Balance wheel

Balance Wheel

The balance wheel is a critical component in mechanical watches and some precision clocks. It is an oscillating device that controls the gear system's speed, ensuring the timepiece's accuracy.

History

The balance wheel, as a timekeeping device, has a long history dating back to the 14th century. The earliest mechanical clocks used a verge escapement mechanism with a crude balance wheel without springs. The invention of the hairspring by Robert Hooke and Christiaan Huygens in the 17th century significantly improved the balance wheel's accuracy.

Design and Function

The balance wheel consists of a weighted wheel that oscillates back and forth at a constant rate. One complete oscillation, termed a 'tick', moves the watch's hands forward. The balance wheel's speed is adjusted by changing the wheel's moment of inertia. This is achieved by altering the position of weights on the balance wheel, a process known as 'regulating'.

The balance wheel works in conjunction with the escapement, which gives the balance wheel the impulses to keep it oscillating, and the hairspring, which provides the restoring force to keep the balance wheel's oscillations regular.

Modern Developments

In the 20th century, new materials and technologies have been introduced to improve the balance wheel's performance. For example, alloys like Invar and Elinvar have been used to reduce the effects of temperature changes on the balance wheel's rate.

See Also

• Clock
• Watch
• Escapement
• Hairspring
• Horology