CHAPTER 19
Wheels
At this point, you have some wonderful motors that are only spinning themselves. In this chapter, you’ll
be introduced to a variety of wheels and some criteria to aid you in selecting a pair of wheels for the line-
following robot.
Anatomy of a Wheel
Most wheels consist of two parts (see Figure 19-1). First, there’s the tire, which is the rubbery part that grips
the surface. Then, there’s a sturdy core, which distributes the motor force and retains the wheel’s shape.
Figure 19-1. An ordinary wheel with the rim partially pulled out
The portion of the tire that usually contacts the ground is called the tread. The sidewall is the portion of
the tire that runs perpendicular to the tread, forming the shape of the tire. The shoulder is the transition area
between the tread and the sidewalls. The bead is a lip designed to fit snuggly into the rim.
The rim is a made of a firm material that the tire rests against. On some wheels, individual spokes
connect the rim to the hub. The hub attaches the wheel to the motor shaft or drive train.
Of course, there are many types of wheels that don’t exactly fit this model. Even so, most of the basic
terminology is still applicable.