Abstract: The present invention is a high-precision positioning post having alternag parallel cuts transversing the center-line of the shaft body and which are perpendicular to the major axis of the shaft. The shaft further comprises a bearing rod internal to the shaft which is acted on by a screw. As the screw is turned, the bearing rod forces the end of the shaft to axially translate an object without rotation. This allows an object integral to the shaft or mounted on the shaft to be translated and located along the major axis of the shaft without rotation of the object. In an alternate embodiment the present invention may be used to isolate vibration by inclusion of dampers in the hollow shaft. A third embodiment uses the basic design as a vibration isolation mechanism for buildings.

Abstract: The present invention relates to a passive mass damper for broadband suppression of vibrations. The mass damper preferably includes a bob supported by nonlinear springs with high secant stiffness and low tangent stiffness. The mass damper is mounted on a machine or other source of vibration. The vibration generated by the machine is transmitted to the mass damper and induces off phase vibration of the bob which suppresses the inducing vibration.

Abstract: A tuned vibration absorber includes a mounting plate having at least two, and alternatively four, mounting holes in spaced relationship from a longitudinal center axis of the plate. An elastomeric spring is bonded to the mounting plate. A main tuning mass is bonded to the elastomeric spring opposite the mounting plate, and fine tuning masses are riveted directly onto the main tuning mass. The elastomeric spring and main mass both have a rectangular profile to maintain a low profile height from the mounting plate. A cover is formed of a single sheet of metal bent to form a rectangular box with one open side. The cover includes mounting flanges with holes that align with the mounting holes on the mounting plate. For mounting the vibration absorber on a stiffening ring of an aircraft frame, a spacing plate is positionable between a portion of the mounting plate and the stiffening rib of an aircraft frame, and adjacent to an overlapping secondary stiffening ring to provide a flat mounting surface.

Abstract: Torsional vibrations in a rotating structure having a relatively large mass and subject to varying frequencies of torsional excitation are damped by determining the frequency of torsional excitation of the rotating structure and coupling to the rotating structure a damping pendulum of smaller mass to provide an absorber unit rotating therewith. The angular displacement of the damping pendulum relative to the rotating structure is continuously monitored, and the frequency of excitation is determined. The monitored displacement of the damping pendulum together with the mass damper characteristics of the absorber unit are processed to output a signal which produces a control torque on the damping pendulum proportional to the monitored displacement of the damping pendulum with a controlled time delay to produce control torque on the damping pendulum substantially equal to the torsional excitation of the rotating structure.

Abstract: An apparatus for absorbing vibrations in a structural member, such as in an aircraft fuselage, has a mounting member for attaching to the structural member. Two masses are coupled in a cantilevered manner to the mounting member by a plurality of flexible rigid members, such as rods or plates, which act as a spring that allows the masses to vibrate with respect to the mounting member. The spring-mass assembly has a resonant frequency that matches the frequency of the vibrations in the structural member. A mechanism, connected between the two masses, exerts a variable force on the plurality of rigid members to compensate for changes in their stiffness due to changes in temperature and thereby maintain the resonant frequency substantially constant. Preferably the mechanism includes a bimetallic element that has a shape which changes with temperature variation to produce the variable force.

Abstract: A damping mounting structure for use between two members for isolating motion changes which incorporates a plurality of dampers connected between the two members in a closed geometric shape and which uses cross connections between the dampers located on opposite sides of the geometric shape so that translation motion between the two members is less stiff than rotational motion between the two members.

Abstract: An apparatus for damping dynamic response in a primary structure in one, two or three dimensions, includes a secondary mass, and a spring and a viscoelastic element, the spring and viscoelastic element interposed between the primary structure and the secondary mass. The apparatus may include a housing for the secondary mass, the spring and the viscoelastic element, should the spring, viscoelastic element, or both the spring and viscoelastic element, be interposed between the secondary mass and the housing. A method for damping dynamic response in a primary structure in one, two or three dimensions is also disclosed.

