Abstract:
A tractor-trailer for hauling a load is provided which is convertible from a conventional steering arrangement to a stinger steering arrangement to maneuver relatively long loads around tighter corners, roundabouts and other obstacles. The tractor-trailer includes a rear wheel assembly with a telescoping reach and a towing tractor including a chassis and a stinger to selectively attach to the telescoping reach of the rear wheel assembly. The stinger is movably coupled to the chassis to move between a stowed configuration for conventional steering and a deployed configuration for stinger steering.

Description:
BACKGROUND 
     Technical Field 
     This disclosure generally relates to tractor-trailers and more particularly to tractor-trailers and towing tractors thereof that are convertible from a conventional steering arrangement to a stinger steering arrangement. 
     Description of the Related Art 
     Long haul tractor-trailers are known which feature conventional steering arrangements wherein the rear wheels of the trailer are aligned parallel to the hauled load. In this manner, the rear wheels may be considered passive. As a result, it is often difficult for such vehicles, particularly those having trailers of the 53 foot variety, to maneuver around tighter corners, roundabouts and other obstacles because the rear wheels do not track with the front wheels and tend to cut corners. As such, various tractor-trailer combinations may be provided with active steering of the rear wheels to assist in negotiating corners, roundabouts and other obstacles. In this context, active steering may refer to steering arrangements in which the rear wheels may be rotated relative to the hauled load to assist in steering activities. Some examples of tractor-trailers with active steering arrangements may be found in U.S. Pat. Nos. 3,972,540, 3,993,326, and 4,660,848 and European Patent No. 0034032, which are incorporated herein by reference in their entirety. Various known tractor-trailers having active steering functionality, however, may suffer from a variety of drawbacks or deficiencies. For example, the tractor-trailers may be overly complex or may require custom tractor units that may not be well suited to tow common trailer configurations, thereby diminishing the versatility of such tractors. 
     BRIEF SUMMARY 
     Embodiments described herein provide tractor-trailers and towing tractors thereof that are particularly versatile and enable conversion between passive and active rear wheel steering configurations. More particularly, the tractor-trailers are convertible between a passive steering configuration and a stinger steering configuration. Advantageously, the tractor-trailer may be converted to a stinger steering configuration or arrangement when hauling loads in-city and converted to a conventional passive steering configuration or arrangement when hauling loads cross-country, for example. 
     In one embodiment, a tractor-trailer for hauling a load may be summarized as including a rear wheel assembly having a telescoping reach and a towing tractor including a chassis and a stinger movably coupled to the chassis to selectively attach to the telescoping reach of the rear wheel assembly. The stinger may be movably coupled to the chassis to move between a stowed configuration for passive steering and a deployed configuration for stinger steering. 
     The stinger of the towing tractor may be configured to pitch up and down when the stinger is in the deployed configuration and attached to the telescoping reach of the rear wheel assembly. Moreover, when the stinger is in the deployed configuration, it may be selectively locked to restrain movement fore and aft and side-to-side. For this purpose, the towing tractor may include a lock to selectively lock the stinger in the deployed configuration. For example, a lock may be provided which includes an inflatable member that is activated with a pressurized air system of the towing tractor. The chassis of the towing tractor may further include a rail system and the stinger may be slidably coupled to the rail system to move between the stowed configuration and the deployed configuration. When the stinger is in the deployed configuration and in an unlocked configuration, a coupling end of the stinger may be movable side-to-side to assist in aligning the stinger with the telescoping reach of the rear wheel assembly. After the stinger is aligned and connected to the telescoping reach, the stinger may be locked to limit movement thereof. For example, the stinger may be locked from moving fore and aft or from yawing side-to-side, while nevertheless being able to pitch up and down as described earlier. 
     The rear wheel assembly of the tractor-trailer may include a rear chassis and a bolster. The bolster may have a locked configuration in which the bolster is fixedly secured to the rear chassis and an unlocked configuration in which the bolster is rotatably coupled to the rear chassis. In this manner, the bolster can be selectively locked and unlocked to allow the load carried thereby to rotate relative to the rear chassis during steering activities. 
