A grab is a

mechanical device A machine is a physical system using power to apply forces and control movement to perform an action. The term is commonly applied to artificial devices, such as those employing engines or motors, but also to natural biological macromolecul ...

with two or more

jaw The jaw is any opposable articulated structure at the entrance of the mouth, typically used for grasping and manipulating food. The term ''jaws'' is also broadly applied to the whole of the structures constituting the vault of the mouth and serv ...

s (sometime clamshell-shaped), used to pick things up or to capture things. Some types include: *Roundnose grab *Clamshell grab *Orange-peel grab **in Dutch and German they are called ''poliep grijpers/ Polypengreifer'' = " polyp grabs". There are different ways of open/close the grabs: *electro-hydraulic / diesel-hydraulic *mechanical by rope(s) (1-rope, 2-ropes, 3-ropes, 4-ropes) Grabs can be used for: *dredging *bulk handling (e.g. loading/unloading ships) *salvage (e.g. ship-wrecks, oil) *seabed sampling

History

The mechanical grab, specifically the clamshell grab,

Donald Routledge Hill Donald Routledge Hill (6 August 1922 – 30 May 1994)D. A. King, “In Memoriam: Donald Routledge Hill (1922-1994)”, ''Arabic Sciences and Philosophy,'' Volume 5 / Issue 02 / September 1995, pp 297-302 was a British engineer and historian of sc ...

, "Mechanical Engineering in the Medieval Near East", ''Scientific American'', May 1991, p. 64-69 was invented by the

Persian Persian may refer to: * People and things from Iran, historically called ''Persia'' in the English language ** Persians, the majority ethnic group in Iran, not to be conflated with the Iranic peoples ** Persian language, an Iranian language of the ...

Banu Musa Banu or BANU may refer to: * Banu (name) * Banu (Arabic), Arabic word for "the sons of" or "children of" * Banu (makeup artist), an Indian makeup artist * Banu Chichek, a character in the ''Book of Dede Korkut'' * Bulgarian Agrarian National Union ...

brothers and described in their ''

Book of Ingenious Devices The ''Book of Ingenious Devices'' (Arabic: كتاب الحيل ''Kitab al-Hiyal'', Persian: كتاب ترفندها ''Ketab tarfandha'', literally: "The Book of Tricks") is a large illustrated work on mechanical devices, including automata, publi ...

'' in the 9th century. It was an original innovation by the Banu Musa that does not appear in any earlier Greek works. The grab described by the Banu Musa was used to extract objects from underwater, and recover objects from the beds of streams.

References

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Tools Iranian inventions {{tool-stub

History

See also

References

External link