Master-cylinder for electro-hydraulic brake system

The master cylinder for a motor vehicle electrohydraulic brake has a cartridge (28) to simulate reaction forces on the brake pedal. The cartridge (28) has a piston (42) subjected to brake fluid master cylinder pressure on one face (44) and having a resistance spring (48) engaging the opposite face (46). The spring is a helicoidal spring with a spacer (80) between two coils to allow contact of the coils with the spacer beyond a preset brake fluid pressure.