Winches all have motors that drive or power the drum that spools the wire. An electric winch uses an electric motor. This electric motor is powered by electricity, just like a drill motor. Current changes on opposing poles spin a magnet that powers the motor and turns the winch. Since a winch is so heavy-duty, the electric motor on a winch must be robust with a solid electrical system that can handle a lot of charge. The winch motor also needs to adjust to handle heavier loads.
Some winches have gears that allow them to pull up very heavy loads. These gears can be very simple like bike gears. One small gear operated by an electric motor can turn a much larger gear, therefore increasing the amount that can actually be pulled. Advanced winches can also have what are called planetary gear trains or elliptical gears. As you might guess, these work like planets orbiting the sun. One small gear rotates around a larger gear, making it easier to pull up large objects. Winches can have any type of gear assembly, but most are elliptical or ordinary gear trains with successively smaller gears.
Electric winch operate on a power supply like any other electrical machine. They can be powered by either AC or DC systems. Many ATV winches are DC powered and run right off an ATV battery. Other truck and trailer winches run on simple 12-volt DC power. These can be rigged to run off the truck's electrical system while the truck is on and the alternator running. This can help the winch be more efficient since it will receive more power than running from a dry battery. A winch will not completely drain the battery system if operated while the truck is off. Winches do not use a large amount of electricity; mainly their gear system is doing all of the work.