Shock-absorbing actuator for fitting to landing gear of heavier-than-air aircraft, in particular helicopters

A shock-absorbing actuator for fitting to the landing gear of heavier-than-air aircraft, the actuator comprising a cylindrical body and an open-ended hollow rod forming an annular piston that slides in sealed manner inside the cylindrical body, together with hydraulic damping diaphragm means surmounted by a volume of hydraulic fluid delimiting a low-pressure gas chamber, and force peak-limiting means that come into play in the event of a crash landing, wherein the cylindrical body includes a separator piston that is movable between two associated abutments and delimiting two hydraulic fluid chambers, one of which communicates directly with the inside of the hollow rod in which the hydraulic damping diaphragm means is disposed, and the other of which is adapted to communicate via a first distributor valve with the hydraulic circuit of the aircraft, said first distributor valve being automatically closed at the end of lowering the landing gear, said cylindrical body and said hollow rod also delimiting an annular chamber which is also adapted to communicate via a second distributor valve with said hydraulic circuit, said first and second distributor valves thus making it possible to cause the shock-absorbing actuator to extend or retract in order to lower or raise the landing gear, and wherein the force peak-limiting means is disposed in an extension body extending beyond an end wall of the cylindrical body forming one of the abutments of the separator piston.