Abstract: In a quick-action flap, in which opening occurs by means of hydraulic actuation and closing can be initiated by a spring, two independent systems are provided, namely a servo system. (1) and a flap disk system (2), which are connected to one another via a coupling (1a, 2a). The coupling itself has, between the coupling part (1a) on the servo side and the coupling part (2a) on the flap disk system side, a free-wheel which makes it possible for the forces occurring upon impact of the flap disk (14) on the seating ring in the flap casing (9) to be divided up in accordance with the kinetic energy of the moving masses of each system (1, 2). The free-wheel thus distributes the stressing over two successive impacts, whereby the stress in the lever (12) of the flap disk (14) is reduced by approximately one half. A hydraulic brake in the servo system (1) ensures that the closing speed of the flap disk is kept constant approximately in the last third of the closing process.

Abstract: Butterfly valve actuated by a servo-motor, opening taking place by means of hydraulic force and closing by means of spring force. The hydraulic force must overcome the torque due to the flow, and the force of the closing spring. The excess hydraulic force of the servo-motor (2) during the end phase of the opening procedure is stored (3) and released during the closing procedure, whereby the closing time (t) can be minimized.