14516AU ORIGINAL Complete Specification Applicant: CIMC Rolling Stock Australia Pty Ltd Title: An improved discharge door system Address for Service: LESICAR PERRIN, 49 Wright Street, Adelaide, South Australia 5000, Australia The following statement is a full description of this invention, including the best method of performing it known to me/us: I An improved discharge door system The present invention relates to an improved discharge door system and, in particular, to an improved discharge door system for a rail wagon, incorporating a second cylinder for providing bias to the system and ensuring that a master and slave door are opened and closed 5 according to a predetermined sequence. BACKGROUND OF THE INVENTION A common type of railroad wagon in use today is the open top wagon of the type wherein the load may be discharged through two discharge doors on the underside of the body. Such wagons are used to haul coal, phosphate and other commodities. After wagons are positioned 10 over an unloading pit, the two discharge doors (a master and slave door) are opened, allowing the material within the wagon to be emptied into the pit. Existing wagon bottom door systems operate using a linkage system between the master and slave doors which ensures that they open and close in a sequential manner. When in a closed position, the slave door is held up against a stop by way of the linkage system, and the master 15 door is held up against a lip on the slave door by way of an air cylinder, the lip acting as a stop and seal. The linkage system, which includes a number of pivot arms, typically includes what is known in the art as an "over-centre" locked configuration. An air cylinder is associated with the linkage system between the doors and when actuated, the linkage system causes the master door to first open down and away from the lip, 20 and then the slave door to also move down and away from the stop. When the cylinder stops, the doors are located in an open position and lading is cleared from the wagon. When the cylinder is actuated to initiate a closing sequence, the linkage system causes the slave door to first rise and close against the stop, and the master door to then close up once again against the slave door lip. There are a number of problems associated with this type of discharge door system. In 25 particular, there are factors which may adversely affect the opening and closing sequences of the discharge doors. In fact, tests undertaken by the Applicant have shown that the doors closing in a desired sequence is random and not at all guaranteed. Firstly, the doors are un-stable and can swing quite freely when open. Therefore, their spaced apart distance during the final moments of discharge may decrease, and if the lading is 30 wet, it can be retained on a door and retard that door during the closing process. The wrong door 2 could also be retarded if lading is not totally cleared from between the pit rails. Furthermore, because of their ability to swing freely, the wrong door may try to close first. The closing sequence could also be affected if the bearings on the slave door are stiffer than those on the master door. 5 Secondly, the slave door can bounce away from the stop when closing and this allows the master door to travel past the slave and close first, resulting in a mis-closure. Such a mis-closure does not have the correct orientation to seal against lading leakage. Also, the linkage system may not be correctly locked in an "over-centre" position, so when lading is dumped into the wagon next, the doors may swing open, 10 Finally, existing wagon discharge door systems known to the Applicant do not include any means of adjustability, nor do they include a secondary system for locking the doors in place. Adjustability is important because it is extremely difficult to manufacture all welded complex rail wagon hopper structure to accept standard length levers and links, and to counter bedding-in of bushes. 15 It is therefore an object of the present invention to overcome at least some of the aforementioned problems or to provide the public with a useful alternative. SUMMARY OF THE INVENTION Therefore in one form of the invention there is proposed a discharge door system for a wagon having a discharge chute along an underside thereof and aligned along a horizontal axis, 20 said discharge door system including: a first and a second door disposed on either side of said horizontal axis, and being shiftable in a direction outwards from said axis between a first position fully closing said discharge chute, and a second position fully opening said discharge chute; a first actuation means for shifting said second door from said first position to said second 25 position, and vice versa; at least one linkage means between said first and second doors, said linkage means causing said first and second doors to open and close in a predetermined sequence when said actuation means is operated; a second actuation means associated with said first door, said second actuation means adapted to 30 provide bias to the system when operated, facilitating movement of the doors in accordance with 3 said predetermined sequence, and ensuring that movement of the doors is minimised when in said first and second positions. Preferably said at least one linkage means causes said first door to open after said second door is opened by way of operation of said actuation means, and said first door to close before 5 said second door is closed by way of operation of said actuation means. Preferably said at least one linkage means includes a boomerang shaped linkage arm comprising a first long arm and a second short arm pivotally connected by a pivot pin, said long arm also being pivotally connected to the first door and the short arm being pivotally connected to the second door along the same axis as said shaft. 10 Preferably said at least one linkage means includes an over-centre locking configuration, wherein when said pivot pin is rotated to a position below said axis, the doors will bias towards said first position, and when said pivot pin is rotated to a position above said axis, the doors will bias towards said second position. In preference the position of said linkage means relative to the first door is adjustable, to 15 thereby facilitate tweaking of the opening and closing sequence. Preferably said discharge door system includes two linkage means on opposite ends of said first and second doors, said first and second linkage means being operatively connected by a shaft extending the length of the wagon. Preferably said first and second actuation means are in the form of air cylinders. 20 In preference said discharge door system further includes a safety hook system adapted to provide a secondary locking means for said first and second doors when located in said first closed position. Preferably said safety hook system comprises a first and a second safety hook moveable between a locked and unlocked position by a third actuation means. 25 Preferably said third actuation means is an air cylinder. In preference said first, second and third air cylinders form part of the same air flow circuit including a single supply and exhaust line.
