Drilling equipment

Claim 1

Improvements in drilling equipment for drilling from rocks into strata of earth and sand, said equipment comprising a drilling unit incorporating a cutter head, casing sections positioned between said drilling unit and said cutter head, and drill rod sections extending through said casing sections and having an axial through channel for the drilling water, the improvements comprising in combination, a first seal made from metal, a second seal made of some softer material, such as rubber or plastics, said seals positioned adjacent one another between said casing and said cutter head and arranged to cooperate for the purpose of preventing ground water and mud from penetrating into said casing, a one way valve arranged in the drill water channel in the drill rod positioned just behind said cutter head, said one way valve formed in a manner known per se by a valve ball, a compression spring arranged to press said valve ball against a valve seat, the drill rod positioned closest to said cutter head being provided adjacent said head with a drill water opening, a seal arranged behind said drill water opening and serving to prevent drill water from flowing between said drill rod and said casing in the direction towards said drill chamber, a pressure sleeve arranged between said casing and the wall of said drill hole, an annular channel formed between said casing and said wall of the drill hole, said pressure sleeve arranged to close off said annular channel against the drill chamber, and a conduit for supply of pressurized medium, such as air or water, said conduit debouching into said annular channel.