Rotating shaft confinement system

Apparatus for limiting the amplitude of transverse vibratory excursions of a rotating shaft, wherein:

• the shaft is mounted in journal bearings, being a left bearing and a right bearing;
• the left bearing includes a left bearing-shaft-portion and a left bearing-housing;
• the right bearing includes a right bearing-shaft-portion and a right bearing-housing;
• the bearing-shaft-portions are components of the shaft, and the bearing-housings are components of a fixed housing of the apparatus;
• the bearings define an axis of rotation of the shaft;
• the bearings are so structured as to constrain the bearing-shaft-portions against radial movement, relative to the respective bearing-housings;
• the remainder of the shaft, other than the left and right bearing-shaft-portions, is termed the un-bearinged-portion of the shaft;
• the structure of the apparatus is such that the left and right bearing-housings constrain the left and right bearing-shaft-portions respectively of the shaft against transverse vibratory excursions, but the left and right bearing-housings do not constrain the un-bearinged-portion of the shaft against radial excursions;
• the shaft includes a rotor, which is mechanically solid with the shaft;
• the rotor lies in the un-bearinged-portion of the shaft, being axially spaced, on the shaft, away from the left and right bearings;
• the rotor has a ring, with an outwards-facing surface, which is concentric with the shaft axis;
• the outwards-facing surface of the ring is circumferentially continuous;
• the apparatus includes several excursion-limiting tappets;
• the tappets are pitched around the ring, and are carried in respective tappet-housings, which are mounted to a hoop of a fixed housing;
• the tappets have respective contact-tips;
• the structure of the apparatus is such that the contact-tips are positioned radially outside, and clear of, the outwards-facing surface of the ring, by respective tappet-clearance distances;
• the tappets are provided with respective operable tappet-adjusters, and respective operable adjustment-locks;
• in respect of each one of the tappets:
• its respective tappet-adjuster is effective, when operated, to move the tappet radially towards and away from the outwards-facing surface of the ring, and thereby to reduce and increase its tappet-clearance, being the distance between its contact-tip and the outwards-facing surface of the ring;
• its adjustment-lock is effective, when operated, to lock the tappet at the adjusted position relative to its tappet-housing, and thereby at its adjusted tappet-clearance;
• the tappet lies in a condition of adjustment in which, when the shaft is turning slowly about the axis defined by the left and right bearings, its tappet-clearance is large enough that the tappet is substantially clear of the outwards-facing surface of the ring;
• its tappet-clearance is small enough that, when the shaft undergoes a radial vibratory excursion, the outwards-facing surface of the ring impacts against the tappet at an amplitude-A of the excursion, being an amplitude that is small enough to be non-damaging to the shaft, bearings, ring, tappets, and fixed housing;
• the structure of the tappet is such as to physically and mechanically restrain the outwards-facing surface of the ring, and thereby the shaft, against an increase in amplitude of such excursions beyond amplitude-A.