| 摘要 |
<p>Inner and outer tubulat drill pipes are splined together for joint rotation and are prevented from moving axially relative to each other by means of a deformables sleeve located in an annular recess between the pipes. A piston beneath the sleeve serves to compress the sleeve axially to cause radial expansion thereof such as will prevent the relative axial movement. The pipe pipes are thus usable in any position between the fully expanded and fully retracted positions. The pipes are carried on a hinged drilling mast which can form part of a crawler or wheeled vehicle.</p> |
