Abstract:
A hydraulically operated side dump railroad car that operates by utilizing high pressure hydraulic fluid from delivered by a pneumatic to hydraulic converter pump located on the railroad car. On the railroad dump car, the hydraulic fluid is pumped from a hydraulic fluid reservoir to the hydraulic ram assembly of the car, without the use of an accumulator for storing pressurized hydraulic fluid. On the other hand, an existing railroad dump car having existing pneumatic equipment can easily retrofitted with the hydraulic system of the present invention with the use of standard train air brake piston and cylinders.

Description:
This application claims the benefit of U.S. Provisional Application Ser. No. 60/057,960 filed Sep. 5, 1997. 
    
    
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates to railroad dump cars. In particular, the present invention is a hydraulically powered system for operating the dumping mechanism of the dump car. 
     2. Description of the Prior Art 
     Side dump railroad cars are used for carrying and unloading bulk materials. The typical car comprises a frame with wheels and a pivotally connected hopper body. The body characteristically consists of side doors that open when the body is tilted at an angle sufficient to discharge the bulk material. 
     These present-day side-dump railroad cars are actuated by pneumatic rams that are attached to the frame of the car. Upon actuation, a piston raises the bed on one end, discharging the material over the other side of the car through the opened side door. 
     The source of compressed air to drive these rams is from an air compressor inside of the locomotive. A disadvantage to the use of pneumatic rams, however, is that they are (i) large, (ii) expensive to service, (iii) because they operate by air pressure, they are difficult to control and regulate under varying load conditions, and (iv), are susceptible to condensing and freezing of water vapor in the rail air lines and system components during cold winter months, thus causing blockage. 
     Probably most important from a safety standpoint relates to the difficulty of precisely controlling the movement of the dump body. This is because high pressure is initially required to begin the dumping process and as the load is removed, less pressure is required to complete the dumping process. When this condition occurs, the reduced compression of the air in the pneumatic ram causes a large and rapid travel in the piston, completing the dumping in an uncontrolled manner. This inability to control the rate of dumping as the load is removed causes great stress on all components of the dump car as the dump bed is slammed to the travel stops. 
     Others have attempted to solve this problem by replacing the pneumatic rams with hydraulic drive rams. A major disadvantage inherent in some systems, such as that depicted in McCormick, U.S. Pat. No. 4,407,202, is the use of a hydraulic accumulator attached to each railroad car to store hydraulic fluid pressure. This accumulator poses a potential safety problem, since hydraulic fluid may be at a pressure of 3000 psi or greater, a valve failure could cause the car to dump unexpectedly, having serious consequences. Therefore, a hydraulically operated side dump railroad car having a dump mechanism that operates at approximately the same rate as a car equipped with a hydraulic accumulator would be an important advancement for railroad operators. 
     SUMMARY OF THE INVENTION 
     The present invention seeks to overcome these and other disadvantages present in the prior art by providing a side dump railroad car that is operated by hydraulic rams but does not require a hydraulic accumulator. Utilizing compressed air from the locomotive or other source, the system for generating hydraulic pressure, in its basic form, includes a pair of opposing air brake cylinders whose actuating arms are connected to a pivoting lever. This lever in turn is connected to the piston of a double-acting hydraulic pump. This hydraulic pump in turn is operatively linked to at least one hydraulic ram that is capable of lifting the dump bed. 
     When the pump mechanism is actuated, air travels into a first air brake actuator and causes movement of its piston outwardly. This piston is connected by a first connecting arm to a centrally located pivot arm, which moves outwardly from the first air brake actuator. The pivot arm is connected to a hydraulic ram, which in turn moves and generates hydraulic fluid pressure. When the first air brake actuator connecting arm reaches its maximum travel, a valve is actuated, allowing air to fill the second opposing air brake actuator and release air pressure from the first air brake actuator. A piston in the second air brake actuator is connected to a second connecting arm that is also connected to the pivot arm. The pivot arm is then moved in the opposite direction by the second connecting arm, causing another stroke of the hydraulic ram and generation of additional hydraulic fluid pressure. When the second air brake actuator connecting arm reaches its maximum travel, a valve is actuated, allowing air to fill the first opposing air brake actuator and release air pressure from the second air brake actuator. In this manner, air pressure is converted to hydraulic pressure to activate the car&#39;s lift system. 