     The tractor-trailer may further comprise a trailer assembly including a coupling pin to attach to the towing tractor, and the towing tractor may include a conventional fifth wheel to receive the coupling pin of the trailer assembly. In this manner, the towing tractor of the tractor-trailers described herein may couple to various conventional trailer arrangements despite their convertible nature. In some instances, the rear wheel assembly may include a rear chassis that is slidably coupled to a container, bed or platform of the trailer assembly to move between a locked configuration, in which an orientation of the rear chassis is fixed relative to the load, and an unlocked configuration, in which the rear chassis is rotatable relative to the load to assist in steering. In this manner, the rear chassis may be repositioned beneath the container, bed or platform of the trailer assembly to activate the stinger steering configuration. In some cases, the telescoping reach may be slidably coupled to the rear wheel assembly to selectively adjust a position of the reach. Other well-known structures and devices associated with tractor trailers and steering systems, such as, for example, landing gear and other tractor-trailer structures, may be provided, but are not shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. 
    
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
         FIG. 1  is a top plan view of a tractor-trailer, according to one embodiment, in a passive steering arrangement. 
         FIG. 2  is a top plan view of the tractor-trailer of  FIG. 1  in an active, stinger steering arrangement, and in which the tractor-trailer is shown turning. 
         FIG. 3  is a side elevational view of the tractor-trailer of  FIGS. 1 and 2  in the active, stinger steering arrangement, and in which the tractor-trailer is shown in a straight-ahead position. 
         FIG. 4  is a side elevational view of a rear portion of a tractor-trailer combination, according to another embodiment, in a passive steering arrangement. 
     
    
    
     DETAILED DESCRIPTION 
     In the following description, certain specific details are set forth in order to provide a thorough understanding of various disclosed embodiments. However, one of ordinary skill in the relevant art will recognize that embodiments may be practiced without one or more of these specific details. In other instances, well-known structures and devices associated with tractor-trailers and steering systems may not be shown or described in detail to avoid unnecessarily obscuring descriptions of the embodiments. 
     Unless the context requires otherwise, throughout the specification and claims which follow, the word “comprise” and variations thereof, such as, “comprises” and “comprising” are to be construed in an open, inclusive sense, that is as “including, but not limited to.” 
     Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in connection with the embodiment is included in at least one embodiment. Thus, the appearances of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more embodiments. 
     As used in this specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the content clearly dictates otherwise. It should also be noted that the term “or” is generally employed in its sense including “and/or” unless the content clearly dictates otherwise. 
     Embodiments described herein provide tractor-trailers and towing tractors thereof that are particularly versatile and enable conversion between passive and active rear wheel steering configurations. More particularly, the tractor-trailers are convertible between a passive steering configuration and a stinger steering configuration. Advantageously, the tractor-trailer may be converted to a stinger steering configuration or arrangement when hauling loads in-city and converted to a conventional passive steering configuration or arrangement when hauling loads cross-country, for example. In addition, it is appreciated that many existing towing tractors may be modified or retrofitted with a deployable stinger assembly to provide functionalities described herein. Accordingly, some embodiments may be directed to retrofit kits and the like for towing tractors as well as towing tractors fitted with a deployable stinger. 
       FIGS. 1 through 3  illustrate one example embodiment of a tractor-trailer  100  that is particularly versatile and may be converted between a passive steering configuration or arrangement PS, as shown in  FIG. 1 , and an active stinger steering configuration or arrangement AS, as shown in  FIGS. 2 and 3 . The tractor-trailer includes a towing tractor  110  and a trailer assembly  120  that is coupleable to the towing tractor  110  to be pulled or hauled thereby. 
     The towing tractor  110  includes a cab  112  and a structural frame or chassis  114 . The frame or chassis  114  is coupled to a plurality of front wheels  116  by one or more axles. The towing tractor  110  further includes a fifth wheel  118  for coupling to a coupling pin (not shown) of the trailer assembly  120 , thereby enabling the trailer assembly  120  or a portion thereof (e.g., front end of a container, trailer bed or platform) to rotate about a pivot axis A 1 . Advantageously, it will be appreciated by those of ordinary skill in the relevant art that the fifth wheel  118  may be positioned and configured to accept various industry standard trailer configurations. In this regard, the towing tractors  110  described herein may be used in conventional hauling operations without regard to the convertible stinger steering functionality of such towing tractors  110 . 
