A damper for damping vibrations of a structure comprises: a first damping unit, comprising a first damping body having a first mass (m.sub.1), a first spring element having a first spring constant (k.sub.1) and a first damping element having a first damping constant (c.sub.1), wherein said first damping body is configured to be attached to said structure via said first spring element and said first damping element; and a second damping unit, comprising a second damping body having a second mass (m.sub.2), a second spring element having a second spring constant (k.sub.2) and a second damping element having a second damping constant (c.sub.2), wherein said second damping body is configured to be attached to said first damping body via said second spring element and said second damping element.

A vibration damper for damping vibrations of a motor vehicle component is disclosed. The vibration damper is passed through by a transverse center plane, and the vibration damper includes a retention apparatus that can be fixed to a motor vehicle component. In embodiments, the vibration damper has at least two receptors that each have an inner side facing the transverse center plane and an outer side facing away from the transverse center plane, has a damper mass with a central longitudinal axis, and has at least two elastomer springs. In embodiments, the elastomer springs couple the damper mass to the receptors with an ability to vibrate, and at least one of the elastomer springs has a connection portion, between the damper mass and respective receptor, that extends at least mainly externally with respect to the respective receptor.

A vibration damper for damping vibrations of a motor vehicle component is disclosed. The vibration damper is passed through by a transverse center plane, and the vibration damper includes a retention apparatus that can be fixed to a motor vehicle component. In embodiments, the vibration damper has at least two receptors that each have an inner side facing the transverse center plane and an outer side facing away from the transverse center plane, has a damper mass with a central longitudinal axis, and has at least two elastomer springs. In embodiments, the elastomer springs couple the damper mass to the receptors with an ability to vibrate, and at least one of the elastomer springs has a connection portion, between the damper mass and respective receptor, that extends at least mainly externally with respect to the respective receptor.

Apparatus and methods to reduce unwanted motion in precision instruments are described. An active vibration-isolation system may include a feedback loop that senses motion of an intermediate mass. In noisy environments, where the feedback loop would otherwise fail or provide inadequate isolation, feedforward control can be implemented to sense floor vibrations and reduce motion of the intermediate mass that would otherwise be induced by the floor vibrations. The feedforward control can reduce motion of the intermediate mass to a level that allows the feedback loop to operate satisfactorily.

Apparatus and methods to reduce unwanted motion in precision instruments are described. An active vibration-isolation system may include a feedback loop that senses motion of an intermediate mass. In noisy environments, where the feedback loop would otherwise fail or provide inadequate isolation, feedforward control can be implemented to sense floor vibrations and reduce motion of the intermediate mass that would otherwise be induced by the floor vibrations. The feedforward control can reduce motion of the intermediate mass to a level that allows the feedback loop to operate satisfactorily.

Hydraulic damper with load regulation as a function of frequency by means of hydraulic inertia composed of a cylinder, comprising an inner chamber, a rod, a main piston and an inertia piston, immersed in a hydraulic fluid, so that the inner chamber is divided into 3 sub-chambers, the main piston comprises a flow path controlled by valves to allow bidirectional flow of fluid between the sub-chambers and the inertia piston comprises a flow path called the inertia channel configured to allow fluid flow between sub-cameras at both sides of the inertia piston.

Methods of attenuating vibration transfer to a body of a vehicle using a dynamic mass of the vehicle via minimizing a particular angular frequency of a wheel. One method includes receiving vehicle information over a time interval and determining, based on the vehicle information, an instantaneous angular velocity that corresponds to a particular angular frequency of the wheel. This method includes generating a gain-and-phase-compensated actuator drive command to counteract a vibration that occurs at the particular angular frequency of the wheel, which is based on the instantaneous angular velocity, and communicating the gain-and-phase-compensated actuator drive command to a hydraulic mount assembly that supports the dynamic mass. This method includes actuating an actuator of the hydraulic mount assembly in response to the gain-and-phase-compensated actuator drive command in order to minimize the vibration transfer to the body due to the vibration that occurs at the particular angular frequency of the wheel.

Method for vibration damping of and vibration damper assembly for semi-submerged or submerged structure, based on separating hydrodynamic added mass from the semi-submerged or submerged structure by means of a vibration damper assembly exhibiting spring and/or damper properties and use the hydrodynamic added mass as a reaction mass in the vibration damper assembly.

Method for vibration damping of and vibration damper assembly for semi-submerged or submerged structure, based on separating hydrodynamic added mass from the semi-submerged or submerged structure by means of a vibration damper assembly exhibiting spring and/or damper properties and use the hydrodynamic added mass as a reaction mass in the vibration damper assembly.

An agricultural machine, the machine comprising: a distributor boom; a sensor for detecting a vibration of the distributor boom; an electronic control device in communication with the sensor; and a mobile mass coupled to the distributor boom and associated with an actuator, the electronic control device, upon detection of a vibration in the distributor boom, configured to actuate the actuator to relocate the mobile mass in the direction of the vibration to be damped with respect to the distributor boom.