Abstract: An active vibration canceler, including a canceler mass that is attached by a spring device to a supported bearing. The canceler mass is movable by a plunger coil arrangement and a permanent magnet so as to result in at least partial suppression of relative movements of the supported bearing in at least one frequency range. The spring device joins the canceler mass and the supported bearing for relative movement in one direction. The spring device includes at least three leaf springs arranged in at least two planes, which leaf springs, in the idle position, extend circumferentially in the same direction.

Abstract: The invention is uniquely "passive-active" in that it brings to bear, sequentially and complementarily, passive vibration control followed by active vibration control. A conventional mount (such as an air mount) is accommodated so as to include, at the mount's foundation-securing plate, at least one motion sensor and at least one vibratory actuator. Each sensor is correlated with an actuator. For each sensor-actuator pair, the electrical feedback loop includes generation by the sensor of a signal resulting from the local vibration of the foundation-securing plate, generation by a processor/controller of a signal derived from the sensor's signal, and exertion upon the foundation-securing plate by the sensor's paired actuator of a vibratory force commanded by the processor/controller's signal. Many preferred embodiments of the inventive apparatus, system and method collocate each sensor with its paired actuator and implement a conventional vibration suppression algorithm involving collocated velocity feedback.

Abstract: The inventively advanced mount accommodates a conventional mount (such as an air mount) so as to include, at the mount's foundation-securing plate, at least one motion sensor and at least one vibratory actuator. Each sensor is correlated with an actuator. For each sensor-actuator pair, the electrical feedback loop includes generation by the sensor of a signal resulting from the local vibration of the foundation-securing plate, generation by a processor/controller of a signal derived from the sensor's signal, and exertion upon the foundation-securing plate by the sensor's paired actuator of a vibratory force commanded by the processor/controller's signal. Many preferred inventive embodiments collocate each sensor with its paired actuator and implement a conventional vibration suppression algorithm involving collocated velocity feedback. The inventive "passive-active" mount uniquely brings to bear, sequentially and complementarily, passive vibration control followed by active vibration control.

Abstract: A damping member includes a damper bracket fixed to an upper link bracket, a mass bracket Joined to the damper bracket via an elastic body, and a mass for vibration control supported by the mass bracket, an upper link bracket is provided on a rear axle housing for supporting one end of the upper link supported at another end thereof relative to a vehicle body, the upper link bracket has a wall portion for accommodating the damping member therein, and a stopper portion is provided on the damper bracket in oposition to an end part of the mass for enclosing the mass in cooperation with the wall portion of the upper link bracket.

Abstract: An active vibration absorber including a frame connected to a structure to be controlled and at least two reaction mass elements operatively connected to the frame. Each of the reaction mass elements is independently movable with respect to said frame. The absorber includes a force generating member for controlling relative movement between the reaction mass elements for damping vibration of the structure. The inventive dual reactive mass absorber requires less control force to produce the same vibration attenuation as conventional single reactive mass absorbers.

Abstract: A double-mass type dynamic damper mounted on a rod-shaped oscillating member, which includes a first damper system and a second damper system that are tuned to two different frequency ranges. Each of the damper systems includes a cylindrical mass member disposed radially outwardly of the oscillating member, and an elastic support member for elastically supporting the mass member with respect to the oscillating member. The elastic support members of the two damper systems are disposed in series and connected to each other in the axial direction. The dynamic damper further includes an elastic connector formed by adjacent parts of the two elastic support members, for elastically connecting axially opposed faces of the two mass members.

Abstract: A container with an inside surface and a mass mounted for oscillation in the container with a pair of bellows in the container each having a bias spring therein and a removable end to expose the interior of the bellows to exchange the spring for easy tuning of the damping characteristics and a plurality of balls, one each positioned in a plurality of troughs around the periphery of the mass proximate the ends there to bear against the inside surface so as to provide low friction oscillation of the mass in the container.

