A damping valve for a hydraulic damper comprises a valve housing comprising an inlet chamber and an outlet chamber. A valve seat is arranged between the inlet chamber and the outlet chamber. A valve element having a cylindrical first portion is slidably received in a cylindrical bore of the valve housing. A second portion of the valve element has a valve surface for selectively engaging and disengaging the valve seat to allow passage of hydraulic fluid between the inlet chamber and the outlet chamber. A spring element is mounted within the valve housing for biasing the valve element into engagement with the valve seat.

A device for self-balancing a rotating part, such as a propeller, along a given axis is disclosed. The propeller 102 coupled to, a drive shaft with freedom for linear movement along longitudinal axis L-L; at least one pair of levers 614/616, comprising a first lever 614-1/616-1 and a second lever 614-2/616-2, that are pivotally mounted on mounting plate 606 at two diametrically opposite points 618; and at least one pair of weights 622 fixed at external ends of the levers 614/616. inner ends of levers 614/616 are operatively coupled to the propeller 102 such that when propeller 102 undergoes a linear movement in any direction along the longitudinal, axis L-L due to unbalance, inner ends of levers are, moved to cause the weights 622 to move to provide a balancing force to neutralize the unbalance in the propeller. An embodiment with only one pair of levers is also disclosed.

A device for self-balancing a rotating part, such as a propeller, along a given axis is disclosed. The propeller 102 coupled to, a drive shaft with freedom for linear movement along longitudinal axis L-L; at least one pair of levers 614/616, comprising a first lever 614-1/616-1 and a second lever 614-2/616-2, that are pivotally mounted on mounting plate 606 at two diametrically opposite points 618; and at least one pair of weights 622 fixed at external ends of the levers 614/616. inner ends of levers 614/616 are operatively coupled to the propeller 102 such that when propeller 102 undergoes a linear movement in any direction along the longitudinal, axis L-L due to unbalance, inner ends of levers are, moved to cause the weights 622 to move to provide a balancing force to neutralize the unbalance in the propeller. An embodiment with only one pair of levers is also disclosed.

A rotor blade coupling device for coupling to a rotor mast having a rotor head centerpiece. The coupling device has at least three rotor blade mountings mounted on the rotor head centerpiece and accommodating at least three rotor blades lying in a rotor plane, and at least one connecting element between adjacent rotor blade mountings. The rotor blade mountings can carry out pivoting motions about a pivoting axis extending vertical to the rotor plane. The at least one connecting element is a damping device, and the rotor blade coupling device has a plate-shaped transfer element, which respectively crosses a rotor blade mounting and is coupled to at least one damping device. The rotor blade coupling device has a simplified design and ensures improved damping of lead-lag motions.

A rotor blade coupling device for coupling to a rotor mast having a rotor head centerpiece. The coupling device has at least three rotor blade mountings mounted on the rotor head centerpiece and accommodating at least three rotor blades lying in a rotor plane, and at least one connecting element between adjacent rotor blade mountings. The rotor blade mountings can carry out pivoting motions about a pivoting axis extending vertical to the rotor plane. The at least one connecting element is a damping device, and the rotor blade coupling device has a plate-shaped transfer element, which respectively crosses a rotor blade mounting and is coupled to at least one damping device. The rotor blade coupling device has a simplified design and ensures improved damping of lead-lag motions.

A rotor system includes a hub assembly, a first, second, and third rotor blade rotatably attached to the hub assembly, a first, second, and third damper pivotally attached to the hub assembly and pivotally attached to the first, second, and third rotor blade, respectively, and a control system operably associated with the first, second, and third damper. A method to control vibratory forces exerted on the hub assembly via the first and second rotor blade includes separately controlling a dynamic spring rate of each of the first and second dampers with the control system.

A rotor system includes a hub assembly, a first, second, and third rotor blade rotatably attached to the hub assembly, a first, second, and third damper pivotally attached to the hub assembly and pivotally attached to the first, second, and third rotor blade, respectively, and a control system operably associated with the first, second, and third damper. A method to control vibratory forces exerted on the hub assembly via the first and second rotor blade includes separately controlling a dynamic spring rate of each of the first and second dampers with the control system.

A replacement vibration absorbing device for replacing a wear wrap on a flexbeam includes a sleeve having a plurality of layers of vibration absorbing material, wherein an edge of the sleeve is cut so that the sleeve may be installed around a generally central portion of a flexbeam.

A replacement vibration absorbing device for replacing a wear wrap on a flexbeam includes a sleeve having a plurality of layers of vibration absorbing material, wherein an edge of the sleeve is cut so that the sleeve may be installed around a generally central portion of a flexbeam.

A rotor assembly has a composite driveshaft extending between a transmission and a yoke for providing torque from the transmission to the yoke to cause rotation of the yoke and a plurality of rotor blade assemblies attached thereto. The rotor hub also has a composite static mast coupled to the yoke and a frame. The static mast being configured to carry the lift and thrust forces from the yoke to the frame.