Abstract:
A rail vehicle having a single frame assembly and a movable platform coupled thereto is provided. The rail vehicle indexes, i.e. advances intermittently, along railroad rails. The movable platform advances in a single direction at a generally steady speed as the rail vehicle indexes along a railroad. The platform is the floor of, or a base for, a cabin preferably having a seat, roof support, and controls for the operator. The platform rides longitudinally with the machine on rollers or slides, thus separating the operator and controls from the rest of the machine. Thus, while the rail vehicle moves in an abrupt stop-and-go manner, the platform and the operator move generally consistently in a single direction.

Description:
CROSS REFERENCE TO RELATED APPLICATION 
     This application claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent Application Ser. No. 61/001,413, filed Nov. 1, 2007 entitled, Continuous moving platform on rail vehicle. 
    
    
     FIELD OF THE INVENTION 
     This application relates to railroad maintenance vehicles and, more specifically to a railroad maintenance vehicle having a platform that moves generally continuously at one speed and in one direction while the rail vehicle repeatedly starts and stops at short intervals. 
     BACKGROUND INFORMATION 
     Generally, a railroad includes at least one pair of elongated, substantially parallel rails coupled to a plurality of laterally extending ties and which are disposed on a ballast bed. The rails are coupled to the ties by metal tie plates and/or spring clips. The ballast is a hard particulate material such as, but not limited to, gravel. Ties may be made from either concrete or wood. The ballast filled space between ties is called a crib. Concrete ties are typically spaced about twenty-four inches apart, whereas wood ties are spaced about nineteen and a half inches apart. 
     During installation and maintenance various operations must be performed at each tie location. For example, ballast must be “tamped,” or compressed, to ensure that the ties, and therefore the rails, do not shift. A tamping device, not surprisingly called a “tamper,” typically consists of at least two pairs of work heads mounted on a motorized vehicle structured to travel on the rails. A work head includes a pair of elongated, vertically extending tools structured to move together in a pincer-like motion as well as being structured to move vertically. The tools, preferably, have two prongs spaced so that each prong may be disposed on opposite lateral sides of a rail. The work head further includes a vibration device structured to rapidly vibrate the tools. In this configuration, a work head may be disposed above a tie with one tool on either side of the tie. Further, the prongs of each tool are disposed on either sides of the rail. Thus, a tool prong is disposed above, and just outside, of each corner of the rail/tie interface. At least two work heads are used so that one work head may be placed over each rail. 
     Initially, the tools are generally vertical and parallel to each other. When actuated, the tool head moves vertically downward so that the tips of the tools, that is the tips of the prongs, are inserted into the ballast to a predetermined depth that is, preferably, below the bottom of the tie. The tools are then brought together in a pincer-like motion thereby compressing the ballast under the tie. Actuation of the vibration assembly further compresses the ballast under the tie. Once the vibration operation is complete, the tools are returned to a substantially vertical orientation and lifted out of the ballast. The tamper then advances to the next tie and the operation is repeated. Typically, a tamping operation lasts about three seconds. 
     The act of advancing the tamper to the next work location may be called “indexing.” Indexing may be performed one tie at a time, or multiple ties at a time. For example, some tamping machines include a set of tamping tools at the front end of the rail vehicle and another set of tamping tools at the back end of the vehicle. After identifying a tie at the work site as the first tie, the front set of tamping tools may work upon the “odd” ties and the back set of tamping tools may work upon the “even” ties. In this situation, the tamper vehicle would index, i.e. move forward, two ties at a time. The tamper vehicle, as well as other rail installation and maintenance vehicles, typically locates the tie/rail interface by locating the tie plate that connects the rail to the tie, e.g. by utilizing a metal detector that travels beside the rail. 
     On conventional indexing machinery, such as, but not limited to tampers, the equipment starts and stops at different intervals as required by the work that has to be performed. In most railroad applications, the indexing motion of different machines is dictated by the tie spacing. Most of the work required on the track is usually performed at each tie location, i.e., tamping of the ballast supporting the ties, lifting and lining of the track panel, spiking of the tie plates for fastening the ties to the rail, anchor removal and/or application, plugging of spike holes, clip application and removal, etc. 
