Hydraulic suspension damper

A hydraulic damper (1), in particular a motor vehicle suspension damper, comprising a tube (2) filled with working liquid, inside of which a slidable piston assembly (3), provided with compression (12) and rebound (11) valve assemblies and attached to a piston rod (4) led outside the damper, is placed, and an additional compression valve system (17), characterised in that the additional compression valve system (17) is attached to the piston rod (4) in a compression chamber (10) and comprises a hollow main body (18) surrounding the piston rod (4) and provided with a substantially flat first abutment surface (19) with a radially inner portion (191) and a radially outer portion (192), in a plane substantially perpendicular to the damper longitudinal axis (L), defining the close position of the system (17), and at least one channel (20) the inlet of which is located within the area of the first abutment surface (19), a compression spring (24) supported within the hollow main body (18) underneath the first abutment surface (19), a substantially rigid and relatively thin plate (26) biased by the spring (24) against a second abutment surface (27), in a plane substantially perpendicular to the damper longitudinal axis (L), defining the open position of the system (17), wherein the plate is free to deflect and displace between said open position to allow free flow of working liquid through said at least one channel (20) of the hollow main body (18), and said close position to substantially restrict the flow of working liquid through said channels (20), and the outside diameter of said hollow main body (18) is less than the inner diameter of the tube (2) and the hollow main body (18) is provided with an annular groove (21) inside of which a cross-cut ring (22) is disposed to form a sliding fit of the hollow main body (18) within the tube (2).