member  606  will pivot upon the pivot pin  610  securing the end of the urging member, as a fulcrum end. The movement at the free end of the urging member  606  will be magnified by the lever arrangement of the urging member, such that the free end of the urging member is moved to the right and encounters a flange  475  of the driveshaft  474 , and thus urges the driveshaft to the right, into the second position of the driveshaft, thereby retracting the teeth of the driving clutch element  502  so as to not be engaged with the driven clutch element  504 . 
     In an embodiment, the pushing member  602  may have a detent  616  that aligns with the roller when the pushing member is advanced downwards. The detent may be in the form of an indentation on the surface of the pushing member  602 , that is sized to accommodate at least a portion of the roller  608 , so that the roller is received within the indentation. The roller  608 , while it is at least partially received within the detent  616 , provides resistance to the pushing member returning to the raised position, and maintains the pushing member in the down position, even in the absence of hydraulic pressure at the first port  612 . In this manner, the hydraulic system may be depressurized (as may be preferred for towing the trailer between locations), and as the pushing member  602  will remain advanced downward, the urging member  606  will continue to urge the driveshaft  474  to remain in the second position, ensuring the clutch  500  will remain disengaged. Thus, with the clutch disengaged, the trailer  1 ′ may be towed as the hub  410  can free-wheel, without the clutch  500  elements being engaged, and without causing unwanted movement of the motor  470  and transmission  460  components. 
     Reversal may be accomplished by removing the hydraulic pressure at the first port  612 , and increasing the hydraulic pressure through the second hydraulic port  614 , which increases the pressure below the seal  604  on the pushing member  602 , and above the fixed seal  605 . The increased pressure from below the seal  604  of the pushing member  602  will overcome the holding force from the roller  608  residing against the detent  616 , and drive the pushing member  602  upwards, away from the driveshaft  474  as the roller  608  leaves the detent  616 , and continued movement of the pushing member  602  upwards will free the roller  608  from encountering the pushing member at all, such that the urging member  606 , along with the roller  608  may pivot upon the fulcrum of the pivot pin  610  and returns to the initial position, whereby the driveshaft  474  is no longer urged to the second position, and can revert to the first position. With the driveshaft no longer urged away from the motor, the clutch  500  becomes engaged as the teeth of the driving clutch element  502  and driven clutch element  504  become engaged, so that the trailer  1 ′ may be self-propelled by rotation of one or more motors  470 . 
     In an embodiment, it is contemplated that the driven clutch element  504  of  FIG.  16 A  may be reversible, so as to present the recessed surface towards the driving clutch element  502 . When reversed in this manner, the clutch  500  will be disengaged, regardless of the position of the driveshaft  474 , such that the hub  410  will free-wheel, though remains subject to braking application, as previously described. In this manner, one wheel hub assembly drive may be disabled, as may be necessary in the event of a malfunction, or equipment breakage. Reversal of the driven clutch element  504  is accomplished by removing the fasteners securing the driven clutch element  504 , and replacing it with the normally exterior facing recessed surface (as can be seen in  FIG.  12 A ) directed inwards. 
     Now with reference to the Figures, the control system  60  will be discussed and generally includes a power system source (i.e. combustion engine, battery) and a control assembly connected (hydraulic and electrical lines) to the rear wheel assembly  310 , the front wheel assembly  340 , and the extension assembly  380 . 
     Regardless of the specific mode of powering the rear wheels  312 , the control system  60  controls starting, stopping and turning the rear wheels  312 , as well as for regulating the speed of the rear wheels  312 . Likewise, the control system  60  also controls starting, stopping and turning the front wheels  342 , as well as for regulating the speed of the front wheels  342 . 
     The control system  60  includes a plurality of controls which may be a series of buttons, levers, or other suitable controls which allow the operator to control expansion and retraction of the front wheel assembly  340  using the extension assembly. 
     In an embodiment, user controls may be provided on the control system  60  for controlling certain other features of the trailer  1 . As shown in the embodiment of  FIG.  1   , an operator stand may sit in operator&#39;s box  62 , allowing an operator to move along with the trailer  1  as the operator controls the trailer  1  movement. The control system  60  therefore provides the operator with the ability to control all features of the trailer  1  from a single location, while standing on the operator stand and moving along with the trailer  1  as the trailer  1  travels under its own power. 
     In a trailing position A, the front wheels  342  are positioned adjacent to the rear wheels  312 , while in the self-propelled position B the front wheels  342  are positioned to equally support the undercarriage chassis  20  and, more particularly, the storage bin  80 . 
     According to the invention, the front wheels  342  are positioned between the trailing position A and the self-propelled position B by the extension assembly  380 . 
