This switch uses only one battery and a single
switch to change the direction of a motor. The switch is made from a couple of two way
switches linked by an insulating rod (R) so that they can both be moved
together.
When the switch is in the position shown in Figure 1 the contact at the
bottom of the motor is positive and the motor turns in one direction.
When the switch is in the position shown in Figure 2 the contact at the bottom of the motor is negative and the motor turns in the opposite direction direction.