Abstract: A percussive action machine includes a housing in which a hammer is movably secured to define a forward stroke chamber and a return stroke chamber. The hammer is provided with an air-distributor fashioned as a sleeve having holes. The hammer is further provided with a device for alternately communicating the return stroke chamber with the forward stroke chamber and with the outside, the device having the form of at least one bore arranged inside the hammer in line with its axis. Communicating with this bore is a tubular control valve extending through the forward stroke chamber and having in its wall at least one hole wherethrough the return stroke chamber alternately communicates with the forward stroke chamber and with the outside.

Abstract: Apparatus for building underground pipelines by forming a casing in a hole from a forming material which is compacted in the direction from the center of the hole towards its walls. The hole is first filled with the forming material throughout its cross-sectional area and then the material is compacted in the direction towards the walls of the hole. Compaction is effected by a device comprising a rod-shaped body adapted for moving through the hole, the front end of the body being provided with a system of radial ribs.

Abstract: A pneumatic impact mechanism for driving rod-like members having a hollow cylindrical casing with a tail portion and a front end portion. The casing accommodates a reciprocating stepped hammer piston defining in the casing, on the tail portion side, a variable volume rear end work chamber in permanent communication with a source of compressed air. The stepped hammer piston defines, on the side of the front end portion, a variable volume front end work chamber.The stepped hammer piston has a through-passing axial bore, and its small-diameter portion cooperates with the tail portion of the casing and has radial passages. There is provided a tubular guide member or element for receiving the rod-like member arranged coaxially with the stepped hammer piston and casing and secured to the tail portion and to the front end portion of the casing in such a manner as to cooperate with the stepped hammer piston and define therewith, with the outer periphery thereof an axial passage.

Abstract: A method of building underground pipelines by forming a casing in a hole from a forming material which is compacted in the direction from the center of the hole toward its walls. The hole is first filled with the forming material throughout its cross-sectional area and then the material is compacted in the direction towards the walls of the hole. Compaction is effected by a device comprising a rod-shaped body adapted for moving through the hole, the front end of the body being provided with a system of radial ribs.