Patent Publication Number: US-2015075645-A1

Title: Handle Mechanism to Prohibit Accidental Valve Operation

Description:
FIELD OF THE INVENTION 
     This invention relates to manually actuated outlet valves for use on a railway tank car. 
     BACKGROUND OF THE INVENTION 
     Conventional railway tank cars have an outlet valve at the bottom of the tank for discharging liquid contents from the tank. An outlet adapter or nozzle normally attaches to the valve to enable the connection of a pipe, hose, or other conduit to discharge liquid into a receiving container. Threaded caps are often used to plug the outlet valve when the tank car is in transit. When it is desired to discharge liquid from the tank car, the cap is unscrewed from the nozzle, and a hose is threaded onto the nozzle in place of the cap. Then the bottom outlet valve is opened in order to discharge the liquid. 
     On most tank cars, the bottom outlet valve is a heavy-duty ball valve projecting slightly downward from the tank. The valve is located above the railway tracks and is directed straight downward. A skid is mounted permanently to the bottom of the tank car surrounding the valve to protect the valve from accidental impact. A valve stem extends horizontally outward from the valve and through the skid. The valve stem has an axis of rotation that lies in a generally horizontal plane and is also perpendicular to the longitudinal axis of the tank car. To open and close the valve, the valve stem is rotated between a first angular position corresponding to the valve being in a closed position and a second angular position corresponding to the valve being in a fully open position. If desired, the angular position of the valve stem may be positioned between the first and second angular positions to partially open the valve. It is widespread in the art to provide an extended handle so that a person can operate the outlet valve and rotate the valve stem when located beside the tank car outside of the tracks. An example of an extended handle assembly is disclosed in U.S. Pat. No. 4,941,410 entitled “Outlet Valve Assembly with an Extended Handle for a Railway Tank Car” assigned to Union Tank Car Company, invented by Thomas H. Dalrymple and Richard Zagrocki, and issuing on Jul. 17, 1990, incorporated by reference herein. The use of an extended handle eliminates the need for a person to crouch down or sit beneath the railway tank car to operate the outlet valve on the bottom of the tank. 
     Bottom outlet valves on tank cars may be unintentionally opened during derailment or other accidental contact. For example, the extended handle illustrated in the above incorporated &#39;410 patent is not designed to maintain the valve in a closed position in the event that a large unexpected force contacts the handle. Some in the industry use removable handles, but such systems still do not lock the outlet valve in the closed position and may open accidentally. 
     SUMMARY OF THE INVENTION 
     The invention pertains to an outlet valve assembly for a railway tank car that prohibits the turning of the valve stem, when the valve is in the closed position, unless the handle is moved into a precise operating location. The invention therefore ensures against accidental operation of the valve due to stresses or shocks incident to transportation such as derailment or other unintentional contact. 
     The invention is directed to an outlet valve assembly designed to be used with an outlet valve mounted on the bottom of a railway tank car for discharging the liquid contents of the tank car. The valve is operable between a closed position that occludes flow through the valve and an open position that permits flow through the valve. A valve stem is connected to and extends from the valve along a generally horizontal axis of rotation. The axis of rotation is also generally perpendicular to the longitudinal axis of the tank car. The valve stem is rotated between a first angular position corresponding to the valve being in a closed position and a second angular position corresponding to the valve being in an open position. The outlet valve assembly also includes an extension shaft having the first end coupled to the valve stem and extending outward from the valve stem. The extension shaft is, for example, pivotally coupled to the valve stem. A second end of the extension shaft is supported by a support bracket mounted on the tank car. A handle is connected to the second end of the extension shaft and swings in an arc in a generally vertical plane along the side of the tank car. The handle is accessible by an operator standing to the side of the railway tank car, and is operative to move the valve, via rotation of the extension shaft and valve stem, between a closed position and open position as the handle is swung between the first angular position and the second angular position. In accordance with one aspect of the invention, a turn prohibitor is located at the first end of the extension shaft and prohibits the turning of the extension shaft, and consequently the valve stem, when the valve is in the closed position and the extension shaft is displaced from the axis of rotation. In this regard, the extension shaft must be aligned along the axis of rotation of the valve stem in order to rotate the extension shaft and valve stem and operate the valve. 
