A hydraulic device for actuating the braking of work vehicles, comprising: - at least one delivery duct, which can be connected to the pressurized branch of a hydraulic circuit; - at least one discharge duct, which can be connected to the discharge and recovery branch of the hydraulic circuit; - at least one feed duct for feeding a hydraulic actuator of a braking system activated by elastic means; - at least one control valve, which is interposed between said delivery duct, said discharge duct and said feed duct and can move on command between at least one first position, in which said delivery duct is connected to said feed duct in order to contrast the action of said elastic means, and at least one second position, in which it connects said discharge duct to said feed duct in order to avoid contrasting the action of said elastic means, said control valve being a three-way slide valve having three positions and a closed center; - safety means for emergency deactivation of the braking system, which comprise auxiliary means for pumping pressurized liquid in said feed duct and a duct for connecting said delivery duct to said discharge duct or to an auxiliary duct which can be connected to an auxiliary reservoir; said auxiliary pumping means being arranged along said connecting duct and being actuatable in order to pump pressurized liquid into said feed duct when said control valve is in said first position, characterized in that said pressurized branch includes an accumulator and in that, when said feed duct and said delivery duct are mutually disconnected by the control valve, liquid drawn from said discharge duct fills the accumulator of said pressurized branch, and in that said auxiliary means for pumping pressurized liquid in said feed duct are operable with said control valve in any position. - at least one delivery duct, which can be connected to the pressurized branch of a hydraulic circuit; - at least one discharge duct, which can be connected to the discharge and recovery branch of the hydraulic circuit; - at least one feed duct for feeding a hydraulic actuator of a braking system activated by elastic means; - at least one control valve, which is interposed between said delivery duct, said discharge duct and said feed duct and can move on command between at least one first position, in which said delivery duct is connected to said feed duct in order to contrast the action of said elastic means, and at least one second position, in which it connects said discharge duct to said feed duct in order to avoid contrasting the action of said elastic means, said control valve being a three-way slide valve having three positions and a closed center; - safety means for emergency deactivation of the braking system, which comprise auxiliary means for pumping pressurized liquid in said feed duct and a duct for connecting said delivery duct to said discharge duct or to an auxiliary duct which can be connected to an auxiliary reservoir; said auxiliary pumping means being arranged along said connecting duct and being actuatable in order to pump pressurized liquid into said feed duct when said control valve is in said first position, characterized in that said pressurized branch includes an accumulator and in that, when said feed duct and said delivery duct are mutually disconnected by the control valve, liquid drawn from said discharge duct fills the accumulator of said pressurized branch, and in that said auxiliary means for pumping pressurized liquid in said feed duct are operable with said control valve in any position.