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Motor Repair

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Motor Repair Powered By Docstoc
					Motor Repair
Small and large appliances have a motor , a heating element , or both. Motors are important
components to hundreds of devices we use in daily life. This guide will show you how
motors work and how to fix them when they don't.

How Does It Work?

A motor turns electrical energy into motion. Actually, it uses electricity's magnetism to
attract, then repel components to rotate a shaft. You can attach fan blades, knife blades,
wheels, or a dozen other components to the shaft to make useful devices. To name a few:
blender, cassette deck, CD player, coffee grinder, computer fan, computer printer head, DVD
player, electric can opener. . .you get the idea. These and hundreds of other functional
gadgets rely on electric motors to give them motion.

Smaller appliances typically use what's called a universal motor. It's simple, efficient, and
relatively inexpensive. It's called "universal" because it can run on either alternating current
(AC) or direct current (DC) power. The part that stands still is called the stator and the
rotating part is the rotor. It's as simple as that.

Some small appliances use a variation called the shaded-pole motor. It works about the same
as the universal motor, but is less expensive to manufacture so it typically goes into lower-
cost, low-load, small appliances.

Larger appliances, as you can imagine, require more power. Many use a split-phase induction
motor to develop more rotating power, called torque, than smaller motors can muster. Split-
phase induction motors, too, have stators and rotors.

Smaller things, such as battery-operated appliances and tools, get their power from DC
batteries so they are made to run on direct current. They don't have much motion or torque,
but they get the job done in a small space.

What's the difference? Usually it's cost. Most manufacturers
use the least expensive motor that does the job. Fortunately,
checking whether a motor runs or doesn't is about the same
for any type of motor. Unless you're adventuresome, you
probably won't dismantle a motor and replace components.
If it works, you'll use it; if not, you'll recycle it.

Many motors include a drive mechanism of some type that
transfers the shaft rotation to some other component. You
can fix or replace drive mechanisms as well (see below).         You can see the commutator and
                                                                 the rotor inside this motor from a
                                                                 variable-speed food mixer.
What Can Go Wrong?
Though efficient, motors can work against themselves. A
small problem can become a big one quickly and, soon, the
motor is damaged beyond repair. Fortunately, most motors
will tell you--sometimes subtly, sometimes not--that they are
having problems. Motors burn out and freeze up; they get
noisy, overheat, and wobble.



                                                                Turning on and off the motor's
                                                                brushes (left, top, and bottom)
                                                                creates a magnetic field that
                                                                makes the motor shaft rotate.

				
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posted:10/28/2011
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