Patent Publication Number: US-3874569-A

Title: Railway hopper butterfly valve actuating mechanism

Description:
DMENTE APR l ISYS SMU 1 UF orpi-1:10  
 DATENED/*PR V l i975 WIIOM v2 @E Q I I l I I ||I N/V @N QQN QON vm QN S Si moi @i opt S w .Nt 1| liv. w\ mmhw (bw Si:---Iiiiifiiiiliill-i:,.--Ii f RAILWAY HOPPER BUTTERFLY VALVE ACTUATING MECHANISM BACKGROUND OF THE INVENTION This invention relates to fluidized gravity discharge outlets, and particularly relates to fluidized gravity discharge outlets for railroad cars utilizing butterfly valves.  
  Stevens U.S. Pat. No. 3,402,971, assigned to the same assignee as the present application, discloses and claims a butterfly outlet and a plenum chamber utilized to discharge particulate lading from hoppers, including railroad cars. However, in order to operate the butterfly valve and sanitary shield disclosed in the Stevens patent, it is necessary&#39; for the railroad operator to move under the car to open and close the same. This is an obvious safety hazard and for this reason it is desirable both to provide a butterfly valve and sanitary shield operating mechanism which can be operated from at least one side of the car. Preferably the operating mechanism is such as to be operable from either side of the car.  
  In Becker U.S. Pat. No. 3,332,363, assigned to the same assignee as the present application, an operating mechanism for a sanitary cover or shield is disclosed and claimed in combination with a gravity gate movable between open and closed positions longitudinally along the car. The operating mechanism for the sanitary shield is operable from the side of the car. It is desirable to utilize an operating mechanism which is operable from the side ofthe car, such as the one shown in the Becker patent, to move a sanitary shield into an open and closed position to cover the discharge opening for the butterfly valve.  
  In Carney and Schipper U.S. Pat. No. 3,659,752, assigned to the same assignee as the present application, a readily removable permeable member is disclosed and claimed for forming the plenum chamber in a fluidized gravity discharge outlet. It is desirable to utilize this readily removable member to form the plenum chamber from the butterfly valve.  
  Therefore it is an object of the present invention to utilize a butterfly valve in a fluidized gravity discharge outlet which is operable from at least one side of the car.  
  It is another object of the present invention to provide a butterfly valve in a fluidized gravity discharge outlet which is operable from both sides of the car.  
  It is another object of the present invention to provide a sanitary cover for the butterfly valve which is operable from the side of the car between open and closed positions.  
  Another object of the present invention is to provide a readily removable permeable member for use in deflning the plenum chamber for the butterfly valve outlet.  
  Other objects will be apparent from the following description and drawings.  
 SUMMARY OF THE INVENTION A fluidized gravity discharge outlet is provided having a butterfly valve and a linkage affixed thereto which is operable from at least one and preferably both sides of the car. A sanitary shield is also provided having a linkage affixed thereto which is operable from either side of the car. If desired, a readily removable permeable member may be provided to define the plenum chamber for the butterfly valve.  
 BRIEF DESCRIPTION OF THE DRAWINGS FIG. l is a top view of the discharge outlet according to the present invention;  
  FIG. 2 is a side view of the discharge outlet of the present invention, including a portion ofthe hopper upon which the discharge outlet is mounted;  
  FIG. 3 is an end view looking from the side of the car inward toward the discharge outlet of the present invention;  
  FIG. 4 is a sectional view along the lines 4-4 in FIG. 2;  
  FIG. 5 is a sectional view along the lines 5-5 in FIG. 4;  
  FIG. 6 is an exploded longitudinal section of the bottom outlet structure shown in general in FIG. 2 with an inner fluid permeable member shown before insertion within the bottom outlet structure;  
  FIG. 7 is a plan view of the link for releasably locking the cover in open and closed positions shown removed from the outlet structure;  
  FIG. 8 is a side view of an operating mechanism for the butterfly valve which is operable from either side of the car;  
  FIG. 9 is a side view of an operating mechanism for the butterfly valve which is operable from either side of the car;  
  FIG. l0 is a plan view&#39; along the lines 10-10, illustrating the contour of the cam groove in the operating mechanism on the left side of the car;  
  FIG. 11 is a plan view along the lines 11-11 illustrating the contour of the cam groove in the operating mechanism on the right side of the car;  
  FIG. 12 is a sectional view along the lines 12--12 in FIG. 9.  
