Page:Motors and motor-driving (1902).djvu/246

214 same, then will remain parallel with the axle. If, however, the steering wheels are set to turn a corner, the wheel being on the inner or smaller curve, then the wheel  will have to move faster than, and the arm  will be pulled through a greater angle than the arm , and the cross-piece  will cease to be parallel with the axle. The parts will take the positions shown by the dotted lines. Such an apparatus could only act through part of one revolution of the wheels, but so far as it acts, it permits the pull on either wheel to remain of equal value, though one wheel moves more quickly than the other.

The principle illustrated by this diagram may now be followed in fig. 4, which illustrates a common form of live axle



driven by a horizontal jointed rod from the motor and a bevel pinion. The functions performed by the parts are the same as those having the same letters in fig. 3.

The differential gear consists of two bevel wheels and, each tooth of which acts in the same way as the arms and  of fig. 3, and two or more bevel pinions  each of which acts in the same way as the cross-piece  in fig. 3, but by means of its teeth bearing upon the teeth  and  of the bevel wheels instead of the one tooth or arm  or  in fig. 3. These bevel pinions are loose upon the pins on the end of the piece , just as the piece  is loose on the pin  in fig. 3, but instead of the pin  being pulled by a rod it is carried round by the bevel wheel , acting in the same way but