     In an exemplary embodiment of the invention, the turn prohibitor at the first end of the extension shaft comprises, in part, a collar on a skid mounted around the valve. The collar has a cylindrical wall with a slot. A locking flange is also provided on the first end of the extension shaft. The locking flange is desirably in the shape of a paddle and is fixed to or integral with the first end of the extension shaft. The first end of the extension shaft and the locking flange reside in and are free to rotate within the cylindrical wall of the collar when the extension shaft is aligned along the axis of rotation of the valve stem. Desirably, the diameter of the paddle shaped locking flange fits closely with slight clearance within the cylindrical wall of the collar. Thus, when the extension shaft is aligned along the axis of rotation of the valve stem, the extension shaft is allowed to rotate about the axis of rotation of the valve stem and move the valve between the closed position and the open position. The slot in the cylindrical wall of the collar aligns with the locking flange on the first end of the extension shaft when the extension shaft is rotated to the first angular position corresponding to the valve being in the closed position. To lock the valve in a closed position, the locking flange is aligned with the slot in the collar and the extension shaft is displaced from the axis of rotation in the direction of the slot thereby causing the flange to interfere with the slot and lock the valve in the closed position. To unlock the valve, the extension shaft must be realigned with the axis of rotation so that the locking flange clears the slot thereby enabling the extension shaft and consequently the valve stem to turn. 
     The support bracket for the second end of the extension shaft allows the second end of the extension shaft to be displaced from the axis of rotation only when the extension shaft is rotated to the first angular position and the valve is in the closed position. An approximate four to five degree (4-5°) displacement from the axis of rotation should be sufficient to create the necessary interference between the locking flange and the slot in the collar. 
     Further, in accordance with another aspect of the invention, a second turn prohibitor is provided at the second end of the extension shaft. This is accomplished in the exemplary embodiment of the invention by including a rotational stop plate on the support bracket mounted to the tank car. The rotational stop plate includes a round clearance hole as well as a flat slot extending away from the round clearance hole in an angular direction corresponding to the first angular position and the closed position of the valve. The second end of the extension shaft has at least one flattened surface, but desirably two flat surfaces. The end with the at least one flattened surface resides in the clearance hole when the extension shaft is aligned with the axis of rotation of the valve stem and resides in the flat slot and is prevented from rotating when the extension shaft is displaced from the axis of rotation. In this manner, the extension shaft is prohibited from turning at both ends when the valve is in the closed position and the extension shaft is displaced from the axis of rotation. 
     When the valve is locked in the closed position, a handle latch assembly mounted on the side of the tank car holds the handle in the first angular position (i.e., valve closed) and also in a radial position that displaces the extension shaft from the axis of rotation of the valve stem. The handle latch assembly must be released before the handle can be moved by the operator to align the extension shaft in the clearance hole on the rotational stop plate and along the axis of rotation before the operator may swing the handle and turn the extension shaft and valve stem. 
     In the event that force is applied, accidentally or unintentionally, to the handle or the extension shaft without prior alignment of the extension shaft to the valve stem axis of rotation, the turn prohibitors at both ends of the extension shaft will prevent the turning the of the extension shaft and consequently the valve stem. This is the case even if the force is so great to deform the handle and/or the extension shaft. For example, even in the event of extreme force that shears the handle or the extension shaft during impact, the locking flange will remain within the interference slot on the collar and prevent the valve from opening. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a side elevation view of a railway tank car having a bottom outlet valve and an outlet valve assembly constructed in accordance with an exemplary embodiment of the invention. 
         FIG. 2  is a detailed view of the area indicated by line  2 - 2  in  FIG. 1 , illustrating the components of the bottom outlet valve and outlet valve assembly. 
         FIG. 3  is an assembly view of components of the outlet valve assembly. 
         FIG. 4  is a lower perspective view of the bottom outlet valve and the outlet valve assembly. 
         FIG. 5  is a view similar to  FIG. 4  showing the extension shaft being displaced from the axis of rotation of the valve stem with the valve in a closed position. 
         FIG. 6  is a view similar to  FIG. 5  showing the extension shaft aligned with the axis of rotation of the valve stem and the valve stem in a closed position, wherein alignment of the extension shaft enables the handle to rotate the extension shaft and the valve stem into an open position. 
