Abstract: Hydraulic actuating apparatus with digital input comprising a movable output member spring biased to a neutral position and capable of moving to one or other of two working positions under the effect of opposing hydraulic means, themselves controlled by binary-type control members;To create two additional working positions for the movable output member (10), the invention provides for each of the driving means to be composed of two active areas (s.sub.1, s'.sub.1 ; s.sub.2, s'.sub.2) acting successively on the output member (10), and for the putting of the first area under pressure to be caused by one of the control members (EV.sub.1, EV.sub.2) while that of the other area is caused by the other control member provided that the output member has already completed a first displacement step in the required direction;Particular application to the control of double-acting hydraulic actuators with two rates of displacement in each direction.