We just learned about the Valve Types.
Another part of machines is a Servo, also called a servomechanism.
This is something that uses special sensors to make a machine move or stop moving if it senses something bad.
When you go to a store and the automatic door is closing but senses you walking through it and stops, that is using a servo.
The servo has a motor that is closing the door, and then the sensor tells it that there is someone there, and it tells the motor to stop.
When it is clear, the servo tells it to close the door.
So a servo is really like a smart machine controller that automatically turns on or off when it needs to.
(from: wikipedia - servomechanism)
Kid Facts - Blast from the past: PGM-11 Redstone