         FIG. 7  shows the handle having been rotated to move the valve stem into an open position. 
         FIG. 8  is a sectional view taken through a turn prohibitor at a first end of the extension shaft showing the extension shaft being displaced and the turn prohibitor locking the valve stem in the closed position. 
         FIG. 9  is a sectional view similar to  FIG. 8 ; however, the extension shaft has been moved to be aligned with the axis of rotation thereby allowing the extension shaft to rotate the valve stem. 
         FIG. 10  is a sectional view taken along line  10 - 10  in  FIG. 9  showing the valve stem in a first position corresponding to the valve being closed. 
         FIG. 11  is a view similar to  FIG. 10  showing the valve stem in a second position corresponding to the valve being open. 
         FIG. 12  is a partial sectional view of a second turn prohibiting mechanism showing the extension shaft being displaced from the axis of rotation of the valve stem. 
         FIG. 13  is a sectional view taken along line  13 - 13  in  FIG. 12 . 
         FIG. 14  is a partial sectional view similar to  FIG. 12 ; however, the extension shaft has been aligned with the axis of rotation of the valve stem. 
         FIG. 15  is a sectional view taken along line  15 - 15  in  FIG. 14 . 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIG. 1 , a railway tank car  10  of a generally conventional construction and arrangement is illustrated. The railway car  10  includes by way of example an insulated cylindrical tank body, having an outer jacket  20 . The tank car is supported on rails  14  by a pair of trucks  12 . A bottom outlet valve  15  (see,  FIG. 3 ) is provided on the bottom surface of the tank car  10  and is located generally above the rails  14 . An outlet valve assembly  16  includes a handle  18  that is used by an operator to turn the valve  15  from the closed position as shown in  FIG. 1  to an open position (see e.g.  FIG. 7 ). 
     Referring to  FIG. 2 , the valve  15  mounted to the bottom of the tank car  10  is surrounded by a protective skid  22 . The area designated by reference number  24  represents a cut-out in the outer jacket to  20 , and the skid  22  is welded to the inner jacket of the tank car  10 . An outlet nozzle  26  is threaded onto the valve  15  and an outlet cap  28  is threaded onto the outlet nozzle  26 . The outlet valve assembly  16 , as mentioned, includes the handle  18  which is turned by an operator in order to open and close the bottom outlet valve  16 . The handle  18  is shown in the closed position in  FIG. 2 . A latch assembly  30  attached to the outer jacket  20  of the tank car  10  is used to hold the handle  18  in the closed position. Support bracket arms  32  support the handle  18  and an extension shaft  34  as discussed below. 
     Referring to now  FIG. 3 , the extension shaft  34  is connected between a stem adapter  36  and an attached end  40  of the handle  18 . The stem adapter  36  is fixed to the valve stem (not shown) and extends through an opening  42  in the skid  22 . The stem adapter  36  includes fingers  44  which have pin receiving holes for a pivot pin  46 . The stem adapter  36  includes a collar  48  into which the valve stem resides and is fixed, e.g. using a pin. The stem adapter  36  is permanently fixed to the valve stem and rotates in unison with the valve stem. The first turn prohibitor  68  (see e.g.  FIGS. 8-11 ) includes a collar  48  that is welded to the outside wall of the skid  22  around the opening  42  for the stem adapter  36 . The collar  48  includes a cylindrical wall  50  having opposing interference slots  52 . The extension shaft  34  includes a locking flange  54  at its first end. The locking flange  54  is in the shape of a flattened paddle and is sized so that the locking flange  54  will reside within the respective interference slots  52  on the cylindrical wall  50  of the collar  48  when the extension shaft  34  is displaced from the axis or rotation  56  of the valve stem. The diameter of the paddle-shaped locking flange  54  is no greater than the inside diameter of the cylindrical wall  50  on the collar  48 , thereby allowing the extension shaft  34  to rotate within the collar  48  when the extension shaft  34  is aligned with the axis of rotation  56 . A pivot hole  58  is located on the extension shaft  34  near the locking flange  54  but positioned slightly towards the middle of the shaft  34 . When assembled, the pivot pin  46  pivotally mounts the extension shaft  34  through pivot hole  58  to the fingers  44  on the stem adapter  36 . This pivotal mount allows the extension shaft  34  to be displaced from the axis of rotation  56  for the valve stem, yet rotate the valve stem when the extension shaft  34  is aligned with the axis of rotation  56 . 
