Abstract: A grease gun comprising a hollow piston rod driven by a pressure fluid upon an annular drive piston at one end of the rod, compressing a supply of grease by an annular plunger at the other end of the rod into a receiving chamber within the piston rod, which chamber cooperates with a stationary surface, upon reversely driving the piston rod, to expel the grease through a conduit from the chamber at a higher pressure than the driving fluid.

Abstract: A cutting machine has at each side of a universally pivotable cutter boom a cutting head which is rotatably supported around an axis extending vertically to the longitudinal direction of the cutter boom and which is advanced in direction of its axis when the cutter boom is pivoted. The cutting heads are propelled by a drive unit via a reduction gearing arranged within the cutter boom, the last stage of the reduction gearing being arranged within cutting heads which are hollow.

Abstract: A bit holder consisting of steel, said bit holder comprising a bore for accommodating the bit shaft and being welded to the cutting head of a cutting machine, characterized in that the bit holder consists of a part of heat-resistant steel of high strength and of a foot consisting of an unalloyed or low alloy steel of good weldability and being welded to said foot over the whole contacting area. In making the holder a blank corresponding to the part accommodating the bit shaft is over the whole contacting area welded to a blank corresponding to the foot to provide a composite blank which is subsequently forged in a forging die.