Fuse device for pneumatic brake booster

A pneumatic brake booster comprising:

• a rigid casing (3), a moving partition sealingly defining a front chamber (3a) and a rear chamber (3b) inside the casing (3), the front chamber (3a) in operation being subjected to a first pressure and the rear chamber (3b) being connected selectively to the front chamber (3a) or subjected to a second pressure higher than the first, a pneumatic piston (5) moving with the moving partition, an axial control rod (8) moving toward the piston (5) as a function of an input force selectively exerted against the action of a return force and directed in an axial direction of actuation (X+) pointing toward the front chamber (3a), the return force urging the control rod (8) toward a return position and the input force urging the control rod (8) toward an actuating position which is dependent upon the input force, a three-way valve (7) connecting the rear chamber (3b) to the front chamber (3a) when the control rod (8) is in the rest position, and subjecting the rear chamber (3b) to the second pressure when it is actuated by movement of the control rod (8) toward its actuated position, and a push rod (21), characterized in that a fuse device having a hollow cylindrical first part (21) one end (25) of which has an inside diameter (d1) and a bowl-shaped second part (24) with a circular bottom equipped on its central external part with a roughly cylindrical stud (29) of an outside diameter (d2) slightly greater, within the tolerances, than the inside diameter (d1) of said end of said hollow cylindrical first part (21), so as to allow said hollow cylindrical first part (21) to be secured to said bowl-shaped second part (24) by forcibly inserting said stud (29) in said hollow end (25) of smaller diameter (d1) said bowl-shaped second part (24) having a circular external groove (30) whose purpose is to weaken the connection between said stud (29) and said bottom (26) of said bowl-shaped second part (24) when a pair of forces is applied to said fuse device, so as to allow said hollow cylindrical first part to detach from said bowl-shaped second part.