Stabilizer for a lower arm of a three-point implement hitch of a tractor, with a first stabilizer element (12) and with a second stabilizer element (16) connected with the first stabilizer element (12) elastically movable, being able to rotate the second stabilizer element (16) with respect to the first stabilizer element (12) for adaptation of the stabilizer length, with a safety pin (58) pivotally articulated in the first stabilizer element (12), which can be engaged for securing against the rotation of the two stabilizing elements (12, 16) with a safety slot (60) configured on the perimeter of the second stabilizing element (16), and with a closing flap (62), which for the blocking of an elastic movement that occurs between the stabilizing elements (12, 16) can be pivoted towards a closed position, with a closure flap section (64) directed in the direction of being configured pivot n towards the safety pin (58) in such a way that the safety pin (58) by releasing the second stabilizer element (16) can also pivot towards the outside of the security slot (60) when the closing flap (62) is in the closed position, characterized in that the closing flap section (64) covers the safety pin (58) as a protection.Estabilizador para un brazo inferior de un enganche de apero de tres puntos de un tractor, con un primer elemento estabilizador (12) y con un segundo elemento estabilizador (16) unido con el primer elemento estabilizador (12) de manera móvil elásticamente, pudiendo girarse el segundo elemento estabilizador (16) con respecto al primer elemento estabilizador (12) para la adaptación de la longitud del estabilizador, con un pasador de seguridad (58) articulado de manera pivotante en el primer elemento estabilizador (12), el cual puede engancharse para el aseguramiento contra el giro de los dos elementos estabilizadores (12, 16) con una ranura de seguridad (60) configurada en el perímetro del segundo elemento estabilizador (16), y con una solapa de cierre (62), la cual
