What is a Balance Wheel?

Balance wheels are simple devices that help to control the speed of movement that occurs within a piece of machinery. Wheels of this type are found in everyday appliances like clocks and watches, as well as in large machines that are used in the manufacturing of different types of products. The concept of the balance wheel has been around for centuries, and has remained mostly unchanged since the Middle Ages.

While there is some difference of opinion as to when the balance wheel was first invented, there is general agreement that mechanized timepieces developed during the 14th century included the use of these wheels. Over the centuries, timepieces of all types, ranging from pocket watches to the large clocks found in the town squares of many municipalities, included the use of a balance wheel. It is only since the 1970’s and the invention of newer digital timepieces that the balance wheel has begun to disappear from some forms of clockwork.

Over the years, different types of metals were used in the construction of balance wheels. Today, the wheels used in some wrist watch designs are composed of a compound known as glucydur, which is composed of copper, iron, and beryllium. Lightweight in design, a balance wheel made with this compound is still very strong, and likely to hold up well over many years of use.

The basic function of the balance wheel can be illustrated by considering the workings in a standard windup clock. The wheel is weighted in a manner that helps to control the movement of the controls, effectively keeping the movement of the second, minute, and hour hands accurate. Usually, the wheel is moved by some type of spring, sometimes referred to as the hairspring or spiral spring. With the aid of the spring, the balance wheel moves from left to right, stopping at the middle point as part of the timing process, while other designs call for steady left and right movement that is not unlike the movement of a pendulum on a grandfather clock.

While many modern machines no longer include a balance wheel, there still exists some equipment that was first put into service in the middle years of the twentieth century that rely on the wheel for such functions as timing the progress of raw materials through the process. In some cases, the wheel is necessary to make sure that the materials are not subjected to extreme temperatures for more than a specific period of time. Machinery of this type is not used as widely today, and is normally replaced as plants switch to new machinery that is capable of producing more finished units in less time.