The primary function of a shaft collar is to retain its position on a shaft. The amount of axial load (pounds or newtons) required to initiate slippage of a properly installed collar is defined as the Axial Holding Power. Since this result is a function of tension induced by the screw as well as the coefficient of friction between the collar and shaft, it can be affected by many variables (smoothness of the friction surfaces, plating or lubrication on shaft or screw, size of screw and wrenching torque applied).
Because there are so many variables involved in determining the actual axial holding power between a specific collar and shaft, it is not possible for Stafford to certify a single value for all situations. Instead, they can provide results that have been obtained from testing under a controlled set of conditions that most accurately represent a standard operating environment. These results should be used as a guide only for projected shaft collar performance, and should not, under any circumstances, be used as guaranteed values. The user must determine the product suitability in a particular application.