Abstract: An apparatus for, and a method of, controlling the torsional damping frequency of a torsional damper using a magneto-rheological fluid disposed between a relatively rotating inertia ring and a surrounding chamber. A coil is continuously wrapped around the chamber and provides at least two slip rings for conducting electricity through the coil from outside the chamber. At least two corresponding wiper contacts electrically connect said slip rings to a source of DC voltage which in turn is controlled by a controller to continuously adjust the damping torsional resistance of the magneto-rheological fluid. A vibration sensor can be associated with the damper and can be signal connected to the controller to continuously adjust the magnetic field through the magneto-rheological fluid to continuously adjust the torsional shear resistance of the fluid, and thereby fine tune damping of the damper.

Abstract: A viscous torsional vibration damper having an annular chamber surrounding a central hub and first and second annular inertia masses located within the annular chamber. The innermost first inertia mass is closely coupled with an inner surface of the working chamber, and has a Teflon bearing arranged between the first inertia mass and the inner surface. The second annular inertia mass is closely mechanically coupled with the first inertia mass by lateral damping units, such as by elastomeric O-rings, such that the combination of the first and second inertia masses and the damping units are substantially freely rotatable within the working chamber due to the Teflon bearing but are arranged to absorb lateral vibrations by the lateral dampers. A viscous fluid is disposed within the working chamber surrounding the inertia masses.

Abstract: A rotary viscous damper having a disc surrounded by a housing and cover, the disc rotatable with a shaft which penetrates the housing, a gap provided between opposite sides of the disc and the inside surfaces of the housing and cover for receiving viscous fluid, and triangularly shaped indentations formed on opposing surfaces of the disc and the housing and cover, the indentations on the housing and the cover arranged at selective rotational positions. Rotation of the disc aligning opposing indentations on the discs and the housing and cover to create a rotary position of minimum torque and when misaligned, a rotary position of maximum torque. The oscillating torque value creates a nominal torque associated with the damper, but can be selectively installed to present a minimum torque at a particular rotational position. The invention is particularly adapted to rotary devices where rotational position can effect the available torque for driving the shaft, such as an exercise bicycle.

Abstract: A viscous damper for influencing and retarding rotation of a shaft, particularly the reel shaft of a roll-down fire door. The viscous damper unit comprises a housing having radially extending lugs, a cover for mounting to a side face of the housing, and a rotor arranged to be trapped between the cover and the housing and rotatable with respect to the housing. The rotor provides a bore for receiving the roll-down shaft for the fire door. The housing lugs are positioned to be selectively locked with respect to the framework of the fire door to prevent rotation during down rolling of the fire door. A viscous material is applied between the housing, the cover, and the rotor which retards the rotation of the rotor with respect to the housing by, shear forces. The housing is arranged to be compatible with a plurality of damping units being axially stacked along the shaft and provides aligned apertures for pinning or bolting the plurality of the housings together.

Abstract: A viscous torsional vibration damper of the kind operating on the shear film principle has a roll spun annular channel shaped housing providing an annular working chamber within which is mounted an annular complementary inertia mass ring and a viscous damping fluid substantially fills shear film spaces between the working surfaces of the inertia ring and confronting working surfaces of the housing within the chamber. Working surface area of the housing within the working chamber has a spinning roll burnished finish. A roll formed rabbet provides a shoulder seat on one wall of the housing with an edge portion of a closure sealed thereto. Laser welding permanently secures the closure to the housing.

Abstract: A viscous torsional vibration damper of the kind operating on the shear film principle has a roll spun annular channel shaped housing providing an annular working chamber within which is mounted an annular complementary inertia mass ring and a viscous damping fluid substantially fills shear film spaces between the working surfaces of the inertia ring and confronting working surfaces of the housing within the chamber. Working surface area of the housing within the working chamber has a spinning roll burnished finish. A roll formed rabbet provides a shoulder seat on one wall of the housing with an edge portion of a closure sealed thereto. Laser welding permanently secures the closure to the housing.