Chuck assembly for a down-hole drill

An assembly for an earth-boring drill assembly, the drill assembly including a casing having a central axis, the assembly comprising:

• a drill bit including a generally cylindrical head;
• a chuck connectable to the casing and operable to support the bit, the chuck having an outer surface with a radially-outwardly extending chuck shoulder;
• a sleeve having an inner surface with a radially-inwardly extending sleeve shoulder engageable with the chuck shoulder to limit axial movement of the sleeve relative to the chuck, one of the chuck and the sleeve defining an axially-extending first slot, the other of the chuck and the sleeve having a first lug, the first lug being positionable in the first slot to limit relative rotational movement between the sleeve and the chuck;
• and
• a retainer assembly provided between the sleeve and the bit, the retainer assembly including
• an axial retainer slot defined by one of the sleeve and the bit, the retainer slot having an axially-extending side wall defining an opening and an axial end wall, and
• a retainer lug supported on the other of the sleeve and the bit, the retainer lug being positionable in the retainer slot through the opening in the side wall, the retainer lug being engageable with the end wall to restrict axial movement of the bit from the sleeve and away from the casing.

A method of retaining a drill bit for an earth-boring drill assembly, the drill assembly including a casing having a central axis, a drill bit including a generally cylindrical head, a chuck having an outer surface with a radially-outwardly extending chuck shoulder, an axially-extending first slot being defined in the shoulder, a sleeve having an inner surface with a radially-inwardly extending sleeve shoulder and a first lug supported on the inner surface, and a retainer assembly including an axial retainer slot defined by one of the sleeve and the bit, the retainer slot having an axially-extending side wall defining an opening and an axial end wall, and a retainer lug supported on the other of the sleeve and the bit, the method comprising the steps of:

• (a) connecting the bit to the chuck;
• (b) positioning the sleeve on the chuck, the chuck being connectable to the casing;
• (c) engaging the retainer assembly including positioning the retainer lug in the retainer slot through the opening in the side wall, the retainer lug being engageable with the end wall to restrict axial movement of the bit from the sleeve and away from the casing;
• and
• (d) engaging the first lug in the first slot to limit relative rotational movement between the sleeve and the chuck.