SERVOMOTOR WITH ADDITIONAL AIR VALVE ACTUATED BY A CONTROL ROD

摘要

The invention relates to a pneumatic braking servomotor using two air pressure sources and comprising a rigid envelope (4) separated by a movable fluid-tight partition wall (4) to form at least two chambers (3a, 3b), the movable partition wall being susceptible of being biased by the difference between the pressures prevailing in the chambers in order to drive a pneumatic piston (5) carrying a valve (7) actuated by a control rod (7), the inside (50) of the piston being separated from the second source by means of a purification filter (14). The control rod (10) slides in a sleeve (16) which traverses the purification filter (14) and presents a widening (100) which forms together with an extremity (162) of said sleeve an additional valve and providing for an additional and direct air admission into the piston (5) when an important braking force is suddenly applied.