ELECTRICITY IN MINING 47 



The hi^h tonsion system is in very common use and can 

 be seen in operation in almost any city where building founda- 

 tions are being excavated in hard material. The low tension 

 sj^stem is riuile po])ular in mines, however, the principal 

 reason being, apparently, that the fuses are less sul)ject to 

 deterioration and can be stored more safely than high tension 

 fuses. 



The electric locomotive is one of the most striking ex- 

 amples of the application of electricity to mining. The first 

 specifically electric mine locomotive employed in the United 

 States was built nearly twenty years ago by Mr. W. M. 

 Schlessinger for the Lykens Valley colliery of the Pennsyl- 

 vania railroad, and at last reports this machine was still 

 in service. It weighed al^out 5 tons and was equipped with 

 32 horsepower electric motors, from which motion was im- 

 parted to the driving wheels by a chain and cog or sprocket 

 connection. The conductor for supplying the current to 

 the locomotive consisted of a light T rail carried on supports 

 parallel to the track at a vertical height of about 5 feet and 

 removed horizontally from the track rail about 20 inches. 

 Current was conducted from this rail by means of three wheels 

 l)ressed against it by a trolley arm, and the track rails were 

 used as the return circuit. The ordinary train for this loco- 

 motive, which operated with a current of 450 volts and from 

 40 to 200 amperes, was 15 cars, each of which weighed 1 ton 

 when empt}' and carried 2.35 tons of coal or 3 tons of rock, 

 There were two haulage lines, one 9,500 feet long, in a drift, 

 and one 10,400 feet long, in a tunnel. 



Another early electric mine locomotive still in use is 

 of 40 horse power capacity and uses current at a pressure 

 of 220 volts, with a wheel gauge of only 36 inches. This 

 machine is 5 feet 6 inches in height and weighs 10,500 pounds 

 with 1,800 pounds added to increase traction. 



Modern mining locomotives range in size — according to 

 the w^ork they are designed to perform — anj^here from 2 

 to 20 tons, and their wheel gauges range from 18 inches to 

 the standard railway gauge of 4 feet 8^ inches. The traction 

 locomotive consists, broadly, of two iron frames within which 

 are contained the motor and driving mechanism, the controller 



