A damper (1) is provided with a body (2) which surrounds an annular compression chamber (3), the damper (1) being furnished with at least one pneumatic compensation chamber (30, 40) and a control piston (4) that can move relative to the body (2), the control piston (4) having a rod (5) which protrudes from the body (2) and a head (6) which slides in the compression chamber (3). The damper is notable in that, the compression chamber (3) comprising a variable-section radial opening (8), the damper (1) is provided with a hydraulic compensation chamber (10) which receives a first fluid expelled from the annular compression chamber (3) via the variable-section radial opening (8) when the control piston (4) moves.