Pneumatic brake booster

A pneumatic brake booster, comprising:

• a drive piston connected by a membrane to a brake booster cylinder to subdivide the brake booster cylinder into a forward chamber and a rear chamber and operate by a pressure drop to push a piston of a master cylinder by means of a push rod, the pressure drop in the brake booster cylinder driving the drive piston being controlled by a plunger valve actuated by the movement of a control rod connected to a brake pedal, the drive piston being thrust into rest position by a return spring supported by a wall of the brake booster cylinder;
• and
• a vibration damper, included with the return spring, wherein the vibration damper includes a part made of an elastic material working compressively, of parallelepipedic external shape, with a length greater than a spacing of two neighboring coils of the return spring prior to installation in the brake booster and whose front and back faces are each equipped with a longitudinal slit penetrating the material mass of the vibration damper, for engagement by way of the two longitudinal slits on the two neighboring coils of the return spring, wherein each of the longitudinal slits penetrates into the material mass of the vibration damper to a respective depth, and the length of the vibration damper minus a sum of the respective depths is less than a spacing of the two neighboring coils of the return spring at rest.