     The trailer assembly  120  may include a rear wheel assembly  121 , which may be, for example, in the form of a dolly or other wheeled assembly. The rear wheel assembly  121  includes a rear frame or chassis  122  that is coupled to one or more rear wheels  124  by one or more axles. The rear wheel assembly  121  may further include a bolster  128  coupled to the rear frame or chassis  122  at a pivot location  126 . The bolster  128  may be configured to receive a load L, such as the aft end of a container or trailer bed or platform and to support the same during operation. The bolster  128  may be configured to include a locked configuration in which the bolster  128  is fixedly secured to the rear frame or chassis  122  and an unlocked configuration in which the bolster  128  is rotatably coupled to the rear chassis  122  about a pivot axis A 2 . One or more bolster locks  129  may be provided for this purpose. Locking devices, including locking devices associated with tractor-trailers and steering systems thereof, are well-known and are not shown or described in further detail to avoid unnecessarily obscuring descriptions of the embodiments. 
     With reference to  FIG. 1 , the bolster  128  may be locked such that it is fixedly secured to the rear frame of chassis  122  when the tractor-trailer  100  is in the passive steering PS configuration. In this locked state, the bolster  128  is unable to rotate about the pivot axis A 2  through the illustrated range of motion  130 . As a result, the rear frame or chassis  122  and rear wheels  124  are maintained parallel to the hauled load L when the bolster  128  is locked. Conversely, with reference to  FIG. 2 , the bolster  128  may be unlocked such that it is free to rotate relative to the rear frame of chassis  122  about the central axis A 2  when the tractor-trailer  100  is in the active steering AS configuration. In this unlocked state, the bolster  128  may rotate through the illustrated range of motion  130 . As a result, the rear frame or chassis  122  and rear wheels  124  may rotate relative to the hauled load L and more closely track the path of the front wheels  116  during turning activities. 
     With reference to  FIGS. 2 through 3 , the rear wheel assembly  121  may further include a telescoping reach  150  in which a compensator portion  152  is extendable to allow a coupling end  154  of the telescoping reach  150  to extend away from the rear frame or chassis  122  as the tractor-trailer  100  turns and to retract toward the rear frame or chassis  122  as the tractor-trailer  100  returns to a straight-ahead position. This extension and retraction of the compensator portion  152  of the reach  150  is represented by the arrows labeled  156 . 
     In some embodiments, the telescoping reach  150  may be movably coupled to the rear frame of chassis  122 , as represented by arrows  158 , to allow the entire reach  150  to be relocated and adjusted to accommodate different loads and/or to position the reach  150  in a storage position when the tractor-trailer  100  is operated in the passive steering PS configuration. 
     With continued reference to  FIGS. 1 through 3 , the towing tractor  110  may further include a stinger  142  having a coupling end  144  to selectively attach to the coupling end  154  of the telescoping reach  150  of the rear wheel assembly  121 . The stinger  142  may be movably coupled to the frame or chassis  114  of the towing tractor  110  to move between a stowed configuration S, as shown in  FIG. 1 , and a deployed configuration D, as shown in  FIGS. 2 and 3 . The stinger  142  may also be configured to pitch up and down when the stinger  142  is in the deployed configuration D and attached to the telescoping reach  150  of the rear wheel assembly  121 , as represented by the arrows labeled  148  in  FIG. 3 . For this purpose, the stinger  142  may have a pin connection or other coupling arrangement that enables the stinger to rotate about a transverse axis of rotation A 3 . 