  FIG. 13 is an elevation along the lines 13-13 in FIG. 9.  
  FIG. 14 is an enlarged side view illustrating the position of the operating mechanism shown in FIG. 9 when the butterfly valve is in closed position; and  
  FIG. 15 is an enlarged side view illustrating the position ofthe operating mechanism shown in FIG. 9 when the butterfly valve is in open position.  
 DETAILED DESCRIPTION The discharge outlet of the present invention is indicated generally at 10 and comprises an outlet hopper section indicated generally at 12 comprising a flange portion 14 having openings therein 16 for bolting the outlet to a hopper structure 18 having a flange portion 19. Hopper outlet portion 12 comprises side walls 20, 22 and end walls 24, 26 which terminate in a discharge opening 28. A butterfly valve 30 is mounted for movement between open and closed positions within opening 28. Butterfly valve is provided with an operating shaft 32 journalled in a casting 34. O-ring seals 35 may be provided about shaft 32 to maintain the discharge conduit seal. Shaft 32 is affixed by appropriate means such as bolting 36 to an extension 38 of the external.  
 butterfly valve operating mechanism 40 which is operable from the side of the car. Operating means 40 comprises shaft means 42 connecting shaft 32 or extension 38 with at least one side of the car. Means to rotate extension 38 is indicated generally at 44 and means adjacent the side of the car indicated generally at 46 is provided for actuating the rotation of shaft 32.  
  According to one embodiment of the present invention the means for rotating shaft 32 and/or extension 38 comprise a bell crank mechanism indicated generally at 48.  
  Bell crank mechanism 48 as is known in the art cornprises spaced apart plates 50 and 52 which may be attached to extension 38 or directly to shaft 32 as desired. Shaft means 42 is affixed to the upper portion of bell crank mechanism 48 between plates 50 and 52.  
  Shaft means 42 may comprise a hollow metal shaft 54 which if desired may be provided with an eye bolt extension 56 affixed to shaft 54, for example, with thread. At the opposite end of shaft 54, means indicated generally at 58 are preferably provided to allow opening of the butterfly valve in stages. For example, a plurality of slots or openings 60 may be provided which engage a cooperating portion 62 affixed to support means indicated generally at 64. The support means 64 may Comprise plates 66 and 68 appropriately affixed, for example, by welding to the support structure of the hopper, for example in the case ofa railroad car, to the side sills 70 as shown in FIGS. 2 and 3.  
  Means to move shaft 54 back and forth are also preferably provided. This may take the form, for example, of a T-connection 72.  
  Thus, in the closed position the T member is placed in the lefthand most opening 60 in FIG. 2. To open the valve, the T member is pulled from right to left in FIG. 2 and the appropriate opening 60 engaged with the fixed portion 62 to open the valve a desired amount. Four positions are shown by way of illustration in which the first position is closed, the second position would open the valve approximately a third, the third position approximately two-thirds and the last fully opened. The valve may be closed completely or in stages by moving the T member from left to right.  
  To prevent butterfly valve 30 from being opened to an over center position, a stop 63 is affixed by welding or other means to shaft 54. This stop 63 will engage support means 64 and prevent butterfly valve 30 from opening to an over center position when fully opened.  
  It will be apparent from FIG. 2 that in closed position T member 72 is within the AAR clearance limits shown dotted and labelled A in FIG. 2.  
  As indicated in FIG. 2, butterfly valve 30 is in an inclined position from the horizontal. This position precludes its operating function from being moved past or to a horizontal position when being closed. Also, this, inclined from horizontal position allows the peripheral flanges to be tapered if desired, permitting a sealing effect when butterfly valve 30 is closed. The tapered edges will engage walls of discharge opening 28 and tend to seal the opening in closing.  
