crank

crank, in mechanics, arm secured at right angle to a shaft with which it can rotate or oscillate. Next to the wheel, the crank is the most important motion-transmitting device, since, with the connecting rod, it provides means for converting linear to rotary motion, and vice versa. There are many conflicting claims concerning the origin of the crank, but it has been reasonably well established that the first recognizable crank appeared in China early in...