Abstract: A music box operating stopping mechanism in which a pull string for winding a coil string can be stopped with a very small force so as to prevent the skin of a finger from being caught by the string as passes through a hole in the case of the music box. A locking member is provided which can pass in and out of the region of rotation of an air braking type speed governor plate which is driven by the coil spring. The locking member is urged out of the region of rotation of the governor plate with an elastic force which is much smaller than the elastic force of the coil string. The string is engaged with the locking member so that when the string is pulled outwardly during playing of music, the locking member is moved into the region of rotation of the governor plate against the elastic force of the string.

Abstract: Disclosed is a method and apparatus for cold-working annular workpieces by applying thereto an internal fluid pressure to cause an enlargement of the diameter thereof through plastic deformation, in which the openings at opposite ends of an annular workpiece are closed by a pair of presser plates through packings which are radially expansible along with the annular workpiece. The contacting surface pressure of the packings and presser plates are controlled to a predetermined value by an arithmetic unit operating on detected values of a main pressure acting internally on the annular workpiece, an auxiliary pressure pressingly holding the presser plates against the respective packings and varitions in the shape of the annular workpiece undergoing the plastic deformation.