  A plenum chamber 142 is shown defined by a permeable member 144 and lower plates 24 and 26. The plenum chamber arrangement may be similar to that described in Stevens U.S. Pat. No. 3,402,971, if desired. Specifically, referring to FIGS. 2 and 4, side and bottom walls 24 and 26 slope downwardly to a central discharge opening 28 in bottom walls 26. Forming discharge opening 28 is a tubular discharge conduit generally designated 134 and having a rim 136 projecting upwardly within bottom outlet structure above bottom walls 26 and spaced inwardly from adjacent side walls 22. Conduit 134 is generally cylindrical and has its longitudinal axis extending in a generally vertical direction. An upper peripheral flange 138 on discharge conduit 134 extends beneath and is secured to bottom walls 26. A bottom peripheral flange 139 on discharge conduit 134 forms a seat for sanitary cover 220. Secured to the upper edge 140 of rim 136 to form a plenum chamber 142 with walls 24, 26 and rim 136 is a fluid permeable load bearing structural member generally designated 144. Fluid permeable member 144 comprises a pair of sections or portions designated 146 each having a portion cut out at 148 to receive tubular conduit 134. Sections 146 join each other at 150 and form plenum chamber 142 about the entire periphery of conduit 134 since fluid permeable member 144 extends about the entire periphery of conduit 134 over bottom walls 26 and between side walls 24.  
  Referring to FIG. 5, permeable member 144 includes an upper permeable sheet 152 having generally parallel faces 154 and 156. Upper face 154 forms a material supporting surface, the material to be unloaded being supported on face 154 moving therealong to opening 28 for discharge. Permeable sheet 152 is formed of a fiber metal material in which metallic fibers, such as stainless steel fibers, are individually dispensed and felted to form a random, interlocked non-woven body which is sintered under reducing conditions at a high temperature to produce welds at interfiber contact points. Alternatively one or more preferably three layers of woven wire cloth may be used which are sintered together as discussed hereinafter.  
  As permeable member 144 has a relatively&#39; large unsupported dimension between walls 24 and 26, the weight of the material or lading supported thereon forms a substantial dead load on permeable member 144 during transit. A rigid perforated plate or base 157 is secured to sheet 152 and is generally coextensive with sheet 152. Perforations 158 extend through plate 157 and may comprise around 60 percent of the entire surface area of the plate. To secure sheet 152 to plate 157, a layer of thermoactive adhesive is first smeared on a face of plate 157 and sheet 152 is then pressed into contact with plate 157. An adhesive which has been found to be satisfactory for bonding sheet 152 to plate 157 is adhesive IEC-2214 produced by Minnesota Mining and Manufacturing Company, Adhesives, Coatings, and Sealers Division, 900 Bush Ave., St. Paul 6, Minn.  
  A permeability of around l0 cubic feet per minute at 2 psi for permeable member 144 has been found to be satisfactory for handling finely-divided particles. This rating may be obtained by employing a metallix sheet 152 or around l/16 inch in thickness with perforations and a plate 157 of around 1/s inch in thickness with apertures or perforations 158 comprising around 60 percent of the entire surface area. For further details of permeable member 144, reference is&#39;made to U.S. Pat. No. 3,237,812, issued Mar. l, 1966 to W. E. Kemp and entitled Apparatus for Handling Bulk Materials, the entire disclosure of which is incorporated by this reference.  
  It is to be understood that any suitable permeable material may be employed as a fluid permeable member if having sufficient rigidity to support a full load of lading within hopper 12 and providing a suitable permeability.  
  To fluidize the material above permeable membmer 144, air under pressure from an air compressor C to plenum chamber 142 through inlet pipe 27 at an air pressure of around 7 psi will effect an air flow into the mass of material supported on the surface of permeable member 144. The air flow will be about the entire periphery of rim 136 of conduit 134.  