Abstract: Broadband particulate absorbers include a suspended container for containing particulate beads that absorb vibration energy over a broad bandwidth so reduce coupled vibrations of mechanical systems over the broad bandwidth. The absorbers preferably include two opposing aluminum containers for containing particulate teflon beads. The aluminum containers are suspended and separated by aluminum I-beams attached to stringers of a rocket subjected during lift off to atmospheric pressure vibrations exerted on the vehicular skin coupling vibration through the stringers to trusses supporting sensitive inertial navigation payloads. The absorbers can be finely tuned using variably thick mass or various amounts of beads for reducing peak vibrations coupled into the payloads.

Abstract: A method and apparatus is described for limiting transient motions between an aircraft power member and aircraft structure. The apparatus incorporates a coupler (20) for use with inertial-type mounts and includes a body portion (21) having a coupler piston (32) telescopically received therein. Upon exceeding a transient relative motion which causes a fluid flow velocity to be exceeded, seat (38) formed on coupler piston (32) interacts with lip (39) on body portion (21) to cause a fluid flow restriction. This method and apparatus restricts and limits transient motions, i.e., acts as a snuffer, to limit further relative motion between an aircraft power member (54) and an aircraft structural member (52). The coupler piston (32) preferably includes a flexible seal (38) formed thereon and orifice (40) therethrough for providing additional throttle-type damping upon snubbing.

Abstract: A device for reducing the vibrations generated on the structure of a helicopter. The helicopter includes a structure with a tail boom and a fin. The structure has a longitudinal vertical mid-plane. The helicopter also has a main lift and propulsion rotor which generate an aerodynamic flow passing through the rotor and induce vibrations on the structure. A damping device for reducing the vibrations has a longitudinal chamber which is equipped with at least one central restriction, which has two elastically urged mobile lateral walls and which is full of a fluid representing an oscillating mass. The damping device is mounted in the tail boom close to the fin so that the direction of travel of the oscillating mass is at least substantially orthogonal to the longitudinal vertical mid-plane.

Abstract: A tuned mass damper using a single predetermined mass connected to springs of predetermined stiffness along each of at least two directions to absorb energy from a vibrating structure to which it is attached and damp the vibrations in a rapid and efficient manner with a minimum of weight and volume used.

Abstract: Disclosed is a tunable damping system for use in reducing vibrations associated with metal cutting and tooling. The tunable damping system may be located in a boring bar, an end mill, a modular tool section or the spindle/tool holder of the metal cutting machine. The tunable damping system incorporates a damper mass, elastomeric supports, and a means to lock the mass so as to determine tuning parameters. A tuner assembly consists of sensors and a microprocessor capable of recognizing the most dynamically flexible mode of vibration. The tuner assembly is also capable, through signal processing and microprocessor controlled algorithms, to direct the operator in implementing the proper tuning adjustments of the tunable damping system.

Abstract: A rod-damper combination comprising an oscillating rod member and a dynamic damper mounted on the rod member is disclosed. The dynamic damper includes a mass portion having a substantially cylindrical shape, and two elastic support members formed on axially opposite sides of the mass portion to elastically support the mass portion. The oscillating rod member includes a small-diameter portion formed at an axially middle portion thereof, and two large-diameter portions formed on axially opposite sides of the small-diameter portion. Alternatively, the rod member includes a middle portion, and two tapered portions on axially opposite sides of the middle portion. The two elastic support members of the dynamic damper are mounted on the two large-diameter or tapered portions of the oscillating rod member, respectively.

Abstract: A dynamic damper for absorbing vibrations in a rotary driveshaft, including a cylindrical mass member having an inner surface and an outer surface, a plurality of elongated connecting members each connecting member extending radially inwardly from the inner surface of the mass member thereby defining a plurality of spaced apart attachment surfaces wherein the cylindrical mass member is affixable to the rotary driveshaft such that the plurality of spaced apart attachment surfaces contacts the rotary shaft, the mass member spaced apart from the rotary shaft and supported by the connecting member to allow the mass member to vibrate by resonance and the connecting members being subjected to compressive deformation between the mass member and the rotary shaft.

