A torque limiter is an automatic device that protects mechanical equipment, or its work, from damage by mechanical overload. A torque limiter may limit the torque by slipping (as in a friction plate slip-clutch), or uncouple the load entirely (as in a shear pin). The action of a torque limiter is especially useful to limit any damage due to crash stops and jams. A torque limiting device is also known as an overload clutch.
A SIMPLE EXAMPLE
A friction plate clutch. Over-torque will cause the plates to slip. A simple example is found in a fixed-spool fishing reel, where the slipping torque is set by means of a large hand nut in order that the reel will turn and allow more line to unwind before the line breaks under the pull of a fish.
BELOW IS A VIDEO THAT ILLUSTRATES THE IDEA OF A TORQUE LIMITER