  A support member 147, FIG. 4, generally cylindrical and having a peripheral rim 148, will permit securing permeable member 144 at discharge opening 28 to said support member 147.  
  Each section 146 of fluid permeable member 144 is substantially flat and may be welded to the upper edge 148 of support 147 and between side walls 24 over bottom walls 26 for forming plenum chamber 142. The outer edges of sections 146 are secured to walls 24 and 26.  
  Alternatively, the plenum chamber may be formed from a relatively removable permeable member as described in Carney and Schipper U.S. Pat. No. 3,659,752. More particularly, as shown in FIG. 6, a relatively removable permeable member 176 may be inserted to define a plenum chamber 200 between permeable member 176 and walls 24 and 26.  
  A fluid permeable member generally indicated 176 has a central opening 178 therein defined by a circular mounting pad 180 having threaded openings 182 therein. Permeable member 176 has an upper peripheral flange 184 with a generally U-shaped resilient gasket 186 extending thereover. Suitable openings 188 are provided in flange 184 and gasket 186. Sides 190 and 192 slope downwardly from flange 184 to the center discharge opening 178. Suitable openings are provided in mating flanges 14 and 15 aligned with openings 188. Studs or bolts 194 fit with openings 188 and nuts 196 draw flanges 414 and 415 together to grip flange 184 and gasket 186 tightly therebetween.  
  To assemble bottom outlet structure 10, fluid permeable member 176 is inserted within the body or housing formed by outlet slope sheets 24 and 26 and is supported on ribs 170A, 170B, 170C, 172 and 174 with circular ring 180 mating and fitting on mounting pad 134. Threaded openings 182 in ring 180 are vertically aligned with openings in mounting pad 134, flange 138. In this position, studs or bolts 198 may be threaded within openings 182 and drawn tight thereby to secure fluid permeable member 176 in position. Then bolts 194 may be inserted within openings 188 and aligned openings in flanges 14 and 15, and then drawn tight by nuts 196 to provide a fluid tight connection between flanges 414 and 415. A plenum chamber 200 is formed between the outer housing of bottom outlet structure 134 and fluid permeable member 176.  
  Fluid permeable member 176 may be formed from a plurality of stainless steel wire mesh layers bonded to each other at contact points by sintering and then calendering. As a specific example, three stainless steel wire mesh layers may be bonded together for a thickness of 0.052 inch with a permeability of between six to 13. A material which has been found to be satisfactory for fluid permeable member is sold under the trademark Dynapore by Michigan Dynamics Division of Ambac Industries, Inc., 1565 Oakman Blvd., Detroit, Mich.  
  In the event it is desired to remove fluid permeable member 176 for inspection, cleaning, repair, or replacement, it is only necessary to remove nuts 196 from studs 194 and then remove studs 198. Permeable member 176 may then be lifted from the housing of bottom outlet structure l0 for assembly or repair.  
  Appropriate means are provided for attaching a source of compressed air to fluidize the plenum chamber indicated generally at 201. The conduit means 202 may comprise a conduit 202 having an elbow therein 204 and an opening 206 into plenum chamber 142. Conduit 202 is supported by flange 208 and may include an elbow 210 and a connection 212 to a flexible hose 214. The flexible hose may, in turn, be connected by appropriate means to a common supply manifold 216.  
  A sanitary shield or cover indicated generally at 220 in FIG. 3, is provided to close discharge opening below butterfly valve 30. The sanitary cover is basically along the lines of that disclosed in Becker U.S. Pat. No. 3,332,363 which is hereby incorporated into the present application by reference. The sanitary door is generally rectangular and is adapted to fit in sealing relationship with appropriate sealing means 222, for example, a gasket of sponge rubber 224.  
  The operating mechanism for moving the sanitary closure between open and closed positions is indicated generally at 226 and comprises a capstan 242 into which an opening and operating bar may be inserted into opening 244.  
