DISPOSITIF ACTIONNEUR HYDRAULIQUE POUR FREINS, NOTAMMENT POUR FREINS D'UN VEHICULE AUTOMOBILE COMPORTANT UN SYSTEME DE REGULATION ANTIBLOCAGE

L'INVENTION CONCERNE UN DISPOSITIF ACTIONNEUR HYDRAULIQUE POUR FREINS, NOTAMMENT POUR FREINS D'UN VEHICULE AUTOMOBILE COMPORTANT UN SYSTEME DE REGULATION ANTIBLOCAGE. CE DISPOSITIF COMPREND UN PISTON POUSSEUR 20 ET UN PISTON AUXILIAIRE 15 SEPARANT LA CHAMBRE DE COMMANDE 14 EN DEUX CHAMBRES DE PRESSION 16, 17 RELIEES PAR DES OUVERTURES 36 ET UNE SOUPAPE ANTIRETOUR 37. UN TROU DE COMPENSATION 38 RELIE AUSSI LES DEUX CHAMBRES ET PEUT ETRE FERME PAR LE PISTON 15 EN CAS DE DEFAILLANCE DU FLUIDE DE PRESSION ARRIVANT D'UNE LIAISON 43 PAR UNE VANNE 42. CECI ETABLIT ALORS UNE LIAISON HYDRAULIQUE ENTRE LA PEDALE DE FREIN ET LE PISTON POUSSEUR, SANS COURSE PERDUE NOTABLE DE LA PEDALE. L'INVENTION S'APPLIQUE AUX FREINS AVEC SYSTEME DE REGULATION ANTIBLOCAGE. Known brake actuating devices include a pressure source and a valve arrangement operated by a brake pedal with the pressure fluid being fed by the valve arrangement to a control chamber which has as one of its boundaries a pressure piston acting on a master cylinder piston. The pressure piston of the known device is operated mechanically by the brake pedal upon failure of the pressure fluid supply. However, the brake pedal travel is increased in so doing. According to the present invention the control chamber has a second piston forming a boundary thereof opposite the pressure piston which keeps a pressure fluid channel open between the control chamber and the valve arrangement in the normal operating condition and closes the pressure fluid channel during failure of the pressure fluid supply so that the pressure piston is operated by the second piston without any appreciable increase in brake pedal travel.