of Water Wheel Terms
Apron- Arc of stone or wooden placed behind a pitch back or beast
shot water wheel to prevent water from spilling from the buckets of the
water wheel before arriving at the lowest point of the fall.
Arms or spokes- extending from the main shaft of a water wheel,
that in turn support the shrouding or rims of the wheel, or spokes of a
large gear wheel.
Back water or watering- is a condition when the stream
rises during a flood and the bottom of the water wheel becomes covered in
water. This is a greater problem with overshot water wheels than other types
because the water exits the wheel. With the overshot water wheel, water
and sometimes air becomes trapped inside the buckets when the water is suppose
to exit the buckets and retards it turning motion.
Breast shot water wheel- a water wheel powered by a head of water
striking the wheel at the point from one-third to two-thirds the height
of the wheel, causing the wheel to revolve in a direction opposite to that
of the flow of the water in the sluice way or mill race.
Buckets- the blades or enclosures formed by blades, around the rim
of a water wheel, against which or into the water flows. They called floats
or paddles when they are a single flat blade or surface. They generally
called elbow buckets or buckets if they are formed from a front plate or
blade and a bottom plate or bucket. The back of the bucket or enclosure
is created by the soling or drum boards.
Bucket water wheel- a water wheel using an enclosed bucket, rather
than a simple blade or float, to harness the water power.
Cant- a segment of one of the rings which form the rim of a water
wheel or wooden gear wheel. In a water wheel the cant is the piece that
has the mortise cut into it to hold the ends of the water wheel float or
Chute- a short trough of wood or iron which conveys the water from
the gate to the buckets of a water wheel. It is generally three feet long.
Clasp arm water wheel- is a timber wheel built up on a circular frame
consisting of two pairs of parallel spokes enclosing the axle at right angles.
Compass arm water wheel- is a timber wheel with radiating spokes,
mortises to the axle. The arms pass through the shaft and are interlocked
together to provide more strength in the water wheel when it is turning.
Drum boards- see sole.
Elbow bucket- the bent or 90 degree water wheel bucket. The elbow
bucket or buckets they are formed from a front plate or blade and a bottom
plate or bucket. The back of the bucket or enclosure is created by the soling
or drum boards.
Felloe- A curved board that acts as a face place, that covers up
the bolt heads of the layers of boards behind it.
Floating or boat mill- a large diameter undershot water
wheel with its gears and machinery inside of a boat and the outboard bearing
mounted on pontoon. Also known as an Hungarian Mill.
Fore bay- a deep receptacle at the end of a mill race, which water
is led into the water wheel or turbine. A reservior or extension of a sluice
or mill race. It is where water is passed to the water wheel.
Flutter water wheel- is a small diameter water wheel that makes a fluttering
sound when operating at a high speed to create a fast stroke or motion.
Greek mill- a simple, early form of horizontal mill, in which
a horizontal water wheel with spoon shaped blades is attached to the millstone
spindle and drives the runner millstone directly, without requiring any
form of gearing.
Gudgeon- a metal journal mounted in the end of the main shaft to
run in bearings mainly on a water wheel but gudgeons take on other shapes
and forms mounted into small shafts either horizontal or vertical. The gudgeon
is a round metal shaft which from the side projects 4 (generally in the
case of water wheel shafts) wings. The wings fit into slots cut in the end
of the water wheel shaft and the remaining end of the journal rides in the
Guide plates- these are metal plates attached to the front side of
the water wheel gate control opening. They direct the water into the buckets
and often change its direction of flow downward. They are often found on
pitch-back, high, middle and low breast shot water wheels. The guide plates
are often installed in a series of three plates in a single gate opening.
High breast shot water wheel- a high breast shot water wheel is
one in which the water fills or strikes the buckets above the axle of the
water wheel shaft. A high breast shot water wheel has elbow buckets.
Horizontal water wheel- a water mill whose wheel revolves in a horizontal
plane but whose main power shaft is vertical in the mill. Also see Greek
mill, and Norse mill.
Hungarian Mill- see Floating Mill.
Hub- an iron flange that either slides over a wooden water wheel
shaft or is mounted onto an iron shaft. Hubs mounted on a wooden water wheel
shaft is wedged in place.
Hybrid water wheel-an iron hub that simply slides over the wooden
shaft and there was no need to cut arm slot holes through the shaft that
would cause rot and decay inside of the shaft. The next stage was the replacement
of the wooden shaft with an iron shaft that had iron hubs onto which a conventional
wooden water wheel was bolted to the iron hubs. Then later wooden elbow
buckets and drum boards were built on an all of the metal work of the water
wheels is of steel construction. This would mean metal hubs, shaft, arms
and bucket shrouds or rim boards.
Iron bands- several iron hoops that are slid over the end of the
water wheel shaft that help hold the gudgeon in place.
Low breast shot water wheel- a low breast shot water wheel is
one in which the water fills or strikes the buckets below the water wheel
shaft. The low breast shot water wheels had deeper buckets to deal with
the increased volume of water required for the low head of water to develop
power equivalent to that obtained by a high breast shot water wheel.