  Cover 220 is supported on a rod or shaft 232 which extends beyond each end of the cover. A hanger plate 234 is secured to each outlet and plate 26 and extends downwardly as shown in FIG. 2. A hanger or link arm 236 adjacent each end of rod 232 is pivotally mounted at its upper end about pin 238 secured to the adjacent hanger plate 234. Rod 232 is pivotally carried by the other lower end of arm 236 for supporting cover 220 and rod 232.  
  Fixed to each end of rod 232 is a hub 240 having an outwardly projecting tubular end 242 with an opening 244 adapted to receive a handspike or the like for rotating rod 232 and swinging cover 220 between open and closed positions. Fixed to rod 232 adjacent each hub 240 is a link 246 bifurcated to form link arms 248 which f1t on opposite sides of hanger plate 234 as shown in FIG. 3. As shown in FIG. 7, a roller 250 is mounted for rotation on pit 252 between link arms 248 and fits within slot 254 in hanger plate 234. Slot 254 extends in a generally vertical direction and roller 250 moves up and down in slot 254 as cover 220 moves between open and closed positions as shown in FIG. 3.  
  To maintain the upper surface of cover 220 generally flat or level as it moves between open and closed positions, a bar 256 is pivotally connected at 258 adjacent its lower end to a lug 260 secured to cover 220. The upper end of bar 256 is pivotally connected at 262 to a downwardly extending projection 264 fixed to the underside of flange 14. Bar 256 forms with hanger arm 236 a parallelogram linkage and maintains the axes of cover 220 oriented during movement thereof upon rotation of shaft 232. Link246 forms a toggle to releasably lock or secure cover 220 in closed position as shown in FIG. 3 and in open stored position as shown by dashed lines in FIG. 3. When roller 250 is in its lowermost position of slot 254, the pivot formed at 252 is below the pivot formed by shaft 232 carrying cover 220. Thus, the weight of cover 220 acting through shaft 232 urges roller 250 downwardly against the end edge defining slot 254 thereby to releasably lock cover 220 in the closed position and in the opened stored position. Hanger arms 236 are freely mounted about shaft 232 and suspend cover 220 for movement between open and closed positions.  
  To open cover 220, a handspike or the like is inserted within tubular end 242 and shaft 232 is rotated in a clockwise direction viewing FIG. 3. Slnce locking link 246 is fixed to shaft 232, the extending end of link 246 is first moved upwardly with roller 250 being swung above the level of rod 232 so that the weight of cover 220 urges link 246 and roller 250 upwardly in slot 254 and cover 220 falls away from the bottom of outlet structure 134. Further rotation of hub 240 and shaft 232 moves cover 220 to the fully open stored position with roller 250 in a lower end of slot 254, and being urged downwardly by the weight of cover 220. In this position, shaft 38 may be rotated to open butterfly valve 30 thereby to permit fluidized gravity discharge of material from railway car l0.  
  Thus to discharge lading from outlet l sanitary cover 220 is opened by actuating capstan 242, swinging cover 220 to an open position as shown in FIG. 3. Air is supplied from a suitable source to air inlet 202 and plenum chamber 200. Air permeates fluid permeable member 176 to fluidize the lading resting above fluid permeable member 176. Then, butterfly valve 30 maybe rotated to an open position upon release of arm 42 and movement of handle 72. After unloading. valve 30 is closed and then cover 220 is swung to closed position upon rotation of hub 240 and shaft 232 in a counterclockwise direction from its position of FIG. 3.  
  Thus, a railway hopper car having a plurality of hopper outlet structure 10 arranged generally centrally of the width thereof, each hopper outlet structure having a discharge opening 28 and a lower cover 220 which may be operated from either side of the railway car. The cover is carried on a rod or shaft 232 which is suspended from hanger arms 236 and means are provided on shaft 232 for releasably holding or locking the cover in both the closed position of the cover and an open stored position thereof. Cover 220 is guided by a parallelogram linkage between open and closed positions so that the upper surface thereof remains generally level and tilting of cover 220 is prevented during movement thereof.  
