A mount bush includes: an inner tubular member; an outer tubular member arranged coaxially with the inner tubular member and surrounding an outer periphery of the inner tubular member with a clearance; and an elastic member connecting the inner tubular member with the outer tubular member, wherein the inner tubular member includes: an inner yoke having a coil therein; and an outer yoke coaxially coupled with the inner yoke at a radially outer position than the coil, and the elastic member has a first and second fluid chambers, facing each other across an axis of the inner tubular member and having magnetic fluid encapsulated therein, whose viscosity varies by a magnetic field, wherein the outer yoke has a communication passage communicating the first fluid chamber with the second fluid chamber, and is provided with a permanent magnet to generate a magnetic field in the communication passage.

A variable stiffness bushing assembly includes an inner tubular member, an outer tubular member coaxially surrounding the inner tubular member, and an elastic member connecting the inner and outer tubular members. The elastic member defines a pair of first liquid chambers that are on opposite sides of an axial line of the inner tubular member and communicate with each other via a first circumferentially extending communication passage defined between one of the outer yokes and the annular large diameter portion, and a pair of second liquid chambers that are on opposite sides of the axial line and communicate with each other via a second circumferentially extending communication passage defined between another one of the outer yokes and the annular large diameter portion. The magnetic fields generated by the two coils are selectively applied to a magnetic fluid flowing through the first communication passage and the second communication passage.

In embodiments, a work vehicle magnetorheological fluid (MRF) joystick system includes a joystick device, an MRF joystick resistance mechanism, and a controller architecture. The joystick device includes, in turn, a base housing, a joystick movably mounted to the base housing, and a joystick position sensor configured to monitor movement of the joystick relative to the base housing. The MRF joystick resistance mechanism is controllable to vary a first joystick stiffness resisting movement of the joystick relative to the base housing in at least one degree of freedom. The controller architecture is configured to: (i) detect when unintended joystick motion conditions occur during operation of the work vehicle; and (ii) when detecting unintended joystick motion conditions, command the MRF joystick resistance mechanism to increase the first joystick stiffness in a manner reducing susceptibility of the joystick device to unintended joystick motions.

Embodiments of a work vehicle magnetorheological fluid (MRF) joystick system includes a joystick device having a base housing, a joystick movably mounted to the base housing, and a joystick position sensor monitoring movement of the joystick relative to the base housing. An MRF joystick resistance mechanism is controllable to vary a joystick stiffness resisting movement of the joystick relative to the base housing in at least one degree of freedom. A controller architecture is coupled to the joystick position sensor and to the MRF joystick resistance mechanism. The controller architecture is configured to: (i) command the MRF joystick resistance mechanism to increase the joystick stiffness when the joystick is moved into a first predetermined detent position to generate a first MRF detent; and (ii) selectively activate a first detent-triggered function of the work vehicle based, at least in part, on joystick movement relative to the first MRF detent.

In a fluid-filled vibration damping device in which multiple fluid chambers filled with a magnetic functional fluid communicate with each other by an orifice path, and a magnetic unit applying a magnetic field to the orifice path is provided in a state of being externally inserted to an outer cylindrical member, the magnetic unit includes a magnetic field generation part forming a magnetic field and a magnetic path formation part inducing a magnetic flux, the magnetic field is applied from a magnetic gap part of the magnetic path formation part arranged on an outer circumference of the orifice path to the orifice path, and on an outer circumferential surface of the outer cylindrical member, an installation part to which an outer mounting member realizing linking between the outer cylindrical member and a vibration damping linking target member is installed is biased from the magnetic field generation part in an axial direction.

A magnetorheological fluid with balanced viscosity and sedimentation properties includes: a magnetic material; a medium to allow the magnetic material to be dispersed therein; a dispersant to disperse the magnetic material within the medium while forming a magnetic material holding structure to hold the magnetic material; and a reinforcing agent to reinforce the magnetic material holding structure. An amount of the magnetic material is 25 wt % to 75 wt % relative to a sum of the medium and the magnetic material. An amount of the medium is 25 wt % to 75 wt % relative to the sum of the medium and the magnetic material. An amount of the dispersant is 0.5 wt % to 6 wt % relative to the sum of the medium and the magnetic material. An amount of the reinforcing agent is 5 wt % to 300 wt % relative to a weight of the dispersant.

A head unit device for controlling motion of an object includes a chamber filled with a shear thickening fluid (STF) and a piston. The piston is housed within the chamber and exerts pressure against the STF from a force applied to the piston from the object. The STF is configured to have a decreasing viscosity in response to a first range of shear rates and an increasing viscosity in response to a second range of shear rates. The piston includes at least one piston bypass between opposite sides of the piston that controls flow of the STF between the opposite sides of the piston to selectively react with a shear threshold effect of the first range of shear rates or the second range of shear rates.

An anti-impact device includes a first connector, an upper outer cylinder, a lower outer cylinder and a second connector which are sequentially connected, where a top of the lower outer cylinder is sleeved with the upper outer cylinder to be movably connected to the upper outer cylinder; an aluminum honeycomb and a magnetorheological buffer outer cylinder are arranged inside the lower outer cylinder, the aluminum honeycomb is arranged at a bottom of a lower end cover, a piston rod is arranged inside the magnetorheological buffer outer cylinder, a top end of the piston rod extends out of an upper end cover and is connected to a collision head, and the piston rod between the collision head and the upper end cover is sleeved with a return spring; and an electromagnetic coil is wound around the piston rod, a damping piston is arranged at a lower part of the piston rod.

Embodiments of a work vehicle magnetorheological fluid (MRF) joystick system includes a joystick device having a base housing, a joystick movably mounted to the base housing, and a joystick position sensor monitoring movement of the joystick relative to the base housing. An MRF joystick resistance mechanism is controllable to vary a joystick stiffness resisting movement of the joystick relative to the base housing in at least one degree of freedom. A controller architecture is coupled to the joystick position sensor and to the MRF joystick resistance mechanism. The controller architecture is configured to: (i) command the MRF joystick resistance mechanism to increase the joystick stiffness when the joystick is moved into a first predetermined detent position to generate a first MRF detent; and (ii) selectively activate a first detent-triggered function of the work vehicle based, at least in part, on joystick movement relative to the first MRF detent.

In embodiments, a work vehicle magnetorheological fluid (MRF) joystick system includes a joystick device. The joystick device includes, in turn, a base housing and a joystick, which is rotatable relative to the base housing and which is biased toward a joystick return position. An MRF joystick resistance mechanism is controllable to vary an MRF resistance force impeding movement of the joystick relative to the base housing, while a controller architecture is coupled to the MRF joystick resistance mechanism. The controller configured to: (i) selectively enable an operator adjustment of the joystick return position by a work vehicle operator; and (ii) when enabling the operator adjustment of the joystick return position, command the MRF joystick resistance mechanism to maintain the MRF resistance force at a predetermined level until the operator adjustment of the joystick return position is terminated.