Abstract: A rod-damper combination comprising an oscillating rod member and a dynamic damper mounted on the rod member is disclosed. The dynamic damper includes a mass portion having a substantially cylindrical shape, and two elastic support members formed on axially opposite sides of the mass portion to elastically support the mass portion. The oscillating rod member includes a small-diameter portion formed at an axially middle portion thereof, and two large-diameter portions formed on axially opposite sides of the small-diameter portion. Alternatively, the rod member includes a middle portion, and two tapered portions on axially opposite sides of the middle portion. The two elastic support members of the dynamic damper are mounted on the two large-diameter or tapered portions of the oscillating rod member, respectively.

Abstract: An apparatus for damping dynamic response in a primary structure, includes a secondary mass, and a spring and a viscoelastic element, the spring and viscoelastic element interposed between the primary structure and the secondary mass. The apparatus may include a housing for the secondary mass, the spring and the viscoelastic element, should the spring, viscoelastic element, or both the spring and viscoelastic element, be interposed between the secondary mass and the housing. A method for damping dynamic response in a primary structure is also disclosed.

Abstract: An apparatus for damping dynamic response in a primary structure in one, two, or three dimensions, includes a secondary mass, and a spring and a viscoelastic element, the spring and viscoelastic element interposed between the primary structure and the secondary mass. The apparatus may include a housing for the secondary mass, the spring and the viscoelastic element, should the spring, viscoelastic element, or both the spring and viscoelastic element, be interposed between the secondary mass and the housing. A method for damping dynamic response in a primary structure in one, two, or three dimensions is also disclosed.

Abstract: The vibration absorber for the absorption of structure-borne sound has a wave conducting element made of mass-spring elements layered on top of each other and extending in the wave propagation direction. The mass-spring elements are configured as bending beams or plates, with a resilience which decreases in the wave propagation direction. The mass-spring elements are connected with each other by spacers which are arranged offset in respect to each other, in such a way that when they are affected by pressure or pulling at least one mass-spring element is bent.

Abstract: Disclosed is a tunable damping system for use in reducing vibrations associated with metal cutting and tooling. The tunable damping system may be located in a boring bar, an end mill, a modular tool section or the spindle/tool holder of the metal cutting machine. The tunable damping system incorporates a damper mass, elastomeric supports, and a means to lock the mass so as to determine tuning parameters. A tuner assembly consists of sensors and a microprocessor capable of recognizing the most dynamically flexible mode of vibration. The tuner assembly is also capable, through signal processing and microprocessor controlled algorithms, to direct the operator in implementing the proper tuning adjustments of the tunable damping system.

Abstract: Vibrations in a structure having a large mass and a multiplicity of frequencies of excitation are damped by determining two principal frequencies of excitation for the structure and coupling thereto a damping member of smaller mass to produce an absorber. The spring damper characteristics of the absorber are determined at these frequencies and the displacement of the damping member is monitored. The monitored displacement of the damping member is processed together with the spring damper characteristics of the absorber to output a signal which produces a force acting on the damping member proportional to the displacement of the damping member with a controlled time delay. This produces two frequencies of vibration in the damping member substantially equal to the determined frequencies of excitation of the large structure and thereby produces resonance of the damping member substantially at the determined frequencies of excitation.

Abstract: An automotive engine is generally provided with an exhaust gas pipe assembly extending generally rearwardly from the engine for discharging exhaust gases. The exhaust gas pipe assembly includes a plurality of exhaust gas pipes, at least one chamber formed intermediately of the exhaust gas pipe assembly, a first support member disposed in the proximity of the engine, and at least one second support member disposed in the proximity of the chamber. The first support member can effectively absorb relative displacement between the exhaust gas pipe assembly and the vehicle body in a direction transversely of the vehicle body whereas the second support member can effectively absorb relative displacement between the exhaust gas pipe assembly and the vehicle body in a direction longitudinally of the vehicle body.

