Hammer drill

In a hammer drill, a combination, comprising a movable tool having a longitudinal axis and a first end portion provided with at least one substantially axially extending recess formed on the outer surface thereof and closed at both its axial ends;

• a driving element substantially coaxial with said tool, said driving element having a second end portion adjacent said first end portion and directly transmitting axial impacts from said driving element to said tool without transmission of torque, said second end portion of said driving element being provided with at least one further substantially axially extending recess formed on the outer surface thereof and closed at both its axial ends;
• a tool holder transmitting torque from said driving element to said tool without transmission of axial impacts said tool holder including a sleeve-shaped member coaxially surrounding said first and said second portions and having a longitudinal axis, said sleeve-shaped member being provided with one and further substantially radially extending through bores formed in a wall thereof and axially spaced from one another;
• means for limiting axial movement of said sleeve-shaped member relative to said tool, including a radially movable ball-shaped element located in one radially extending through bore of said sleeve-shaped member and engaging said axially extending recess of said tool;
• means for retaining said ball-shaped element in said radially extending through bore of said sleeve-shaped element and including a further sleeve-shaped member coaxially surrounding said sleeve-shaped member and having a longitudinal axis, said further sleeve-shaped member being axially movable and rotatable relative to said sleeve-shaped member and having a working position in which it is pressed against the latter, said further sleeve-shaped member having a first axial section overlapping an inlet end portion of said radially extending through bore of said sleeve-shaped member in said working position so as to outwardly limit said radial movement of said ball-shaped element;
• means for limiting axial movement of said sleeve-shaped member relative to said driving element including a further radially movable ball-shaped element located in said further through bore of said sleeve-shaped member and engaging said further axially extending recess of said driving element;
• and drive means for driving said driving element.