     Now with reference to  FIGS.  1 - 4   , the storage bin  80  generally includes a platform  82 , a plurality of retaining walls  84 , a tailgate  90 , and a pair of cover sections  94 . 
     The platform  82  includes a planar section extending substantially parallel with the frame  10 . In the shown embodiment, the platform  82  is a rectangular metal plate. However, one skilled in the art should appreciate that the platform  82  could be manufactured using different shapes and other materials, such as lumber, composite, and other metals. For instance, the platform  82  may include a framed metal structure on which a plurality of wood planks are arranged. 
     The plurality of retaining walls  84  includes a pair of side retaining walls  86  and a retaining end wall  88 . In the shown embodiment, each retaining wall  84  is metal plate. However, one skilled in the art should appreciate that each retaining wall  84  could be manufactured using other materials, such as lumber, composite, and other metals. For instance, each retaining wall  84  may include a framed metal structure on which a plurality of wood planks is disposed along the framed metal structure. 
     The plurality of retaining walls  84  is positioned and secured along outer edges of the platform  82  and, in particular, along a top planar surface thereof. In the shown embodiment, the pair of side retaining walls  86  are positioned along opposite longitudinal sides of the platform  82 , while the retaining end wall  88  is positioned at trailing end of the platform  82 . Each retaining wall  84  extends substantially perpendicular with respect to the top planar surface of the platform  82 . Each retaining wall  84  is mechanically secured to the platform  82 , for instance, using a weld or plurality of known mechanical fasteners. In addition, the retaining end wall  88  is secured to a pair of common ends of the side retaining walls  86 . In the embodiment shown, the retaining end wall  88  is mechanically secured to the pair of side retaining walls  86 , for instance, using a weld or other known mechanical fasteners or adhesives. 
     As shown, the tailgate  90  is positioned along a leading end of the platform  82 , opposite the retaining end wall  88  positioned along the trailing end thereof. In the embodiment shown, the tailgate  90  is made of a metal. However, one skilled in the art should appreciate that the tailgate  90  could be manufactured using other materials, such as lumber, composite, and other metals. For instance, tailgate  90  may include a framed metal structure on which a plurality of wood planks is disposed along the framed metal structure. 
     As shown, the tailgate  90  is positioned along an outer edge of the platform  82  and extends substantially perpendicular to the top planar surface thereof. The tailgate  90  is secured to the platform  82 , for instance, through a rotating fastener device, such as a rotating hinge  92  positioned at bottom of the tailgate  90  and connecting to the platform  82 . The rotating hinge  92  permits rotation of the tailgate  90  from a secured closed vertical position to one in which the tailgate  90  rotates away from the retaining end wall  88  making the platform  82  accessible. However, one skilled in the art should appreciate that other design are possible. For instance, the tailgate  90  may be pivotably mounted to side retaining walls  86  such that the tailgate  90  pivots away from the outer edge of the platform  82  or from the side retaining walls  86 , much like known dump trucks. 
     Each cover section  94  is a rectangular metal structure having a planar surface. Each cover section  94  is positioned along and connected to upper outer edges of the pair of side retaining walls  86  using a plurality of hinges  96 . However, one skilled in the art should appreciate that other designs are possible. For instance, other known rotating mechanisms could be used. Each cover section  94  measures approximately half a width as measured between the pair of side retaining walls  86 . 
     A pair of stops  98  are provided and positioned along a common side at opposite ends of the cover section  94 . In particular, each stop  98  is disposed along an outer edge of the cover section  94  that is proximate to the side retaining wall  86  when assembled. Each stop  98  is a metal plate having one end secured to the cover section  94 . In an exemplary embodiment, the stop  98  is semi-circle shaped having a free end configured to abut the side retaining wall  86  when the cover section  94  rotates about the hinge  96 . The stop  98  configuration determines that angle at which the cover section  94  is positioned in an open position. For instance, if the stop  98  has a 135 degree semi-circle shape, then the cover section  94  will be positioned at a 45 degree angle with respect to a plane extending across top surfaces of both side retaining walls  86 . 
     In the shown embodiment, a plurality of wall supports  99  are provided and disposed along outer surfaces of the platform  82 , the retaining walls  84 , the tailgate  90 , and the cover sections  94 . The wall supports  99  provide reinforcement for the planar surfaces of each of the outer surfaces. In the shown embodiment, each wall support  89  is a tubular structure of metal that is mechanically secured to the outer surfaces, for instance, using a weld. However, one skilled in the art should appreciate that other known fastening means are possible, including but not limited to screws, nuts and bolts, and adhesives. 
     Now with references to  FIGS.  4 - 6  and  8   , the extension device  100  according to the invention will be described. As shown, the extension device  100  includes the following major components: a first extension section  102 , a second extension section  120 , and a storage bin platform section  180 . 
