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US 4,136,556 AGranted
Device to monitor movement of a surface
AssigneeMassachusetts Institute of Technology
InventorGlenn A. Graham
Life of this patent
Estimating the term…
Abstract
A device to monitor movement of a surface such as, for example, the roof of a mine tunnel or the like and to provide an indication if that movement exceeds some predetermined creep rate or velocity. The device includes a sensing member formed of a material whose precise creep characteristics as a function of stress and strain are known. The device includes a sensing member formed of a material whose precise creep characteristics as a function of stress and strain are known.
Claims11
A device to monitor movement of a surface that comprises, in combination:
- an expansion anchor that is inserted into the bulk of the material behind the surface to be monitored to reach a stable stratum therein;
- a creep-resistant, force-generating, elongate member;
- an anchor block to rest against the surface whose movement is to be monitored;
- the expansion anchor being secured to one end of the elongate member and the anchor block being attached to the other end of the elongate member so that said elongate member is in tension between the two;
- and means to denote if the tension of the elongate member exceeds some predetermined amount, the creep-resistant, force-generating elongate member being operable to measure velocity or creep rate of movement of said surface and the tension on the elongate member being a function of said velocity.
2 more elements
Dependencies are inferred from the claim text.