Cycloidal Speed Reducer

grabcad

PM oil impregnated or die cast gears yield four distinct back-to-back cycloid gear pairs, resulting in a full reduction from motor to output shaft. Step files of individual parts in assembly locations are developed using FreeCad, but notes indicate difficulty producing AP214 assemblies. MathCAD analysis of gears reveals speed reduction and stress levels using the Lewis method, which appears to have been incorrectly applied due to a mistaken gear ratio. The actual speed ratio is 586.5:1. PM material data for public knowledge is insufficient to determine the cyclical yield strength of gears, requiring specific manufacturer information. Zamak, a die cast material used for over 50 years in casting gears, provides available data. Gears produced on an Atlas lathe built in the 1940s and those manufactured until the 1960s are examples. A spring pre-loads all ball bearings except for the compound gear, offering an alternative choice of cam roller bearing for the compound gear. This type of bearing retains component position due to lips between races and rollers. Additional seals can be added. The second output bearing is a PTFE-based material with wear and creep resistance. However, the issue arises from the gap needed for the journal bearing, which increases deflection of the internal output gear more than the fixed internal gear. An alternate choice is a roller bearing adapted to the small remaining space to the boundary. Additional space might be available by switching the output to the 50-tooth gear. The accuracy of the FreeCad gear model is unknown due to missing radius in tooth roots and tips, leading to high stress levels. The effect of tolerances and gaps must be addressed by a specialist with gear design experience. For example, adjusting eccentricity can handle bearing clearances, while stress analysis should determine bending stress in teeth and the ring supporting them, press-fit into a housing or onto a bearing.