Method and booster which are intended to detect the braking of a vehicle, and method of producing such a booster

Method of detecting braking of a vehicle provided with a master cylinder (202, 400) and with a primary piston (200) having a piston axis, characterized in that the method comprises providing a plunger (220, 305, 404) having a plunger axis, the plunger being arranged parallel to the primary piston (200) with the plunger axis spaced from the piston axis, the plunger being operable to reproduce movements of the primary piston (200), and a sensor (230, 300) which senses movement of the plunger (220, 305, 404), and sensing movement of the plunger to detect a braking operation, characterized in that providing includes securing the plunger (220, 305, 404) to the primary piston of the master cylinder (200) by a plate (210, 406) situated in a casing of a booster (250) associated with the master cylinder (202, 400), the plate extending radially from the primary piston, the plunger being secured to the plate spaced radially from the primary piston, and characterized in that providing includes securing the plunger (220, 305, 404) to the plate (210, 406) by a spring (412) having contiguous turns.