     Conventional equipment performing track maintenance consists mostly of machines carrying one or two operators. These machines accelerate (under their own power), to the ties requiring work. As they approach the tie, they rapidly slow down to a stop, perform the required work and index to the next tie to repeat the cycle. This work is performed sometimes at a cycle rate of less than three seconds. During this acceleration and deceleration, the operator is being pushed backward and forward by the dynamics of the machine he is riding. The operator is working in a very uncomfortable environment, subject to fatigue, stress and difficulty to perform the required duties of his work. 
     One existing machine designed to alleviate the problem on the operator, consists of splitting the machine in two segments: one half of the machine does the indexing and a first work function while the other half moves at a constant speed while sometimes performing a different work function. The operator sits on the continuous moving portion of the machines. This system is normally employed on large machines and works in a satisfactory manner, however, the system is very expensive and cumbersome. For example, two different machines and two drives are required, the system is not practical for smaller and lighter machines due to the additional weight required to achieve an effective tractive effort, and the system requires sophisticated electronics required to control the motion of the two segments relative to each other. That is, without sophisticated electronics controlling the motion of the two segments, the two segments may collide and damage each other and/or injure an operator. 
     SUMMARY OF THE INVENTION 
     At least one embodiment of the disclosed invention provides a rail vehicle having a single frame assembly and a movable platform coupled thereto. The movable platform advances in a single direction at a generally steady speed as the rail vehicle indexes along a railroad. This overcomes the disadvantages of having a bifurcated machine. The platform is the floor of, or a base for, a cabin preferably having a seat, roof support, and controls for the operator. The platform rides longitudinally with the machine on rollers or slides, thus separating the operator and controls from the rest of the machine. A movement device such as, but not limited to, pneumatic or hydraulic cylinders, electric, pneumatic or hydraulic motors or electric linear actuators are structured to move the platform longitudinally with respect to the machine frame assembly. The rail vehicle also has a navigation system equipped with an encoder wheel, or other tracking device, that measures the linear movement of the machine on the track. If an encoder wheel is used, the motion of the vehicle is measured in pulses per revolution. While the encoder wheel is turning in a clockwise motion, (forward), the actuator on the platform retracts proportionally to the number of pulses of the encoder wheel (interpreted by a PLC or computer). When the encoder wheel is not turning, the actuator on the platform moves the platform forward at a speed consistent with the platform prior speed relative to the ground. 
     In this configuration, the operator remains generally immobile in respect to the machine lurching forward. As the machine keeps moving forward, the platform is pulled backwards in respect of the machine while maintaining a generally consistent forward motion relative to the ground. As the machine is being decelerated to a stop, the rate and number of pulses of the encoder wheel cause the actuator controlling the platform position to push the operator station forward at variable adjustable rates. While the machine is stopped to perform the work, the platform keeps moving forward relative to the ground, generally, at the same speed as before. As the machine starts to index forward, the cycle of the platform is repeated. Thus, in relation to the ground, the platform is continually moving forward at a generally consistent speed. This system substantially eliminates fatigue and stresses on the operator, and it is adaptable to any type of rail vehicle with few modifications of the operator&#39;s platform. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       A full understanding of the invention can be gained from the following description of the preferred embodiments when read in conjunction with the accompanying drawings in which: 
         FIG. 1  is a side view of a railroad maintenance vehicle having a movable platform in an aft position relative to the vehicle frame assembly. 
         FIG. 2  is a side view of a railroad maintenance vehicle having a movable platform in a medial position relative to the vehicle frame assembly. 
         FIG. 3  is a side view of a railroad maintenance vehicle having a movable platform in a forward position relative to the vehicle frame assembly. 
     
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     As used herein, a “single frame assembly” means that the frame assembly moves as a unit relative to a fixed point and that the front of the frame assembly is at a fixed distance from the back of the frame assembly. That is, while the frame assembly may have two or more parts that are articulated relative to each other, the frame assembly does not have distinct units or segments structured to travel on a pair of rails. 
     As used herein, “coupled” means a link between two or more elements, whether direct or indirect, so long as a link occurs. Unless otherwise noted, this does not include elements resting on, or supported by, a surface. For example, a seat in an automobile is coupled to the engine via the frame and other components. The seat is not, however, coupled to an adjacent automobile via the ground. 
     As used herein, “directly coupled” means that two elements are directly in contact with each other. 
     As used herein, “fixedly coupled” or “fixed” means that two components are coupled so as to move as one while maintaining a constant orientation relative to each other. 