     Operation of the dumping mechanism is commenced by a hydraulic valve that selectively causes the hydraulic fluid pressurized by the converter pump to flow into at least one hydraulic ram. The pressurized hydraulic fluid causes the hydraulic ram to move the dump bed causing removal of materials contained therein. Also, an advantage of the present system is the ability to hold a dump body in mid-position for extended periods of time, unlike pneumatically-driven systems. 
     Noteworthy in the present system is the lack of an oil or hydraulic accumulator tank or device. Hydraulic fluid is pumped from a hydraulic fluid reservoir directly into the hydraulic rams that lift the dump bed. The oil reservoir of the present invention serves as a supply source for the hydraulic oil and as a return vessel for oil following use in the hydraulic drive rams. A pressure relief valve maintains the pressure in the oil reservoir well below that required to move the hydraulic drive rams, and thus the oil reservoir does not serve as a hydraulic accumulator. The present invention therefore provides a safer mechanism for moving the dump body of a side dump railroad car. 
     In other embodiments, it is envisioned that the hydraulic pump mechanism that converts pneumatic pressure to hydraulic pressure will be a part of each individual dump car. In alternative embodiments, a larger pneumatic to hydraulic system may be placed on an auxiliary railroad car and serve to actuate the hydraulic rams of a series of side-dump railroad cars. Moreover, it is contemplated that hydraulic power from a locomotive&#39;s hydraulic pump could be used to activate the dump car&#39;s hydraulic mechanism. 
     The hydraulic system of the present invention further eliminates safety problems that may occur when using a hydraulic storage accumulator that holds the hydraulic fluid pressure even after the air pressure source is disconnected. For example, should the hydraulic accumulator tank become compromised, the release of high pressure oil may be dangerous to railroad workers and equipment. Moreover, a safety hazard exists with accidental movement of the hydraulic valve, which may result in an unintended dumping of the car contents. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a perspective view showing a hydraulically powered side dump railroad car utilizing the present invention. 
     FIG. 2 is a schematic diagram of the hydraulic system of the present invention. 
     FIG. 3 is a sectional view showing the position of the hydraulic rams when pivoting the dump body for unloading. 
     FIG. 4 shows a side view of the hydraulic rams in the process of tilting the dump body. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     The present invention is a side dump railroad car that is operated by hydraulic rams supplied with pressurized hydraulic fluid from a pneumatic to hydraulic converter pump. Utilizing compressed air from the locomotive, internal combustion engine, or other source, a pair of opposing air brake cylinders is actuated whereby actuating arms attached to the pneumatic air brake cylinders connected to the piston of a double-acting hydraulic pump. This hydraulic pump in turn is operatively linked to at least one hydraulic ram that is capable of lifting the dump bed. In preferred embodiments of the invention, each side dump railroad car carries its own pneumatic to hydraulic converter pump, such as the one set forth in FIG.  2 . An advantage of such an arrangement is that each car may be independently dumped, irrespective of a common source of hydraulic pressure. Should a failure of one car&#39;s converter pump occur, however, then it is possible to operatively connect the adjacent car&#39;s converter pump to the failed car&#39;s hydraulic system to effectuate dumping of materials in the dump body. 
