This article illustrates a prototype of an industrial exoskeleton designed at the Politecnico di Torino Department of Mechanical and Aerospace Engineering (DIMEAS) to be worn to support the trunk while bending forward for prolonged periods during parts assembly operations, thus preventing muscle fatigue. The prototype is an active exoskeleton and has motorized hip joints. The operator's trunk is guided during forward bending and upright lifting. The entire bending phase is assisted by the exoskeleton. It can work in various conditions, such as in a free mode when the operator needs to have his legs free in the movement, in a active condition, following the operator’s trunk flexion, in a flexed stationary phase when the operator has his trunk flexed. The physiological difference between the hip and the lumbo-sacral joints was solved in the actuation group by means of a jointed four-sided mechanism. There are various anthropometric adjustments. Some optimizations were carried out to improve the geometry and the axial length of the actuation group and to analyse the functioning of the jointed four-sided mechanism. The prototype was constructed and it shows a low weight and suitable dimensions. In the future some experimental tests will be carried out using it.