In mechanical gear systems, dust, noise, vibration, and tooth wear are generated by frictions among gear teeth, and suppressing friction requires lubrication. Magnetic gears transmit torque by magnetic forces without contact and so avoid contact-related problems. The present paper discusses magnet arrangements and the shape of stationary gear teeth to improve transmission torque in surface magnet type magnetic gear transmission mechanisms.
 K. Atallah, S. D. Calverley and D. Howe, “Design Analysis and Realization of a High-Performance Magnetic Gear,” IEEE Proceedings of Electric Power Applications, Vol. 151, No. 2, 2004, pp. 135-143. doi:10.1049/ip-epa:20040224
 K. T. Chang, D. Zhang, J. Z. Jiang, C. H. Liu and Y. J. Zhang, “Design of a Magnetic-Geard Outer-Rotor Permanent-Magnet Brushless Motor for Electric Vehicles,” IEEE Transactions on Magnetics, Vol. 43, No. 6, 2007, pp. 2504-2506. doi:10.1109/TMAG.2007.893714
 L. N. Jian, K. T. Chau, Y. Cong, J. Z. Jiang, C. Yu and W. L. Li, “Comparison of Coaxial Magnetic Gears with Different Topologies,” IEEE Transactions on Magnetics, Vol. 45, No. 10, 2009, pp. 4526-4529.
 T. Ikeda, K. Nakamura and W. Ichinokura, “A Way to Improve Efficiency of Permanent-Magnet Magnetic Gears,” Journal of the Magnetic Society of Japan, Vol. 33, No. 2 2009, pp. 130-134. doi:10.3379/msjmag.0901RG8016
 P. O. Rasmussen, T. O. Andersen, F. T. Jorgensen and O. Nielsen, “Development of a High-Performance Magnetic Gear,” IEEE Transactions on Industry Applications, Vol. 41, No. 3, 2005, pp. 764-770. doi:10.1109/TIA.2005.847319
 Hitachi, Neomax Engineering, “Development of High Torque Gear (Beat-Max).” http://www.hitachi-metals.co.jp/press/news/2011/n0721.htm
 T. Fujita, Y. Ando, K. Nagaya, M. Enokizono, T. Todaka and K. Sugiura, “Evaluation Test on Prototype Surface Magnetic Gears with Magnetic Flux Concentration and Normal Magnet Arrangement for Practical Use,” Proceedings of Symposium on Electromagnetics and Dynamics, Nagoya, 2011, pp. 86-91.