| 摘要 |
A portable drilling rig comprises telescoping inner (12) and outer (10) elongated mast sections the inner section being movable and having sprockets (86, 88, 90, 92) at its upper and lower ends. Chains secured to the outer mast section near its upper end are wrapped around the upper and lower sprockets and connect to a drill head which is guided for movement along the inner mast section. The chain and sprocket arrangement causes the drill head to move, at twice the rate of movement of the inner mast section, from a location near the lower end of the outer mast section when the mast sections are collapsed to a location near the upper end of the inner mast section and well above the upper end of the lower mast section when the mast sections are extended. The mast can be carried horizontally, when collapsed, by a relatively short vehicle, but is capable of handling long lengths of drill pipe. The drill head is pivotable so t hat drill pipe can be attached and detached near ground level.
|
