Importance

Loading Importance Indicators...

Abstract

A retractable drill bit system for a ground drill includes drill bit assembly, a bit assembly sleeve, and a transport member. The drill bit assembly is engagable with a drive sub attached to the bottom of the ground drill with the drill bit assembly being selectively expandable and collapsible between a transport position in which the drill bit assembly is transported through the ground drill by the sleeve and transport member and a cutting position in which the drill bit assembly locks into the drive sub and cuts the hole. The drill bit assembly in the cutting position is able to cut a hole substantially greater than the diameter of the ground drill itself. The drill bit assembly includes a circular bit attached at a lower most end of the sleeve and bit segments retained in slots formed in the sleeve. Each segment is provided with a lever that extends radially inwardly of the sleeve and engages the transport member. The transport member is arranged coaxially with and extends inside the sleeve, with the transport member or sleeve being resiliently coupled together to allow relative linear sliding motion. The lower end of the bit assembly sleeve extends beyond a lower end of the transport member. The drill bit assembly is coupled to the bit assembly sleeve and transport member so that linear motion of the lower ends of the sleeve and the transport member urges the segments radially outwardly from engagement of the levers with the transport member.

Loading the Abstract Image...

First Claim