     A rail vehicle  10 , shown as a tamping machine  12 , includes a single frame assembly  14 , a propulsion device  16  structured to move the rail vehicle  10 , an operating device  18 , shown as at least one tamping device  20  structured to tamp ties as set forth above, a navigation system  24  and a movable platform assembly  30  having a platform  32  structured to support an operator cabin  34 . The platform  32  may be supported in many ways including, but not limited to a cantilever manner, as shown in  FIG. 1 ; the platform  34  may have one or more wheels  36  on the lower side thereof which may, or may not, travel in tracks (not shown), as shown in  FIG. 2 , and the platform  32  may be supported by one or more rails  38  as shown in  FIG. 3 . 
     As is known in the art, the rail vehicle  10  moves over a pair of rails  1  disposed on a series of ties  2  which are further disposed on a bed of ballast  3 . The rail vehicle frame assembly  14  includes a plurality of rigid frame members  15  and a plurality of rail wheels  17  structured to travel on the rails  1 . 
     In operation, the rail vehicle  10  stops when the at least one tamping device  20  is disposed over a first tie  2 . The at least one tamping device  20  then tamps the first tie  2 , as described above. The rail vehicle  10  then advances until the at least one tamping device  20  is disposed over another, second tie  2 . The at least one tamping device  20  then tamps the second tie  2 . This operation is repeated for each tie  2 . As each tamping operation lasts for just a few seconds, the rail vehicle  10  makes a number of starts and stops while moving along the rails  1 . Thus, the frame assembly  14  moves with a rapid intermittent motion. Alternate embodiments include two or more tamping devices  20 . Where there are two or more tamping devices  20 , the rail vehicle  10  may advance over more than one tie  2  for each cycle. For example, if alternating ties  2  are identified as “odd” and “even” numbered ties  2 , and if there are two tamping devices  20 , the rail vehicle  10  typically advances over two ties  2  so that a first tamping device  20  tamps the “odd” numbered ties  2  and a second tamping device  20  tamps the “even” numbered ties  2 . 
     The navigation system  24  is structured to track the position of the rail vehicle  10  relative to a fixed location, such as, but not limited to, a location on the ground, as well as the position of each tie  2 . The navigation system  24  is further structure to control the propulsion device  16  to effect the forward motion of the rail vehicle  10  and to stop the rail vehicle  10  when the at least one tamping device  20  is positioned over the tie  2  to be tamped. That is, the navigation system  24  includes, or communicates with, a tie detection system (not shown) as is known in the art. 
     The movable platform assembly  30  also includes a movement device  40  structured to move the platform  32  forward and aft relative to the rail vehicle frame assembly  14 . More specifically, the movement device  40  includes a control device  42 , preferably a programmable device such as, but not limited to, a programmable logic circuit or computer. The movement device  40  has an actuator  41  (shown schematically) which may be, but is not limited to, pneumatic or hydraulic cylinders, electric, pneumatic or hydraulic motors or electric linear actuators. The movement device actuator  41  is coupled to, and structured to move, the platform  32  longitudinally with respect to the frame assembly  14 . The movement device  40  is further structured to monitor the position of the platform  32  relative to the rail vehicle frame assembly  14 . This may be accomplished in many ways including, but not limited to, monitoring the extension of the pneumatic or hydraulic cylinders, having positioning sensors disposed on the rail vehicle frame assembly  14  and/or platform  32 , or having a draw string transducer, aka a string pot, extending between the rail vehicle frame assembly  14  and the platform  32 . The “positioning data” is converted to an electronic signal and communicated to the control device  42 . The control device  42  is also in electronic communication with the navigation system  24  and structured to receive movement data therefrom, as described below. The control device  42  is structured to actuate the movement device actuator  41  to move the platform  32  forward or aft relative to the rail vehicle frame assembly  14  in response to the movement of the rail vehicle frame assembly  14  relative to a fixed location. More specifically, the control device  42  is structured to maintain the platform  32  moving forward relative to a fixed location at a generally constant speed regardless of the motion of the rail vehicle frame assembly  14 . 
