Patent Publication Number: US-6338605-B1

Title: Tractor and system for unloading trailers from railcars

Description:
TECHNICAL FIELD OF THE INVENTION 
     This invention relates in general to the transportation of truck trailers on flat bed railcars and, in particular to, a tractor and system for unloading truck trailers from railcars that prevents inadvertent knockdown of the stanchion that supports the trailer on the railcar during transportation thereof. 
     BACKGROUND OF THE INVENTION 
     Without limiting the scope of the present invention, its background is described with reference to transporting trailers on flat bed railcars, as an example. 
     It is well known in the art of truck trailer transportation over the railroad system, that the trailers must be loaded and secured to railcars. The process typically involves backing a tractor that is attached to the trailer onto the railcar until the trailer reaches the desired location. Once in this position, a hook from the tractor may be engaged with a stanchion on the railcar that will be used to support the trailer during transportation on the railcar. Once the hook is engaged with the stanchion, the driver may set the trailer brakes, disengage the tractor from the kingpin of the trailer and pull slowly forward. 
     Now, as the tractor is moving forward, the trailer remains stationary. Thus, as the tractor moves forward, the tractor&#39;s fifth wheel moves toward the front of the trailer, making room for the top plate of the stanchion. As the driver continues to move forward, the vertical strut of the stanchion is pulled to the upright position. When the vertical strut is erect and locked, a release trigger on the stanchion is placed in its fully extended position. With the stanchion properly erected under the trailer, the driver lowers the tractor&#39;s fifth wheel thereby lowering the trailer onto the top plate of the stanchion. 
     Next, the driver disengages the hook from the stanchion and pulls forward to a point where the tractor&#39;s fifth wheel is partially out from under the trailer&#39;s threshold plate. The driver then raises the fifth wheel to a position above the level of the trailer threshold plate, releases the trailer brakes and pushes the trailer back until the trailer&#39;s kingpin engages the stanchion&#39;s top plate which ties the trailer to the stanchion and secures the trailer to the railcar. The driver may then exhaust the brake hoses, disconnect the hoses from the trailer and drive off the deck of the railcar. The trailer may now be transported on the railcar over the rail system. 
     Once the trailer arrives at its intended location, the trailer must now be removed from the railcar. To achieve this, the driver backs the tractor onto the railcar and under the front of the selected trailer with the tractor&#39;s fifth wheel in its lowest position. The driver then raises the fifth wheel into contact with the threshold plate under the trailer and connects the trailer air brake hoses. The driver then applies the trailer brakes and backs the tractor against the release trigger of the stanchion. This causes the release trigger to depress and in turn release the top plate of the stanchion from the kingpin allowing the vertical strut of the stanchion to fold down. With the stanchion out of the way and the full weight of the trailer transferred to the tractor, the driver backs further to couple the fifth wheel of the tractor with the trailer&#39;s kingpin and tests the coupling by applying forward motion against the still applied trailer brakes. The driver may then release the trailer brakes and remove the trailer from the railcar. 
     It has been found, however, that with conventional tractors, when the driver backs the tractor on the railcar toward the stanchion, the release trigger of the stanchion may be inadvertently contacted by the trigger actuator of the tractor causing the premature release of the top plate of the stanchion from the kingpin and prematurely allowing the vertical strut of the stanchion to fold down. Attempts have been made to overcome this problem, such as that described in U.S. Pat. No. 5,452,982. The system described therein, however, requires the driver of the tractor to back up into the stanchion until the bumper of the tractor contacts the stanchion, move the tractor forward to provide clearance between the tractor and the stanchion, operate the trigger actuator from a retracted position to an extended position and then back the tractor up again such that the trigger actuator of the tractor will engage the trigger of the stanchion, thereby allowing the vertical strut of the stanchion to fold down. 
