Preface -- 1. Keynotes: 1. Arnaudov, K., Karaivanov, D. Alternative method for analysis of complex compound planetary gear trains - essence and possibilities.- 2. Bostan, I. Planetary precessional transmissions: synthesis and generation technologies -- 3. Ene, N., Dimofte, F. New tendencies in the design of modern aerospace transmissions -- 4. Hlebanja, J., Hlebanja, G. An overview of the development of gears -- 5. Hlebanja, J., Hlebanja, G. Recent development of non-involute cylindrical gears -- 6. H�ohn, B-R. Future transmissions for wind turbines -- 7. H�ohn, B-R., Stahl, K., Oster, P., Tobie, T., Schwienbacher, S., Koller, P. Grinding burn on gears - correlation between flank load-carrying capacity and material characteristics -- 8. Mihailidis, A., Nerantzis, I. Recent developments in automotive differential design -- 9. Miltenović, V., Banić, M., Miltenović, A. Load capacity of worm gears -- 10. Ognjanović, M., Ristić, M. Gear system reliability-based design of gear drive units -- 11. Radzevich, P. S. On fundamentals of the scientific theory of gearing -- 12. Spitas, C. Spitas, V. Towards optimum involute gear design by combining addendum and thickness modifications -- 13. Spitas, C. Spitas, V., Rajabalinejad, M. Dynamical simulation and calculation of the load factor of spur gears with indexing errors and profile modifications for optimal gear design -- 2. Theory, Design and Experimental Researches on Power Transmissions: 14. Alipiev, O., Antonov, S., Grozeva, T. Regarding the effect of the rack-cutter fillet on the undercutting of gears -- 15. Barbaraci, G., Virzi' Mariotti, G. Influence of uncertainties on PD tuning -- 16. Bucur, B., Bolos, V. Comparative experimental study on noise and vibration level of gearbox with worm face-gear with reverse tapered pinion -- 17. Cananau, S., Dobre, G. CAD/CAE approach of the strain and stress static analysis for spur gear pairs -- 18. Climescu, O., Jaliu, C., Saulescu, R. On the efficiency of a planetary speed increaser usable in small hydros -- 19. Darbinyan, H. Surface and kinematical joint formation from standpoint of task based conceptual design method -- 20. Darbinyan, H. Task based conceptual design method for gear chamfering mechanisms -- 21. Dobreva, A. Theoretical investigation of the energy efficiency of planetary gear trains -- 22. Ene, N., Dimofte, F. The influence of the sleeve elastic deformations on the wave bearing performance in heavy loaded transmissions -- 23. Hlebanja, G, Hlebanja, J. Contribution to the development of cylindrical gears.- 24. Ivanov, K., Yaroslavceva, E. Transfer of motion by closed contour - basis of CVT -- 25. Kraynev, A., Salamandra, K., Raghavan, M. Synthesis of the two-stream transmissions -- 26. Laurian, T., Marian, V. G., Prisecaru, T. Experimental analysis of a kinetic energy recovery system intended for small and medium passenger cars -- 27. Mate, C. Z., Faluvegi, E., Cristea, L. Mathematical simulation in center of gravity position and effect of weight for a biped robot -- 28. Nenov, P. Trifonov, T., Velchev, D., Ronkova, V. Irregular speed of rotation in the Hooke's joint - visualization and study of its influence on the value of the forces into the pivot and on the strength of the forks -- 29. Nenov, P., Kaloyanov, B., Angelova, E. Geometrical blocking contours (GBC) as an instrument for high-technology design of geometry of involute external and internal gear drives -- 30. Ognjanović, M. Ristić, M., Vasin, S. Bearings failure of gear drive unit caused by gear resonance -- 31. Radulescu, M. The transmission coefficient of hydrostatic drivers -- 32. Spitas, V. Spitas, C. Design of loboid gear pairs using involute discretization -- 33. Trajcevski, L., Geramitchioski, T. Cams-software program to design and synthesis of cams mechanisms -- 34. Vasie, M., Mundo, D., Andrei, L. New algorithm for variable speed gear generation process -- 3. Product Development, Manufacturing and Metrology:- 35. Buiga, O., Haragas, S. Single-row planetary gearbox gearings optimization using genetic algorithms -- 36. Kurokawa, S., Umezaki, Y., Hoga, M., Ishimaru, R., Ohnishi, O., Doi, T. Application of MEMS technique