Abstract: An overload protection coupling for limiting the torque transmitted between two elements of a rotating power transmission system comprises coaxial driving and driven members journalled for relative rotation. The members are drivingly connected to each other by one or more rod-like tensile breaking piece devices effective between first pairs of radial projections on the driving and driven members. One or more reaction devices are effective between second pairs of radial projections on the driving and driven members to ensure that the rod-like breaking piece devices are in pre-tension to a predetermined level approximately equivalent to the maximum torque transmitted by the coupling to increase fatigue life of the breaking piece devices. In some embodiments, the tensile breaking piece devices and reaction devices may be effective between just one pair of radial projections.