Braking device, comprising: - a base body associable with the frame of a towing vehicle; - at least one control apparatus of the braking of a trailer adapted to adjust the pressure of a work fluid along a control line connectable to the braking system of the trailer and along an additional line operatively connectable to the automatic and/or parking brake of the trailer itself; - first command means associable at least with the parking brake of the towing vehicle and actuatable for the operation of the same; - second command means operatively connected to said control apparatus and actuatable to send a work fluid under pressure along said control line and operate the braking of the trailer; - third command means operatively connected to said control apparatus and operable between a normal operating position, in which they maintain the work fluid under pressure along said additional line in order to maintain the automatic and/or parking brake deactivated, and a parking position, in which they reset the pressure of the work fluid along said additional line so as to activate the automatic and/or parking brake; - a lever comprising at least a first portion hinged to said body, associated with said first command means and movable between a home position and at least a braking position in which the first command means themselves are deactivated and activated respectively, there being provided removable blocking means of said first portion in said braking position, and at least a second portion, graspable by an operator, hinged to said first portion, which is associated with said second command means and movable between a home position and at least a braking position in which said second command means are deactivated and activated, respectively; - activation means of said third command means operatively connected to said lever and adapted to displace from a first work position, in which they maintain said third command means in the normal operating position, to a second work position, in which they bring said third command means to the parking position, as a result of the displacement of said first and of said second portion (12a, 12b) to the relevant braking position and home position respectively; characterized by the fact that said activation means comprise at least one command lever hinged around a fulcrum, at least one supporting element of said fulcrum locked together with said first portion, wherein said command lever is connected, on opposite sides of the fulcrum itself, to said second portion and to said third command means respectively, said command lever rotating in a first way as a result of the relative rotation of said second portion with respect to said first portion during the displacement of the second portion itself towards the relative braking position, so as to maintain said third command means in the normal operating position, and rotating in a second way opposite to the previous one, as a result of the return of said second portion to the home position and with said first portion in the braking position, so as to bring said third command means to the parking position. - a base body associable with the frame of a towing vehicle; - at least one control apparatus of the braking of a trailer adapted to adjust the pressure of a work fluid along a control line connectable to the braking system of the trailer and along an additional line operatively connectable to the automatic and/or parking brake of the trailer itself; - first command means associable at least with the parking brake of the towing vehicle and actuatable for the operation of the same; - second command means operatively connected to said control apparatus and actuatable to send a work fluid under pressure along said control line and operate the braking of the trailer; - third command means operatively connected to said control apparatus and operable between a normal operating position, in which they maintain the work fluid under pressure along said additional line in order to maintain the automatic and/or parking brake deactivated, and a parking position, in which they reset the pressure of the work fluid along said additional line so as to activate the automatic and/or parking brake; - a lever comprising at least a first portion hinged to said body, associated with said first command means and movable between a home position and at least a braking position in which the first command means themselves are deactivated and activated respectively, there being provided removable blocking means of said first portion in said braking position, and at least a second portion, graspable by an operator, hinged to said first portion, which is associated with said second command means and movable between a home position and at least a braking position in which said second command means are deactivated and activated, respectively; - activation means of said third command means operatively connected to said lever and adapted to displace from a first work position, in which they maintain said third command means in the normal operating position, to a second work position, in which they bring said third command means to the parking position, as a result of the displacement of said first and of said second portion (12a, 12b) to the relevant braking position and home position respectively;