Crank

machines · levers · engines

Turns motion two ways. A crank can take circular spinning motion and change it into back-and-forth motion, or take back-and-forth motion and change it into spinning. It's like a translator between two different types of movement.

Like a bicycle pedal. The crank on a bicycle works the same way as the one in engines. When you push the pedal down and around in circles, the crank converts that into motion that moves the bike forward.

Partners with a rod. A crank works with a connecting rod attached to its end. As the crank spins in circles, it pulls and pushes the rod back and forth, kind of like how your arm bones work together when you move.

Powers car engines. In car engines, tiny explosions push rods back and forth really fast, and cranks turn that pushing motion into the spinning that makes the wheels go round and round.

Found on fishing reels. When you turn the handle of a fishing reel to wind up your line, you're turning a crank that makes the reel spin and collect the fishing line.