Torque limiters act as an overload device in machine drives using sprockets, toothed or V-belt pulleys. These devices are extremely easy to use and offer complete operating security. The torque limiter protects mechanical parts and machines which may be subject to overloading of various kinds, by slipping when the torque demand exceeds a pre-set value. It maintains re-engagement at the pre-set torque when the overload torque has passed; no resetting is required. Slip torque is pre-set by adjustment of the spring force on the pressure plate and friction surfaces.