A Mine-Car Which Unloads Itself 



Start the mechanism, and the car will be loaded, driven 

 to its destination, emptied and returned in one minute 



ANEW drop-bottom mining car is 

 being used in the larger mines of the 

 country. It operates automatically. 

 It is loaded by automatic chutes; it is 

 driven in trains by an 

 electric motor and it is 

 even dumped by me- 

 chanical trippers. The 

 car is of larger capacity 

 than previous types, 

 although the distance 

 from its top to the 

 rails is only a little 

 over two feet. 



The bottom of each 



^ 1 1. 



The three sections which comprise the 

 bottom of the automatic dumping car 



.TRIGGER STRIKES LATCrt IN FIRST TRAP DOOR OF LOADED CAR 



INCLINED TIMBER KNUCKLE CLOSES DOOR 



CAR EMPTY AND LOCKED- 



A car loaded with coal passes over a projection 

 above the tracks. A trigger is operated and 

 the three sections at the bottom of the car 

 open one after the other. The car then moves 

 over a sloping beam and the sections slide up 

 this and are closed and latched once more 



car is divided into three sections. As a 

 train of cars loaded with coal passes over a 

 storage pit, a rail projecting upwards from 

 the track operates a trigger at the rear of 

 each car. The trigger 

 moves sideways and 

 releases the bottom 

 section of the car next 

 to it. The weight of 

 the coal in this section 

 immediately forces the 

 section open. Just as 

 soon as this happens, 

 the middle section 

 is also released. 

 When this middle section has swung 

 open, the construction of the bottom 

 of the car is such as to release the re- 

 maining section also. 



Thus, in a very few seconds all the 

 sections will have swung open and all 

 the coal will have been dumped. The 

 car then travels onward to another 

 mechanism. This automatically closes 

 the bottom sections of the car. It 

 consists merely of a sloping beam 

 against which the opened sections slide 

 as the car moves along. The sections 

 slide to the top of the beam one after 

 the other. They are thus raised up 

 past their catches and successively 

 closed. 



The cars are drawn from the mine 

 by a small electric locomotive. In 

 some mines, however, neither motor 

 nor mule is required to draw the loaded 

 cars to the storage pits. Instead the 

 roadway of the cars is made sloping. 

 The weight of the loaded cars is suffi- 

 cient in these cases to furnish the 

 drawing power. In the run back to 

 the mine the locomotive is, of course, 

 used. The cars are empty on this 

 return trip, so that little electric power 

 is needed. 



The cars are of all-steel construction 

 and will last for many years. Besides 

 their simplicity of operation, they can 

 haul the coal far more quickly than can 

 other types. From fifteen to twenty 

 two-and-a-half-ton cars are operated 

 in one minute without requiring the 

 slightest attention after being started. 



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