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.* covers most entries* covers ''Buck'', ''Crown Tree'', ''Pintle'', ''Samson Head''

Watermill machinery

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

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

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

;Great Spur Wheel
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''

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

;Layshaft
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.

;Overdrift
Millstones driven from above are known as ''Overdrift'' stones.

;Pit Wheel
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''.

;Rim Drive
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''.

;Runner Stone
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''.

;Stone Nut
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.

;Turbine

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''.

;Underdrift
Millstones driven from beneath are known as ''Underdrift'' stones.

;Upright Shaft
The ''Upright Shaft'' in the main driven shaft in a watermill. It carries the ''wallower'', ''Great Spur Wheel'' and sometimes a ''Crown Wheel''.

;Wallower
The ''Wallower'' is a small gear at the base of the ''upright shaft'' in a watermill, it is driven by the ''Pit Wheel''.

; Waterwheel
A ''waterwheel'' is a source of power for a watermill. It is mounted on the ''axle'' and drives the mill by a ''Pit Wheel'' or ''Rim Drive''. In some watermills, the ''Waterwheel'' was replaced by a ''Turbine''.

Windmill machinery

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

;Brake Wheel
The ''Brake Wheel'' is the main driving wheel in a Smock or Tower mill, and in some post mills. It is carried on the ''Windshaft'' and drives the ''Wallower'' on the ''Upright Shaft''

;Buck
The ''Buck'' is an East-Anglian term for the body of a post-mill.

;Centrifugal governors

Governors are used to regulate the distance and pressure between millstones in windmills in the 17th century.

;Crown Tree
The ''Crown Tree'' is the central, single baulk of timber, usually oak, that rests on top of the post in a post mill. Attached to it are the side-girts and the rest of the frame of the ''buck''.

;Crown wheel
In a windmill, a ''Crown Wheel'' is an auxiliary gear on the ''Upright Shaft''.

;Fantail
A ''fantail'' is a small windmill which is used to keep a windmill facing into the wind automatically.

;Great Spur Wheel
The ''Great Spur Wheel'' is carried on the ''Upright Shaft''. It drives the ''Stone Nuts''. Millstones driven by the ''Great Spur Wheel'' can be either ''Overdrift'' or ''Underdrift''.

;Head Wheel
The ''Head Wheel'' is carried on the ''Windshaft'' in a Post Mill and has a brake around its circumference. It drives a ''Stone Nut'', Millstones driven by the Head Wheel are always ''Overdrift'' stones.

;Middling

See ''Stock''

;Overdrift
Millstones driven from above are known as ''Overdrift'' stones.

;Pintle
The pivot centering a post mill on top of the main post.

;Runner Stone
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''.

;Sails

The ''Sails'' are the source of power in a windmill. They are carried on the ''Windshaft''. Most windmills had four sails, although some had five (Boston), six ( Waltham, Lincs) or eight sails Heckington, Lincs and there is one recorded twelve sailed windmill (Cottenham, Cambs).

''Common Sails'' have a lattice framework over which a sailcloth is spread. These were the earliest type of sails in northern European windmills.

''Spring Sails'', invented in 1772 by Andrew Meikle, have shutters adjusted by a spring. Each sail is adjusted individually and, as with ''Common Sails'' the mill has to be stopped to enable an adjustment to be made.

''Roller Reefing Sails'', invented in 1789 by Stephen Hooper, use a canvas strip wound around a roller in the place of shutters. The mill does not have to be stopped in order to adjust the sails.

''Patent Sails,'' invented in 1819 by William Cubitt, combine the shutters of the ''Spring Sail'' with the automatic adjustment of the ''Roller Reefing Sail''. Single Patents have shutters on the trailing side of the sail, Double Patents have shutters on both sides of the sail for its whole length.

;Samson Head
An iron collar and plate bearing that fits over the ''pintle'' of a post-mill's post, that supports the weight of the ''crown tree'', around which the ''buck'' of the mill is constructed. An example is visible at High Salvington windmill.

;Stock
The beam that passes through the canister of the windshaft, which the sails are bolted onto.

;Stone Nut
The ''Stone Nut'' is a small gear driven by the ''Great Spur Wheel'', ''Head Wheel'', or ''Tail Wheel''. It drives the ''Runner Stone'' either from above (''Overdrift'') or below (''Underdrift'').

;Tail Wheel
The ''Tail Wheel'' is carried on the ''Windshaft'' in a Post Mill and drives a ''Stone Nut''. Millstones driven by the Tail Wheel are always ''Overdrift'' stones.

;Trestle
The ''Trestle'' is the substructure of a Post Mill, usually enclosed in a protective structure called a roundhouse, which also serves as a storage facility. Post mills without a roundhouse are called Open Trestle Post Mills.

;Underdrift
Millstones driven from beneath are known as ''Underdrift'' stones.

;Upright Shaft
The ''Upright Shaft'' is the main vertical shaft found in Smock and Tower mills. It is also found in some Post mills. It carries the ''Wallower'' at its top end, and a ''Great Spur Wheel'' at the bottom end. The ''Great Spur Wheel'' drives two or more ''Stone nuts''.

;Wallower
The ''Wallower'' is a driven gear at the top of the ''Upright Shaft'' in Smock, Tower and some Post mills. It is driven by the ''Brake Wheel''

;Windshaft
The ''Windshaft'' carries the ''Sails'' and also the ''Brake Wheel'' (Smock and Tower mills, and in some Post mills) or the ''Head Wheel'' and ''Tail Wheel'' in a Post Mill. Windshafts can be wholly made of wood, or wood with a cast iron Poll End (where the ''Sails'' are mounted) or entirely of cast iron.

See also

* "A Researcher's Guide to Local History Terminology" - Abecedary

References

{{reflist

External links

A Short Guide to Green’s Mill and How it all Works

Mill Machinery
Windmills
Watermills