Abstract:
A vehicle designed to haul loads may be provided, which may be effectively extended and load hauling capacity increased with a detachable trailing tag axle that may include a framework with a front, a rear end, an axle attached to near the rear of the framework, wheels attached to the axle, and a mechanism near the front of the framework for stabilization when the tag axle assembly is standing alone. A holding mechanism near the front of the tag axle assembly may be used to attach the tag axle assembly to a portion of the vehicle chassis, such as a receiving mechanism at the rear of the vehicle chassis.

Description:
RELATED APPLICATIONS 
       [0001]    This application claims priority to U.S. provisional patent application 61/133,175, filed on Jun. 26, 2008, which is incorporated by reference herein in its entirety. 
     
    
     FIELD 
       [0002]    This application relates generally to auxiliary vehicle equipment. More particularly, this application relates to trailing tag axles for load transportation vehicles such as dump trucks. 
       BACKGROUND 
       [0003]    Large trucks have been used for years as an efficient way to transport large and heavy loads from one location to another over roads and bridges. To reduce the wear inflicted upon roads and bridges by the transport of such loads, government regulations limit the weight of these loads. The regulations have been based on the longitudinal distance between sets of wheels, particularly between the front and rear wheels of the vehicle. Load size can be legally increased by increasing the distance between the front and rear wheels of the vehicle. With the desire to carry the maximum possible load, trailing tag axle assemblies have been added to vehicles to legally increase load capacity by increasing the effective length of the vehicle. 
         [0004]    Trailing tag axle assemblies previously made and currently in use are generally attached to the vehicle in a manner intended to be permanent (i.e. bolted or welded directly to the vehicle). Because these assemblies are not intended to be removed from the vehicle, the assemblies are generally made to move between a raised and lowered position, usually by the means of hydraulic actuators or similar motion inducing apparatus, to stow the assembly on the vehicle when not in use. This allows them to be lowered to an operating position when needed and raised to a storing and inactive position when not needed or, when dumping a load. 
         [0005]    There are several disadvantages to the trailing tag axle assemblies previously used. One disadvantage is that with the trailing tag axle generally being of a non-detachable nature, it is still attached to the vehicle when not in use. Some materials hauled by vehicles use all available cubic volume in a cargo portion of the truck without maximizing the weight load that can be legally carried, thereby obviating the need for the trailing tag axle. In these situations the attached trailing axle adds unnecessary weight to the vehicle and can increase the wear on the vehicle, such as the tires, or may interfere with desired vehicle operations. 
         [0006]    The previous tag axle assemblies can be cumbersome when disengaging a load by interfering with the operation of a tailgate or other door assembly. Many times the axle assembly is stored over the rear door of the truck body and therefore interferes with raising the gate. This is particularly true with a high-lift gate that is hinged toward the front of the dump body to raise it high over the load. This is important when large rock, riprap or the like is dumped. It can also interfere with the accuracy of placing a load by being between the vehicle and the desired unloading location (e.g. a hopper on an asphalt paving machine). 
         [0007]    Another disadvantage of previous tag axle assemblies is that in the stored (stowed) position the tag axle assembly may cause the overall height of the vehicle to be greater than governmental regulations allow. 
       SUMMARY 
       [0008]    A vehicle, such as a dump truck, panel truck, garbage hauler, container hauler, etc., may be provided with a chassis, front wheels attached to a front axle mounted near the front end of the chassis, rear wheels attached to a rear axle mounted near the rear end of the chassis, a body attached to the chassis, and a cargo support portion mounted to the chassis for carrying a load. In some embodiments, the detachable trailing tag axle could include of a framework with a front, a rear end, an axle attached to near the rear of the framework, wheels attached to the axle, and a mechanism near the front of the framework for stabilization when the tag axle assembly is standing alone. A holding mechanism near the front of the tag axle assembly may be used to attach the tag axle assembly to a portion of the vehicle chassis, such as a receiving mechanism at the rear of the vehicle chassis. 
         [0009]    Some embodiments of the holding mechanism may include one or more engagement bodies, such as pins, hooks, etc. The engagement bodies may be configured to be releasably coupled to receiving bodies, such as holes, flanges, bars, etc., in a portion of the vehicle, such as in the body, the chassis, the cargo support, etc., by mechanical means. The holding mechanism may be driven by an actuator hydraulically, mechanically, electrically, etc., to engage the engagement bodies with the receiving bodies. In some embodiments, the holding mechanism, including drive actuator, may be located on the vehicle with the receiving bodies being located on the trailing tag axle assembly. 
