Patent ID: 6099081
Filing Date: 2000-08-08
Classification: E21C

Abstract:
A pick box comprising: an elongated aperture to receive, in use, a removable liner sleeve having an enlarged head, said pick box providing a seating surface extending orthogonally with respect to said elongated aperture for engagement, in use, by the enlarged head, wherein the internal periphery of said elongated aperture and the complementary external periphery of an inserted sleeve are so profiled as to prevent relative rotation, and said internal periphery of said elongated aperture is interrupted to provide at least one surface for engagement, in use, with a retainer device of an inserted sleeve, said interruption to said internal periphery of said elongated aperture being by the provision of a plurality of recesses or grooves formed by a screw-thread cut into said internal periphery of said elongated aperture.