Master cylinder with dynamically adjustable hydraulic reaction

A hydraulic-reaction master cylinder comprising:

• a cylindrical body delimiting a variable-volume working chamber filled with a brake fluid;
• a main piston mounted to selectively slide in said working chamber in a first axial direction to reduce the volume of said working chamber, said main piston being pierced with an axial bore, said axial bore being delimiting a variable-capacity reaction chamber subject to a variable pressure;
• a reaction piston closing said reaction chamber and mounted to slide in said axial bore in said first axial direction to reduce the capacity of said reaction chamber;
• and
• a non-return valve selectively allowing fluid to flow from said reaction chamber to said working chamber, said reaction chamber being annular in shape and communicating selectively with said working chamber through an axial passage or through said non-return valve, said reaction piston being stepped and having an axial stub for selectively closing off said axial passage, said non-return valve being characterised by being annular in shape and having a sealing cup held in an annular cage which defines said axial passage, said sealing cup being pierced with axial orifices for selectively allowing fluid to flow from said reaction chamber to said working chamber by being deformed to allow fluid to flow around said sealing cup.