         [0010]    Similarly, in some embodiments, the detachable trailing tag axle may have a need for connections to the vehicle air, electrical, or other supply, as well as braking apparatus, and may further include shock absorption devices, or other components as required or desired to comply with ride comfort and transportation regulations. 
         [0011]    A trailing tag axle, as described herein, may provide one or more additional axles and wheels extending from the rear of the chassis, thereby increasing the distance between the front wheels and the furthermost rear wheels, and allowing greater loads to legally be carried by the vehicle. Some embodiments may also overcome the problem of adding weight and wear to the vehicle by providing a trailing tag axle that may be easily, quickly, and/or completely detachable from the vehicle when not needed. 
         [0012]    Similarly, some embodiments may also overcome the problem of being cumbersome and interfering with tailgate or door operations, since the trailing tag axle can be detachable and left in a convenient location until unloading is completed. Thus, it would not interfere by not being present. This may also be helpful when unloading accuracy is important (e.g. when dumping into a hopper of a paving machine). 
         [0013]    These and other aspects of the present invention will become more fully apparent from the following description and appended claims. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    The following description can be better understood in light of Figures, in which: 
           [0015]      FIG. 1  is a perspective view of an exemplary embodiment of a detachable trailing tag axle attached to a vehicle; 
           [0016]      FIG. 2  is a side elevation view of an exemplary embodiment of a detachable trailing tag axle detached from a vehicle; 
           [0017]      FIG. 3  is a side elevation view of an exemplary embodiment of a detachable trailing tag axle; 
           [0018]      FIG. 4  is a plan view of an exemplary embodiment of a detachable trailing tag axle; 
           [0019]      FIG. 5  is a side view of an exemplary embodiment of a detachable trailing tag axle and vehicle attaching and detaching areas in a detached position; 
           [0020]      FIG. 6  is a side view of an exemplary embodiment of a detachable trailing tag axle shown in an attached position; and 
           [0021]      FIG. 7  is a side view of an exemplary embodiment of a detachable trailing tag axle and vehicle attaching a detaching areas in a detached position. 
       
    
    
       [0022]    Together with the following description, the Figures demonstrate and explain the principles of detachable trailing tag axles and associated methods. In the Figures, the size and relative placement of components and regions of illustrated devices may be exaggerated or modified for clarity. The same reference numerals in different drawings represent the same element, and thus their descriptions may not be repeated. Some drawings may omit certain components not necessary for describing the illustrated embodiments, but which would be known to those of ordinary skill in the art to be present in a trailing tag axle. 
       DETAILED DESCRIPTION 
       [0023]    As in the illustrated embodiments, aspects and features of detachable trailing tag axles and associated methods are disclosed and described below. The following description supplies specific details in order to provide a thorough understanding. Nevertheless, the skilled artisan would understand that the apparatus and associated methods of using the apparatus can be implemented and used without employing these specific details. Indeed, the devices and associated methods can be placed into practice by modifying the illustrated devices and associated methods and can be used in conjunction with any other apparatus and techniques conventionally used in the industry. For example, while this description focuses on detachable trailing tag axles for vehicles such as dump trucks, embodiments employing the principles described herein may be used on or with trailers, flat-bed trucks, panel trucks, or other load-hauling machinery, mechanisms, vehicles, devices, etc. without departing from the scope of the devices described herein. 
         [0024]      FIG. 1  illustrates a detachable trailing tag axle  100  attached to vehicle  180 . Trailing tag axle  100  may include frame  150 , with longitudinal members  152  and cross members  154 , supported by wheels  160  and suspension system  168 . Vehicle  180  may be any vehicle that may be aided by effective extension of the wheelbase to accommodate increased loading, such as a dumptruck illustrated in the Figures. Vehicle  180  may include tailgate  186  to allow for off-loading of a load in vehicle  180 . 
         [0025]    Referring generally to  FIGS. 1-6 , an exemplary embodiment of trailing tag axle  100  may include frame  150 , tag axle attachment assembly  110 , including pin attachment assembly  111  and compensator assembly  130 , and wheels  160 . Vehicle  180  may be any vehicle that may be aided by effective extension of the wheelbase to accommodate increased loading, such as a dumptruck illustrated in the Figures. 
