Railway hopper car sliding gate closing mechanism
BACKGROUND AND SUMMARY OF THE INVENTION 
     The present invention pertains to an apparatus for holding a horizontal sliding gate against the frame defining the discharge opening of a railroad hopper car. When a hopper car is holding a fluidized lading such as fine particles of bauxite, bentonite, cement, flour, etc., problems are encountered with respect to that fluidized lading sifting between the gate and the frame even though the gate presumably is in the closed position. One solution has been to use gaskets of rubber or the like. If the gasket is to provide an effective seal it must be pressed securely against the gate, but this can interfere with the horizontal movement of the gate and/or result in excessive wear of the gasket. Thus various devices have been devised which will give the gate, in addition to its normal horizontal movement of opening and closing, a vertical movement when it is in the horizontal position below the opening. Thus such vertical movement acts to move the closed gate away from the gasket or the discharge opening so that the normal horizontal movement then can take place with less interference. Conversely, as the gate is moved to the closed position the final part of the movement includes at least a component which is vertical. 
     One device for such a vertical movement employs some blocks on the underside of the gate which move onto rollers as the gate approaches the closed position thereby raising the gate against the part of the frame defining the discharge opening (e.g., U.S. Pat. No. 3,845,726, issued Nov. 5, 1974). Such an apparatus has the problem that the gate is raised even before it reaches its final closed position, the result being that there still is horizontal movement after the gate has been raised. That is, while this solution reduces the portion of the opening movement during which the gate is raised, it does not eliminate it altogether. Another device employs fluid or mechanical pressure to lower and raise the gate before and after the horizontal movement of the gate takes place. Examples thereof are seen in U.S. Pat. No. 3,224,382, issued Dec. 21, 1965. In the mechanical pressure version, shafts along each side of the gate and parallel to the path of horizontal movement of the gate are rotated and as this is done protrusions on the shafts cam the shafts and gate upwardly. Such devices, however, add significantly to the apparatus required and thus to the overall cost, etc. Furthermore, they often necessitate two separate operations to move a gate to and away from the closed position, i.e., an operation to achieve the vertical movement as well as the normal operation to achieve the horizontal movement. 
     As compared to some such prior art devices, the present invention provides a vertical component of movement as a part of finally locating the gate in the closed position and in its initial movement away from the closed position. Thus the drag occasioned by the horizontal gate movement commences to be relieved almost immediately in the part of the gate movement away from the closed position and recommences only at the very final stage of the gate movement to the closed position. As compared to other prior art devices, the parts that must be added to the conventional gate structure in creating an embodiment of the invention are very nominal. Thus the added cost is relatively limited. Embodiments of the invention do not require a second operation or manipulation. The normal horizontal actuation of the gate supplies the power to achieve the vertical movement. The invention employs pivoted lever arms which engage abutments on the bottom of the gate as the gate is moving in its final part of the horizontal movement toward the closed position with the levers pivoting to an upright position thereby lifting the gate against the bottom of the frame structure and gaskets, if any, surrounding the discharge opening. 
     Further objects and advantages will become apparent from the following description taken in conjunction with the drawings. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a hopper discharge opening with the gate being held in place by an embodiment of the invention; 
     FIG. 2 is a section seen at line 2--2 of FIG. 1, with the gate in the closed position; 
     FIG. 3 is a view similar to that of FIG. 2, but with the gate partially open; and 
     FIG. 4 is a section as seen at line 4--4 of FIG. 2. 
    
    
     DESCRIPTION OF SPECIFIC EMBODIMENT 
     The following disclosure is offered for public dissemination in return for the grant of a patent. Although it is detailed to ensure adequacy and aid understanding, this is not intended to prejudice that purpose of a patent which is to cover each new inventive concept therein no matter how others may later disguise it by variations in form or additions or further improvements. 
     The drawings illustrate that part of the frame, generally 10, of a railway hopper car about the discharge opening 11. At this point the frame has four sloping sides 12-15 which actually define the opening 11 and which provide a chute through which the lading of the car can be discharged through the opening. A gate, generally 17, is used to close the opening. Gaskets 18 may be employed to achieve a better seal when the gate is in the closed position of FIG. 2. The frame has sides 19 and 20 which define a path or way along which the gate moves between the open and closed position. Affixed to the sides 19 are supports 21 on which the gate rests and slides during its horizontal movement. Along the bottom of the gate are a pair of racks 23. These racks are engaged by pinions 24 secured to a shaft 25. Shaft 25 is positioned to the side of the opening 11 across which the gate moves during its horizontal movement and transversely to the path of movement and is suitably journaled in frame 10. A suitable opening and closing mechanism 26 is secured to the shaft for rotating the shaft to open or close the gate as desired. When the gate is in the fully opened position it is out to the right of that side of the opening defined by side 15, as viewed in FIGS. 1 or 3. 
