| 摘要 |
<p>There is disclosed a pilot bit (20) for an earth excavating device ( 10) comprising an elongate body (25) having a proximal end (27) adapted for coupling to a rotating shall (11) of the earth excavating device (10) and a distal end (23). A plurality of blades (21) extend radially from and being substantially equidislantly spaced about the elongate body (25) such that each blade (21) extends in a spiral at least partially along a length of the elongate body (25). At least one of the blades (21) has a plurality of cutting faces (24, 26, 28) formed therein at predetermined distances along a length thereof. Each cutting face having a cutting edge (24a, 26a, 28a) that extends substantially perpendicular to a longitudinal axis of the elongate body (25) so as to define a plurality of cutting planes.</p> |