  An alternative means for operating the butterfly valve 30 from one or both sides of the car is shown in FIG. 8. This means is indicated generally at 270 and comprises a crank 272 having a handle thereon 274 which is affixed to the side of the hopper or car by means of a bracket 276. Rotation of the handle causes rotation of the crank and transmits motion to shaft 278 which in turn transmits motion into a worm gear 280. The worm gear 280 is, in turn, connected to a pinion gear 282. The pinion gear 282 is connected to either extension 38 or shaft 32 to open and close the butterfly valve 30.&#39;Detents or stops may be provided to fix the butterfly valve in various open positions in a manner similar to that described in connection with operating means 58.  
  If operation from one side of the car only is desired, shaft 278 will extend to that side of the car only. If operation from both sides of the car is desired, shaft 278 is preferably made in two pieces with a handle 274 and a crank 272 at each end. The shafts 278 are joined into worm gear 280 by appropriate means such as set screws (not shown). At final installation and alignment, shafts 278 and worm gear 280 can be welded together if desired. Since opening the leading edge of butterfly valve 30 will be moving from a closed position to an open position an accurate distance of, for example, approximately degrees, a 90 degree segment of pinion gear 282 will usually be sufficient.  
  A housing 271 supported on a bracket (not shown) can be affixed to outlet hopper section 18, to cover and protect worm gear 280 and pinion gear 282 if desired. Shafts 278 can be journaled into and out of housing 271.  
  It will be apparent that the linkage arrangement operable from either side of the car falls within the AAR clearance limits shown dotted in FIG. 8.  
  Brackets 276 comprise a vertical member 284 preferably having a top formed section 286. Formed section 286 can be fastened to hopper 18 by appropriate means such as welding. Vertical member 284 can be formed at the lower edge to fit hollow cylindrical member 288 which can journal shaft 278. Vertical member 284 can be braced or supported by a gusset 290 which also can be welded or otherwise affixed to hopper 18. If desired, collars 292 may be provided on each side 0f cylindrical member 288 and can be secured to shaft 278 by means of set screws (not shown). These collars 292 help to maintain the operating mechanism 270 in a balanced static condition.  
  Movement of crank 272 by handle 274 can be controlled by detents or stops as stated above which will limit the turning motion imparted to shaft 278 and prevent butterfly valve 30 from being moved to an over center position with relation to the vertical axis.  
  Itis apparent in FIG. 8 that turning of handle 274 on the left side in a clockwise direction will rotate butterfly valve 30 to an open position. It is also apparent that handle 274 on the right side has revolved in a counterclockwise direction. Therefore, the opening and closing of butterfly valve 30 from either side of the vehicle can be controlled by rotating the handle 274 in a direction as indicated on a directional plate (not shown) adjacent to the handle 274.  
  It will thus be apparent that by the foregoing mechanism, the butterfly valve 30 may be opened and/or closed from either side ofthe car.  
  In FIGS. 9-15 another embodiment of means to open and close the butterfly valve from both sides of the car is illustrated. The means are indicated generally at 300 and comprise a shaft 302. The shaft is mounted on brackets 304 and 306 affixed by appropriate means, for example, by welding, to the hopper 301. The shaft further haslhandles 308 and 310 extending longitudinally of the car as in FIG. 10 and 11. Shaft 302 is affixed at its midportion by appropriate means, for example, by bolts 312 to an operatior 314. Operator 314 is provided with a slot 316 through which an arm 318 is movable therein by means of a bearing 320. A spring 322 is mounted on extension 323 of shaft 302 between operator 314 and bolts 312. In FIG. 14 the butterfly valve is shown in the closed position and is shown in the open position in FIG. 15. It will be apparent that operator 314 moves arm 318 from right to left FIG. 9 in order to move the butterfly valve to the open position. Spring 322 is biased to the open position so that upon movement of operator 314 and arm 318 from left to right to close the butterfly valve, shaft 302 must be given sufficient left to right force to overcome the spring to secure the butterfly in closed position.  
