A strand jack (also known as strandjack) is a jack used to lift very heavy (e.g. thousands of tons or more with multiple jacks) loads for construction and engineering purposes.[1] Strandjacking was invented by VSL Australia's Patrick Kilkeary & Bruce Ramsay in 1969 for concrete post tensioning systems, and is now widely used for heavy lifting, to erect bridges, offshore structures, refineries, power stations, major buildings and other structures where the use of conventional cranes is either impractical or too expensive.
Strandjack at Freybridge in Berlin–Spandau 52° 30′ 42,11″ N, 13° 12′ 11,7″ O
Strand jacks can be used horizontally for pulling objects and structures, and are widely used in the oil and gas industry for skidded loadouts. Oil rigs of 38,000 t have been moved in this way from the place of construction on to a barge. Since multiple jacks can be operated simultaneously by hydraulic controllers, they can be used in tandem to lift very large loads of thousands of tons. Tandem use of even two cranes is a very difficult operation. [2]
How it worksedit
A strand jack is a hollow hydraulic cylinder with a set of steel cables (the "strands") passing through the open centre, each one passing through two clamps - one mounted to either end of the cylinder.
The jack operates in the manner of a caterpillar's walk: climbing (or descending) along the strands by releasing the clamp at one end, expanding the cylinder, clamping there, releasing the trailing end, contracting, and clamping the trailing end before starting over again. The real significance of this device lies in the facility for precision control.
The expansion and contraction can be done at any speed, and paused at any location. Although a lone jack may lift only 1700 tons or so, there exist computer control systems that can operate 120 jacks simultaneously, offering fingertip feel movement control over extremely massive objects.
In constructionedit
Strand jacking is a construction process whereby large pre-fabricated building sections are carefully lifted and precisely placed. The alternative would be to do all assembly in situ, even if expensive, technically risky, or dangerous.
Strand jacks used for heavy lifting and skidding operations are owned and operated by a large number of construction and heavy lifting companies around the world. They are currently manufactured by a small number of companies based in Europe.[clarification needed][citation needed]
strand, jack, this, article, needs, additional, citations, verification, please, help, improve, this, article, adding, citations, reliable, sources, unsourced, material, challenged, removed, find, sources, news, newspapers, books, scholar, jstor, september, 20. This article needs additional citations for verification Please help improve this article by adding citations to reliable sources Unsourced material may be challenged and removed Find sources Strand jack news newspapers books scholar JSTOR September 2013 Learn how and when to remove this template message A strand jack also known as strandjack is a jack used to lift very heavy e g thousands of tons or more with multiple jacks loads for construction and engineering purposes 1 Strandjacking was invented by VSL Australia s Patrick Kilkeary amp Bruce Ramsay in 1969 for concrete post tensioning systems and is now widely used for heavy lifting to erect bridges offshore structures refineries power stations major buildings and other structures where the use of conventional cranes is either impractical or too expensive Strandjack at Freybridge in Berlin Spandau52 30 42 11 N 13 12 11 7 O Contents 1 Use 2 How it works 3 In construction 4 Notable uses 5 ReferencesUse edit nbsp Animation of a strand jackStrand jacks can be used horizontally for pulling objects and structures and are widely used in the oil and gas industry for skidded loadouts Oil rigs of 38 000 t have been moved in this way from the place of construction on to a barge Since multiple jacks can be operated simultaneously by hydraulic controllers they can be used in tandem to lift very large loads of thousands of tons Tandem use of even two cranes is a very difficult operation 2 How it works editA strand jack is a hollow hydraulic cylinder with a set of steel cables the strands passing through the open centre each one passing through two clamps one mounted to either end of the cylinder The jack operates in the manner of a caterpillar s walk climbing or descending along the strands by releasing the clamp at one end expanding the cylinder clamping there releasing the trailing end contracting and clamping the trailing end before starting over again The real significance of this device lies in the facility for precision control The expansion and contraction can be done at any speed and paused at any location Although a lone jack may lift only 1700 tons or so there exist computer control systems that can operate 120 jacks simultaneously offering fingertip feel movement control over extremely massive objects In construction editStrand jacking is a construction process whereby large pre fabricated building sections are carefully lifted and precisely placed The alternative would be to do all assembly in situ even if expensive technically risky or dangerous Strand jacks used for heavy lifting and skidding operations are owned and operated by a large number of construction and heavy lifting companies around the world They are currently manufactured by a small number of companies based in Europe clarification needed citation needed Notable uses editKursk submarine disasterUses outside of construction Costa Concordia disaster in the ship salvage phase References edit nbsp Wikimedia Commons has media related to Strand jacks Strand Jacks What are they Strand Jack Lifting Retrieved from https en wikipedia org w index php title Strand jack amp oldid 1173127483, wikipedia, wiki, book, books, library,
