An earth boring machine 10 with a frame and a linearly movable slide 22 on the frame has an apparatus for holding and rotationally driving a boring rod 24, and a forward feed drive for moving the slide parallel to the boring direction. The machine with especially small space requirement creates a large force for movement of the slide 22 in and opposite to the forward feed direction. Moreover, the forward feed drive of the earth boring machine 10 has a rotationally drivable forward feed spindle 20 arranged on the frame 18, which spindle is received by a spindle nut non-rotationally connected with the slide 22.

An underground directional boring machine includes a frame and a drive mechanism slidably mounted on the frame. A drill string is coupled to the drive mechanism for rotation and longitudinal advancement and retraction. A drive assembly moves the drive mechanism along the frame. The drive assembly includes two hydraulic cylinders coupled to the drive mechanism and extending in opposite directions. Free ends of the hydraulic cylinders are releasably secured to the frame at any one of a plurality of positions along the length of the frame. Selective pressurization of the cylinders results in sequential movement of the drive mechanism along the frame by alternative extension and retraction of the cylinders.

This invention provides a roof bolt installation apparatus including a drill stabilizing mechanism including a base having a cylindrical bore therein, and a stabilizing rod extendable from the base and slidably located in the bore. The rod has a distal end, and a drill stabilizing end plate is mounted on the rod distal end. The roof bolt installation apparatus also includes a drilling unit which is adapted to rotatably carry a drill, the drilling unit being slidably mounted on the drill stabilizing mechanism, and a mechanism for moving the drilling unit along the drill stabilizing mechanism. The roof bolt installation apparatus also includes a drill depth control device including a base, a top adapted to engage the mine roof, and at least two bars connected between the drill depth control base and the drill depth control top. The bars pass through openings in the drill stabilizing plate.

In apparatus for producing and expanding earth boreholes and for destroying and replacing underground pipelines or for driving in pipes, a feed drive and a rotary drive having a plug-in coupling comprising a chuck and a locking portion at the end of a string is located in a frame. The string comprises a plurality of sections or lengths having an internal screw thread at one end and an external screw thread on the locking portion at the other end, which at the same time is provided with a key face to hold fast said string section while it is screwed together with the next following string section.

The invention relates to a ground working implement, particularly for underground working, having a slide displaceable relative to a base by means of a lifting cylinder arrangement. It is on the one hand connected to the slide and on the other to the base and has two oppositely acting lifting cylinder means. A particularly compact, stable arrangement is brought about in that the two lifting cylinder means have in each case one lifting cylinder with cylinder casing, which are juxtaposed and are firmly interconnected.