Abstract:

ESDU 92005 gives a direct method for finding the minimum allowable prime circle radius based on the criteria that the maximum pressure angle does not exceed a specified value and that profile undercutting is avoided.

ESDU 82023 provides an alternative approach that handles offset followers as well, but is a geometric iterative procedure. Two methods are given here: one finds the minimum radius and the corresponding maximum diameter of the roller follower while the other finds the minimum radius when the size of the follower is known. The methods apply to DRD or DRRD follower motion defined by a single law. A hand calculation may be used based on graphs provided, or a computer program (ESDUpac A9205). Both methods apply to six cam laws (simple harmonic, cycloidal, modified trapezoidal acceleration, modified sine acceleration, and 3-4-5 or 4-5-6-7 polynomial).

Notes on the derivation of the method are included, together with step-by-step design procedures and guidance on the use of the program with a detailed explanation of the input and the output. Worked examples illustrate the practical application of the procedures during the design of such a mechanism.