         [0026]    Pin attachment assembly  111 , best shown in  FIG. 4 , may include kinematic pin linkage  116  employed to engage attachment pins  114  through retaining holes in frame  150 , and through retaining holes  196  of vehicle  180  when attached to vehicle  180 , described in further detail below. Pin attachment assembly  111  may include actuator  112 , to engage and disengage pin linkage  116  and pins  114  from connection with vehicle  180 . Pin linkage  116  may include a centrally pivoted member pivotally attached off-center to actuator  112 , and two secondary links, one pivotally attached by its end at each end of the centrally pivoted member with the other end of each of the secondary links pivotally attached to one attachment pins  114  on opposite lateral sides of frame  150  from each other. Thus when the actuator  112  is actuated it causes pin linkage  116  to move by rotating the centrally pivoted member, which, in turn, pushes or pulls the secondary links, which then move attachment pins  114  to engage or disengage trailing tag axle  100  from vehicle  180 . 
         [0027]    Pin attachment assembly  111  may be activated by actuator  112  and controlled by valve  122  located in supply line  118  connected to supply tank  120 . Supply tank  120  may contain pressurized air to drive actuator  112 . Supply tank  120  may be provided compressed air from attachments with vehicle  180  and may be capable of holding enough air to drive actuator  112  through several cycles without replenishment. In some embodiments, supply tank  120  may also be used to drive air brakes in trailing tag axle  100 , or multiple supply tanks may be used for pin attachment assembly  111 , suspension  168 , break systems, either individually, or in combination. In other embodiments, actuator  112  may be a hydraulic actuator driven by hydraulic fluid. The hydraulic fluid may be pumped with a hand-pump, or may be electrically pumped. Similarly, actuator  112  may also be an electric actuator powered with a battery or other power supply, such as power supplied by vehicle  180  through supply lines. 
         [0028]    Compensator assembly  130 , as best illustrated in  FIG. 5 , may include kinematic compensator linkage  132 , which may be employed to compensate for bumps and dips in the ground and to provide flexibility and safety to trailing tag axle in certain conditions to avoid damage to vehicle  180  or trailing tag assembly  100 . Compensator linkage  132  may include latch  134 , for attaching to pin  198  on vehicle  180 , pivotally attached to one end of compensator a centrally pivoted member of compensator linkage  132 . Compensator centrally pivoted member of compensator linkage  132  may then have compensator cylinder  136  pivotally attached to the other end. In some embodiments, compensator linkage  132  may be modified to alter the mechanical ratio of movement between the cylinder and distance achieved between frame  150  and vehicle  180  at pin  198 . In other embodiments, compensator linkage may have a single member with latch  134  at one end and extending into cylinder  136  on the other. 
         [0029]    A distance between pin  198  and holes  196  may be such that the mechanical advantage of compensator assembly  130  may be optimized for a desired size of compensator assembly  130 , depending on the load to be carried, the horizontal distance between axle  162  and attachment pins  114 , and the vertical distance between pin  198  and holes  196 . In some embodiments the desired load to be carried by trailing tag axle  100  may be pre-selected by adjusting the various mechanical distances and by selecting a compensator assembly  130  of a desired size to accommodate the desired load. For example, in some embodiments, the vertical distance between pin  198  and pin holes  196  may be about 22 inches, the horizontal distance between attachment pins  114  and axle  162  may be about 110 inches, and the compensator assembly may be rated between about 6-7.5 tons. 
         [0030]    Cylinder  136  may be a hydraulic cylinder connected to accumulator  131  to maintain a generally constant load required to extend or compress cylinder  136 . Accumulator  131  may be any accumulator or similar device used in the industry. For example, accumulator may be a Nitrogen and hydraulic fluid compensator with a fluid line connected to cylinder  136  such that when cylinder  136  extends or compresses, fluid is moved between cylinder  136  and accumulator  131 , thereby changing the pressure in the Nitrogen chamber. The compressive or vacuum forces from the Nitrogen chamber maintains force on cylinder  136  to resist movement of cylinder  136  due to movement of trailing tag axle  100  with respect to vehicle  180 . 