     Therefore, a need has arisen for a tractor and system that avoids inadvertent contact between the trigger actuator of the tractor and the trigger of the stanchion to avoid premature fold down of the vertical strut of the stanchion. A need has also arisen for such a tractor and system that does not require complicated tractor maneuvering including multiple steps of moving the tractor backward and forward to knock down the stanchion to avoid the inadvertent contact between the trigger actuator of the tractor and the trigger of the stanchion. 
     SUMMARY OF THE INVENTION 
     The present invention disclosed herein provides a tractor and system for removing a trailer from a railcar that avoids inadvertent contact between the trigger actuator of the tractor and the trigger of the stanchion, which prevents premature fold down of the vertical strut of the stanchion. The tractor and system of the present invention achieve this result without requiring complicated tractor maneuvering such as multiple steps of moving the tractor backward and forward to knock down the stanchion. 
     The tractor of the present invention comprises a trigger actuator and a bumper that interact with the stanchion on the railcar. The trigger actuator is fixed to the frame of the tractor in a single position such that it may selectively interact with the trigger of the stanchion to knock down the stanchion and allow coupling of the trailer with the tractor. The trigger actuator selectively interacts with the trigger of the stanchion based upon the position of the bumper. Specifically, when the bumper is in the extended position and the tractor is adjacent to the stanchion, the trigger actuator does not engage the trigger of the stanchion. Conversely, when the bumper is in the retracted position and the tractor is adjacent to the stanchion, the trigger actuator may engage the trigger of the stanchion. 
     To prevent interaction between the trigger actuator of the tractor and the trigger of the stanchion when the bumper is in the extended position, the bumper extends to a point beyond the trigger actuator. To allow interaction between the trigger actuator of the tractor and the trigger of the stanchion when the bumper is in the retracted position, the bumper may be retracted to a point at or behind the trigger actuator. 
     The system of the present invention comprises a stanchion on the railcar that has raised and lowered positions. The stanchion includes a lock for locking the stanchion in the raised position and a trigger for unlocking the lock. The system also comprises a tractor having a trigger actuator fixably mounted thereto for engaging the trigger of the stanchion and a bumper for selectively allowing and preventing the trigger actuator from engaging the trigger. The trigger actuator is prevented from engaging the trigger when the bumper is in its extended position as the bumper comes in contact with the stanchion before the trigger actuator comes in contact the trigger. To allow engagement of the trigger actuator with the trigger, however, the bumper is operated to the retracted position such that the trigger actuator will contact the trigger before the bumper contacts the stanchion, thereby unlocking the lock and allowing the stanchion to fold down. 
     The method of the present invention involves positioning the tractor on the railcar, backing the tractor toward the stanchion until the bumper contacts the stanchion without engaging the trigger actuator of the tractor with the trigger of the stanchion, operating the bumper from the extended position to the retracted position and backing the tractor toward the stanchion to engage the trigger actuator of the tractor with the trigger of the stanchion, thereby unlocking the stanchion and operating the stanchion to its lowered position. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a more complete understanding of the present invention, including its features and advantages, reference is now made to the detailed description of the invention, taken in conjunction with the accompanying drawings in which like numerals identify like parts and in which: 
     FIG. 1 is a side elevation view of a tractor of the present invention backing up to a trailer supported by a stanchion on a railcar; 
     FIG. 2 is a side elevation view of a tractor of the present invention with the bumpers thereof in contact with a stanchion supporting a trailer on a railcar; 
     FIG. 3 is a side elevation view of a tractor of the present invention with the bumper in the retracted position and the trigger actuator in contact with the trigger of a stanchion that is supporting a trailer on a railcar; and 
     FIG. 4 is a side elevation view of a tractor of the present invention coupled to a trailer after knocking down a stanchion on a railcar. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the making and using of various embodiments of the present invention are discussed in detail below, it should be appreciated that the present invention provides many applicable inventive concepts which can be embodied in a wide variety of specific contexts. The specific embodiments discussed herein are merely illustrative of specific ways to make and use the invention, and do not delimit the scope of the invention. 
