A device for obtaining a predetermined linear force, includes a first elastic force elements and a force output elements in the form of a non-elastic, flexible elongated member, a force transformation elements arranged between the first elastic force element and the force output element, such that a pulling of the force output element creates a tension in the first elastic force element. The force transformation element is arranged and designed such that the pulling force required on the force output element decreases with the distance the force output element is pulled. The device includes a second elastic force element and a second force output element attached thereto wherein the pulling force required on the second force output element increases with the distance the force output element is pulled. The two force output elements are connected to each other such as to summarize the forces.