     FIG. 1 shows the hydraulically actuated dump system as it is used on a conventional side dump rail car  100 . Car  100  includes a conventional car frame  105  and a dump body  110  of conventional construction. Frame  105  also has wheels  115  operatively connected. In preferred embodiments, the present invention includes four hydraulic rams  120   a ,  120   b ,  120   c , and  120   d  positioned two on each side of frame  105 . Hydraulic rams  120   a ,  120   b ,  120   c , and  120   d  are pivotally mounted to outward extending frame members  125   a  and  125   b , preferably two per side of the car. Hydraulic rams  120   a ,  120   b ,  120   c , and  120   d  are positioned on the opposite side of center sill  16  and are pivotally connected to outwardly extending frame members  125 . The rams are pivotally connected to members  125   a  and  125   b  of car frame  105  at pivot points  130   a  and  130   b  as shown in FIG. 1, FIG.  3 A and FIG.  3 B. Hydraulic rams  120   a ,  120   b ,  120   c , and  120   d  are telescopic hydraulic rams, which are pivotally connected at their upper ends to dump body  110  at pivot points  130   a  and  130   b.    
     To dump the contents of dump body  110  on one side of the car, hydraulic rams  120   a  and  120   b  are energized, thereby lifting the other side of dump body  110 . FIG. 3 illustrates an embodiment similar to FIG. 1 in which a side of dump body  305  is lifted by an actuated ram  315   a . Conversely, to dump the contents on the opposite side of the car, hydraulic rams  120   c  and  120   d  are actuated, thereby lifting their side of the dump body  110 . In one typical embodiment of the present invention, hydraulic rams  120   a ,  120   b ,  120   c , and  120   d  are telescopic-type hydraulic lift rams. 
     FIG. 2 shows a representative pneumatic to hydraulic converter pump  200  according to the present invention. In this illustrative embodiment, hydraulic fluid pressure is generated by utilizing the auxiliary air supply of the train supplied by auxiliary air input line  203  to actuate pneumatic ram  216   a  or  216   b , which rams may be, for example, standard train brake air cylinders. In preferred embodiments, these cylinders are 12 inch air brake cylinders. Converter pump  200  may be part of each railroad car, or alternatively converter pump  200  may be on a separate railroad car and be hydraulically connected to a plurality of hydraulically operated dump cars. 
     In other embodiments, auxiliary air input line  203  is connected to the train&#39;s auxiliary air system and to air reservoir  201 , to provide pressurized air at approximately 90 psi or above. Pneumatic to hydraulic converter pump  200  converts the low pressure air to a much higher hydraulic pressure to operate hydraulic rams  235   a  and  235   b . Air reservoir  201  may have drain cock  202  connected thereto. 
     When control valve  212  is opened, air travels into first air brake cylinder  216   a  and causes movement of its piston outwardly. This piston is connected to centrally located pivot arm  220  pivotally connected at pivot point  221 . Pivot arm  220  moves outwardly from first air brake cylinder  216   a . Pivot arm  220  is further connected to hydraulic booster pump  218  that generates hydraulic fluid pressure. Hydraulic booster pump  218  may be, for example, a double acting hydraulic booster pump. When first air brake cylinder reaches its maximum travel, limit switch  222   b  is actuated, allowing air to fill second opposing air brake cylinder  216   b , while releasing air pressure from first air brake cylinder  216   a . Second air brake cylinder  216   b  is opposedly connected to pivot arm  220 , which then moves in the opposite direction, causing another stroke of hydraulic booster pump  218  and generation of additional hydraulic fluid pressure. When second air brake cylinder  216   b  reaches its maximum travel, limit switch  222   a  is actuated, allowing air to fill first opposing air brake cylinder  216   a  while releasing air pressure from second air brake cylinder  216   b.    
     Hydraulic fluid  224  is drawn from reservoir  225  through filter  227  and ball check valves  229  into hydraulic booster pump  218 . Ball check valves  229  allow hydraulic fluid  224  to enter to hydraulic booster pump  218  at low pressure. When high hydraulic pressure is generated by hydraulic booster pump  218 , hydraulic fluid exits at high pressure through ball check valves  229 , through ported valve  232  and into drive rams  235   a  and  235   b . Ported valve  232  controls hydraulic fluid flow into hydraulic drive rams  235   a  and  235   b . In this manner, air pressure reciprocating between air cylinders  216   a  and  216   b  is converted to hydraulic pressure to activate the railroad car lift system. 
