A ploughing apparatus comprising: - a frame structure, such as a ploughing wing or a ploughing wing support, - a blade structure coupled to a lower part of the frame structure by means of a joint, the blade structure comprising a blade and a blade holder, - and a release mechanism connected to the blade structure for turning the blade structure backwards in the case of an impact with an obstacle, the release mechanism comprising: - two levers (5, 7) coupled in series by means of a movable joint placed between the two levers (5, 7), wherein the first of said two levers is articulated at its lower end to the blade structure by means of a first joint and the second of said two levers is articulated at its upper end to the frame structure by means of a second joint which is placed higher than the first joint, wherein the movable joint is placed higher in relation to the ground than a straight line extending through the first and second joints (9, 11), such that the force of the obstacle effective on the blade structure pushes the movable joint upwards, - a spring member connected at its lower end to said movable joint and at its upper end to the frame structure, wherein - a force effective on the blade structure is transferred to the two levers (5, 7), and to the returning spring member, when an impact force effective on the blade structure moves the blade structure and the two levers (5, 7), characterized in that the second of said two levers is coupled by means of the second joint to a rigid lever being rigidly mounted to the frame structure and having a curved shape, inside which the movable joint can be received. - a frame structure, such as a ploughing wing or a ploughing wing support, - a blade structure coupled to a lower part of the frame structure by means of a joint, the blade structure comprising a blade and a blade holder, - and a release mechanism connected to the blade structure for turning the blade structure backwards in the case of an impact with an obstacle, the release mechanism comprising: - two levers (5, 7) coupled in series by means of a movable joint placed between the two levers (5, 7), wherein the first of said two levers is articulated at its lower end to the blade structure by means of a first joint and the second of said two levers is articulated at its upper end to the frame structure by means of a second joint which is placed higher than the first joint, wherein the movable joint is placed higher in relation to the ground than a straight line extending through the first and second joints (9, 11), such that the force of the obstacle effective on the blade structure pushes the movable joint upwards, - a spring member connected at its lower end to said movable joint and at its upper end to the frame structure, wherein - a force effective on the blade structure is transferred to the two levers (5, 7), and to the returning spring member, when an impact force effective on the blade structure moves the blade structure and the two levers (5, 7), - two levers (5, 7) coupled in series by means of a movable joint placed between the two levers (5, 7), wherein the first of said two levers is articulated at its lower end to the blade structure by means of a first joint and the second of said two levers is articulated at its upper end to the frame structure by means of a second joint which is placed higher than the first joint, wherein the movable joint is placed higher in relation to the ground than a straight line extending through the first and second joints (9, 11), such that the force of the obstacle effective on the blade structure pushes the movable joint upwards, - a spring member connected at its lower end to said movable joint and at its upper end to the frame structure, wherein - a force effective on the blade structure is transferred to the two levers (5, 7), and to the returning spring member, when an impact force effective on the blade structure moves the blade structure and the two levers (5, 7),