Patent Publication Number: US-4321872-A

Title: Automatic hopper unloading device

Description:
The object of the present invention relates to an automatic hopper unloading device, particularly for hoppers disposed on railroad cars. 
     Railroad cars designed to carry granular or powdered products, such as coke fines, are provided with hoppers closed at the bottom by swinging doors which are to be opened automatically at a predetermined point on the track so that the product will flow out, and which then are to be reclosed automatically at a second, also predetermined, point. 
     Closing the bottom of hoppers by means of two doors with horizontal axes perpendicular to the longitudinal axis of the car is known, these two doors being kept in closed position by a locking device actuated by an obstacle placed along the track on which the vehicle rides. The two doors are opened under the influence of the weight of the material contained in the hopper and compress a return device. When the doors reach the fully open position, they actuate a locking device which holds them in this position, enabling the material contained in the hopper to flow out. The car, continuing to move, reaches a second obstacle which releases the lock holding the doors open, so that the latter reclose under the influence of the return member. 
     In all known devices, the return means allowing the doors to close, are elastic means, such as springs, oleo-pneumatic jacks or other similar devices, whereof the tension is directly proportional to the degree of opening of the doors. That is, the return devices are at maximum resistance when the doors reach the fully open position. This has many drawbacks. It can happen, as a matter of fact, that if the product is flowing out with difficulty, the doors will not open sufficiently to reach the fully open position in which they become locked by the mechanism provided for holding them open. Since the doors reclose as the weight of the product acting on them diminishes, the hopper is emptied incompletely. The action of the elastic means holding back the doors can sometimes have a retarding effect on the outflow of the product, to the point where it is sometimes necessary to provide mechanisms to vibrate the sides of the hopper in order to complete the unloading. Finally, when the doors are locked in open position, the pressure exerted on them by the elastic means is at a maximum. If the locking means accidentally releases while a workman is scraping the sides of the hopper to finish off an incomplete unloading, he can be very seriously injured by the door suddenly closing. 
     It is the object of the present invention to eliminate all of the aforesaid drawbacks by disposing a return mechanism in such a way that its resistance to the opening of the doors diminishes, as this opening increases, to a point low enough so that the doors will remain open of their own weight. The mechanism is connected for closing to a control means, actuated by an outside obstacle, which causes the action exerted by the return mechanism to increase until this action reaches a level high enough to overcome the resistance due to the weight of the doors, and reclose them. 
     The device according to the present invention is formed by at least one pair of doors with horizontal axes, perpendicular to the longitudinal axis of the car. Each door of a pair is equipped with a lever, the levers of the two doors being disposed in opposite directions, and connected to one another by a connecting rod. A control level is provided which is linked by a connecting rod to one of the door levers. A return lever, held back by a spring, is engaged by the said control lever, the position of the return lever relative to the control lever being such that when it pivots under the thrust of the control lever, itself entrained by the doors, the return torque which it exerts on the control lever diminishes until it reaches a lever lower than the torque exerted on the same control lever by the door levers. As this position of the return lever is passed, the doors remain open by the effect of their own weight. 
     The device also includes a mechanism for locking the doors in raised and closed position. The locking mechanism is actuated by a maneuvering arm that can be actuated either by an operator or by a fixed obstacle disposed at a suitable point. 
     It is preferable that the locking mechanism itself be made inoperative by a safety lock. 
    
    
     By way of example, and to facilitate comprehension of the invention, the attached drawings show in: 
     FIG. 1, a view in lateral elevation of a preferred embodiment of the mechanism according to the invention; 
     FIG. 2, a plan view of FIG. 1; 
     FIG. 3, an enlarged view of a detail of FIG. 1; 
     FIG. 4, an exploded view of an alternative embodiment of FIG. 3; and 
     FIG. 5, a diagrammatic view illustrating the automatic unloading of a hopper containing the mechanism according to the invention. 
    