4 Preferably said air flow circuit is configured to ensure that unless air is being supplied to the third air cylinder, thereby unlocking said safety hook system, air cannot be suppled to the second and third cylinders. In preference exhaust air from said second cylinder is retarded to thereby retard closing 5 of the second door. In preference said wagon is a rail wagon. In a further form of the invention there is proposed a discharge door system for a wagon having a discharge chute along an underside thereof and aligned along a longitudinal axis thereof, said discharge door system including: 10 a slave and a master door disposed on either side of said horizontal axis, and being shiftable in a direction outwards from said longitudinal axis between a first position fully closing said discharge chute, and a second position fully opening said discharge chute; a first air cylinder associated with said master door for shifting the master door from said first position to said second position, and vice versa; 15 two linkage systems on opposed ends of said slave end master doors, said linkage systems linking said doors such that when said first air cylinder is actuated, the master door opens followed by the slave door, and when the first air cylinder is retracted, the slave closes followed by the master door; a second air cylinder associated with said slave door which when operated in conjunction with 20 the first air cylinder provides bias to the linkage system, thereby facilitating sequential movement of the master and slave doors and ensuring that the doors remain stationary when in said first and second positions. BRIEF DESCRIPTION OF THE DRAWINGS 25 The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate several implementations of the invention and, together with the description, serve to explain the advantages and principles of the invention. In the drawings: Figure 1 illustrates an enlarged perspective view of a wagon first end including a discharge door system in accordance with the present invention; 5 Figure 2 illustrates an end view of the wagon first end, when the discharge door system is in the closed position; Figure 3 illustrates an end view of the wagon first end, when the discharge door system is in the open position; 5 Figure 4 illustrates an end view of the wagon second end, when the discharge door system is in the closed position and a safety hook system is in the locked position; Figure 5 illustrates an end view of the wagon second end, when the discharge door system is in the open position and the safety hook system is in the unlocked position; Figure 6 illustrates a side view of the wagon including the discharge door system on a first 10 end, and the safety hook system on the second end; Figure 7 illustrates an air flow diagram for the discharge door system and safety hook system of the present invention; and Figure 8 illustrates a partial end view of the wagon first end, including an adjustment means associated with the discharge door system of the invention. 15 DESCRIPTION OF THE PREFERRED EMBODIMENTS The following detailed description of the invention refers to the accompanying drawings. Although the description includes exemplary embodiments, other embodiments are possible, and changes may be made to the embodiments described without departing from the spirit and scope of the invention. Wherever possible, the same reference numbers will be used throughout the 20 drawings and the following description to refer to the same and like parts. Referring now to Figure 1, there is shown part of a discharge door system 10 according to a preferred embodiment of the present invention, associated with a first end of a rail wagon or hopper 12. The wagon 12 is a container like structure having an open top and a pair of bottom doors 14a and 14b which are pivotally moveable between a closed position (as shown) for 25 transporting lading 16, and an open position for discharging lading 16 from the wagon 12 when positioned above a pit (not shown). When opening, the doors 14a and 14b are adapted to rotate about their respective pivot pins 18 and 20, which are positioned to facilitate an outward sliding motion of the doors from 6 beneath the wagon when opening. A first air cylinder 22 is pivotally mounted at one end to a horizontal beam 24 welded to the wall 26 of the wagon first end, above and adjacent door 14b to provide power for the system 10 of the present invention. A spring 28 is used as a tensioning means on the free end of the first cylinder 22. A second or "priority" cylinder 30 is also pivotally 5 mounted at one end to the