Typically, unloading stations for unloading rail cars are made to be in fixed locations. Such fixed unloading stations are often deep pits with concrete side walls with conveyers made to catch material dropped from the rail cars, conveying the material upward out of the pits to, for example, load into dump trucks for transporting elsewhere, to stock pile the material or to feed other conveyer systems. These unloading stations are very costly to build and maintain and, as a result, it is often difficult to justify expanding into new geographical areas to build new fixed unloading stations. Furthermore, due to the limited proximity locations of the unloading stations, their can also be high cost in transporting the bulk material in dump trucks from the unloading stations to a final destination.
Many attempts have been made to correct the problem of unloading rail cars in locations without the use of fixed unloading stations. However, such attempts have not matched the efficiency of unloading rail cars at the fixed unloading stations. For example, U.S. Pat. No. 5,402,874, to Dahlin et al., discloses a conveyer coupled to a motor vehicle for conveying bulk material being dumped from the bottom of a rail car to another location, such as a dump truck. While in use, the conveyer remains coupled to the motor vehicle and is positioned laterally above the motor vehicle with a conveyer bottom end under the rail car and a conveyer upper end located above the dump truck. This conveyer system may be efficient for moving bulk material from a single rail car; however, time is wasted for re-set up between each rail car since the conveyer system requires retracting and re-set up to begin conveying the material from a subsequent rail car. Further, since the conveyer system is linear, time is wasted in positioning and aligning the conveyer bottom end to the appropriate location where the bulk material is dumped from the rail car. In addition, the linear type of conveyer system is limited to bottom dumping from a single shoot in the rail car and, further, the flow of materials from the shoot may have to be restricted in order to avoid over-flow of the material onto the linear type of conveyer system.
U.S. Pat. No. 6,561,742, to Crawford et al., discloses a rail car unloading apparatus utilizing a trackhoe mounted to the top of a rail car. The trackhoe requires a ramp to drive onto the upper surface of the rail car and then is mounted to the upper surface with a support bracket assembly. The upper surface of the rail car is then opened and the trackhoe is used for removing the contents of the rail car. Although this system facilitates removing the bulk material at locations other than a fixed unloading station, this system is limited in the speed by which the trackhoe can remove the bulk material from the rail car. Further, this system is inefficient in initial set-up time and the set-up time required for unloading subsequent rail cars. Additionally, trackhoes cannot remove all the material from the rail cars and, therefore, additional steps often must be taken to completely clean the material from the rail car, causing additional man-power and wasted time.
Therefore, it would be advantageous to develop an apparatus and method for unloading material from rail cars that is readily movable to different locations and is as efficient in unloading material from multiple rail cars as that which is employed for unloading rail cars at fixed unloading stations.