one option

sliding trench shield=escudo deslizante

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Edmonton's EPCOR Utilities installs electrical vaults on “easy ...
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Efficiency's Universal Slide Rail is a component shoring system comprised of steel panels (similar to trench shield sidewalls) and vertical steel posts. ...
www.epi-shields.com/.../116-edmontons-epcor-utilities-insta... - En caché
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Trench Shoring Shields On GlobalSpec
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...and transportation, chemical processing, electrical, electronic, filtration, marine, .... Steel Trench Shields Manhole Shields Slide Rail Systems ...
www.globalspec.com/industrial.../trench_shoring_shields - En caché
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4121:1-5-26 Trenches and excavations
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Formato de archivo: PDF/Adobe Acrobat - Vista rápida
three feet of an energized underground electrical conductor whose location ... (9) Portable trench boxes, safety cages or sliding trench shields may be used ...
www.ohiobwc.com/downloads/blankpdf/OAC4123-1-5-26.pdf - Similares
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Slide Rail Systems - Trench Shoring - BakerCorp
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Trench Shoring · Slide Rail Systems · Modular Aluminum Shields · Aluminum Hydraulic Shoring · Specialty · Steel Trench Shields ...
www.bakercorp.com/trench-slide-rail.asp - Estados Unidos - En caché - Similares

Hope it helps
Saludos :))

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Note added at 1 hr (2010-06-22 21:31:55 GMT)
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Asker: Many thanks for your help, I thought it may have a strange name and had no time to look as I am on the last rush of docs. :-0))

Re: I think that we are here for that. It is good to be helpful :))

A trench box (also called a trench shield) may be placed in the trench to prevent trench failures from injuring workers. A trench box consists of two large plates, usually made of steel, which are parallel to the walls of the trench, and horizontal cross-members which hold the two plates apart. The lower edge of the box rests on the bottom of the trench, and the top edge extends above the tope of the trench. The workers stay between the plates of the trench box, so that if the wall of the trench collapses, the dirt will be stopped by the trench box. As work progresses, the trench box is pulled along the trench with a backhoe.