Device for measuring the torque of a hairspring

Device for the dynamic or static measurement of the torque of a hairspring for a balance wheel-hairspring oscillator, comprising:

• an arbor on which a seat is arranged,
• a benchmark element, benchmark flywheel or hairspring, associated with said arbor,
• pivoting means for pivoting said arbor,
• means for keeping the outer end of said hairspring fixed relative to said arbor during the measurement,
• elastic elements provided on a portion of said seat, and
• means for acting on said elastic elements,
• wherein the inner end of said hairspring is secured to a collet, the diameter of the seat of the arbor is of a dimension to allow a driving connection by friction with the wall of an axial aperture of the collet, and the elastic elements are formed to bring, under the action of the action means, the section of the portion of the seat forming the driving connection from a greater dimension to a smaller dimension than that of the axial aperture of the collet.