Retainer system for roof-mine tool bit

Claim 1

A retainer system for detachably coupling a drill bit member to a drill steel member or the like comprising a drill bit member having a cutting tip at one end and having an axial bore formed therein and adapted to slidably receive a shank portion of a drill steel member, said bit member having an elongated cylindrical body portion formed with a generally T-shaped key-way slot configured so as to be recessed radially to a greater depth than said bore, said key-way slot having an axially extending portion extending from the open end of said cylindrical body portion and merging into a radially extending slot portion, said radially extending slot portion having a substantially greater arcuate length than the actual length of said axially extending portion, said drill steel member having a unitary cylindrical shank portion and an outwardly extending key-way member of a one-piece construction merging with said shank in an arcuate direction by a chamfer means, and made unitary with said shank portion and having a radial length slightly less than the corresponding radial dimension of the actual portion of said key-way slot so as to be slidably received therethrough and into the radial portion of said key-way slot so as to limit rotational movement of said bit and drill steel members relative to one another and to prevent axial movement of said bit member relative to said drill steel member in the installed position thereof.