US Patent 7207400 Coupler and roof drill bit assembly using such coupler

A coupler for use in connecting together in a driving relationship a first member and a second member in a drill bit assembly. The coupler includes an elongate body that has opposite axial forward and rearward ends as well as contains a longitudinal bore. The elongate body further has a mediate collar wherein there is a forward body portion axial forward of the collar and a rearward body portion axial rearward of the collar. The forward body portion is suitable to drivingly engage the first member. The rearward body portion is suitable to drivingly engage the second member. Each one of the forward and rearward body portions carries seal. The elongate body further carries a retention member.