A pistonless double-acting cylinder apparatus comprises a piston rod member, a first cylinder member disposed on the piston rod member, a second cylinder member disposed on an end surface of the first cylinder member, a tie rod which connects the first cylinder member and the second cylinder member, nuts provided on both ends of the tie rod, a first sealing ring located between the first cylinder member and the second cylinder member, a first cushion and a second cushion disposed on the piston rod member. The piston rod member comprises a piston rod left section, a first sealing gasket disposed on the piston rod left section, a piston rod middle section disposed on an end surface of the first sealing gasket, a second sealing gasket disposed on an end surface of the piston rod middle section, a piston rod right section disposed on the second sealing gasket.

To provide a chain tensioner that can suppress oil leakage from a gap between a plunger bore and a plunger to achieve stable damping characteristics and that can avoid an increase in production cost, with a simple structure. The chain tensioner includes a packing member that is provided on an inner circumferential side of the plunger bore and that suppresses oil leakage from a cylindrical outer surface of the plunger. The plunger is provided with an oil leak passage that extends from an oil pressure chamber inside the plunger to the outside.

A fluid leakage detection system has a detection space to which working oil leaked out through a rod seal is guided; the rod seal being configured to seal an annular gap between a piston rod and a cylinder head; a sensor unit configured to detect pressure in the detection space; and a controller configured to acquire detected result from the sensor unit, wherein the controller has: a calculation unit configured to calculate a pressure parameter representing a pressure fluctuation in the detection space; a determination unit configured to determine occurrence of leakage of the working oil based on the pressure parameter; and the pressure parameter includes an upper limit value and a lower limit value of the pressure fluctuation obtained from the detected result detected by the sensor unit within a predetermined detection period.

A hydraulic piston actuator, which may be used for an aircraft nacelle assembly, includes a housing, a piston, an end gland, and a bearing ring. The housing is concentrically disposed along an axis. The piston is adapted to axially reciprocate within the housing. The end gland is disposed radially between the housing and the piston. The bearing ring is disposed radially between the end gland and the piston.

A head end seal assembly for a hydraulic cylinder may include a cylinder seal carrier having a seal carrier bore with a main seal groove and a coating ring groove adjacent the main seal groove. A main seal disposed within the main seal groove is fabricated from a resilient material and engages a rod outer surface of a rod to substantially prevent leakage of pressurized fluid from the hydraulic cylinder. A coating ring disposed within the coating ring groove is fabricated from a thermoplastic polymer such as Teflon and engages the rod outer surface such that portions of the thermoplastic polymer are deposited into indentations on the rod outer surface as the rod slides past the coating ring to smooth the surface and reduce abrasion between the rod and the main seal. A second coating ring on the opposite side of the main seal may coat the rod as it moves in the opposite direction.

A piston-cylinder unit having a cylinder housing (1) with a cylinder interior (2) and a piston (3) arranged in cylinder interior (2), from which a piston rod (4) starts and is guided out from the cylinder housing (1) through an opening and at the same time is sealed with respect to the cylinder housing (1) by a piston rod seal (12) arranged on the cylinder housing (1). A sliding sleeve (11) made of plastic and entrained by the piston rod (4) is arranged on the piston rod (4), and the piston rod seal (12) bears against said sliding sleeve.

A fluid leakage detection device includes: an annular member attached to a cylinder head, the annular member being configured such that a piston rod is inserted through the annular member; a passage formed in the annular member, the passage being configured such that a working fluid is guided to the passage from a gap between an outer circumference of the piston rod and an inner circumference of the cylinder head; and a detector configured to detect the working fluid guided through the passage, wherein the annular member includes a press-fitted portion, the press-fitted portion being configured to be press-fitted to an annular groove formed in the cylinder head.

A modular electrohydraulic actuator including an electric motor, a hydraulic pump driven by the electric motor, and a hydraulic actuator in fluid communication with the hydraulic pump. The hydraulic actuator includes a hydraulic cylinder supporting a pressure sleeve in which a piston and rod is adapted for reciprocating motion in response to a supply of pressurized fluid to a first side or a second side of the piston, wherein at least one of the electric motor, hydraulic pump, hydraulic cylinder, piston, piston rod or the pressure sleeve supported in the hydraulic cylinder is selectively removable and replaceable with a different component to vary at least one performance characteristic of the electrohydraulic actuator.

A seal structure is provided which enables a reduction in the number of components and an improvement of the stability in sliding of the seal portion or the backup ring portion. A sealing structure seals two members which move relative to each other, in which a seal portion or a backup ring portion placed between the two members and a bearing portion similarly placed between the two members are formed into an integral structure. The seal portion or the backup ring portion is integrally provided to one end portion in the axial direction or both end portions in the axial direction of the bearing portion having a cylindrical shape. The seal structure is used as a piston seal or a rod seal in hydraulic and pneumatic devices in which a piston is inserted into a shell or a cylinder tube.

Hydraulic pressure booster and method includes a low-pressure segment including a hydraulic cylinder and a hydraulic piston, which is displaceable in both axial directions of the hydraulic cylinder and opposing high-pressure segments located on each axial end of the low pressure segment. Each high-pressure segment includes a plunger piston movable in a high-pressure cylinder via the hydraulic piston. Each high-pressure cylinder is arranged in a clamping sleeve, both of which are positioned between the hydraulic cylinder and a valve body. For each high-pressure segment, a clamping piston, which includes a pressure surface applying pressure to the high pressure cylinder and a high pressure seal for the plunger piston and a pressure surface on which pressure from the hydraulic piston is applied, is axially displaceable in the hydraulic cylinder so that the high-pressure cylinder is in compressive contact with the hydraulic cylinder and the valve body.