NOVELTY - The machine present in the form of an unloading tank to deconstruct its contents during emptying, comprises a hydraulic motor for driving rotation of any accessory, a hydraulic valve (420) to change the direction of rotation of hydraulic motor, and a unit (450) for controlling the hydraulic valve to capture a pressure difference in the fluid flowing in two pipes and connecting a control valve and another hydraulic cylinder to provide a bistable signal of the hydraulic control valve. The hydraulic valve is 4/2 type pipe with electric control valve interposed on motor supply lines.    USE - The machine is useful as an unloading compost aerator tank to deconstruct its contents during emptying (all claimed), and in a tractor to pull a feed from a forage silo such as maize or grass, feed it into the tank and then to distribute to animals.    ADVANTAGE - The machine can easily reverse the direction of rotation of any its accessory thus capable of controlling the operation of another motor or hydraulic cylinder, and ensures simple loading and unloading of the tank, while avoiding the projection of material beyond the tank load.    DETAILED DESCRIPTION - The machine present in the form of an unloading tank to deconstruct its contents during emptying, comprises a hydraulic motor for driving rotation of any accessory, a hydraulic valve (420) to change the direction of rotation of hydraulic motor, and a unit (450) for controlling the hydraulic valve to capture a pressure difference in the fluid flowing in two pipes and connecting a control valve and another hydraulic cylinder to provide a bistable signal of the hydraulic control valve. The hydraulic valve is 4/2 type pipe with electric control valve interposed on motor supply lines and connected to pipelines of control valve. The control unit comprises a bidirectional hydraulic actuator connected to two field lines, a switch and/or electrical bistable impulse relay (470) arranged to be operable by the actuator for transmitting a signal to the bistable signal and hydraulic valve. The hydraulic actuator is a dual effect hydraulic cylinder. The silo comprises a loading or unloading tank, and an operating arm having its free end for driving at the motor. The operating arm is pivotably mounted between a release position and a changing position on the supply cup as a result of rotation. A unidirectional flow restrictor (480) is interposed in the supply pipe to reduce the fluid flow in along a flow direction through the hydraulic motor. The operating arm carries a deflector intended to return a product extracted from the silo in the bottom of the cup by the rotor in a direction of rotation of the hydraulic motor. A check valve is installed in downstream of the supply line of the distributor.    DESCRIPTION OF DRAWING(S) - The figure shows a schematic view of an unloading tank.    Hydraulic block (400)    Hydraulic valve (420)    Control unit (450)    Bistable relay (470)    Flow restrictor. (480)