Tolerance rings [motor-overload protection]

Designers are constantly facing the challenges of packing more and more functionality into ever-smaller spaces while improving power and performance. Mechanical overload protection for drive-train systems has long been desirable but, in the past, has required bulky and expensive slip-clutch mechanisms. Tolerance rings have traditionally been used to compensate for machining tolerances or differential thermal expansion effects, but developments in tolerance ring technology outlined in this article are enabling them to be more widely used as simple, low-cost, nondestructive overload-protection devices. The principles of tolerance-ring design are outlined here, along with an explanation of the factors affecting the resulting design parameters, such as assembly force, radial load capacity, spring compression, and slip torque. We also present examples of successful overload-protection applications from the appliance and automotive industries.