Mill machinery

This glossary of mill machinery covers the major pieces of machinery to be found in windmills, watermills and horse mills. It does not cover machinery found in modern factories.

The axle carries the waterwheel. It can also carry the Pit Wheel at its opposite end.

The Bedstone is the bottom of a pair of millstones. It does not move. The upper stone is called the Runner Stone.

The Crown Wheel is a driving wheel located at the top of the Upright Shaft

The Great Spur Wheel is a large gear attached to the Upright Shaft. It drives one or more Stone Nuts in a corn mill. If mounted on a Layshaft it is called a Spur Wheel and only drives one Stone Nut

An internal framework supporting the gears and millstones. This isolation prevents damage to the building from the vibrations of the workings.

A Layshaft in a watermill is a horizontal shaft, carrying a Wallower and one or more Spur Wheels. The term can also refer to a minor shaft driving machinery by pulleys and belts.

Millstones driven from above are known as Overdrift stones.

The Pit Wheel is mounted on the opposite end of the axle to the waterwheel. It drives the Wallower on the Upright Shaft or Layshaft.

Some waterwheels have a rack attached to the circumference, which drives the mill via a pinion mounted on a separate axle, which has a Pit Wheel at its opposite end. This is known as Rim Drive.

The Runner Stone is the topmost of a pair of millstones. It is driven by the Stone Nut. The lower stone is called a Bedstone.

A Stone Nut is a small gear driven by the Great Spur Wheel or Spur Wheel. It drives the Runner Stone. In most watermills, the stones are driven from below. These are called Underdrift stones. A few watermills drove the stones from above, known as Overdrift stones.

In some watermills, a Turbine was used as a source of power instead of a Waterwheel. In many cases, the Turbine was installed when a watermill was modernised, although a few mills were built new with Turbines.

Millstones driven from beneath are known as Underdrift stones.

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Wikipedia