A miniature electric railway is a thing that attracts the attention of almost any person. The cost of a toy electric locomotive is beyond the reach of many boys who could just as well make such a toy without much expense and be proud to say they "built it themselves." The electric locomotive described herewith uses for its power a small battery motor costing about $1. The first thing to do is to make the wheels and axles. If one has no lathe, the wheels can be turned at some machine shop. Four wheels are made from a round bar of metal, as shown in Fig. 1. Each wheel is 1/4 in. thick and 1 in. in diameter, with a 1/16-in. flange and a 1/4-in. hole drilled in the center. Each pair of wheels is fitted on a 1/4-in. axle, about 2-5/8 in. long. One of the axles should be fitted with a grooved belt wheel, as shown. Make the frame from three pieces of heavy brass, as shown in Fig. 2.
The Different Parts for Making the Electric Locomotive
The first piece, or main part of the frame, is made from brass, 3/4 in. wide and 16 in. long, bent into an oblong shape and the ends soldered or bolted together. If the ends are to be soldered, before doing so drill four 1/4-in. holes 1 in. from the ends and insert the ends of the axles. The other two pieces are 1/2-in. wide and of the dimensions shown in the sketch. These pieces are riveted in the middle of the oblong frame, each in its proper place. The motor is now bolted, bottom side up, to the top of the piece fastened to the frame lengthwise. A trolley, Fig. 3, is made from a piece of clock spring, bent as shown, and a small piece of tin soldered to the top end for a brush connection. A groove is made in the tin to keep the trolley wire in place.
The trolley wire is fastened to supports made of wood and of the dimensions given in Fig. 4. The trolley should be well insulated from the frame. The parts, put together complete, are shown in Fig. 5. Run a belt from the pulley on the motor to the grooved wheel on the axle, as shown in Fig. 6, and the locomotive is ready for running.
In making the connections the travel of the locomotive may be made more complicated by placing a rheostat and controlling switches in the line, so that the engine can be started and stopped at will from a distance and the speed regulated. Automatic switches can be attached at the ends of the line to break the circuit when the locomotive passes a certain point.
One connection from the batteries is made to the trolley wire and the other to a rail. The connection for the motor runs from one binding post to the trolley and this connection must be well insulated to avoid a short-circuit. The other binding-post is connected to the frame.
The cost of making the wheels and purchasing the track will not be over $1.50. The track can be made from strips of tin put in a saw cut made in pieces of wood used for ties. This will save buying a track. --Contributed by Maurice E. Fuller, San Antonio, Texas.