A rotary-wing aircraft includes a fuselage, and an external device. The fuselage is provided with a rotary wing. The external device is mounted on the outside of the fuselage. The external device includes a mounting device, a mass variation device, and a damper. The mounting device is fixed to the fuselage and disposed so as to project in a lateral direction of the fuselage. The mass variation device is mounted on the mounting device and has mass that varies as the mass variation device is used. The damper couples the fuselage to the mounting device and supports the mounting device. The damper includes a stiffness variable mechanism configured to change stiffness of the damper in response to variation in the mass of the mass variation device.

A vibration-damping device including: a first mounting member configured to be mounted to one of components of a vibration transmission system; a second mounting member configured to be mounted to an other of the components of the vibration transmission system; a main rubber elastic body connecting the first mounting member and the second mounting member elastically to each other; a bracket attached to the second mounting member, the bracket having a mounting part configured to be mounted to the other of the components of the vibration transmission system; a tubular outer member secured press-fit to the second mounting member; a mass member disposed within the tubular outer member; and a support rubber fixed at an outer peripheral part of the mass member, the support rubber elastically connecting the tubular outer member and the mass member to constitute a dynamic damper.

A hydraulic bearing for supporting an assembly of a motor vehicle includes a carrying bearing portion and a support portion. In embodiments, a working chamber that is fillable with hydraulic fluid is formed in the carrying bearing portion, and a compensating chamber that is fillable with hydraulic fluid is formed in the support portion. A nozzle disc, through which the flow can pass and which delimits the working chamber from the compensating chamber, may be arranged between the carrying bearing portion and the support portion, and a damping duct for the fluidic communication of the working chamber with the compensating chamber may be formed in the nozzle disc. In embodiments, the two chambers, the damping duct, and the hydraulic fluid may form a first damping system for damping vibrations of lower frequencies and a second damping system may be formed for damping vibrations of higher frequencies.

Disclosed herein are hydraulic actuators and methods for the operation of actuators having variable relative pressure ratios. Further disclosed are methods for designing and/or operating a hydraulic actuator such that the actuator exhibits a variable relative pressure ratio. In certain embodiments, the relative pressure ratio of the hydraulic actuator may be dependent on one or more characteristics (such as, for example, frequency or rate of change) of an oscillating input to the hydraulic actuator.

Externally-damped electromechanical valve assemblies well-suited for deployment within high vibratory operating environments, such as those associated with work vehicle engines, are provided. In embodiments, the valve assembly includes a housing through which a flow passage extends, a valve element positioned in the flow passage, a valve actuator, and control electronics electrically coupled to the valve actuator. The valve assembly may also contain a constrained layer damper including a first mass element and a first viscoelastic layer. The first mass element is mounted in suspension to the housing exterior for movement relative thereto when the first mass element is excited by vibrations transmitted through the housing. Constrained between the first mass element and the housing exterior, the first viscoelastic layer deflects in shear as the first mass element moves relative to the housing to attenuate the vibrations transmitted through the housing by conversion of vibrational energy to heat.

Flexible spring member and end closure assemblies include a flexible spring member-defining a spring chamber. An end closure body includes an outer peripheral surface portion and an elongated damping passage extending axially into end closure wall in a spiral arrangement about longitudinal axis. End closure body is positioned along an end of flexible spring member with flexible wall permanently attached along outer peripheral surface portion such that a substantially fluid-tight joint is formed between flexible spring member and end closure body. Gas spring and gas damper assemblies as well as methods of assembly are also included.

A damping air spring for heavy-duty vehicle axle/suspension systems. The damping air spring includes a first chamber and a second chamber and at least one opening between the first chamber and second chamber to provide restricted fluid communication between the first chamber and the second chamber. An adsorptive material is disposed within the first chamber or the second chamber and works in conjunction with the at least one opening to provide damping characteristics to the air spring over a first and second critical range of frequencies.

A damper unit for use in a vibration-reducing assembly for a steering wheel is disclosed. An elastomeric damper element is molded on an inner sleeve and includes a plurality of elastomeric ribs forming a radially outer engagement surface, and a plurality of elastomeric support studs, which are mutually spaced in a circumferential direction are flexible in all directions transverse to said axis. Methods for making a damper unit and a damper assembly are also disclosed.

A shock absorber includes: a first passage through which a working fluid flows from a chamber inside a cylinder; a second passage which communicates with the chamber; a damping force generation mechanism which is provided in the first passage, a communication hole which is provided with at least a part of a passage of the second passage and is formed in a piston rod communicating with at least the chamber; a housing which has a passage of least a part of the second passage; a free piston which is movably provided inside the housing and defines the second passage into an upstream side and a downstream side of a flow of the working fluid when the piston moves in one direction, and an elastic body which is provided between the free piston and the housing. The free piston is formed of a resin material.

The present disclosure relates to a vibration control device and a frequency-sensitive shock absorber having the same. A vibration control device includes a sub-piston rod coupled to an end of a piston rod, a pilot valve unit penetrated by and coupled to the sub-piston rod, in which pressure is formed by a fluid introduced through the sub-piston rod, and a fixing member located in a lower portion of the pilot valve unit and fastened to the sub-piston rod to fix the pilot valve unit, wherein the pilot valve unit comprises a free-piston provided to reciprocate in a vertical direction according to a change in the pressure formed by the fluid.