horizontal beam 24, but above and adjacent door 14a. Each cylinder 22 and 30 includes a rod 32 and 34 respectively which when actuated, moves inwardly or outwardly of the cylinder, inward movement occurring during closing of the doors, and outward movement occurring during opening of the doors. The purpose of the priority cylinder 30 will be described in more detail below. The way 10 in which each air cylinder works is well known in the art. and it is within the scope of the present invention to use any suitable power source (manual, electric, liquid, steam) to operate them. A preferred air flow configuration is also described in more detail below. A linkage system 36 between the doors 14a and 14b is used to ensure that they opened and close in a predetermined sequence. In particular, the linkage system 36 is used to ensure that 15 during the closing sequence, door 14b acts a master door which opens first and closes last, and door 14a acts as a slave door which opens last and closes first, As mentioned in the preamble, in conventional systems which do not incorporate a priority cylinder 30, this sequence is not always followed. In the embodiment shown, the slave door 14a also includes a lip 37 along its length, which abuts with a stop (not shown) when in the closed position. During the closing sequence, 20 the master door 14b closes against the lip 37, which acts as a stop and a seal so that lading is not leaked. The linkage system 36 is shown in detail in Figures 2 and 3, which illustrate the doors in a fully closed position and a fully open position respectively. As shown in Figures 4 and 5, such a linkage system is also present on the opposite end of the wagon, however, for the purpose of 25 brevity, this will not be described in detail as it operates in the same way. A rotatable shaft 38 extends the length of the wagon 12 along one side thereof, connecting the ends of the master door 14b. This can best be seen in the side view of Figure 6. Mounted on the end of the shaft 38 is a first end of a "boomerang" linkage arm 40 which comprises a short arm 42 and a long arm 44, pivotally connected by a pivot pin 46. The shaft is 30 configured to rotate together with rotation of the short arm 42, and it is this interaction which enables the linkage system on the opposed end of the wagon to operate in a corresponding 7 manner. The second end of linkage arm 40 is pivotally connected to a plate 48 which is adjustably attached to the slave door 14b. The means of adjustment of plate 48 is not shown in Figures 1-5, but will be described in more detail below. The rod 32 of the first air cylinder 22 is pivotally connected at its end to a linkage arm 5 50. The linkage arm 50 is in turn pivotally connected to the first end of the boomerang linkage arm 40, that is, to short arm 42, via an extension shaft 52 extending along the same axis as shaft 38 a short distance outwards from the door 14b. The linkage arm 50 includes a cutout section 54 for engaging the extension shaft 52 during opening, as will become evident. The linkage system is therefore configured in an "over-centre" locking configuration, whereby when the pivot pin 46 10 is located below the horizontal plane 56 of the extension shaft 52, the doors will remain biased in a closed position, but as soon as the pivot pin 46 moves above the horizontal plane 56, the master door 14b will begin to open. In Figure 2, the doors 14a and I4b are in a closed position and the rods 32 and 34 of the air cylinders are not extended. The opening sequence of the doors to move from their position in 15 Figure 2 to the open position in Figure 3, is as follows: * the first and priority air cylinders 22 and 30 are actuated and the respective rods 32 and 34 extend outwardly; * the outward extension of the rod 32 causes the linkage arm 38 to rotate clockwise, and the spring 28 causes the cylinder 22 in the meantime to rotate anticlockwise to an almost 20 vertical position as shown in Figure 3; " the cutout section 52 eventually engages the extension shaft 52, causing the pivot pin 46 of the boomerang linkage arm 40 to move upwardly, and when it is "over centre", that is, above the horizontal plane 56, the master door I4b begins to swing open; and * the boomerang linkage arm in the meantime opens the slave door 14a by way of 25 anticlockwise rotation of the small arm 42, which causes the long arm 44 to move outwards, thereby opening the slave door 14a. The closing sequence involves the above steps, in reverse order, and is initiated by exhausting the air cylinders 22 and 30 and thereby retracting the cylinder rods 32 and 34.