Abstract: A hydraulic inertial vibration isolator is connected between a vibrating body and an isolated body. The vibration isolator comprises a cylinder which includes two chambers and a piston therebetween. The chambers are connected by a tuning passage in which a solid tuning slug is slidably disposed. The chambers and the portion of the tuning passage not occupied by the tuning slug are filled with liquid. Bypass passages connecting the tuning passage to the chambers allow the liquid pressures in the chambers to equalize when the amplitude of the tuning slug's oscillatory motion is sufficiently large, thereby limiting the tuning slug's amplitude. Dashpots axially disposed adjacent to either end of the tuning slug act to damp excessive tuning slug motion and to bias the tuning slug toward the center of the tuning passage.

Abstract: A vibration isolation system comprises four tunable dual-axis hydraulic inertial isolators, an array of accelerometers, and a controller. The controller inputs signals from the accelerometers and outputs signals to tune the isolators to minimize the vibration transmitted from a vibrating body to an isolated body. The isolators are tuned by varying the dimensions of their tuning passages or by application of magnetohydrodynamic force to the liquid within the tuning passages.

Abstract: A method and mounting for active vibration control of a vibrating body mounted to a supporting body, or vice versa, via a mounting which includes an intermediate body, wherein the intermediate body is substantially passively decoupled from the vibrating body and the supporting body, at least over part of the frequency range over which vibrations are to be controlled, and over said at least part of the vibration frequency range compensating forces are applied to the intermediate body in response to vibrations detected within it.

Abstract: Vibrations in a structure having a large mass are damped by coupling thereto a damping member of smaller mass and continuously monitoring the frequency of excitation of the structure produced by applied load(s) and the displacement of the damping member. The monitored frequency of excitation and displacement of the damping member are processed together with data relative to the mass, stiffness and damping characteristic of the damping member. A signal is outputted to produce a force acting on the damping member proportional to the displacement of the damping member with a controlled time delay to produce a frequency of vibration in the damping member substantially equal to the monitored frequency of excitation of the structure, this produces resonance of the damping member substantially at the monitored frequency of excitation and is effective to damp substantially the vibrations of the structure at the monitored frequency of excitation.

Abstract: An active vibration damper for a reciprocating machine part, comprising an inertial mass that can be displaced in the direction of the reciprocating motion and a support plate that can be fastened to the machine part. The inertial mass and the support plate are connected to one another by a spring element. The natural frequency of the vibrating system constituted by the inertial mass and the spring element is at most as great as the frequency of the reciprocating motion. The inertial mass can be moved by plunger coil fastened to the support plate so as to be immobile with respect thereto, and the spring element can be deformed by the plunger coil. The inertial mass consists of a cup-shaped magnet that at least partly concentrically surrounds the plunger coil radially on the inside and outside. The cup-shaped magnet is guided by a guideway parallel to the axis of the plunger coil.

Abstract: A rotatable machine component with a ring of resilient material secured to it in the vicinity of at least one axially projecting collar. The collar has a continuous annular groove around it that cuts into its contour radially, and the ring is secured in the groove just by snapping into it. The ring and the rotatable component rest loosely against each other, when the component is not rotating, without internal tension in the ring.

Abstract: A damping device is constituted by a substantially cylindrical damper body (1) with an axial through bore (6), where the bore (6) accomodates a central pipe (3) which e.g. can lead a cooling liquid. The central pipe (3) is connected rigidly to or into the machine element to be damped, preferably in a cylindrical and axial cavity in a boring bar (9). Ring-shaped, elastic spring elements (2) placed in the ends of the damper body (1) and between the central pipe (3) and the damper body (1), as well as damping oil (4) in the clearance between the central pipe (3) and the damper body (1) transform motion energy into heat and provide the damping action. The stiffness of the spring elements (2) can optionally be adjusted.

