A drilling machine includes a boom assembly which has two straight parallel longitudinal beams of extruded steel, each of a section defining straight parallel inwardly and outwardly facing ways, a drilling head in a carriage and rollers guiding said carriage for linear movement of said drilling head parallel to said inwardly facing ways, two straight parallel longitudinal boom extension members and rollers guiding said boom extension members in said outwardly facing ways, and cross members linking said boom extension members to form a frame, plate braces linking said beams in longitudinally spaced planes perpendicular to the axes of the beams, said plate braces being apertured to provide clearance for assembly and normal movement of said carriage, said drilling head, and drill tubes passing through said drilling head, and further longitudinal members linking said plate braces to form a cradle of the boom assembly, said cradle having brackets for pivotally supporting the boom assembly on a base. The carriage for the drilling head can be actuated by a hydraulic cylinder forming a single double ended piston rod, through chains anchored to the cradle and to the carriage and passing over sheaves attached to opposite ends of the piston rod.

An automatic drive hammer system, particularly adapted to use in the Standard Penetration Test, is mounted on a drill rig in such a way that it can be swung and translated to an on-hole working position. A hammer reciprocating mechanism is so mounted that its weight is not borne entirely by the drill rod, the hammer is dropped free through an accurately predetermined height onto an anvil isolated from the reciprocating mechanism so that all of the energy from the falling hammer is transmitted to the drill rod, and the hammer will not be lifted and released if the anvil is not in place.

A drilling device has a drilling mast and a movable drifter thereon with a drill rod stabilizing device for stabilizing drill rods in position during drilling. The stabilizer travels along the mast along with the drifter, and includes a locking arm that automatically opens and closes the stabilizer to allow passage of drill rods into an out of the drill line from storage, while supporting the drill rods during drilling. In a substantially vertical drilling position, the stabilizer is moved downwardly by gravity, and upwardly by the drifter's drive chain, which is retained in contact with the stabilizer by a pick-up link on the drive chain contacting stop blocks on the stabilizer. In a substantially horizontal drilling position, the stabilizer is moved in a return direction by the pick-up link and stop block combination. The stabilizer is advanced in the opposite direction by the drifter's pick-up link, which is retained in contact with the stabilizer by a pair of spaced-apart rollers on the stabilizer that frictionally contact and retain the pick-up link and stabilizer together.

A hydraulically operated drilling apparatus having a main mast on which an extension is mounted having a rope winch or the like for operating a rotary drilling head or power capstan. The drilling head is guided on a pair of diametrically opposed rails fixed on the outer circumference of the mast along its entire length and is pulled by a cable of a block and tackle system activated by a hydraulic power drive located within the mast. The cable of the block and tackle system which in part runs on the exterior of the mast passes into the mast and is caused to run over a movable pulley sheave secured at each end of the mast. The sheaves at the end of the mast are mounted on bearings which also anchor the cable, which bearings are securely and integrally formed with end caps or covers, sealing the end of the mast.

A mobile drilling rig includes a rectangular tube which is used for the derrick and is normally transported on the vehicle in a generally horizontal attitude. The derrick is pivoted to vertical position by a hydraulic cylinder. A pulldown system located inside the tube includes a double-acting hydraulic pulldown cylinder, drive pinions mounted to the piston rod, one gear rack fixed inside the tube and another gear rack slidable inside the tube. A drill-driving powerhead is slidably mounted on the outside of the tube and is connected to the slidable gear rack. The pinions connected to the pulldown cylinder piston rod engage both racks and, with a piston stroke less than half the length of the tube, drive the power head essentially the full length of the tube for the pull-down function.