     The other end of the extension shaft  34  has two flattened, parallel surfaces  60 . When assembled, the end of the extension shaft  34  with the double flat surfaces  60  extends through a rotational stop plate  38  on the support structure  32  and is attached to the end  40  of the handle  18 . The rotational stop plate  38  includes a circular hole  62  and a displacement slot  64 . The diameter of the circular hole  62  is selected to be commensurate with the diameter of the extension shaft  34  so that the extension shaft  34  can rotate within the circular hole  62  on the rotational stop plate  38  when the extension shaft  34  is aligned along the rotation of axis  56  of the valve stem. The displacement slot  64  in the embodiment shown in the drawings has flat edges extending away from the circular hole  62  at a 45° angle when the support bracket  32  is mounted to the tank car  10 . The specific angle of the displacement slot  64  is not necessarily important; however, the difference between the closed and open position in a conventional bottom outlet valve is a quarter turn or 90°. It is important, nevertheless, when mounting the system to the tank car that the displacement slot  64  align with the angular position of the valve stem when the valve  15  is in the closed position. In a similar fashion, it is important that the interference slots  52  on the cylindrical wall  50  of the collar  48  align in the same angular direction as the closed position of the valve  15  and the displacement slot  64  in the rotational stop plate  38 . The direction of the double flat surfaces  60  is desirably the same as direction of the locking flange  54 . The width of the displacement slot  64  is selected to allow the extension shaft  34  across the double flat surfaces  60  to be displaced upward and into the upward end of the slot  64 . Of course, this can only occur when the handle  18  has turned the extension shaft  34  into the angular position corresponding to the valve  15  being closed. The latch mechanism  30  includes a pin and chain  66  to lock the latch  30  when the handle  18  has been turned into the closed position and raised to displace the extension shaft  34 . 
     The above components are preferably provided as a kit for retrofitting an existing railway tank car  10 . The components are preferably made of carbon steel or stainless steel and all welds are standard to the industry. 
       FIG. 4  shows the assembled outlet valve assembly  16  mounted to a tank car jacket  20  and latched in a closed position with the handle  18  locked into the latch  30 . In  FIG. 4 , the extension shaft  34  is displaced from the axis of rotation  56  of the valve stem. As shown in  FIG. 4 , a first turn prohibitor  68  is located at the skid  22  and a second turn prohibitor  70  is located on the support bracket  32 . The first turn prohibitor  68  comprises the collar  48  with interference slots  52  and cylindrical wall  50  welded to the skid  22 , the paddle-shaped locking flange  54  on the extension shaft  34 , and the stem adapter  36  and pivot pin  46 . The second turn prohibitor  70  comprises the displacement slot  64  in the rotational stop plate  38 , the double flat surfaces  60  on the distal end of the extension shaft  34 , and the latch  30  that holds the handle  18  in the closed position. 
       FIG. 8  shows a detailed view of the first turn prohibitor  68  at the skid  22  when the valve stem is turned into the closed position. In  FIG. 8 , the extension shaft  34  has been rotated and displaced from the rotational axis  56  of the valve stem. The displacement causes the locking flange  54  to move into and within interference slot  52  in the cylindrical wall  50  as shown in  FIG. 8 . Note that the section through  FIG. 8  is not a vertical section, but is taken along a 45° angle in order to illustrate the turn prohibiting device  68  in a closed position. 
       FIGS. 12 and 13  illustrate the second turn prohibitor  70  when the valve  15  is in the closed position and the extension shaft  34  has been displaced from the axis of rotation  56  of the valve stem. In  FIG. 12 , the second turn prohibitor  70  is illustrated with the double flat side  60  of the extension shaft  34  being displaced up into the displacement slot  64  on the rotational stop plate  38 . Note that the section in  FIG. 12 , again is cut along the slot  64  in order to schematically illustrate operation of the invention. Note that the handle  18  is mounted perpendicularly to the extension shaft  34  and therefore angles with respect to vertical towards the tank car jacket  20  when the handle  18  is latched in the closed position as shown in  FIG. 4 .  FIG. 13  is a view of the second turn prohibitor  70  with the handle  18  latched in the closed position taken along  13 - 13  in  FIG. 12 .  FIG. 13  clearly illustrates the double flat surfaces  60  within the slot  64  preventing the extension shaft  34  from rotating. 
