A threaded fastener has a casing enclosing at least three radially inwardly biased arcuate segments positioned to engage the threads of a bolt or hollow threaded member. The casing defines spaced apart internal frustoconical surfaces positioned to engage corresponding surfaces of the segments in the...http://www.google.es/patents/US5427488?utm_source=gb-gplus-sharePatente US5427488 - Quick acting nut or coupling assembly