8 The addition of the priority cylinder 30 to the slave door 14a is critical to provide bias to the system, thereby overcoming the problems with conventional door systems of this type. The priority cylinder 30 ensures that the slave door 14a is first to close, regardless of whether there is excess lading left on the door, and that the slave door 14a is held open to mitigate against a 5 reduced opening gap due to unstable swinging. The priority cylinder 30 also prevents bounce of the slave door during closing, ensuring that a mis-closure does not take place. Turning now to the opposite end of the wagon, Figures 4 and 5 illustrate the way in which a third air cylinder 60 can be actuated to open and close safety hooks 62 and 64 associated with door 14b and 14a respectively. The safety hooks 62 and 64 are adapted to rotate about their 10 respective pivot pins 66 and 68 between a locked position in which the doors are engaged by the hooks, and an unlocked position in which the doors are disengaged by the hooks. The air cylinder 60 is in a floating configuration, whereby one end is pivotally attached to safety hook 64, and the cylinder rod 70 is pivotally attached to safety hook 62. The outwardly extending extension shaft 52 mentioned above in relation to the first end linkage system, is also 15 present here, and it is this shaft 52 which is engaged by safety hook 62. Although not mentioned earlier, the slave door also includes an outwardly extending element associated with bracket 48. It is this element (not shown) on the second end of the wagon which is engaged by safety hook 64. The safety hook system must be operated before attempting to open the doors 14a and 20 14b as a safety measure. This is to ensure that the doors do not accidentally swing open and lading is discharged at an inappropriate time. For example, in the case of rail wagons, impromptu opening of the doors could cause a train derailment. The doors may accidentally swing open if a component in the linkage system breaks, the loss of a pin, opening valve failure, amongst other reasons. Both ends of the wagon are viewable from a side profile in Figure 6. 25 Figure 7 illustrates an air flow circuit diagram 72 for supplying air to and from the three cylinders 22, 30 and 60 used in the discharge door system 10 of the present invention. Supply air 74 is allowed to pass to the circuit when an actuator 76 is operated. Actuation and exhaust of each cylinder is controlled using control valves 78, 80 and 82 associated with cylinders 22, 30 and 60 respectively. T-pieces 84 are used to connect the various air hoses. The skilled addressee 30 would realise that unless air is being supplied to cylinder 60, that is, unless the safety hooks 62 and 64 are in their unlocked position, air cannot be supplied to cylinders 22 and 30.
9 A one-way flow control valve 86 is also present in the exhaust line out of cylinder 22. The purpose of this control valve 86 is to retard the exhaust, that is, to retard the retraction of rod 32 so as to prevent bouncing of the master door l4b from lip 37 of the slave door 14a. The air line 88 represents the path to atmosphere. 5 It was mentioned earlier that the plate 48 is adjustably connected to the slave door 14a. Figure 8 illustrate an adjustment apparatus 90 mounted to the slave door 14a including an adjustment nut 92, which when loosened, allows for movement of the plate 48 along the end width of the slave door 14a to a desired position. The plate should be moved to a position which ensures the doors will correctly engage during the opening and closing sequence and it may take 10 some tweaking to locate this position. Once found, the adjusting nut 92 can then be tightened and the plate 48 will be locked at that position. The adjustment apparatus 90 is particularly useful when retrofitting the discharge door system 10 of the present invention onto existing wagons which have varying distances between the side walls of the wagon, and the point where the doors 14a and 14b meet. Also, it is 15 extremely difficult to manufacture an all welded rail wagon hopper structures to accept standard sized components including linkage arms and the like, and to counter bedding-in of bushes. The skilled addressee should now realise the benefits of the present invention. The discharge door system 10 alleviates all problems associated with conventional wagon bottom door systems in that it provides bias to the system, ensures that the slave door opens and closes 20 exactly when it should, and prevents bounce off, which is a typical cause of mis-closure. The improved door system 10 further includes an incorporated adjustment method which allows for adjustment of the linkage system relative to the slave door, and a safety hook system which ensures that the doors cannot be opened once the hooks are in a closed position. Further advantages and improvements may very well be made to the present invention 25 without deviating from its scope. Although the invention has been shown and described in what is conceived to be the most practical and preferred embodiment, it is recognized that departures may be made therefrom within the scope and spirit of the invention, which is not to be limited to the details disclosed herein but is to be accorded the full scope of the claims so as to embrace any and all equivalent devices and apparatus.