     As thus far described, the structure is conventional. 
     As a matter of reference, side 15 defines the side of the opening 11 across which the gate moves as it is traveling between the closed and open position. Below the opposite side (i.e., that defined by side 13) are a pair of pivoted lever arms or levers 30. These levers are journaled on pins 31 secured to frame 10. The pins define axes which are generally horizontal and transverse to the path of movement of the gate 17. The lever arms or levers have a tail piece 32 which is arranged to abut a portion 33 of frame 10. Thus the frame serves as a stop to limit the movement of the lever in a clockwise direction (as viewed in FIGS. 2 or 3) to the position of lever arm 30 in FIG. 3. For each of the lever arms or levers 30 the gate has a block 34 secured to the underside of the gate. The underside of each block is formed with a socket which is defined by three abutments. Thus there is a downwardly facing abutment 36, an abutment 37 facing away from side 15 and an abutment 38 facing toward side 15. 
     Below the gate and intermediate the sides 13 and 15 are a pair of lever arms or levers 40. These lever arms or levers are pivotally mounted on pins 41 secured to the frame 10. The pivotal axes are again generally horizontal and transverse to the path of movement of the gate. The frame includes a stop 42 for each lever arm to limit the downward pivotal movement to the position illustrated in FIG. 3. For each lever arm there is a respective block 43 secured to the underside of the gate. The bottom face of each of blocks 43 define a socket which includes three abutments 44-46 corresponding to abutments 36-38, respectively. 
     Below side 15 there are two lever arms or levers 48 which are secured to shaft 25 for rotation therewith. Cooperating with each of the lever arms or levers is a block 49 secured to the underside of gate 17. Like the previous blocks, each block 49 has a downwardly facing socket defined by three abutments 50-52 corresponding to abutments 36-38, respectively. 
     FIGS. 1 and 2 illustrate the gate in the fully closed position. It is up against the bottom edges of sides 12-15 about the opening 11. The gaskets 18 about the opening are compressed by the gate. The rounded distal ends of the lever arms or levers 30, 40, 48 form noses which bear against the downwardly facing abutments 36, 44, 50, respectively, to hold the gate in this raised position. Now assuming that the gate is to be moved to its open position, shaft 25 is rotated in a clockwise direction as viewed in FIGS. 2 and 3. This rotation causes lever arms or levers 48 to bear against the side facing abutments 51 and the pinion 24 to bear against rack 23 forcing the gate to the right in FIGS. 1-3. As the gate so moves, side facing abutments 38 and 46 bear against the nose ends of lever arms or levers 30 and 40, respectively, in a sense such as to pivot those levers clockwise as viewed in FIGS. 2 and 3. The pivotal movement of the lever arms or levers 30, 40, 48 cause the distal ends of those lever arms or levers to descend almost immediately thus allowing the gate to move downwardly away from the gaskets 18 and the bottom edges of the sides 12-15. Continued movement of the gate in the opening direction (i.e., as indicated by arrow 54) results in the continued downward movement of the levers until the gate rests upon supports 21. The levers are free to rotate to the FIG. 3 position at which they are arrested by the respective stops with the distal ends of the levers being below the gate and below the lower ends of side facing abutments 38 and 46. The gate is then moved to the fully opened position in the conventional manner. 
     Assuming that the gate is to be closed from the opened position, the shaft 25 is rotated counterclockwise. This causes the gate to move in the reverse of arrow 54. As the gate approaches the position at which it will be completely below opening 11, the abutments 38 and 46 pass across the tops of the lever arms but the abutments 37, 45 which face away from side 15 are below the distal ends of the lever arms or levers 30, 40, respectively, and are thus positioned to contact the levers adjacent their distal ends. Thus with continued movement of the gate to the left in FIG. 3 the abutments 37, 45 cause the lever arms or levers 30, 40, respectively, to pivot in a counterclockwise direction. As this occurs the distal ends of the lever arms or levers rise to a higher elevation thus lifting the gate. Of course, during the final closing of the gates the lever arms or levers 48 will have moved into the sockets on the bottoms of blocks 49 and will have similarly been raising the trailing part of the gate. Ultimately the gate is raised to the closed position of FIG. 2. 
     While I prefer to have the lever arms or levers 48 (below side 15) mounted on the shaft 25, embodiments could be constructed in which the levers are pivoted separately as are lever arms or levers 30 and 40. Any such modification should retain the characteristic of the disclosed embodiment in that no two of the blocks 34, 43 and 49 travel in a common path as the gate is moved, i.e., they are at different distances from the top and bottom edges of the gate as it is viewed in FIG. 1. 
     Some hopper cars may have gates that are not truly horizontal but may have some degree of pitch. Of course, the present invention is usable therewith and the term &#34;generally horizontal&#34; as employed herein is used loosely to be applicable to such inconsequential variations.