Patent ID: 7640998

Claim:
An excavation apparatus comprising: a mast having a mast first end and a mast second end, and a mast planar surface; a sled slidably mounted on the mast planar surface; sled driving means supported by the mast for driving the sled along the mast planar surface from proximate the mast first end to proximate the mast second end, and for driving the sled back along the mast planar surface from proximate the mast second end to proximate the mast first end; an outer kelly section attached to the sled, the outer kelly section having a first end and a second end such that the outer kelly section first end is nearer to mast first end than is the outer kelly section second end, the outer kelly section also having a straight longitudinal axis and a central longitudinal cavity; outer kelly section bushing means secured to the mast proximate the mast second end for maintaining the outer kelly section in a slidable relationship relative to the outer kelly section bushing means, and for maintaining the longitudinal axis of the outer kelly section approximately parallel to the mast planar surface; an inner kelly section having a first end and a second end such that the inner kelly section first end is nearer to outer kelly section first end than is the inner kelly section second end, the inner kelly section having a straight longitudinal axis and a central longitudinal cavity, and at least a longitudinal portion of the inner kelly section including the first end thereof are acceptable into the central longitudinal cavity of the outer kelly section; extension and retraction means for extending and retracting the inner kelly section partially out of and partially back into the outer kelly section a proportional distance equal to at least about twice a distance that the sled is moved along the mast planar surface, and for preventing slippage of the inner kelly section relative to the outer kelly section; rotary drive means attached to the sled and having a drive shaft having an axis, the rotary drive means connected to and rotates a telescopic shaft means, the telescopic shaft means for providing a variable length, the telescopic shaft means having a first end connected to the drive shaft of the rotary drive means, and a second end for attaching an excavation tool, wherein the telescopic shaft means is also for permitting the simultaneously extension and retraction of the telescopic shaft means as the inner kelly section extends from and retracts into the central longitudinal cavity of the outer kelly section, whereby, when the sled driving means is activated in a first direction the sled is driven towards the mast second end and the inner kelly section is extended out of the central longitudinal cavity of the outer kelly section, and whereby, when the sled driving means is activated in a second direction that is the opposite of the first direction the sled is driven towards the mast first end and the inner kelly section is retracted back into the central longitudinal cavity of the outer kelly section.