Self-propelled percussive machine for boring holes

A self-propelled percussive machine for boring holes in rocks comprising:

• a housing;
• an impact mechanism accomodated in said housing and having a reciprocating hammer piston;
• a rock-destroying member mounted on the forward part of said housing, the hammer piston of said impact mechanism imparting impact pulses to said rock-destroying member during its reciprocation;
• an air-supply duct for supplying compressed air both to said impact mechanism for operating it and to the hole face for removing rock disintegration products from the borehole;
• means for preventing said self-propelled machine from moving away from the hole face during the operation, said means being mounted on said housing and comprising an elastic tubular member having an internal space in permanent communication with said air-supply duct, said elastic tubular member including radial projections and being deformed under the action of the compressed air to urge said radial projections against the borehole wall thus preventing the self-propelled machine from moving away from the hole face during the operation, said tubular member defining a clear space with the wall of the hole which space is permanently open during the operation, said housing defining an open passage with the wall of the hole leading to said clear space so that rock particles can flow continuously from the hole via said passage and clear space under the action of the compressed air.