US Patent 6905298 Telescopic nut

A nut assembly is disclosed that will ensure that the shank of a bolt that features a measurable grip length will pass through the contact plane of adjoining members. The nut assembly also allows the desired compressive force in the adjoining members to be attained by using a telescopic feature of the nut to allocate additional thread action for the bolt, enabling the bolt to be drawn into the nut further than what would be allowed by a standard nut. The adaptability of the nut assembly can eliminate the need for washers or shims to adjust the shank penetration of the bolt. The nut assembly is useful for application in which the specified thread length and the grip length of the bolt is incompatable with the abutment thickness of the adjoining members.