;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. ;Mace :A cross- or square-shaped piece of metal on the top of the spindle from which the runner stone is balanced. ;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==