Free-wheel mechanisms transmit rotary motion in only one direction. They are widely used, for example, in hydraulic transformers, pulsed continuous transmissions, inertial automatic torque transformers, electrical starters for motors, and metal- and wood-working drives. Unfortunately, existing free-wheel mechanisms are insufficiently reliable and durable and in many cases limit the reliability of the drive as a whole. Thus, the insufficient life of free-wheel mechanisms delays the use of inertial automatic continuous transmissions, which have many benefits over existing transmissions.In most known free-wheel mechanism, the whole torque is transmitted through locking elements such as balls, rollers, eccentric wheels, pawls, slide blocks, and wedges, whose operation at large loads may limit the life of the mechanism. Therefore, in the present work, we propose a relay-type free-wheel mechanism, in which only a small part of the torque is transmitted through the locking element; the remainder is transmitted through long-lived elements. The relay-type free-wheel mechanism reduces the load on the weak locking elements by one or two orders of magnitude in comparison with existing designs.In this paper a method is proposed for calculating and selecting the main parameters of relay-type free-wheel mechanisms, which are characterized by considerable load capacity, reliability, and durability.