Nenad Marjanović

A New Design of a Two-Stage Cycloidal Speed Reducer

A new design of a two-stage cycloidal speed reducer is presented in this paper. A traditional two-stage cycloidal speed reducer is obtained by the simple combination of singlestage cycloidal speed reducers. A single-stage reducer engages two identical cycloid discs in order to balance dynamical loads and to obtain uniform load distribution. Consequently, the traditional two-stage reducer has four cycloid discs, in total. The newly designed two-stage cycloidal speed reducer, presented in this paper, has one cycloid disc for each stage, that is, two cycloid discs in total, which means that it is rather compact. Due to its specific concept, this reducer is characterized by good load distribution and dynamic balance, and this is described in the paper. Stress state analysis of cycloidal speed reducer elements was also realized, using the finite elements method (FEM), for the most critical cases of conjugate gear action (one, two, or three pairs of teeth in contact). The results showed that cycloid discs are rather uniformly loaded, justifying the design solution presented here. Experimental analysis of the stress state for cycloid discs was realized, using the strain gauges method. It is easy to conclude, based on the obtained results, that even for the most critical case (one pair of teeth in contact) stresses on cycloid discs are in the allowed limits, thus providing normal functioning of the reducer for its anticipated lifetime. [DOI: 10.1115/1.4004540]

Some characteristics of electricity production by stationary parabolic, cylindrical solar concentrator

Stationary parabolic, cylindrical solar concentrator for electricity production consists of the absorber (with photovoltaic panels and water pipes) and parabolic, cylindrical reflector (with metal surface) and has geometrical concentration ratio up to 4. Direct solar radiation approaches the concentrator aperture at different angles and pathways. For different aperture angles and different kinds and types of metal surfaces of the reflector, the investigation of long concentrator of this type would be that of how efficiently the direct solar radiation reaches absorber to be converted to electricity.

Determination of Real Clearances Between Cycloidal Speed Reducer Elements by the Application of Heuristic Optimization

The actual cycloidal speed reducer elements differ from their theoretical ideal due to existing tolerances; therefore, the cycloid disc behaves like a corrected one. This study is oriented towards determining contacts in corrected cycloid speed reducer profiles from the aspect of geometry. Based on this geometry, an objective function was developed for the optimization with some limitations. Heuristic optimization was used to determine the position of the cycloidal drive elements when a contact was established and, consequently, to determine clearances in other places. Some limitations were set so that the model could reflect a real contact. In this study, a TLBO algorithm was used for the optimization of a cycloidal speed reducer. Clearances were analysed for different correction values of the cycloid disc profile of an actual cycloidal drive and the optimization procedure was presented. The results provide a real picture of the contact in the presence of inevitable machining tolerances.