Patent ID: 8286520

Claim:
A telescopic actuator comprising: a main rod; an auxiliary rod; a cylinder in which the main rod is mounted to slide telescopically along a sliding axis between a retracted position and an extended position, the auxiliary rod being mounted to slide telescopically in the main rod along said sliding axis between a retracted position and an extended position, a controlled retaining means selectively operable for retaining the auxiliary rod in the retracted position inside the main rod or releasing the auxiliary rod so that the auxiliary rod is free to move with respect to said main rod, and brake means for braking sliding of the auxiliary rod in the main rod in the extension direction, said braking means being distinct of retaining means, wherein the auxiliary rod has a thread on an outside surface, wherein the main rod carries at its end a rotary bearing that centers the auxiliary rod inside the main rod, wherein a reversible helical connection is disposed between the rotary bearing and the thread of the auxiliary rod, wherein the main rod co-operates via the reversible helical connection with the thread of the auxiliary rod such that extension of the auxiliary rod causes the rotary bearing to rotate, and wherein the brake means is arranged to brake rotation of the rotary bearing during extension of the auxiliary rod.