     As shown, the first extension section  102  is shown and generally includes a pair of lower supports  104  reciprocally connected to the support beams  12  and a lower lifting actuator assembly  106  connected to the front support  16 . 
     Each lower support  104  is an elongated structural support and, in the shown embodiment, a metal plate. Each lower support  104  includes a plurality of fastener receiving through-holes  108  positioned at a trailing end, leading end, and a middle section thereof. The pair of lower supports  104  are positioned parallel, and are rotatably secured to the frame  10  using fasteners. The lower lifting actuator assembly  106  includes a pair of hydraulic actuators connecting to the front support  16  at one end and to the middle section of the lower support  104  at another end thereof using fasteners. 
     As shown, the second extension section  120  is shown and includes a boom support  122 , a sliding support  124 , a sliding mechanism  130 , an upper lifting actuator assembly  140 , and an articulating arm assembly  150 . 
     The boom support  122  is elongated structural beams and, in the shown embodiment, a tubular metal beam. The boom support  122  includes a pair of fastener receiving brackets  123  with through holes positioned at a trailing end thereof and extending completely there through. 
     As shown, each sliding support  124  is an elongated structural beams having a boom support receiving passageway  126  opening from a trailing end thereof and extending there through a body of sliding support  124 . The boom support receiving passageway  126  is shaped to receive the boom support  122  and, as shown, a cross section area of the boom support receiving passageway  126  is larger than a cross section area of the boom support  122 . As a result, a leading end of the boom support  122  is positioned through the boom support receiving passageway  126 . 
     In the shown embodiment, each sliding support  124  is a tubular metal beam. Each sliding support  124  includes a fastener receiving through-hole  128  positioned at a leading end thereof and extending completely there through. 
     The sliding mechanism  130  is positioned between and connected to the boom support  122  and the boom support receiving passageway  126 . 
     Each sliding mechanism  130  includes an actuator section  132  which may be a known hydraulic cylinder having a barrel, a piston, piston rod, seals, and seal glands. However, one skilled in the art should appreciate that other actuator systems operated by a source of energy, such as electric current, hydraulic fluid pressure, or pneumatic pressure. 
     In the shown embodiment, the upper lifting actuator assembly  140  includes a pair of hydraulic actuators  142  is positioned between frame  10  and the second extension section  120 . Each hydraulic actuators  142  includes an actuator  174  which may be a known hydraulic cylinder having a barrel, a piston, piston rod, seals, and seal glands. However, one skilled in the art should appreciate that other actuator systems operated by a source of energy, such as electric current, hydraulic fluid pressure, or pneumatic pressure. 
     As shown, in an exemplary embodiment of the invention, the articulating arm assembly  150  is a pair of plate like members (see  FIG.  8   ) rotatably connected to the sliding support  124  and the storage bin  180  using the storage bin platform section 
     As shown, the storage bin platform section  180  is shown and generally includes a platform  182 , a platform cross member  184 , a tilting actuator cross member (not shown), and a pair of bin tilting actuators (not shown). 
     Now with reference to  FIGS.  1 ,  10 , and  11   , operation of the trailer  1  or  1 ′ according to the invention will be described. 
     Building materials can be loaded and secured in the storage bin  80  at a location different than the work site. A truck (not shown) connects to the frame  10  using the trailer hitch  22 . The operator positioned the front wheel assembly  340  apart from the rear wheel assembly  310  using the extension assembly  380 . The front wheel assembly  340  and the rear wheel assembly  310  are set to drive and steer using the control system  60 . The trailer  1  or  1 ′ then can operate as a standard trailer and be towed behind the connected truck to the work site. 
     The operator then uses the control system  60  to move the trailer  1  or  1 ′ to a desired location on the work site using the drive system of the front wheel assembly  340  and the rear wheel assembly  310 , as described above. The operator may now use the control system  60  to stabilize the trailer  1  or  1 ′. 
     Once the operator has determined that the trailer  1  is in position to unload building materials from the storage bin  80 , the operator can manage the stabilizers (not shown), as known and well understood by those skilled in the art, to stabilize and level the trailer  1  or  1 ′. The operator then uses the control system  60  to control the extension device  100  and position of the storage bin  80 . 
     The operator can use the control system  60  to control the vertical and horizontal position of the storage bin  80 . In addition, the operator can slide the storage bin  80  horizontally with respect to frame  10 . 
     The foregoing illustrates some of the possibilities for practicing the invention. Many other embodiments and fields of use for the trailer  1  or  1 ′ are possible and within the scope and spirit of the invention. It is, therefore, intended that the foregoing description be regarded as illustrative rather than limiting.