for micro gear metrology -- 37. Kuzmanović, S., Mitrović, R., Rackov, M., Miltenović, D. Evaluation and choice of conceptual solutions for a universal geared engine reducer -- 38. Mihailidis, A., Pupaza, C. Design optimization of high ratio planetary systems -- 39. Miloiu, G. The numerical calculus of hobs used to cut W-N gears -- 40. Moldovean, G., Butuc, B., Velicu, R. The optimization of the straight bevel gears used in the mechanical transmissions of a PV tracker -- 41. Tudose, L., Kulcsar, G., Stănescu, C. Pareto approach in multi-objective optimal design of single-row cylindrical rolling bearings -- 42. Vladu, M. R., Dobre, G., Mirica, R. F. On evaluation methods in product development. Application on mechanical transmissions -- 43. Ishimaru, R., Sakuragi, I., Izumi, N. A fundamental study on the improvement for chipping characteristics in gear hobbing with carbide tipped hob.- 44. Ivanović, L., Josifović, D., Ilić, A. Modeling of trochoidal gearing at the gerotor pump -- 45. Pozdirca, A., Oltean, A., Albu, C. S. New worm technologies manufacturing on the NC lathe -- 4. Load capacity, structure and components: 46. Aleksić, V., Vistać, B., Milović, L. Methodological approach to recovery of the cracks on the turbine-shaft at hydroelectric power plant Djerdap II -- 47. Arnaudov, K., Karaivanov, D., Dimitrov, L. Some practical problems of distribution and equalization of internal loads in planetary gear trains.- 48. Bostan, I., Dulgheru, V. Development of planetary precessional transmission with multicouple gear -- 49. Faluvegi, E., Mate, C. Z., Cristea, L. Mathematical model of the bevel gears flanks considering the cutting machine type -- 50. Iamandei, A., Miloiu, G. Motor drives of modern drilling and servicing rigs for oil & gas wells -- 51. Ivanović, L., Josifović, D., Ćatić, D., Ilić, A. Testing of the electromotor power transmitter properties --  52. Jelić, M., Atanasovska, I. The new approach for calculation of total mesh stiffness and nonlinear load distribution for helical gears --  5. Maintenance, operating and industrial applications: -- 53. Atanasovska, I., Jelić, M., Mitrović, R., Momcilović, D. The influence of corrosion on stress concentration factor at shaft to flange radius: -- 54. Pozdirca, A. Noncircular planetary gears applied to scissors -- 55. Tica, M., Dobre, G., Barbaraci, G., Virzi' Mariotti, G. Optimal damping constant of the quarter car shock absorber -- 56. Geramitc, T., Trajcevski, L. Vibration impact on life bearings from fan unit for fresh air in Thermo Power Plant REK Bitola -- 57. Onofrei, R., Dobre, G., Mirica, R. F., Pali, M. On measurement and processing data of the real loading. Application to cement equipment components -- 58. Seiciu, P. L. Design of a mechatronic HIOSKI system for recovery of the disabled persons.-  6. Education: -- 59. Miltenović, V., Banić, M., Miltenović, A. The new model of education of product engineer on university of Nis -- Author Index.

This books contains the Proceedings of the 4th International Conference on Power Transmissions, that was held in Sinaia, Romania from June 20 -23, 2012. Power Transmissions is a very complex and multi-disciplinary scientific field of Mechanical Engineering that covers the different types of transmissions (mechanical, hydraulic, pneumatic) as well as all the machine elements involved, such as gears, bearings, shafts, couplings and a lot more. It concerns not only their basic theory but also their design, analysis, testing, application and maintenance. The requirements set to modern power transmissions are really tough to meet: They need to be more efficient, stronger, smaller, noiseless, easier to produce and to cost less. There is a strong demand to become easier in operation and maintenance, or even automatic and in maintenance-free. Last but not least, they should be easily recycled and respect the environment. Joint efforts of specialists from both academia and industry can significantly contribute to fulfill these needs. The main goal of this conference was to bring together experts from all over the world and present the latest developments in the field of Power Transmissions.