         [0031]    By connecting compensator assembly  130  to vehicle  180 , compensator cylinder  136  may then maintain a certain pressure for a given position with the help of accumulator  131  and fluid line  138 . In this manner, compensator assembly  130  may allow trailing tag axle  100  and frame  150  to rotate about attachment pins  114  of pin assembly  11 , while maintaining the load sharing capabilities of trailing tag axle  100 . 
         [0032]    For example, if vehicle  180  with attached trailing tag axle  100  were to cross a set of railroad tracks that were raised above the level of the road and therefore had a sudden and steep slope leading up to the tracks, as vehicle  180  moved up the slope to cross the tracks the front wheels would rise with the road to the level of the tracks while the rear wheels stayed at the level of the road. If trailing tag axle  100  were rigidly attached to the vehicle  180  such that it could not pivot about the horizontal axis provided by the attachment of trailing tag axle  100  to vehicle  180  through attachment pins  114 , then the front wheels of vehicle  180  and wheels  160  of trailing tag axle  100  would be the only wheels in contact with the road. 
         [0033]    This would cause two major problems. First, all the weight of the vehicle  180  including any load in cargo box  184  would be supported by two steering axles. Not only would that be a violation of regulation but it could cause considerable damage to vehicle  180  and the road. Second, the rear wheels of load carrying vehicles  180  are typically the driving wheels. With these wheels off the road vehicle  180  would be unable to move. Compensator assembly  130  does not allow this situation happen because the trailing tag axle  100  is allowed to rotate about attachment pins  114  while still bearing some of the load. 
         [0034]    Framework  150  may be formed using rigid members  152  arranged in a longitudinal manner and may be braced laterally with rigid cross members  154 . Support jack  140  may be attached to any portion of frame  150 , such as rigid cross member  154 , such that trailing tag axle  100  may be supported in a position to be attached to vehicle  180 . Support jack  140  may be raised and lowered as required for travel, attachment, etc. 
         [0035]    Wheels  160  may be attached to axle  162  and to frame  150  through suspension system  168 . Suspension system, wheels  160 , and axle  162  may be any type an set-up used to support loads with wheels. Other systems, such as brakes, steering, etc. may also be added, as one skilled in the art would understand, to control the wheels  160 . 
         [0036]    Fixtures, cables, lines and so forth, as well as the appropriate connectors (not shown), may be supplied to allow for connection of trailing tag axle  100  to vehicle  180  through supply lines to control braking, steering, lights, etc. 
         [0037]    Vehicle  180  may have a frame  182 , and may include cargo box  184  with tailgate  186  to allow for off-loading of a load in vehicle  180 . Vehicle  180  may include vehicle connection assembly  190 , which may include attachment points, such as horn  194  with holes  196 , and pin  198 , to facilitate connection to trailing tag axle  100 . Horn  194 , holes  196 , and pin  198 , along with any structures necessary to provide components of connection assembly  190  may be attached to frame  182  of vehicle  180 . In some embodiments, horn  194  may not be necessary as holes  196  may be located directly in components of frame  182 . 
         [0038]    Attachment of trailing tag axle  100  to vehicle  180  may be accomplished by backing vehicle  180  up to trailing tag axle  100  such that horn  194  engages trailing tag axle  100  and aligns attachment pins  114  with retaining holes  196 . During the backing procedure compensator latch  134  may automatically latch onto pin  198  of vehicle  180 . Once vehicle  180  and trialing tag axle  100  are properly aligned, the vehicle operator would then engage the attachment pins  114  by controlling valve  122  to drive actuator  112 , thereby moving linkage  116  and engaging attachment pins  114  through retaining holes  196  in vehicle  180  to establish and maintain connection between trailing tag axle  100  and the vehicle  180 . The vehicle operator may then connect all necessary and desired supply lines from trailing tag axle  100  to vehicle  180 . Support jack  140  may then be raised so that it does not interfere with the operation of vehicle  180  with trailing tag axle  100  attached. With trailing tag axle  100  attached, vehicle  180  can be operated normally with an effectively extended wheelbase. 
