LOCOMOTIVE 



3479 



LOCOMOTOR ATAXIA 



Freight Service. Great hauling power is 

 needed in the freight service; accordingly the 

 boilers of locomotives are large and the wheels 

 relatively small. The Mallet articulated com- 

 pound locomotive, which came into use in 

 1904, is essentially two locomotives, the rear 

 end of one being attached to the forward end 

 of the other. Some of these long locomotives 

 are made with a joint, so they may bend in 

 going round a curve. The most powerful loco- 

 motive ever built was turned out of the Bald- 

 win Locomotive Works in 1914. It weighs 

 853,000 pounds and hauled a train of 251 loaded 

 freight cars as a test. Modern freight engines 

 cost $18,000 t'o $20,000 each; their life is about 

 thirty years. See STEAM ENGINE; RAILROAD. 



The Electric Locomotive. Of late years the 

 electric locomotive has become a serious rival 

 of the steam locomotive. It has certain points 

 of marked superiority. It usually develops 

 more hauling power in proportion to its weight. 

 It does not "freeze up" in cold weather, like 

 the steam boiler; it requires no coal, and in a 

 mountainous country it creates a great saving 

 by "regenerating" on slopes much of the power 

 it has expended on steep grades. In cities like 

 New York, where steam locomotives are not 

 permitted on Manhattan Island, the smoke 

 nuisance is greatly lessened. 



Structure. The electric locomotive does not 

 in the least resemble a steam locomotive; it 

 looks from the interior more like an ordinary 

 express car. The striking thing about such a 

 locomotive is its simplicity of structure ; it con- 

 sists of a frame carrying one or more motors, 

 geared to the driving axles, and a number of 

 switches to regulate the power. It collects 

 power either from a wire overhead or from a 

 number of sliding "shoes" passing along a third 

 rail, electrically charged. 



The motors are driven by dynamos in a 

 central power house. A motor is itself a kind 

 of dynamo. For an explanation of how the 

 dynamo converts mechanical energy into elec- 

 trical energy and of how the motor converts 

 electrical energy into the power to do work, see 

 the articles DYNAMO; ELECTRIC MOTOR. The 

 force is imparted to the driving wheels in one 

 of several ways. In one type of locomotives, 

 the revolving armature shaft carries cogwheels, 

 which fit into toothed wheels connecting with 

 the axles of the driving wheels. In another 

 type, the rotating armatures impart a similar 

 motion to the driving wheels by an arrange- 

 ment of cranks and connecting rods like those 

 seen in the steam locomotive. Motors of this 

 type recently installed by the Pennsylvania 

 Railroad weigh 45,000 pounds each. 



Efficiency. The electric locomotives used by 

 the New York Central Railroad are fifty-seven 

 feet long and weigh 110 tons. They are driven 

 by eight motors, each of 325 horse power. Lo- 

 comotives of the type used by the New York, 

 New Haven & Hartford Railroad have eight 

 motors of 170 horse power each. They are 

 capable of pulling a heavy train at the rate of 

 sixty miles an hour. 



The largest electric locomotives ever built 

 were designed for the Chicago, Milwaukee & 

 St. Paul Railway. They were constructed to 

 haul freight and passenger trains through the 

 mountainous regions of Montana and Idaho, 

 where the extreme elevation is 6,300 feet. 

 These engines weigh 260 tons each and are 112 

 feet 8 inches long. They have a pull of 3,440 

 horse power and were designed to supplant the 

 huge Mallet engines in use up to 1915. See 

 ELECTRIC RAILWAY. 



Consult Sinclair's Development of the Loco- 

 motive Engine; Kirkman's The Locomotive; 

 Prothero's Railways of the World. 



LOCOMOTOR ATAXIA, lo homo 'tor atak' 

 si a, a disease of the spinal cord, characterized 

 by a staggering gait, in which the lower limbs 

 do not seem to be under control. It occurs usu- 



