Wheel train (horology)

A wheel train is a set of gears or wheels that work together to help measure time in a clock or watch. The wheel train starts with a main wheel, called the barrel or mainspring. The main wheel turns, and it powers the other small gears or wheels in the wheel train, which are connected to each other in a line. The last wheel in the wheel train is connected to a hand on the clock or watch, and it helps move the second, minute, and hour hands on the clock or watch. The gears inside the wheel train move at different speeds, so they help break up the motion of the main wheel into very short and exact movements so the clock or watch can mark the exact time.