Patent Application
20150075645
This invention relates to manually actuated outlet valves for use on a railway tank car.
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 '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.
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.
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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.
From
The process of opening the valve 15 begins as shown in
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.
