Vibration isolator

A vibration isolator comprising:

• a canister having ends closed by first and second end caps;
• a shaft able to move inside the canister, the shaft comprising a piston shaped part separating the canister into a first part defined between the piston shaped part of the shaft and the first end cap, and a second part defined between the piston shaped part of the shaft and the second end cap, said first part comprising at least one first resilient element providing a damping function and able to be compressed by a compression movement of the shaft on a first nominal stroke, and said second part comprising at least one second resilient element providing a damping function and able to be compressed by a tension movement of the shaft on a second nominal stroke;
• wherein a washer is disposed around the shaft, one side of the washer being in contact with the at least one second resilient element of the second part of the canister, the other side of said washer being able to be in contact with the piston-shaped part of the shaft when the vibration isolator operates in tension and able to be in contact with a ring-shaped inner wall of the canister when the vibration isolator operates in compression;
• wherein at least one of the first and second end caps is screwable on the canister in order to adjust a pre-load exerted on said at least one of the first and second resilient elements through said element and said washer such that a step of tangential stiffness occurs at the transition between the two nominal strokes;
• and
• wherein the tangential stiffness of the vibration isolator is, on the entire second nominal stroke of the shaft, at least twice as strong as the tangential stiffness on the entire first nominal stroke of the shaft.