     The navigation system  24  is, preferably, equipped with an encoder wheel  44 , or other tracking device, that measures the generally linear movement of the rail vehicle  10  over the rails  1 . If an encoder wheel  44  is used, the motion of the rail vehicle  10  is measured in pulses per revolution. That is, the speed (rotation/time) for each revolution of the encoder wheel  44  is tracked. While the rail vehicle frame assembly  14  is moving forward, the encoder wheel  44  is turning in a counterclockwise motion, as shown in the figures. The speed of the rail vehicle frame assembly  14 , or “movement data,” is determined either constantly (analog) or, more typically, many times each second (digital), and that data is converted to an electronic signal and communicate the signal to the control device  42 . Thus, the control device  42  is structured to compare the positioning data from the movement device  40  to the movement data from the navigation system  24  and determine the relative motion of the rail vehicle frame assembly  14  and the platform  32  and to adjust the motion of the platform  32 , that is, actuate the movement device actuator  41  to move the platform  32  forward or aft, so that said platform  32  moves forward relative to a fixed location at a generally constant speed. 
     Again, using a typical tamping operation as an example, the rail vehicle frame assembly  14  will move forward rapidly, stop and perform a tamping operation, then move forward rapidly again until the tamping device  20  is over the next tie  2  to be tamped, stop and perform the tamping operation on the second tie  2 . This cycle, move-stop-tamp, is repeated until all ties  2  are tamped. In order for the movement device  40  to provide a constant forward motion to the platform  32 , the movable platform assembly  30  must move the platform  32  in different directions relative to the rail vehicle frame assembly  14  depending upon the stage of the cycle. 
     For the sake of the following discussion, the platform  32  will be described as having a forward position, a medial position, and an aft position. It is understood that these positions are not fixed relative to the vehicle frame assembly  14  but vary depending upon how far the vehicle frame assembly  14  moves during each cycle as described below. It is also understood that the distance between the forward position and the aft position is, typically, not the total amount of travel available to the platform  32 . That is, the movement device actuator  41  is able to move the platform  32  further forward or aft than is required for a typical tamping operation. 
     Further, for the sake of the following discussion, the operation will be described as occurring some time after the first tie  2  has been tamped and the platform  32  is moving forward at a constant speed relative to a fixed point. It is noted that for the first tie  2  to be tamped, the platform  32  may be still relative to the rail vehicle frame assembly  14  or moving forward at a constant speed relative to a fixed point. Further, it is understood that the tamping cycle will be considered to start just as the tamping devices  20  have completed tamping a tie  2  and have withdrawn to the retracted/upper position. 
     Thus, once the tamping devices  20  have completed tamping a tie  2  and have withdrawn to the retracted/upper position, the rail vehicle frame assembly  14  moves rapidly forward to the next tie  2 . At this time, the control device  42  compares the positioning data from the movement device  40  to the movement data from the navigation system  24  and determines the relative motion of the rail vehicle frame assembly  14  and the platform  32 . As the control device  42 , as part of the movement device  40 , is structured to maintain the platform  32  moving forward at a generally constant speed, the control device  42  causes the movement device actuator  41  to move the platform  32  backwards relative to the rail vehicle frame assembly  14 . This backwards movement of the platform  32  relative to the rail vehicle frame assembly  14  is not at a constant speed. That is, the vehicle frame assembly  14  may lurch forward and stop. Thus, the control device  42  is structured to initially move the platform  32  backwards relative to the rail vehicle frame assembly  14  at a rapid speed. Then, as the forward motion of the rail vehicle frame assembly  14  slows and stops, the relative motion of the platform  32  to the rail vehicle frame assembly  14  also slows, but does not stop. The platform  32  does not move at the same speed as the rail vehicle frame assembly  14 . The platform  32  moves slightly slower in a rearward direction relative to the rail vehicle frame assembly  14 , while the rail vehicle frame assembly  14  moves forward relative to a fixed location. Thus, the platform  32  advances slightly in the longitudinal direction of the rails as the rail vehicle frame assembly  14  indexes an entire tie  2 , or more, forward.  FIG. 1  represents the relative position of the platform  32  relative to the rail vehicle frame assembly  14  at this time. That is, the platform  32  is in the rear position and has just finished a rearward motion as indicated by arrow A. 
     When the rail vehicle frame assembly  14  stops, i.e. when the tamping devices  20  are disposed over the next tie  2  to be tamped, the control device  42  causes the movement device actuator  41  to move the platform  32  forward relative to the rail vehicle frame assembly  14 . This allows the platform  32  to continue to move in the same direction, and at a regular speed, relative to a fixed location on the ground. Further, because the motion of the platform  32  is constant, the operator is not adversely affected by the start-and-stop motion of the rail vehicle frame assembly  14 . The platform  32  continues to move forward relative to the rail vehicle frame assembly  14  during the operation of the tamping devices  20 .  FIG. 2  represents the relative position of the platform  32  relative to the rail vehicle frame assembly  14  at this time. That is, the platform  32  is in the medial position and moving forward as indicated by arrow A. 