     The towing tractor  110  may further include a lock mechanism  160  to selectively lock the stinger  142  in the deployed configuration D. More particularly, the stinger  142  may be selectively lockable to restrain movement of the stinger  142  fore and aft and side-to-side when in the deployed configuration D. For example, in one embodiment, the towing tractor  110  may include a lock mechanism  160  that includes an inflatable member or chamber  160   a  in fluid communication with a pressurized air system  115  of the towing tractor  110 . Pressurized air may be selectively used to inflate the inflatable member or chamber  160   a  and displace a cam or other locking structure such that it engages a pivot pin or other feature at the base of the stinger  142 . The locking mechanism  160  may nest with the pivot pin or other feature of the stinger  142  and may urge it into engagement with a stop. An intermediate flexible member or damper may be positioned between the stinger  142  and the coupling arrangement on the chassis  114  to enable some flexing of the stinger  142  relative to the chassis  114  during operation. Although one specific locking arrangement has been described, it is appreciated that a wide range of locking mechanisms  160  may be used to secure the stinger  142  in the deployed configuration D. Moreover, it is appreciated that, prior to locking the stinger  142 , the stinger  142  may be movable to yaw to side-to-side to assist in aligning the coupling end  144  of the stinger  142  with the coupling end  154  of the telescoping reach  150  of the rear wheel assembly  121 . 
     The frame or chassis  114  of the towing tractor  110  may include a rail system  146  or other structure integral therewith or coupled thereto to enable the stinger  142  to move between the stowed configuration S, in which the stinger  142  may be completely or substantially concealed from view, and the deployed configuration D, in which the stinger  142  may be attached to the telescoping reach  150 . The base end of the stinger  142  may be slidably coupled to the rail system  146  for moving between the stowed configuration S and the deployed configuration D. While in the stowed configuration S, an additional lock mechanism, catch or other structure (not shown) may secure the stinger  142  in position to prevent it from dislodging or inadvertently deploying when the tractor-trailer  100  is used to haul loads L in the passive steering configuration PS shown in  FIG. 1 . 
     Although the example embodiment of  FIGS. 1 through 3  is shown as including a rear wheel assembly  121  with a rotatable bolster  128 , in other embodiments the tractor-trailer  100  may be provided with a rear chassis  122 ′ that is slidably coupled to a container, bed or platform P of the trailer assembly  120 ′ to move fore and aft in a longitudinal direction aligned with the load, as illustrated in  FIG. 4 . The rear chassis  122 ′ may move between a locked configuration (e.g., the rear position shown in  FIG. 4 ) in which an orientation of the rear chassis  122 ′ is fixed relative to the container, bed or platform P of the trailer assembly  120 ′ and an unlocked configuration in which the rear chassis  122 ′ is rotatable relative to the container, bed or platform P of the trailer assembly  120 ′ to assist in steering. In this manner, the rear chassis  122 ′ may be displaced linearly to engage a turntable  123  or other rotatable device that is attached to the container, bed or platform P of the trailer assembly  120  to rotate about an axis A 4 . For this purpose, the rear chassis  122 ′ may include an upper portion  125  that movably engages a linear rail system  131  that extends from a static rear portion  127  of the container, bed or platform P to the turntable  123 . The upper portion  125  may be lockable to along the length of the rail system  131  such that the rear chassis  122 ′ can be locked to the static rear portion  127  to limit rotation of the rear chassis  122 ′ relative to the container, bed or platform P, or such that the rear chassis  122 ′ can be locked to the turntable  123  to enable rotation of the rear chassis  122 ′ relative to the container, bed or platform P. The active steering configuration AS may therefore be activated by moving the rear wheel assembly  121 ′ longitudinally (in this case forward) with respect to the load (e.g., container, bed or platform P), as represented by the arrow labeled  159 . In such embodiments, it may be particularly advantageous to enable longitudinal adjustment of the telescoping reach  150 , as represented by the arrows labeled  158 . 
     Moreover, aspects of the various embodiments described above can be combined to provide further embodiments. All of the U.S. patents, U.S. patent application publications, U.S. patent applications, foreign patents, foreign patent applications and non-patent publications referred to in this specification and/or listed in the Application Data Sheet, including U.S. Provisional Application No. 61/785,447 filed Mar. 14, 2013, are incorporated herein by reference in their entirety. Aspects of the embodiments can be modified, if necessary to employ concepts of the various patents, applications and publications to provide yet further embodiments. 
     These and other changes can be made to the embodiments in light of the above-detailed description. In general, in the following claims, the terms used should not be construed to limit the claims to the specific embodiments disclosed in the specification and the claims, but should be construed to include all possible embodiments along with the full scope of equivalents to which such claims are entitled. Accordingly, the claims are not limited by the disclosure.