Abstract: A piston assembly for a lead-lag damper for a blade mounted on a rotor of a helicopter includes a piston-rod that has an inside surface and a piston-head that extends radially outward therefrom. The piston-rod has two ports extending therethrough on opposing sides of the piston-head. A sleeve is positioned in the piston-rod and has two annular passages that communicate with the respective ports. A valve spool is disposed in and slidingly engages the sleeve. The valve spool has a channel which is in variable fluid communication with two passages. The piston assembly includes a biasing member that biases the valve spool axially away from it. The channel has an axial width configured to variably regulate fluid flow between the two ports to control dampening of the piston-rod in response to centrifugal forces applied to the valve spool.

Abstract: A piston assembly for a lead-lag damper for a blade mounted on a rotor of a helicopter includes a piston-rod that has an inside surface and a piston-head that extends radially outward therefrom. The piston-rod has two ports extending therethrough on opposing sides of the piston-head. A sleeve is positioned in the piston-rod and has two annular passages that communicate with the respective ports. A valve spool is disposed in and slidingly engages the sleeve. The valve spool has a channel which is in variable fluid communication with two passages. The piston assembly includes a biasing member that biases the valve spool axially away from it. The channel has an axial width configured to variably regulate fluid flow between the two ports to control dampening of the piston-rod in response to centrifugal forces applied to the valve spool.

Abstract: A piston assembly including a shaft having a piston arrangement. The piston arrangement has a retract-area on one side and a extend-area on the opposite side. The retract-area is larger than the extend-area so that when fluid exerts a force on the retract-area the piston arrangement generates and applies a retract force to the shaft. Upon release of the fluid pressure to the retract-area and application of the fluid pressure to the extend-area the piston arrangement generates and applies an extend force to the shaft. The retract force is greater than or equal to the extend force.

Abstract: A sleeve for a valve assembly has an annular body with an inside surface extending from a first axial sleeve-end to a second axial sleeve-end. The inside surface has a first cylindrical section and a second cylindrical section with a conical interior seating surface extending therebetween. A groove extends circumferentially around and radially outward in the first cylindrical section and axially away from the conical interior seating surface towards the first axial sleeve-end. The sleeve includes one or more first ports that extend radially through the first cylindrical section and spaced apart from the groove. The one or more first ports are spaced apart from the groove by a lip formed by the first cylindrical section. The lip extends continuously and entirely circumferentially around the first cylindrical surface and extends a predetermined axial distance between the groove and the one or more first ports.

Abstract: A sleeve for a valve assembly has an inside surface having an interior area and a first cylindrical section extending from a first axial end and a second cylindrical section located between the first cylindrical section and second axial end. A conical interior seating surface extends between the first and second cylindrical sections. The conical interior seating surface is metallic. The sleeve includes a groove that extends circumferentially around and radially outward in the first cylindrical section. The groove extends axially away from the conical interior seating surface towards the first axial end. The sleeve has one or more ports extending radially through the first cylindrical section proximate the groove and are spaced apart from the groove by a lip formed by the first cylindrical section. The lip extends a predetermined axial distance between the groove and the port. The lip extends around the first cylindrical section and radially inward.

Abstract: A piston assembly including a shaft having a piston arrangement. The piston arrangement has a retract-area on one side and a extend-area on the opposite side. The retract-area is larger than the extend-area so that when fluid exerts a force on the retract-area the piston arrangement generates and applies a retract force to the shaft. Upon release of the fluid pressure to the retract-area and application of the fluid pressure to the extend-area the piston arrangement generates and applies an extend force to the shaft. The retract force is greater than or equal to the extend force.

Abstract: A sleeve for a valve assembly has an inside surface having an interior area and a first cylindrical section extending from a first axial end and a second cylindrical section located between the first cylindrical section and second axial end. A conical interior seating surface extends between the first and second cylindrical sections. The conical interior seating surface is metallic. The sleeve includes a groove that extends circumferentially around and radially outward in the first cylindrical section. The groove extends axially away from the conical interior seating surface towards the first axial end. The sleeve has one or more ports extending radially through the first cylindrical section proximate the groove and are spaced apart from the groove by a lip formed by the first cylindrical section. The lip extends a predetermined axial distance between the groove and the port. The lip extends around the first cylindrical section and radially inward.