     From  FIGS. 4 ,  8 ,  12  and  13 , it can be seen that the first turn prohibitor  68  located at the skid  22  and the second turn prohibitor  70  located at the support bracket  32  cooperate to prevent turning of the extension shaft  34  and consequently the valve stem when the extension shaft  34  is rotated to the closed position and displaced from the axis of rotation  56  of the valve stem. The first turn prohibitor  68  and the second turn prohibitor  70  not only cooperate in this regard, but are also redundant in the sense that either turn prohibitor  68 ,  70  is capable of preventing inadvertent turning of the extension shaft  34  in case the other fails (i.e., as long as the extension shaft  34  remains attached to the valve stem). 
     The process of opening the valve  15  begins as shown in  FIG. 5  by opening the latch  30  to allow the extension shaft  34  to be moved into alignment with the rotational axis  56  of the valve stem.  FIG. 6  shows the handle  18  unlatched from the latch assembly  30  and the extension shaft  34  slid down the displacement slot  64  to the circular hole  62  in the rotational stop plate  38 . In  FIG. 6 , the extension shaft  34  is aligned with the axis of rotation  56  of the valve stem, but the handle  18  and the angular orientation of the extension shaft  34  remain in the closed position.  FIGS. 9 and 10  shows the position of the first turn prohibitor  68  with the extension shaft  34  aligned along the rotation of axis  56  prior to opening the valve  15  (i.e., corresponding to the position shown in  FIG. 6 ). With the extension shaft  34  aligned, the locking flange  54  resides within the cylindrical wall  50  of the collar  48  clear of the interference slots  52 .  FIG. 10  is a view taken along line  10 - 10  in  FIG. 9  still showing the extension shaft  34  aligned and the locking flange  54  residing within the cylindrical wall  50  of the collar  48  clear of the interference slots  52 .  FIG. 10  also illustrates the locking flange  54  remaining in the angular position corresponding to the valve  15  being closed; however, as shown, the first turn prohibitor  68  does not block the extension shaft  34  from rotating.  FIGS. 14 and 15  depict the second turn prohibitor  70  with the double flat surfaces  60  of the extension shaft  34  moved downward as indicated by arrow  72  in  FIG. 14  and arrow  74  in  FIG. 15  so that the extension shaft  34  aligns with the axis of rotation  56  of the valve stem and sits within the circular opening  62  on the rotational stop plate  38 . This position corresponds to the position shown in  FIGS. 6 ,  9  and  10 . In this position, the second turn prohibitor  70  does not restrict the rotation of the extension shaft  34  about the valve stem rotation axis  56 . 
       FIG. 7  shows a perspective view of the outlet valve assembly  16  with the handle  18  being moved as shown by arrow  76  to rotate the extension shaft  34  in accordance with arrow  78  to open the valve  15 .  FIG. 11  is a view of the first turn prohibitor  68  at the skid  22  taken from a similar perspective as  FIG. 10 ; however, in  FIG. 11  the extension shaft  34  has been rotated in accordance with arrow  78  to turn the fingers  46  on the stem adapter  36  and consequently the valve  15  into the open position.  FIG. 15  again is a view of the second turn prohibitor  70 . Arrow  76  shown in phantom in  FIG. 15  shows the handle  18  moving downward in order to rotate the extension shaft  34  and open the valve  15 . 
     In the foregoing description, certain terms have been used for brevity, clarity, and understanding. No unnecessary limitations are to be inferred therefrom beyond the requirement of the prior art because such terms are used for descriptive purposes and are intended to be broadly construed. The different configurations, systems, and method steps described herein may be used alone or in combination with other configurations, systems and method steps. It is to be expected that various equivalents, alternatives and modifications are possible within the scope of the appended claims. Each limitation in the appended claims is intended to invoke interpretation under 35 U.S.C. §112, sixth paragraph, only if the terms “means for” or “step for” are explicitly recited in the respective limitation.