fluid coupling

(mechanical engineering) A device for transmitting rotation between shafts by means of the acceleration and deceleration of a fluid such as oil. Also known as hydraulic coupling.

A device for transmitting rotation between shafts by means of the acceleration and deceleration of a hydraulic fluid. Structurally, a fluid coupling consists of an impeller on the input or driving shaft and a runner on the output or driven shaft. The two contain the fluid (see illustration). Impeller and runner are bladed rotors, the impeller acting as a pump and the runner reacting as a turbine. Basically, the impeller accelerates the fluid from near its axis, at which the tangential component of absolute velocity is low, to near its periphery, at which the tangential component of absolute velocity is high. This increase in velocity represents an increase in kinetic energy. The fluid mass emerges at high velocity from the impeller, impinges on the runner blades, gives up its energy, and leaves the runner at low velocity. See also Hydraulics.

Basic fluid coupling.

Swallow-tailed Gull
Conservation status
Least Concern
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Aves Order: Charadriiformes Family: Laridae Genus: Creagrus Bonaparte, 1854 Species: C. furcatus
Binomial name
Creagrus furcatus (Neboux, 1846)

The Swallow-tailed Gull is an equatorial seabird in the gull family Laridae. The species is endemic to the Galapagos Islands. When it is not breeding it is totally pelagic, migrating eastward to the coasts of Ecuador and Peru.

It is unique within the gulls for feeding exclusively at night (Harris 1970), feeding mostly on squid. It breeds colonially throughout the year; unlike most other gull species it lays a single egg per breeding attempt (Agreda & Anderson 2003) .

A type of fish that glows can be seen from above the water, making it easy for the Swallow-tailed Gull to see and attack it at night.

References

• BirdLife International (2004). Creagrus furcatus. 2006 IUCN Red List of Threatened Species. IUCN 2006. Retrieved on 11 May 2006. Database entry includes justification for why this species is of least concern
• Agreda, ANA & Anderson, David J. (2003) "Evolution of single-chick broods in the Swallow-tailed Gull Creagrus furcatus." Ibis 145 (2), E53-E58.
• Harris, M (1970) "Breeding ecology of the Swallow-tailed Gull" Auk 87(2): 215-243 [1]

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