A forestry winch provided with an assembly for the measurement of braking power, comprising a drum (2) that is arranged in a housing (1) and to which a hauling wire cable (3) is wound and stored, wherein the drum is pivotally attached on an axle (4) mounted in the housing; a clutch (5) arranged on one lateral side of the drum and connected with the Cardan shaft of a tractor; a drum brake (6) that is circumferentially arranged on another lateral side of the drum; a hydraulic block (7) comprising a hydraulic medium tank, a pump for providing pressure for the hydraulic medium, at! least one control unit in the form of a hydraulic or proportional hydraulic valve for the clutch control, at least one control unit in the form of a proportional hydraulic valve (8) that is connected with the hydraulic cylinder (9) with the belonging piston, a control unit (16) with which the user controls and operates the forestry winch, all said elements being mutually hydraulically connected, wherein the forestry winch comprises a deflection cylinder for deviating and shifting the hauling wire cable from its hauling direction, a measuring instrument (15) for measuring shifts, said instrument having an output signal, a control block arranged inside the housing of the winch and comprising at least one control unit with a regulating algorithm, wherein the control block is connected with the measuring instrument for measuring shifts in a way that allows reception of its output signal and is connected with the hydraulic block in a way that allows the control of the proportional hydraulic valve of the brake.