Abstract: A pneumatic stabilizer for use with a bow, rifle, gun or any other instrument that produces destructive vibrational energy. The stabilizer includes a gas spring having weights secured thereto and structure for releasably attaching the stabilizer to an instrument. When the stabilizer is properly adjusted, it has similar vibrational frequency characteristics similar to the instrument such that the vibrational energy of the instrument is absorbed by the stabilizer.

Abstract: In a vibration-damping device, viscoelastic material which dissipates vibration energy is bonded to a supporting member so as to form a removable unitary assembly which can be coupled to the vibration emitter, the viscoelastic material being clamped between the supporting member and a stressing element.

Abstract: The invention is directed to a damper ring for damping the natural vibration of the rotor blades of an integrally bladed rocket turbine rotor. The invention consists of an integral damper ring which is fixed to the underside of the rotor blade platform of a turbine rotor. The damper ring includes integral supports which extend radially outwardly therefrom. The supports are located adjacent the base portion and directly under each blade of the rotor. Vibration damping is accomplished by action of tuned mass damper beams attached at each end to the supports. These beams vibrate at a predetermined frequency during operation. The vibration of the beams enforce a local node of zero vibratory amplitude at the interface between the supports and the beam. The vibration of the beams create forces upon the supports which forces are transmitted through the rotor blade mounting platform to the base of each rotor blade.

Abstract: A stabilizer for dampening bow string and arrow release forces, which stabilizer includes, in a preferred embodiment, a cylindrical housing fitted with a pair of end caps, one of which end caps receives a threaded stud for mounting the housing on a bow. The opposite end cap is fitted with a tapped opening for mounting one of many accessory items which are well known to those skilled in the art. A flexible, pliant, deformable and resilient suppressor member is disposed inside the cylindrical housing and includes a bore for receiving a metal core. In one embodiment the suppressor member is pinched by means of retaining rings near each end of the core to maintain the core in a selected position. The core is therefore free to exhibit multidirectional movement and depress the resilient suppressor member in response to release of an arrow from the bow, to dampen the arrow release forces, bow string vibration and other forces acting on the bow.

Abstract: An active noise control (ANC) system for a helicopter that is operative to effectively nullify one or more high frequency vibrations emanating from the main transmission gearbox thereof at the gearbox/airframe interface, thereby significantly reducing the interior noise levels of the helicopter, that is design optimized to minimize the number of actuators required, and that is design optimized to minimize contamination forces arising from operation of the system actuators. The ANC system includes modified transmission beams that are mechanically stiffened to function as rigid bodies with respect to the one or more of the high frequency vibrations, a plurality of actuators disposed in combination with the modified transmission beams, a plurality of sensors disposed in combination with the modified transmission beams in a collinear, spaced apart functional correlation with respective actuators, and controllers interconnecting individual actuators with respective functionally correlated sensors.

Abstract: The disclosure relates to a damper pulley that exhibits a good damping effect and has a preferable resonance ratio. An annular damper-mass member is joined to an annular surface of a plate portion of a pulley through a first resilient rubber member. Two fan-like concave portions are formed in the surface of the annular damper-mass member, which faces the annular surface of the plate portion, at symmetrical positions with respect to the center of rotation of the pulley. Two projections are formed on the annular surface of the plate portion so as to perpendicularly project into the fan-like concave portions. A second resilient rubber member is interposed between each concave portion and projection. When torsional vibrations are exerted, each second resilient rubber member produces compression deformation, thereby generating a large spring force, whereby the resonance frequency against the torsional vibrations sufficiently increases even when the inertia moment of the mass member is increased.

Abstract: A vibration eliminator or suppressor for an actuating element of a set of components or aggregate, such as the clutch arrangement of a motor vehicle. A transitional element between a wire cable or a linkage and a lever of the aggregate is constructed as a cage, wherein the lever is floatingly or swimmingly supported within the cage through a prestressed two-component rubber spring, with the lever being fixedly connected with the rubber spring, and a weight being fastened to the cage. Through the intermediary of this structure there is achieved a complete isolation of any vibrations between the clutch shift and the clutch drive train due to the rubber spring.