     As the tamping operation is being completed, the platform  32  moves into the forward position, shown in  FIG. 3 . Once the tamping operation is complete and the tamping devices  20  are withdrawn to the retracted/upper position, the cycle begins again. That is, once the platform  32  is in the forward position, the rail vehicle frame assembly  14  may move forward again. Once the rail vehicle frame assembly  14  begins to move rapidly forward, the control device  42  is structured to move the platform  32  backwards relative to the rail vehicle frame assembly  14  at a rapid speed as described above. 
     Thus, despite the fact that the rail vehicle frame assembly  14  is moving in a stop-and-go manner, the platform  32  moves forward at a generally constant speed. The relative motion of the platform  32  relative to the rail vehicle frame assembly  14  is accomplished by comparing the positioning data from the movement device  40  to the movement data from the navigation system  24 . Further, it can be seen that because the platform  32  moves forward at a generally constant speed and because the ties are not always evenly spaced, the forward, medial, and aft positions of the platform  32  may vary. That is, for example, when two ties  2  are close together, the forward motion of the rail vehicle frame assembly  14  will occur for a shorter period of time and for a shorter distance. Thus, the platform  32  will not move a great distance rearwardly as the vehicle frame assembly  14  moves between these two ties  2 . Conversely, if two ties  2  have a greater than normal spacing, the forward motion of the rail vehicle frame assembly  14  will occur for a longer period of time and for a greater distance. Thus, the platform  32  will move a greater distance rearwardly as the vehicle frame assembly  14  moves between these two ties  2 . 
     Generally, the rail vehicle  10  moves forward at a greater speed than the platform  32 . Thus, when the rail vehicle frame assembly  14  is moving forward to position the at least one tamping device  20  over a tie  2 , the platform  32  is moving backward relative to the rail vehicle frame assembly  14 . The platform  32  moves backwards at a speed slower than the rail vehicle frame assembly  14  is moving forward, thus the platform  32  actually moves forward relative to a fixed location. When the rail vehicle frame assembly  14  is stopped to engage the at least one tamping device  20 , the platform  32  is moving forward relative to the rail vehicle frame assembly  14 . In this configuration, the platform  32  moves forward relative to a fixed location at a generally constant speed. However, while the platform  32  moves forward relative to a fixed location at a generally constant speed, the actual speed of the platform  32  relative to a fixed location may be varied. That is, the tamping operations, or other work, may require more time at one tie  2  location than at a different tie  2  location. Accordingly, the control device  42  is also structured to adapt the speed of the platform  32  based on additional data. 
     For example, during a tamping operation the platform  32  is moving forward at a first speed. Sensors (not shown) on the at least one tamping device  20  may provide feedback indicating the progress of the tamping operation. The feedback is input into the control device  42 . Alternately, the operator may provide the input into the control device  42  indicating that the tamping operation is slow or not complete. If the control device receives input indicating that the tamping operation requires additional time, the control device  42  adjusts the speed, i.e. slows the speed, of the platform  32  accordingly. That is, in this example, the control device  42  slows the forward speed of the platform  32  relative to both the rail vehicle frame assembly  14  and a fixed location. If the tamping operation requires an extended period of time, i.e. more than a typical tamping operation, the control device  42  gently slows the platform  32 , and may stop the platform  32  motion, until the tamping operation is completed. Preferably, the control device  42  causes the movement device  40  to stop the platform  32  at a forward location, as described above. Then, when the tamping operation is complete, the control device  42  causes the movement device  40  to move the platform  32  rearwardly as the rail vehicle frame assembly  14  moves forward to the next location. As set forth above, the movement of the platform  32  rearwardly is at a slightly slower speed than the forward movement of the rail vehicle frame assembly  14 . The combined effect of these two motions is that the platform  32  starts to move slowly forward relative to a fixed location. Thus, while the platform  32  may stop moving, the change in motion is not abrupt. That is, the platform  32  is structured to not start or stop in an abrupt manner. 
     While specific embodiments of the invention have been described in detail, it will be appreciated by those skilled in the art that various modifications and alternatives to those details could be developed in light of the overall teachings of the disclosure. Accordingly, the particular arrangements disclosed are meant to be illustrative only and not limiting as to the scope of invention which is to be given the fall breadth of the claims appended and any and all equivalents thereof.