This paper describes a new rocker-belt mechanism. The mechanism is made up of a rocker, a timing belt that operates the rocker, a series of sprockets and a curved element. The latter, which is referred to as profile, represents the heart of the mechanism. One point of the belt is attached to a point on the rocker. The belt is wound around the sprockets and the profile. If the profile is properly shaped, for a given range of rotation angles of the rocker, the belt does not become slack. This work shows how to design such a profile; it turns out that the profile shape, which is related to several geometric parameters, is expressed by means of a non-linear differential equation. Eventually, the proposed approach is validated by an example.