Abstract: The present invention relates to a device for elastic connection between two components in order to transmit the static forces from one to the other in the axis of the device and to filter the associated vibratory excitations, comprising an elastic return mechanism (4) connected to a first and a second component and at least one swinging mass (5) located at one end of a lever arm, the lever arm articulated, in the vicinity of its other end, on the first and second components. The lever arm (6) consists of at least two portions (7, 8) articulated on one another, the first portion (7) being articulated on the first (2) and second (3) components in the vicinity of its end (7a) opposite that (7b) articulated on the second portion (8), and the second portion (8) being articulated, in the vicinity of its end (8a) articulated on the first portion (7), on the second component (3) and carrying the mass (5) at its opposite end (8 b).

Abstract: In a device for damping torsional vibrations of the body of a convertible vehicle, an elastically mounted weight is used. The damper is mounted elastically on a frame of a windshield by slide bearings and at a distance from the frame, relatively free to vibrate in the transverse directions of the vehicle. The damper has a frequency equal to the torsional natural frequency of the vehicle in the area of the frame, with the bearings having a sliding resistance determined by their geometry. The damper is elastically mounted by at least one central slide bearing on the frame element, with the damping weight having a leaf spring element at each end and mounted to abut the frame element and to permit transverse movement of the damping weight.

Abstract: A damper is provided on a convertible for the dampling of bodyside torsional vibrations in the area of the windshield frame. This damper is arranged particularly on the frame of the windshield and is held by way of elastic slide bearings. The damper is arranged in the open at a distance from the frame and can swing relatively freely in the transverse directions of the vehicle so that natural torsional frequencies of the vehicle on the frame are damped.

Abstract: A vibration damping assembly incorporating an attenuating body formed from viscoelastic material is disclosed. The body may, in a preferred embodiment, be made up of a plurality of plates stacked together and separated with spacers. The viscoelastic material is preferably high impact polystyrene. The damping system is advantageously mounted on an enclosure panel of a loudspeaker to attenuate the vibrations of the panel, thereby minimizing audio signals which usually emanate therefrom and interfere with the desired speaker output.

Abstract: The suspension device is interposed between the rotor and the fuselage of the helicopter for filtering the vibration exciting forces and moments coming from the rotor. In this helicopter, a speed reducer (1) is provided in a housing mounted on the fuselage (22) by rigid oblique bars (28). According to the invention, there are disposed around the housing of the speed reducer, in a number equal to the number of rigid oblique bars (28), monodirectional antiresonant means (20,21,23,23a,23b,25) connecting the upper ends of the rigid oblique bars (28) to the speed reducer (1).

Abstract: Vibration damper for damping vibrations in a surface (20) of an object (21). The damper consists of an oscillating body (1) which is movably connected to the surface such that it is brought to oscillate so that the oscillating body transmits forces to the object which are principally oppositely directed to the forces which, through vibration, act on the object. The vibration damper displays a locating part (19) made from a shaped permanent material and intended to be fixedly attached to said surface (20) of the object (21). The locating part displays one or several inwardly-directed vibration-transmitting support walls (26-29). The oscillating body (1) is at least partially enclosed in a damping body (10) made from an elastic material, and the damping body is held in the locating part through cooperation with the inwardly directed walls (26-29).

Abstract: A bypass valve with selective characteristics for controlled and adjustable dashpots. It has pressure-activated check valves that are reversed by means of a slide that can assume two positions and is activated by an electromagnet. Springs can be designed to dictate the characteristic of the dashpot independent of the type of piston employed.

Abstract: A ski is provided with a device for damping vibrations which arise in use in the ski by the effect of impacts between the asperities of icy snow and the tip and tail of the ski itself. The device consists of at least one concentrated mass which is floatingly carried by at least one end of the ski in such a way as to be free to move in the vicinity of this end.