  On opposite sides of the car means indicated generally at 330 and 332 are provided to allow positioning of butterfly valve 30 in partly open positions. The means 330 and 332 comprise respectively blocks 334 and 336 mounted upon brackets extensions 338 and 340. Cooperating contours 342 and 344 are provided in the blocks.  
  Considering first operation from the left side of the car as viewed in FIG. 9, if it is desired to move butterfly 30 from the closed to the open position rotate the operation handle 310 clockwise as shown in FIG. 13 and at the same time pull upwardly from the car. In so doing the handle follows the initial portion 346 of contour 344 and an initial stop is provided at position 348 for allowing opening of the butterfly approximately onethird. If it is desired to open the butterfly further, the handle is again rotated further clockwise and at the same time a pulling action is carried out to move the handle along the contour portion 350 and assume the next stop at position 352. In this position butterfly 30 will be approximately two-thirds open. Additional clockwise movement will move handle along the contour 354 to the fully opened position 356. The number of partially opened positions may, of course, be varied as desired and other contours than those illustrated may be utilized.  
  The converse occurs if the operator wishes to open the valve from the opposite side of the car. The fully closed position in contour 342 is in the outermost position of block 334 as indicated at 358. In order to open the butterfly, the operator rotates handle 308 counterclockwise and at the same time pushes on shaft 302 to move handle 308 along contour portion 360 and into the partly opened position indicated at 362. Further, counter-clockwise rotation and further pushing will open the valve further and the handle may be seated in the position 364. Further counter-clockwise rotation and pushing will result in the fully open position indicated at 366 after following contour 368.  
  It will be apparent that when the operator is opening the valve one side of the car the handle is following the corresponding contour section on the opposite side of the car. However, it will not be necessary for a second operator to be present at the other side of the car to be certain that the contour is followed. This will happen automatically. To move the butterfly into the closed position from the right side of the car, the operator rotates the valve clockwise and pulls to assume the various positions, and finally&#39; to assume the fully closed position at 358 the force of spring 322 must be overcome.  
  It will thus be apparent that by the foregoing mechanism the butterfly valve 30 may be opened from either side of the car.  
 What is claimed is:  
  1. A hopper outlet for use with a railway hopper car comprising:  
 a bottom discharge opening positioned generally centrally of the width of the railway car; a butterfly valve mounted upon a longitudinally extending first shaft within said discharge opening; said valve adapted to open and close said discharge opening; an arm affixed to said first shaft externally of said outlet; said arm operable by a second shaft extending transversely to at least one side of the car; a contour block mounted on said side of the car to control movement of said second shaft; said second shaft being movable by transverse and longitudinal movement through a plurality of open positions and a closed position in said contour block to move said valve between a plurality of open positions and said closed position relative to the discharge opening for controlling discharge of lading from the hopper structure; a frame about said bottom discharge opening extending downwardly therefrom generally beneath the valve when in closed position; an elongate bottom cover having its longitudinal axis extending transversely of the car and adapted to fit against the lower surface of said frame; and a parallelogram linkage pivotally connected to the cover and operable at least from said one side of the car to move said cover between open and closed positions.  
 2. A hopper outlet according to claim l wherein said arm engages said second shaft directly.  
  3. A hopper outlet according to claim l wherein said arm engages an operator mounted on said second shaft.  
  4. A hopper outlet according to claim 3 wherein a generally vertical slot is provided in said operator and wherein a pin integrally affixed to said arm is movable vertically in said slot as said second shaft moves transversely in moving said valve between said open and closed positions.  
  5. A hopper outlet according to claim 3 wherein resilient means are provided resiliently biasing said second shaft into at least one of said open and closed positions.  
  6. A hopper outlet according to claim 5 wherein said resilient means comprises a coil spring.  
  7. A hopper outlet according to claim 1 wherein a contour block is mounted upon both sides of the car, and wherein said transverse shaft extends to both sides of the car and wherein said valve is operable from either side ofthe car, said shaft moving through both of said contour blocks to open and close said valve.  
  8. A hopper outlet according to claim 7 wherein said parallelogram linkage is operable from both sides of the car to move said cover between open and closed posi-