Page:Popular Science Monthly Volume 91.djvu/412

 The Most Powerful Locomotive in the World

It weighs 260 tons; it is 76 feet long, and it takes cur- rent from a trolley wire no bigger than a lead pencil

By William H. Easton

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��The power of this loco- motive is equal to that of one hundred trolley- cars, or 14,000 horses, or 56,000 of the strong- est men. It consumes enough current to light over 200,000 25-watt electric lamps; and many a town of 25,000 inhabitants has an elec- tric plant of smaller capacity. This is be- cause high voltage is used in distributing the strong electric current

���A glance at the illustra- tion shows apparently eight driving wheels on each side, but there are actually only six. The wheels on each end are gears which are driven by the motors and which in turn drive the driving wheels through the connecting rods. By this arrangement, the motors can be lo- cated up in the cab and not down on the axles as in a trolley car

��THOUGH hardly more impressive in appearance than an ordinary bag- gage car, the electric locomotive illustrated has the distinction of being by far the most powerful thing on wheels. Exerting its maximum effort, it can develop 7,000 horsepower, which is fifty per cent more than its closest rival, also an electric, can do.

It is not necessary for the entire main line of railroad to become congested be- fore trouble is experienced, for, since a passage is no wider than its narrowest point, one congested section sets the limit to the capacity of the whole.

Such a section exists between Altoona and Johnstown, Pa., where the freight traffic is unusually heavy, amounting to 300,000 tons a day. Trains over this di- vision must push up steep grades, pass around the famous Horseshoe Curve, and run through a long tunnel. Though the railroad is not particularly embarrassed at present, it is taking no chances, and some time in the future its new huge elec- tric locomotive, with many more like it,

��It Rides Easier Than a Steam Locomotive

Each gear wheel carries a set of coiled springs. The reason for these springs is as follows: When a steam engine starts, the piston does not move with a sud- den blow, because there is a cushion of steam behind it which is compressed and eases the shock. But a motor, in endeavoring to start a heavy train through a solid gear train, strikes its gears sharply and thus sets up heavy stresses. By the use of these springs, a cush- ion is introduced between motor and driving wheels

��will be handling the traffic through this "neck of the bottle," as such a section is graphically called.

Trains so long that three of the largest steam locomotives can barely move them will be rushed up the grades by two electric locomotives at twenty miles an hour. In this way the capacity of the division will be more than doubled and all danger of congestion here will be removed for many years to come.

One peculiarity of the electric locomo- tive is that its speed of twenty miles an hour cannot be exceeded whether running on electric power or coasting down hill. In the latter case the motors act as generators and return current to the line, and since power is required to generate current, a most effective braking action results which prevents runaways. At the same time the coasting speed can be regulated by the controllers, just as is the speed under power. Air brakes are therefore not need- ed while coasting and are simply held for emergency use and for bringing the train to a full stop.

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