CHAPTER 17 ■ DC MOTORS
Gearhead motors almost always reduce the speed of the motor in exchange for increased twisting force
(torque). Recall that at optimal voltage, a DC motor rotates way too fast to be useful to most robots. With a
gearhead reduction, the robot can carry heavier loads while moving at the desired speed.
Because the DC motor still has the same two wires coming from it, a gearhead motor is just as easy to
use as a plain motor.
Looking Inside a Spur Gearhead Motor
A spur gearhead motor (see Figure 17-24) begins with an ordinary DC motor. A series of smaller gears
touching larger gears is placed within a rigid frame called a box. The gears are usually greased and then
protected with a cover to prevent dirt, grime, and stray wires from getting jammed in the works. Screws hold
the gearbox tightly on top of the DC motor.
Figure 17-23. Gearhead motor
Figure 17-24. Spur gearhead motor consists of: (left to right) DC brush motor, spur gearbox, gearbox cover,
and joining screws