Schütz (hydraulic engineering)
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Possibility of sudden tidal waves also due to the action of the dam gates
In hydraulic engineering, a contactor is a system (gate valve, gate plate ) for regulating the flow of water in pipes or for shutting off and damming watercourses or sluices. Larger systems are called weirs .
Types and functionality
In the simplest case, the plate gate or lifting gate , the cross-section of a watercourse is blocked by a rectangular, vertical wooden or metal plate, called a protective board, when this is lowered to the bottom of the watercourse. When blocked, the water is dammed up on one side of the plate to form an upper water ; that exerts pressure on the plate towards the underwater , which increases with increasing water depth. This pressure presses the plate into vertical guide grooves on the sides of the hydraulic structure. If the plate and grooves are made of steel, sufficient sealing is achieved even with a few centimeters of overlap, at least at the water levels of one to three meters that are common in mill tunnels. The protective board thus blocks the cross-section as long as the level of the headwater - or a surface wave , a surge - does not exceed its upper edge.
A drain is made possible and takes place under the table by lifting it mechanically. The friction forces in the guide that are caused by the pressure of the water must be overcome. Gradual raising of the protective board causes gradual drainage. A weir to the side, which also limits the level of the headwater, increases the volume of temporarily retained water.
Thanks to their own weight and a certain amount of friction, simple small contactors can work manually, using a lever or with a rope or chain hoist using a winch .
However, parallel guidance via two toothed racks (mostly ladder-like, i.e. cross-bolts between two heavy-plate strips), which are linked to the upper edge and whose drive pinions sit on a shaft, is widespread, whereby the drives are synchronized. The shaft is driven by a self-locking worm gear, either manually using a crank or by an electric motor . To operate and maintain the contactor, but also to observe and cross the watercourse, a footbridge often runs over the barrel and a roof protects the gearbox and the footbridge from rainwater. Some contactors of this type are still in operation when they are 100 years old with renewed wooden boards, especially if they are not used for ongoing control but only for simple shut-off functions. An example can be found at the Mühlgang in Graz .
Larger shooters require a hoist , for example with revolving chains, rack or worm drive, which also guarantee that a certain position can be reached. Modern contactors (see below) are moved hydraulically or with electric lifting cylinders. The automation of a small power plant, for example, allows remote action.
Depending on the shape of the watercourse (which is always open on the surface), if a gate closes at an unusually fast rate, especially at high speeds of the flow or shooting of the water stream, increased water pressure can occur due to the slowing down of the water.
With the double contactor , the panel is divided so that the parts can be operated independently of one another. Double and segment gates (see below) are used to fill or empty larger lock chambers . With older locks, they are located directly in the lock gates or in the perimeter. In modern ship locks, the slides are located in longitudinal channels.
The hook gate works in a similar way - a vertically movable weir bolt with two panels. It allows the upper part to be lowered so that alluvial deposits, river sediments and ice can be drained away.
With the rotary contactor (folding contactor ), the plate is rotated around a horizontal axis, which enables finer control of the water flow with good power transmission. The latter is also the case with the segment contactor , where a segment-like solid steel body is pivoted into the opening from above. Both types are related to the water slide in their construction .
use
The first applications probably already existed in the Neolithic Age - for example for artificial irrigation of agricultural land, as has been documented in many places since early antiquity. Gates were also used to guide the water to mills and water wheels - as a so-called “movable mill weir ”, which was also used in mining . Plate gates also served as damming for the wood drift and sometimes as plate or double gates for relief channels against floods. Further applications are e.g. B. keeping the water level constant in groundwater canals or infiltration systems.
The applications follow two basic principles:
- In the case of shooters defending in the narrower sense, a flow of water is regulated but not interrupted; the flow over or under the contactor or contactors even when they are closed.
- With one or more shooters than closing mechanisms but also can barrages and sluices for flood protection and slide work in irrigation and drainage networks, the water flow temporarily prevent it completely.
See also
- Squeegee
- Wiktionary: Schütz - explanations of meanings, word origins, synonyms, translations
Literature and web links
- New Brockhaus Volume 4, Wiesbaden 1960
- Contactor / hydraulic engineering, hook contactor
