Hydro-expansion chuck

A hydraulic expansion chuck comprising:

• a chuck body;
• a hydraulic expansion mechanism;
• and a reducing bushing, the hydraulic expansion mechanism integrated into the chuck body, the hydraulic expansion mechanism comprising an expansion bushing, a first region of an inner surface of the expansion bushing substantially cylindrical relative to a first axis, the first region of the inner surface of the expansion bushing located between a first plane and a second plane, the first plane and the second plane each perpendicular to the first axis, a second region of the inner surface of the expansion bushing located between a third plane and a fourth plane, the third plane and the fourth plane each perpendicular to the first axis, at least a first portion of the second region of the inner surface of the expansion bushing being non-cylindrical, at least part of the reducing bushing in a space defined by the inner surface of the expansion bushing, a first part of an outer surface of the reducing bushing located between the third plane and the fourth plane, at least a first portion of the first part of the outer surface of the reducing bushing being non-cylindrical, said first portion of the second region of the inner surface of the expansion bushing being aligned with said first portion of the first part of the outer surface of the reducing bushing, whereby contact between said first portion of the second region of the inner surface of the expansion bushing and said first portion of the first part of the outer surface of the reducing bushing prevents rotation of the reducing bushing about said first axis relative to the expansion bushing, at least a first portion of an inner surface of the reducing bushing being non-cylindrical, said first portion of said inner surface of the reducing bushing thereby being configured to contact a non-cylindrical portion of an outer surface of a shank tool to prevent rotation of the shank tool about said first axis relative to the reducing bushing.