How Watch Hands Work

Hands

At their most basic, a watch's hands are pointing devices attached at the center of a dial. As they move around the dial, they point at markings on the dial that denote hours, minutes and seconds. Watch hands need some help in their journey around the dial. Our system of measuring time in 60-unit segments came down to us from the Babylonians. We can thank them for the complexity of watch hands.

Watch Power

First, watch hands need a power source of some kind, either mechanical or quartz. Mechanical watches rely on the methodical uncoiling of a spring, while quartz watches rely on a small electrical charge from a battery to release energy. Additionally, quartz watches may have either a digital display (lighted numerals) or an analog display in the form of hands.

Power Release and Regulation

When a mechanical watch is wound, it stores up energy in its spring. If it weren't controlled in some way, the spring would release the energy immediately. However, the end of the spring is stuck in the teeth of a small gear, creating rotation motion. In turn, the gear or gears are connected with a component called an escapement, which transforms this rotational motion into a back-and-forth movement known as oscillation. A balance wheel keeps the interval of oscillation steady, while the escapement's regulation of this motion causes the watch's hands to move at precise intervals we use to tell time.
Gears, springs, escapements and hands are usually made of steel; thus, keeping a watch free of moisture is almost mandatory, unless the case is waterproof.
Quartz watches that use hands as time indicators work in much the same way. However, instead of having a spring and a balance wheel, a quartz watch uses a battery instead of a spring and a tuning fork instead of a balance wheel.
No matter which power source a watch uses, the escapement regulates the rate of oscillation and converts that motion into the mechanical movement of the hands.

Movement of the Hands

Each time a gear turns, the energy is relayed to the escapement, which then turns the hour, minute and seconds wheels pinned to the hands of the watch. The hour wheel is larger in circumference than the second wheel; consequently, it takes 60 times as long to make a one revolution as does the minute hand. Similarly, the seconds wheel is much smaller than the minute hand and revolved 60 times faster.