Impact drilling tool

A power tool comprising, in combination, a housing;

• a spindle element mounted in said housing for rotation about an axis and for displacement in axial direction;
• drive means for rotating said spindle element;
• and means for subjecting said spindle element to axially oriented impacts, including an impact element mounted in said housing at least for reciprocation in direction of said axis, means for reciprocating said impact element driven by said drive means, a blind axially oriented bore in one of said elements and having a first impact surface, and an axially oriented extension on the other element and received in said blind bore of said one element and having a second impact surface which impacts said first impact surface upon axial displacement of said impact element in direction toward said spindle element, wherein said drive means also rotates said impact element;
• and wherein said reciprocating means includes at least one cam surface at an outer circumferential surface of said impact element, which cam surface extends helically over a part of said circumferential surface and has an axial depression, biasing means urging said impact element toward said spindle element, and at least one cam follower element retained in said housing against axial displacement and adapted to engage said cam surface of said impact element to thereby displace said impact element away from said spindle element against the action of said biasing means when engaging the helical portion of said cam surface and to release said impact element for rapid displacement toward said spindle element under the action of said biasing means when encountering said axial depression, wherein said impact element has at least one helical projection extending radially outwardly of said outer circumferential surface and having said cam surface, said depression being an interruption of said helical projection, and wherein said spindle element and said impact element are mounted in said housing for axial displacement between a normal drilling position in which said cam follower element is located out of the path of rotation of said helical projection, and an impact drilling position in which said cam follower element cooperates with said cam surface of said helical projection.