A chain or belt is used to connect two sprockets, with one being the ‘driver’ and the other being ‘driven’. Motion or force then drives them, which transmits power or changes the torque or speed of a mechanical system.
Sprockets with more teeth are able to move heavier amounts of weight, however they produce more friction, which reduces operating speed.
As a chain passes over, it wears away the notches, so if they’ve become sharpened or hooked at the tip instead of being blunt they need to be replaced.
Common uses of sprockets
They’re regularly used on bicycles to pull a linked chain to turn the movement of the rider's feet into rotation of the bike’s wheels.
Sprockets are also used on tracked vehicles such as tanks and farming machinery. They line up with the links of a track and pull them as it rotates, allowing the vehicle to move. This distributes the weight of the vehicle across the entire track, which is what enables tracked vehicles to travel across uneven ground more carefully.
In film cameras and film projectors, sprockets are used to hold the film in place and move it as photographs are taken. They're also used to thread movies on film.