MotionRebuild shelfUnplug and unscrew

DC gearmotor

Also called gear motor, planetary motor, window motor.

A brushed or brushless motor already fitted with a gearbox. Torque is the point. The ratio is almost never printed on the toy ones.

If you are new to this category

These parts spin, push, or pump. A motor is a machine that turns electricity into turning. Some start turning as soon as you connect a battery. Others look identical and will not move until a small circuit tells them which coil to power next. The label, or the number of wires, is how you tell them apart.

Count the thick wires before you apply power. Two wires usually mean a brushed motor that can run from a battery. Three thick wires usually mean a brushless motor. Keep the board that came with a brushless motor.

A brushed motor

Two wires mean you can try a low, current-limited voltage and it should spin. The case often hides a label. If the only label you can find is on the machine, that voltage is the one to believe, not a hobby guess.

Lithium-ion cells. A punctured, crushed, overcharged, or reverse-charged cell vents and burns hot enough to ignite the bench. Swollen pouches are already failed.

Specification. The right-hand column is what is typical. The label on the part in your hand wins if they disagree.
What to look for	Usual figure
Output	A few RPM (door lock, antenna) up to a few hundred RPM (drill gearbox, robot toy)
Drill planetary	High torque, high speed in, plastic or sintered gears. Impact drivers eat the plastic.
Stall	Can strip plastic teeth or demagnetize a small rotor. Fuse it.

Volts are electrical pressure, amps are how much current is flowing, and ohms are how hard the part resists that flow. A higher voltage than the part was built for is how salvage parts die on the bench. If a cell in the table says “read the stamp”, that stamp is the whole specification.

What people actually use it for

Slow mechanical jobs
Robot joints if you add your own encoder
Replacement for a dead appliance gearbox of the same family

Leave this one when

Gears are already dust, or the gearbox is welded shut and you needed a known ratio.

Buying a new one is the better idea when

When the ratio must be exact. Salvage ratios are measured, not specified.

How to tell if this one still works

Spin by hand. Gritty or skipping teeth is scrap. Then a brief low-voltage run while you count output revolutions against a mark.

Step-by-step on the bench: Identify an unknown motor

Tools you will want: Meter, Marker to count turns.

Words on this page

Short meanings, so the rest of the entry is readable if you are not already doing this every weekend.

brushless: A motor with no brushes. It usually has three thick wires and will not spin from a battery alone. It needs the circuit it came with, or a matching driver.
torque: Twisting strength, as opposed to speed. A gearbox trades speed for torque. That is why a drill can turn a screw slowly with force.
RPM: Revolutions per minute. How fast the shaft turns. A microwave turntable motor is a few RPM. A blender motor is many thousands.
stall: The shaft is powered but not turning, because the load is too heavy. Current jumps. Plastic gears strip. Fuses exist for this moment.

Where people actually find it

4 notes, most useful first. “Leave it” means the part is in that machine and you should not take it: it is dangerous, worn out, or only useful if you already know that exact repair.

Harvest at a glance
From	Call	How many	How often	Where it sits
Cordless drill	Worth it	1	always	The front.
Digital camera	Worth it	1–2	usually	Zoom and focus.
Electric toothbrush	Worth it	1	usually	The handle.
Treadmill	Bonus	1	usually	Incline.

Worth pullingCordless drill1 · always
In this particular machine
Planetary gearbox. The whole point of the tool.
Where to look
The front.
How to get it out
Do not lose the thrust washers.
The condition to expect
Plastic planets strip on impacts.
Worth pullingDigital camera1–2 · usually
In this particular machine
Tiny, plastic gears.
Where to look
Zoom and focus.
How to get it out
The stripped one is the fault. Its neighbors are fine.
The condition to expect
Mixed.
Worth pullingElectric toothbrush1 · usually
In this particular machine
Tiny, low voltage.
Where to look
The handle.
How to get it out
The gearbox is finer than you want to reassemble.
The condition to expect
Good.
Bonus, if you are already in thereTreadmill1 · usually
In this particular machine
A smaller DC motor, often still high voltage. Read it.
Where to look
Incline.
How to get it out
Do not mix it up with the main motor.
The condition to expect
Good.