Abstract: The invention relates to a pneumatic booster operated by a plunger (9) housed in a bore (61) and carrying a moving seat (102) intended to interact selectively with a shut-off member (111), this member being itself capable of interacting selectively with a fixed seat (101).According to the invention, the plunger (9) comprises a cylindrical body (91) and a collar (92) sliding between a front stop (911) and a rear stop (912) of the body, an anterior section (921) of the collar (92) being engaged between the cylindrical body (91) and the bore (61), a posterior section (922) of the collar (92) carrying the moving seat (102), and it being possible furthermore for the collar (92) to be held temporarily stationary in the bore independently of the movement of the body (91), by means of a channel (14) and of a snap ring (13), in order to allow extended operation of the booster after a sharp braking action.

Abstract: A proportional solenoid valve for regulating pressure of fluid supplied to a system. The solenoid valve has high-pressure inlet (1), a low-pressure inlet (2) and an outlet (3) through which fluid under controlled pressure is supplied to the system. The solenoid valve has a body (4) with bore (5) therein for retaining a regulating slide valve (9). The regulating slide valve (9) is subjected to a pressure acting on a cross-section (S), to the force of a spring (10) and to a force exerted by an electromagnet (14,15). Movement of the slide valve brings about a communication between the high-pressure inlet (1) and the outlet (3) and communication between the low-pressure inlet (2) and the outlet (3) as a function of a control valve (16). The control valve (16) is located between the high-pressure inlet (1) and the outlet (3) and the high-pressure inlet (1) and low-pressure inlet (2) are isolated from one another by the slice valve (9) as long as said control valve is not open.