    
     Referring to the drawings, and more particularly to FIG. 5, it is seen that the car 1 has four hoppers 2, 3, 4 and 5, closed at their bottoms by respective pairs of doors 6, 7 8 and 9. The door mechanisms are identical and symmetrical so only one is described in detail. 
     Door 6a of door pair 6 is mounted pivotally on a horizontal axis 10 (FIG. 5), perpendicular to the longitudinal axis of the car 1, and door 6b of pair 6 is mounted on a similar axis 11. Door 6a is provided with a lever 12 directed upward, door 6b is provided with a lever 13 directed downward, and these two levers are linked to one another by a connecting rod 14 disposed diagonally. The length of connecting rod 14 is adjustable. 
     On the upper end of connecting rod 14, one end of a connecting rod 15 is articulated, the other end being articulated to the upper end of arm 18 of a control lever 16. 
     The control lever 16 is a bell-crank with two arms, forming an angle between themselves of more than 90°, typically about 120°. At the junction of these two arms, lever 16 is mounted pivotally on an axis 17 parallel to axes 10 and 11. At the end of the lower arm 19 of lever 16, a roller 20 is disposed. 
     A return lever 21 is urged against the arm 18 of control lever 16. Return lever 21 is connected to a cross-shaft 22, parallel to axes 10, 11 and 17, the shaft 21 itself being connected to a lever 23 that is generally parallel to lever 21 and biased back by a traction spring 24, anchored at 25 on the frame of car 1. 
     It will be seen that when doors 6a and 6b are unlocked, they open downward under the influence of the weight of the material stored in hopper 2. The opening movement of the two doors 6a and 6b is combined by connecting rod 14 so that the two doors simultaneously exert a force on connecting rod 15 causing lever 16 to pivot to the left (counterclockwise) in FIG. 1. The pivoting of lever 16 is effected against the return force of spring 24, which is transmitted to arm 18 of control lever 16 by return lever 21. As lever 16 pivots towards the left, lever 21 is entrained in the same direction as it pivots around the axis of shaft 22. As a result, lever 21 tends to become more and more parallel to spring 24, and hence the leverage of the return torque acting on the end of arm 18 of control lever 16 constantly diminishes. This return torque therefore constantly decreases in magnitude as the doors open, and finally reaches a level such that it is incapable of returning the doors even when hopper 2 is empty and the material no longer forces them to open. 
     Doors 6a and 6b therefore remain fully open in a stable position. Their opening is practically instantaneous and they oppose the opening with an elastic resistance of decreasing value. The result, on the one hand, is a much better emptying of the hopper and a stable, fully open position which eliminates any accidental reclosing either before all of the material has flowed out, or when an operator is working inside the opening of the doors. 
     When the doors are open, the control lever 16 and the return lever 21 occupy the positions represented by the dash lines (FIG. 1). 
     When roller 20 rolls against an obstacle 26 (FIG. 5) with an gentle slope, arm 19 rises, causing control lever 16 to pivot in a direction opposite to the previous one. Lever 21 drops and the elastic return torque continuously rises until it exceeds the minimum value necessary to overcome the resistance due to the weight of doors 6a and 6b. The closing then continues in an accelerated manner until the doors are completely closed. 
     Since levers 12 and 13 are not in the same plane and since connecting rod 14 is adjustable in length, it is possible to combine the door closing movements so that the closing movement of door 6b will be somewhat ahead of that of door 6a, or vice versa. Thus, there will not be any interference between these closing movements. 
     Door 6a has, at its end, a bar 27 which engages in the opening 28 of a swinging hook 29, this opening 28 being formed between two convex surfaces 30 and 31 on swinging hook 29. Hook 29 is pivotally mounted around an axis 32, parallel to axes 10, 11, 17 and 22 and carries a roller 33 at its end opposite opening 28. 
     Roller 33 presses against the middle arm 35 of a T-shaped lever 34. Lever 35 has a middle arm 35 and two transverse arms 36 and 37 extending therefrom. Lever 35 is mounted pivotally at the junction point of these three arms on an axis 38 parallel to axis 32. 
     The end of the upper arm 36 of the T-shaped lever 34 is linked by a connecting rod 39 to a lever 40 which, in the example shown, is connected to a maneuvering lever 41. When maneuvering lever 41 is actuated in one direction or the other, either by an operator or by striking a fixed obstacle disposed beside the track, it moves lever 40 upward or downward and lever 40, through connecting rod 39, exerts force on the T-shaped lever 34. As arm 35 rises, it disengages roller 33. Hook 29 is no longer held and swings downwardly under the force exerted by bar 27, and the doors open. 
     The car continues to move forward as it is being unloaded, and lever 41 passes by the obstacle which caused it to pivot. Lever 41 moves to its place in unlocked position. 
     As the doors close, bar 27 strikes convex surface 31, causing hook 29 to swing, roller 33 rolls up against inclined plane 35a, causing lever 34 to pivot until it again presses against the end of arm 35, in which position it is aligned with axis 38. 
     Preferably, as shown in FIGS. 1 and 5, the pairs of doors 6 and 7 of hoppers 2 and 3 are combined so as to open together. The various mechanisms of doors 7a and 7b are identical and symmetrical to those described above. However, the levers of doors 7a, 7b are attached to arm 18 of lever 16 by a connecting rod 14a serving the same purpose as connecting rod 14. Moreover, connecting rod 39 of the locking mechanism for the doors 7 is controlled by a lever 40a symmetrical to lever 40 and connected with the latter. Furthermore, the two lower arms 37 of the two symmetrical levers 34 are linked to one another by a connecting rod 42 containing a spring 43 so that the two levers may swing away from one another under the influence of rollers 33. 
     The limiting open positions of the doors are defined by rubber stops 44. 
     In order to prevent an accidental movement of maneuvering lever 41, the latter is immobilized by a safety lock formed by a movable latch 45 (FIG. 3) fitting in a notch 46 formed on the double lever 40-40a. The upward swing of latch 45 is controlled by a rod 47 controlled by a handle 48. 
     Preferably, as shown in FIG. 3, a swinging stop 49, is rotatably mounted on lever 40-40a, and returned by a spring 50. It closes on notch 46 when latch 45 is raised, so that once this latch has been raised it can no longer fall back into notch 46, but falls back onto stop 49. The latter, which projects slightly above the upper side of lever 40-40a, is retracted laterally when the said lever returns to neutral position, so that latch 45 can return to notch 46. 
     Thus, when a train composed of hopper cars provided with the automatic unloading device according to the invention, passes before the unloading station, just one man is needed to actuate lever 48, and all the subsequent operations can be effected automatically. 
     FIG. 4 represents an exploded view on a large scale of an alternative embodiment of the system represented in FIG. 3. It may be preferable to have lever 41 free on its axis and not connected to double lever 40-40a when safety mechanism 48 has not been actuated. Thus, if this lever 41 accidentally strikes an obstacle placed along the track, the impact will have no effect on the mechanism. 
     As shown in FIG. 4, lever 40-40a and maneuvering lever 41 are mounted loose on an axis 49 and lever 41 has a notch 46a identical to notch 46. Latch 45 is normally in raised position. When latch 45 is lowered by the movement of rod 47, it falls into the two notches 46 and 46a and thus connects the two levers 40 and 40a.