| 摘要 |
PERCUSSION DRILL A percussion drill includes a control arbor in which a hammer piston is longitudinally reciprocally disposed. Front and rear casing sections are threadedly coupled to the control arbor in a manner preventing longitudinal movement of the arbor relative to the casing sections. A drill bit is secured to the front casing section, and is repeatedly struck by the piston to effect a percussion drilling operation. A rear sub is secured to the rear casing section, and a front end of the rear sub projects telescopingly into a rear end of the control arbor to radially support the latter.
|