         [0039]    Detachment of the trailing tag axle  100  may be accomplished by finding a suitable spot to park trailing tag axle  100  where it will not interfere with the unloading of vehicle  180 . With vehicle  180  securely parked, the vehicle operator may then lower support jack  140 , disconnect all supply lines, disengage the attachment pins  114  from retaining holes  196  to disconnect the trailing tag axle  100  from the vehicle  180 , and disengage compensator linkage  132 . Compensator assembly  130  may be disengaged by lifting compensator latch  134  off of connection with pin  198 . A handle, as shown in  FIG. 7 , may be present to assist in lifting compensator latch  134 . It may be necessary to strike compensator latch  134  upwardly with an object such as a piece of wood, mallet, hammer, etc, to disengage compensator assembly  130 . In some embodiments, an actuator may be used to lift compensator latch  134 . Vehicle  180  may then be driven away from trailing tag axle  100 . This procedure may allow the vehicle  180  to move about the load dumping area freely and trailing tag axle  100  will not interfere with the process of disengaging a load. 
         [0040]    In another embodiment, as shown in  FIG. 7 , trailing tag axle  200  may include frame  250 , compensator assembly  230 , pin assembly  211 , and support jack  240 . Pin assembly  211  and compensator assembly  230  of trailing tag axle  200  may couple with vehicle  280  through attachment assembly  290 . Pin assembly  211  may function similarly to pin assembly  111  as described in reference to trailing tag axle  100 . Compensator assembly  230  may include compensator latch  234  and compensator cylinder  236 . Compensator cylinder  236  may function similarly to compensator cylinder  136  as described above, attaching to accumulator  231  through supply line  238 . 
         [0041]    Compensator latch  234  may be shaped and designed such that it works in conjunction with hitch  298  of vehicle  280 . Hitch  298  may be of the ring-type conventionally provided on vehicles such as dump trucks, military vehicles, etc. In some embodiments, hitch  298  may be a ball-type hitch with latch  234  being configured to engage hitch  298 . The function of compensator assembly  230  is fundamentally similar to that of compensator assembly  130 , in the compensator assembly  230  allows frame  250  of trailing tag axle  200  to rotate about the pins of pin assembly  211 , when required by road conditions, by allowing cylinder  236  to extend in a generally linear direction, while reducing the number of components, such as compensator linkage  132 . 
         [0042]    In some embodiments, compensator assembly  230  may also include additional linkage components to alter to the position of components of compensator assembly for convenience, for other components of trailing tag axle  100 , or to modify or adjust the mechanical leverage and ratio of movement between compensator latch  234  and cylinder  236 . 
         [0043]    The structures on detachable trailing tag axle  100 ,  200  typically accomplish five basic functions. They increase the overall length of the vehicle  180 ,  280  to legally accommodate larger loads, support some of the load on the ground, attach and detach from vehicle  180 ,  280 , compensate for bumps and dips, and shock absorb, brake, and steer in a manner familiar to one skilled in the art. For example, when detachable trailing tag axle  100 ,  200  is attached to vehicle  180 ,  280 , the length of frame  150 ,  250  from the front of trailing tag axle  100 ,  200  to the center of wheels  160  increases the total length of vehicle  180 ,  280 , thus legally providing for heavier loads to be carried. Also, pin assembly  111 ,  211  and compensator assembly  130 ,  230  allow for easy attachment and detachment of trailing tag axle  100 ,  200  from vehicle  180 ,  280 , thus not impeding tailgate  186  or the load disengaging capabilities of vehicle  180 ,  280 . Compensator assembly  130 ,  230 , including compensator linkage  132 , compensator latch  134 ,  234 , and cylinder  136 ,  236  along with accumulator  131 ,  231  allow trailing tag axle  100 ,  200  to conform to bumps and dips in the ground without damaging frame  150 ,  250  or vehicle  180 ,  280  while still distributing a load carried by vehicle  180 ,  280  throughout all of the axles, including axle  162  of trailing tag axle  100 . 
         [0044]    In addition to any previously indicated modification, numerous other variations and alternative arrangements may be devised by those skilled in the art without departing from the spirit and scope of this description, and appended claims are intended to cover such modifications and arrangements. Thus, while the information has been described above with particularity and detail in connection with what is presently deemed to be the most practical and preferred aspects, it will be apparent to those of ordinary skill in the art that numerous modifications, including, but not limited to, form, function, manner of operation and use may be made without departing from the principles and concepts set forth herein. Also, as used herein, examples are meant to be illustrative only and should not be construed to be limiting in any manner.