Fig. 265.—Details of the Bearing which supports the Wheel and Axle.
Each shaft is composed of two pieces of "Bessemer" rod held together by a short piece of fiber rod having a hole in each end into which one end of each piece of iron rod is driven. The wheels fit tightly on the other end of each of these pieces. They should be spaced so as to run on rails two inches apart.
Fig. 266.—The Wheels and Axle.
The purpose of the fiber rod is to insulate the halves of the axle from each other. The electric current which operates the car is carried by the two rails which form the track, and if the axles were made in one piece or the halves joined together so as to form an electrical connection, the battery furnishing the current would be short-circuited, because the current would pass along the two rails and across the axles instead of through the motor.
One pair of wheels are fitted with a grooved pulley one inch in diameter.
It is hardly necessary to say that the wheels and axles should be perfectly aligned, and should run true.
Fig. 267.—The Motor.