| 摘要 |
<p>A rotary drilling head assembly having a main body through which an axial bore is formed for sealingly receiving, in an axially rotatable and longitudinally slidable manner, a driving member therethrough, thereby enabling the driving member to be moved longitudinally respective to the head while it is being axially rotated by the turntable. An outflow passageway conducts fluid flow away from the head, while a second seal means controls fluid flow between the relative rotating parts of the assembly. -1a-</p> |