     Operation of the dumping mechanism is commenced by a hydraulic valve that selectively causes the hydraulic fluid pressurized by the converter pump to flow into at least one hydraulic ram. Pressurized hydraulic fluid  224  causes hydraulic ram  235   a  and  235   b  to move the dump bed, thus causing removal of materials contained therein. Also, an advantage of the present system is the ability to hold a dump body in mid-position for extended periods of time, unlike dump bodies that are lifted by pneumatic rams. 
     In the embodiment shown in FIG. 2, the hydraulically powered control system includes control valve  212 , which may be actuated by the operator to cause rams  235   a  and  235   b  to be filled with hydraulic fluid  224 . Lowering hydraulic rams  235   a  and  235   b  is accomplished by engaging valve  232  to release hydraulic fluid  224  back into reservoir  225 . Pressure relief valve  228  prevents overpressure from developing in reservoir  225 . 
     The operation of valve  212  causes dump body to be raised by rams  235   a  and  235   b . It is recognized that rams  235   a  and  235   b  may be placed on either side of the car, to allow for dumping of car contents on either side. Hydraulic booster pump  218  increases the low air pressure that is typically generated by a locomotive air pump to hydraulic pressure of about 2,000 psi. 
     FIG. 3 shows an end perspective of a typical side dump railroad car of the present invention, showing dump bed  305  in a raised position following energizing of ram  315   a  with pressurized hydraulic fluid. The location of pivot points  310   a  and  310   b  between a bottom  316  of dump bed  305  and end of rams  315   a  and  315   b  are shown. In addition, rams  315   a  and  315   b  are pivotally connected to frame  320  of the side dump railroad car to allow free rotation. Ram  315   b  is shown in an unenergized state. If it is desired to lift dump body  305  on the opposite side, then ram  315   a  is unenergized, and ram  315   b  is filled with pressurized hydraulic fluid to lift dump body  305 . FIG. 4 depicts a side view of side dump railroad car  400  showing rams  425   a  and  425   b  partially extended to lift dump body  405 . Air reservoir  401  is shown attached to car frame  420 , and supplies air pressure to operate pneumatic to hydraulic converter which in turn supplies hydraulic pressure to rams  425   a  and  425   b . Hydraulic ram supports  425   a  and  425   b  are pivotally connected to frame  420 , and support hydraulic rams  425   a  and  425   b , allowing hydraulic rams  425   a  and  425   b  to pivotally rotate on car frame  420  as dump body  405  is raised. An aspect of hydraulic ram supports  425   a  and  425   b  is that they retrofit directly into the same frame supports that were used by the pneumatic rams. Thus, to retrofit a car from pneumatically powered rams to hydraulically powered rams is greatly simplified using the frame supports of the present invention. 
     In another preferred embodiment, the requirement for an auxiliary air line as the ultimate primary source of power can be eliminated entirely. In place of such an air driven pump, an auxiliary hydraulic pump may be employed to drive the hydraulic rams. The auxiliary hydraulic pump may be powered by, for example, an internal combustion engine. The principal advantage of this embodiment is that it does not require an auxiliary air line, and as such, allows side dump cars to be used in trains having cars not so equipped. In addition, such an auxiliary pump may be used to power a plurality of side-dump railroad cars so equipped. 
     It is also recognized that the present invention also has uses in other types of dump cars. Such cars include, for example, a bottom dump slide gate car or any other car in which a movable gate for unloading the contents of a railroad car is required. 
     The apparatus disclosed and claimed herein can be made and executed without undue experimentation in light of the present disclosure. While the apparatus and methods of this invention have been described in terms of preferred embodiments, it will be apparent to those of skill in the art that variations may be applied to the apparatus and in the steps or in the sequence of steps of the method described herein without departing from the concept, spirit and scope of the invention. More specifically, it will be apparent that certain dimensions of the various components making the invention, as well as methods of storage, deployment and attachments may be varied to achieve the same or similar results. All such similar substitutes and modifications apparent to those skilled in the art are deemed to be within the spirit, scope and concept of the invention as defined by the appended claims.