An electrorheological fluid which comprises a dispersion medium containing fluorine atoms in an amount larger than 0 wt % but not larger than 50.0 wt % and particles for electrorheological fluid use that are contained in the dispersion medium in an amount of 10-50 vol % of the total volume of the dispersion medium and the particles, the particles comprising a sulfonic-acid-group-containing polymer having a sulfonic acid group content of 30-70 wt %.

A damper includes a pressure-sensitive damping control circuit that selectively permits fluid flow from a first chamber to a second chamber. A piston varies a volume of the first chamber. A blow-off piston is movable between a closed position, wherein fluid flow through the control circuit is substantially prevented, and an open position, wherein fluid flow through the control circuit is permitted. The damper also includes a first source of pressure. A fluid pressure created by compression of the damper applies an opening force to the blow-off piston moving the blow-off piston in a direction toward the open position against a resistance force provided by the first source of pressure. The resistance force exceeds the opening force until the pressure created by forces tending to insert the piston rod into the first fluid chamber exceeds the pressure in the first source of pressure by a predetermined amount.

Generally described, aspects of the disclosed subject matter are directed to through-shaft dampers. In accordance with aspects of the present disclosure, the through-shaft dampers generally include a shaft having a piston traveling within a body, a first chamber for a damping fluid, and a second chamber for a gas. The chambers are separated by a movable wall associated with an insert and configured to provide a volumetric change of the second chamber that is inverse to a volumetric change of the damping fluid. The insert is configured such that the sealing surfaces of the movable wall do not interface the shaft during use of the damper. In this regard, a significant reduction in the total displacement traveled by the seals is realized.

Generally described, aspects of the disclosed subject matter are directed to through-shaft dampers. In accordance with aspects of the present disclosure, the through-shaft dampers generally include a shaft having a piston traveling within a body, a first chamber for a damping fluid, and a second chamber for a gas. The chambers are separated by a movable wall associated with an insert and configured to provide a volumetric change of the second chamber that is inverse to a volumetric change of the damping fluid. The insert is configured such that the sealing surfaces of the movable wall do not interface the shaft during use of the damper. In this regard, a significant reduction in the total displacement traveled by the seals is realized.

A subsea damper unit comprising a cylinder body (C) equipped with an internal damper chamber (9) filled with damper oil (A), said damper chamber (9) contains a through-running piston rod (D) with a piston (7) that divides the damper chamber (9) into two chamber parts (9a,9b), and where the piston (7) is equipped with one or more valves (3) that permit fluid communication between said chamber parts (9a,9b). Mounted to each end of the cylinder body (C) is a compressible and fluid-filled chamber (F) with a fluid (B) that takes up the same pressure as the surrounding water pressure, where respective fluid chambers (F) are in fluid communication with each other, and the cylinder body (C) comprises a pressurization valve or membrane (3) that transmits the pressure from said fluid (B) in at least one of the compressible fluid chambers (F) to the damper oil (A) in the damper chamber (9).

A subsea damper unit comprising a cylinder body (C) equipped with an internal damper chamber (9) filled with damper oil (A), said damper chamber (9) contains a through-running piston rod (D) with a piston (7) that divides the damper chamber (9) into two chamber parts (9a,9b), and where the piston (7) is equipped with one or more valves (3) that permit fluid communication between said chamber parts (9a,9b). Mounted to each end of the cylinder body (C) is a compressible and fluid-filled chamber (F) with a fluid (B) that takes up the same pressure as the surrounding water pressure, where respective fluid chambers (F) are in fluid communication with each other, and the cylinder body (C) comprises a pressurization valve or membrane (3) that transmits the pressure from said fluid (B) in at least one of the compressible fluid chambers (F) to the damper oil (A) in the damper chamber (9).

Methods and apparatus to control movement of a component are disclosed herein. An example apparatus includes a housing defining a bore and a piston disposed inside the bore. The piston is to be coupled to a movable component disposed outside of the bore. The example apparatus further includes a fluid flowline in fluid communication with a first chamber of the bore and a second chamber of the bore. The first chamber is on a first side of the piston, and the second chamber on a second side of the piston. The example apparatus also includes a valve to control fluid flow through the fluid flowline. The valve is to be in a first state to enable the piston to dampen movement of the component, and the valve is to be in a second state to enable the piston to hold the component substantially stationary.

Methods and apparatus to control movement of a component are disclosed herein. An example apparatus includes a housing defining a bore and a piston disposed inside the bore. The piston is to be coupled to a movable component disposed outside of the bore. The example apparatus further includes a fluid flowline in fluid communication with a first chamber of the bore and a second chamber of the bore. The first chamber is on a first side of the piston, and the second chamber on a second side of the piston. The example apparatus also includes a valve to control fluid flow through the fluid flowline. The valve is to be in a first state to enable the piston to dampen movement of the component, and the valve is to be in a second state to enable the piston to hold the component substantially stationary.

A passive damper with a cylinder and piston arrangement, the cylinder being arranged to be connected to a first item, the cylinder having a first chamber and a second chamber. The piston arrangement is connected to a second item, the piston arrangement comprising a piston movable in the cylinder. A fluid passage is associated with a one-way valve. Damping fluid substantially freely flows through the fluid passage in a first direction of movement of the piston arrangement in the cylinder and the damping fluid is restricted from flowing through the fluid passage in a second direction of movement of the piston arrangement in the cylinder. Damping fluid relatively freely flows around the piston when the piston is in the second chamber of the cylinder and the damping fluid is restricted from flowing around the piston when the piston is in the first chamber of the cylinder.

A passive damper with a cylinder and piston arrangement, the cylinder being arranged to be connected to a first item, the cylinder having a first chamber and a second chamber. The piston arrangement is connected to a second item, the piston arrangement comprising a piston movable in the cylinder. A fluid passage is associated with a one-way valve. Damping fluid substantially freely flows through the fluid passage in a first direction of movement of the piston arrangement in the cylinder and the damping fluid is restricted from flowing through the fluid passage in a second direction of movement of the piston arrangement in the cylinder. Damping fluid relatively freely flows around the piston when the piston is in the second chamber of the cylinder and the damping fluid is restricted from flowing around the piston when the piston is in the first chamber of the cylinder.