Computer Aided Design for High Mechanical Efficiency of Wolfrom Type Speed Reducers
Abstract Wolfrom type planetary speed reducers are complex planetary transmissions, formed of three simple planetary mechanisms that have the same carrier H. The main characteristic of this kind of reducers is the large transmission reduction ratio (usually by a factor of 100 ... 300), obtained with a relatively small sized reducer. Generally, high transmission ratio reducers have the capability to output high torque. Considering the fact that their physical size is small, there are high normal loads between the teeth of the component gears and in the bearings, increasing the internal losses of the system. The object of this paper is to help the designer of this type of speed reducers to find the limits of the transmission ratio corresponding to an acceptable mechanical efficiency and size. We have expressed all the relations as functions of only three variables (z1, a and δ), that best define the integer type of relations involved in this paper. Based on these relations, we have created a computer program to optimize the value of the total mechanical efficiency of the planetary train.