     Referring to FIG. 1, a tractor backing up to a trailer supported by a stanchion on a flat bed railcar is schematically depicted and generally designated  10 . As explained above, a trailer  12  may be transported over the railroad system by securing trailer  12  to a railcar  14  (only the surface of which is depicted). Trailer  12  is initially attached to railcar  14  by operating a stanchion  16  from the lowered position to the raised position using a hook  18  of a tractor  20  as is well known in the art. Once stanchion  16  is in its raised position, the driver of tractor  20  may set the trailer brakes, disengage tractor  20  from the kingpin (not pictured) of trailer  12  and pull slowly forward. 
     As the fifth wheel  22  of tractor  20  moves forward, the top plate or fifth wheel  24  of stanchion  16  couples with the kingpin of trailer  12 . As the driver continues to move forward, the vertical strut  26  of stanchion  16  is pulled to the upright position. When vertical strut  16  is erect and locked, a release trigger  28  of stanchion  16  is placed in its fully extended position placing stanchion  16  in the position depicted in FIG.  1 . 
     To unload trailer  12  from railcar  14 , tractor  20  is backed up onto railcar  14  until tractor  20  is under trailer  12 . A pair of positively controlled bumpers  30 , only one of which is shown, extend rearwardly from tractor  20  and are operable between an extended position and a retracted position. A fluid motor  32  controls the position of bumpers  30 . Tractor  20  also has a trigger actuator  34  that is fixably mounted to the tractor frame in a single position. Trigger actuator  34  selectively engages and actuates trigger  28  on vertical strut  26  of stanchion  16 . 
     As best seen in FIG. 2, the bumpers  30  are initially extended beyond the trigger actuator  34  such that when tractor  20  is backed up to stanchion  16 , bumpers  30  engage vertical strut  26  before trigger actuator  34  comes in contact with trigger  28  of stanchion  16 . As trigger actuator  34  is fixed to the frame of tractor  20 , trigger actuator  34  may be selectively prevented from engaging trigger  28  based upon the position of bumpers  30 . Specifically, when bumpers  30  are in the extended position and tractor  20  is adjacent to stanchion  16 , trigger actuator  34  does not engage trigger  28  of stanchion  16 . To prevent such interaction between trigger actuator  34  of tractor  20  and trigger  28  of stanchion  16  when tractor  20  is backing up, bumpers  30  extend to a point beyond trigger actuator  34  to ensure that bumpers  30  contact vertical strut  26  of stanchion  16  before trigger actuator  34  of tractor  20  contacts trigger  28  of stanchion  16 . 
     As depicted in FIG. 3, the driver may now operate bumpers  30  from the extended position to the retracted position using fluid motor  32 . Once bumpers  30  are operated from the extended position to the retracted position, trigger actuator  34  is in a position at or beyond bumpers  30 . In this configuration of bumpers  30  and as tractor  20  backs up, trigger actuator  34  of tractor  20  will contact trigger  28  of stanchion  16  before bumpers  30  engage vertical strut  26 . With further backward movement of tractor  20 , trigger actuator  34  depresses trigger  28  to unlock stanchion  16 , strut  26  and fifth wheel  24  such that stanchion  16  can collapse when engaged by bumpers  30 . 
     As best seen in FIG. 4, with continued backward movement of tractor  20  stanchion  16  collapses with the weight of trailer  12  shifting from fifth wheel  24  of stanchion  16  to fifth wheel  22  of tractor  20 . Thereafter, additional backward movement of tractor  20  causes the trailer king pin  36  to couple with fifth wheel  22  of tractor  20 . The driver may now connect the brake hoses of tractor  20  to trailer  12  and releases the trailer brakes to allow removal of trailer  12  from railcar  14 . 
     While this invention has been described with a reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications and combinations of the illustrative embodiments as well as other embodiments of the invention, will be apparent to persons skilled in the art upon reference to the description. It is, therefore, intended that the appended claims encompass any such modifications or embodiments.