Apparatus for measuring errors in concentricity relative to two surfaces of rotation

Apparatus for measuring errors in concentricity relative to first and second nominally coaxial surfaces of rotation which define a hole in a mechanical part, comprising a first support for the part, a second support, a first mechanical reference means supported by said second support to cooperate with the first of said surfaces of rotation, measurement means coupled with said first mechanical reference means to cooperate with the second surface of rotation and effect dimensional measurements thereon, a second mechanical reference means supported by said second support and rigidly connected to said first mechanical reference means, floating connecting means and thrust means arranged between said first mechanical reference means and said second mechanical reference means and said second support to permit simultaneously the first said mechanical reference means to remain in contact with the first surface of rotation and said second mechanical reference means to cooperate with at least one point of a first section of said second surface of rotation, rotatable means adapted to produce a substantially rotary relative movement between the part and said second support;

• and processing and indicating means connected to said measurement means, said measurement means comprising a measuring device mechanically coupled with said first reference means and said second reference means to carry out, during said relative motion, dimensional measurements on a second section of said second surface of rotation, said measuring device including an arm having at least one degree of freedom with respect to said first and second mechanical reference means, a feeler fastened to said arm to enter into contact with a point of said second section of said second surface of rotation, and a transducer adapted to provide signals responsive to the linear dimensions of said second section.