Patent ID: 8172485

Claim:
An end coupling for a shaft having an external thread, the coupling having an axis and comprising: a body having a lead portion incorporating a leading end; a tail portion incorporating a trailing end, the tail portion having an external drive face to be connected to a drive to impart rotation to the coupling about the axis; and an abutment arrangement disposed on an exterior of said tail portion and forming an external abutment surface that faces said leading end, wherein the body defines a passage extending along the axis between said leading and trailing ends, a first portion of the passage extending from the leading end and having a first diameter, and a second portion of the passage disposed adjacent the first portion and having a length that extends from an end of the first portion to the trailing end of the tail portion, the second portion of the passage having a second diameter that is larger than said first diameter for the entire length of the second portion, and a first thread extending along at least part of the first portion of the passage and being configured to threadingly engage an external thread on a shaft.