Middle or mid beast shot water wheel- a middle breast shot
water wheel is one in which the water fills or strikes the buckets at the
water wheels axle or shaft. The middle breast shot water wheels had deeper
buckets to deal with the increased volume of water required for the low
head of water to develop power equivalent to that obtained by a high breast
shot water wheel.
Noria water wheels- are huge wooden water wheels, known as norias,
which once scooped water from the river and deposited it into the aqueducts,
which then supplied homes, public buildings and farms. The are a form of
undershot water wheel and clay pots are attached to the rim of the water
wheels. These wheels are about 20 meters (90 feet) in diameter and still
turn today, although their water is not used. The are mainly located in
the town of Hama, in Syria.
Norse mill- a horizontal mill similar to the Greek mill, but with
straight inclined blades to facilitate the removal of ice in winter. The
wheel is attached to the millstone spindle and drives the runner millstone
directly, without requiring any form of gearing.
Overshot water wheel- a water wheel powered by a head of water
striking the wheel just behind its vertical center or just forward of its
vertical center of its highest point of rotation. Thus causing the water
wheel to revolve in the same direction as the flow of water in the sluice
box or sluice way.
Poncelet water wheel- an improved type of under shot water wheel,
fitted with curved metal floats invented by General J.V. Poncelet.
Rim plate or shroud plate- the outer covering of the sandwiched
sections of the felloe, cant and shroud boards. A piece of either wooden
or metal plate molding that cover the outer edges to protect the wood and
its layers from damage by water and ice. This covering is either screwed
down or bolted down tight against the circumference of both rims of the
water wheel. This covering also keeps the front bucket board in place.
Sagebien water wheel- a high volume slow rotating water wheel.
The elbow buckets go to the full depth of the water wheel shaft. Built by
A. SAGEBIEN (1807-1892) a hydraulics engineer, it was classified as a historical
monument in 1987. His water wheel is located at the Trilbardou plant on
a Paris canal. In the pump room is the giant water-wheel (11 meters in diameter,
6 meters wide).
Shaft (main shaft, water wheel shaft, mill shaft or king pin)- The
wooden shaft made of white oak. It is often made from the trunk of a single
tree that holds the water wheel.
Shock- a phenomenon will develop if water is directed upon the water
wheel not in the direction the water wheel rotates, which will retard and
in many cases stop the water wheel from turning especially in water wheels
that are out of balance.
Shroud (shrouding) or rim boards- the rim of a water wheel,
which forms the sides of the bucket enclosures.
Sole (soling)- the inner lining of a water wheel, forming bottom
of the bucket. Also called drum board, sole boards.
Starts- the short arms or spurs or arms projecting from the rim of
a water wheel, to which the floats or paddles are fastened.
Suspension Water Wheel- A hybrid water wheel that is constructed
with a combination of wood and metal that is mounted on a hub with metal
rods that act as the arms of the water wheel. This is similar to that of
a bicycle wheel.
Tide water wheel- a type of water wheel powered by the tidal flow.
Tub water wheel- a horizontal water wheel mounted in a tub, constructed
of wooden blades, the water enters from a tube or chute, at an angle striking
the wheel, which then rotates in a horizontal plane.
Undershot water wheel- a water wheel powered by a head of water
striking the wheel at the point near the bottom of the wheel, causing the
wheel to revolve in the direction opposite to that of the flow of water
in the sluice box or mill race.
Ventilating buckets- a water wheel buckets designed with holes
or vents to ease the flow of water and to release trapped air. In wooden
wheel are round holes with leather flaps that open to ease entry and to
release air as the wheel turns. The most common type of water wheel found
on is the breast wheel.
Vertical water mill- a traditional water powered mill, driven by
a vertical water wheel.
Vertical water wheel- a mill with a vertical mounted water wheel
on a horizontally mounted axle. The undershot, breast shot and over shot
are the forms of this type of water wheel.
Water box- a wooden or metal box at the end of a sluice
box or water pipe where the water may regain its height, even out the flow,
and where the gate is for the wheel. The water leaves the box by a chute
onto the wheel. The classic water box is flound on the Fitz Water Wheels.
Water rights- the right to use thewater from a stream to operate a mill.
Usually obtained by agreement witha landowner througharbiration by court
and state approval.
Water house or wheel pit- the area of the mill which the main gearing
is located and where the water wheel or turbine(s) may be.
Water mill- a mill building whose machinery is fitted to operate
using water as its power source.
Water power- the power of falling water capable of driving machinery,
the water rights possessed by a mill to use water power to perform machanical
Water wheel- a water powered wheel used by weight and percussion
upon a vertical or horizontal wheel used to perform mechanical work, in
a place called a water mill.
Wedges- are found on a water wheel that hold the gudgeon in place
and they hold the water wheel arms also in place.
Wooden water wheel- a traditional wooden water wheel is made out
of seasoned white oak.
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