Page 164 - Making things move_ DIY mechanisms for inventors, hobbyists, and artists

Chapter 6 Options for Creating and Controlling Motion 143

FIGURE 6-15 Linear motor controlling shoe lift (credit: Adi Marom)

Linear motors

plunger and expect it to hold. Dynamic thrust is the maximum weight of something
you can expect the motor to move. For example, the 25 lb actuator from ServoCity in
Figure 6-14 (the smallest one) will not lift you up if you weigh 150 lbs, but it will hold
your weight if fixed in one place.

Solenoids

Solenoids work like a motor that translates (moves in or out) instead of spinning. A
solenoid consists of a housing, a plunger, and usually a spring that returns the plunger
to a resting state once the power is off. There’s a coil of wire around the plunger, and
when electricity flows through that coil, it either attracts or repels the plunger to give
you a short, linear stroke—good for pushing buttons and making robotic instruments.
If you have a doorbell, it most likely has a solenoid in it. When you press the button,
it closes a circuit that makes a solenoid turn on, which moves the plunger and hits a
chime.