The Tainter gate is a type of radial arm

floodgate Floodgates, also called stop gates, are adjustable gates used to control water flow in flood barriers, reservoir, river, stream, or levee systems. They may be designed to set spillway crest heights in dams, to adjust flow rates in sluices and c ...

used in

dam A dam is a barrier that stops or restricts the flow of surface water or underground streams. Reservoirs created by dams not only suppress floods but also provide water for activities such as irrigation, human consumption, industrial use ...

s and

canal lock A lock is a device used for raising and lowering boats, ships and other watercraft between stretches of water of different levels on river and canal waterways. The distinguishing feature of a lock is a fixed chamber in which the water lev ...

s to control water flow. It is named for

Wisconsin Wisconsin () is a state in the upper Midwestern United States. Wisconsin is the 25th-largest state by total area and the 20th-most populous. It is bordered by Minnesota to the west, Iowa to the southwest, Illinois to the south, Lake M ...

structural engineer Structural engineers analyze, design, plan, and research structural components and structural systems to achieve design goals and ensure the safety and comfort of users or occupants. Their work takes account mainly of safety, technical, economic ...

Jeremiah Burnham Tainter. A side view of a Tainter gate resembles a slice of

pie A pie is a baked dish which is usually made of a pastry dough casing that contains a filling of various sweet or savoury ingredients. Sweet pies may be filled with fruit (as in an apple pie), nuts ( pecan pie), brown sugar ( sugar pie), swe ...

with the curved part of the piece facing the source or upper pool of water and the tip pointing toward the destination or lower pool. The curved face or skinplate of the gate takes the form of a wedge section of

cylinder A cylinder (from ) has traditionally been a three-dimensional solid, one of the most basic of curvilinear geometric shapes. In elementary geometry, it is considered a prism with a circle as its base. A cylinder may also be defined as an infin ...

. The straight sides of the pie shape, the

trunnion A trunnion (from Old French "''trognon''", trunk) is a cylindrical protrusion used as a mounting or pivoting point. First associated with cannons, they are an important military development. Alternatively, a trunnion is a shaft that positions a ...

arms, extend back from each end of the cylinder section and meet at a trunnion which serves as a pivot point when the gate rotates. Pressure forces on a submerged body act perpendicular to the body's surface. The design of the Tainter gate results in every pressure force acting through the centre of the imaginary circle of which the gate is a section, so that all resulting pressure force acts through the pivot point of the gate, making construction and design easier. When a Tainter gate is closed, water bears on the convex (upstream) side. When the gate is rotated, the rush of water passing under the gate helps to open and close the gate. The rounded face, long radial arms and bearings allow it to close with less effort than a flat gate. Tainter gates are usually controlled from above with a chain/gearbox/

electric motor An electric motor is an Electric machine, electrical machine that converts electrical energy into mechanical energy. Most electric motors operate through the interaction between the motor's magnetic field and electric current in a Electromagneti ...

assembly. A critical factor in Tainter gate design is the amount of stress transferred from the skinplate through the radial arms and to the trunnion, with calculations pertaining to the resulting friction encountered when raising or lowering the gate. Some older systems have had to be modified to allow for frictional forces which the original design did not anticipate. In 1995, too much stress during an opening resulted in a gate failure at Folsom Dam in northern California. The Tainter gate is used in water control dams and locks worldwide. The

Upper Mississippi River The Upper Mississippi River is the portion of the Mississippi River upstream of St. Louis, Missouri, United States, at the confluence of its main tributary, the Missouri River. History In terms of geologic and hydrographic history, the Upper ...

basin alone has 321 Tainter gates, and the

Columbia River The Columbia River (Upper Chinook: ' or '; Sahaptin: ''Nch’i-Wàna'' or ''Nchi wana''; Sinixt dialect'' '') is the largest river in the Pacific Northwest region of North America. The river rises in the Rocky Mountains of British Columbia, C ...

basin has 195. A Tainter gate is also used to divert the flow of water to San Fernando Power Plant on the

Los Angeles Aqueduct The Los Angeles Aqueduct system, comprising the Los Angeles Aqueduct (Owens Valley aqueduct) and the Second Los Angeles Aqueduct, is a water conveyance system, built and operated by the Los Angeles Department of Water and Power. The Owens Valley ...

. The Tainter gate was invented in 1886 by Jeremiah Burnham Tainter (1836–1920), an employee of lumber firm Knapp, Stout and Co., for use on the company's dam that forms

Lake Menomin Lake Menomin is a reservoir on the Red Cedar River, in Dunn County, Wisconsin, USA. Its name is derived from the Ojibwe name for this lake, ''Manoominikaani-zaaga'igan'' meaning "Abundant with Wild Rice Lake." Along the lake's western and sou ...

in the United States.

References

{{Reflist Structural engineering Canals Dams Hydrology Flood barriers