Tham khảo tài liệu 'gear noise and vibration episode 2 part 4', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | 200 Chapter 11 Reference 1. Romax Ltd. 67 Newgate Newark NG24 1HD. Copyright Marcel Dekker Inc. All rights reserved. Marcel Dekker Inc. 270 Madison Avenue New York New York 10016 12 Planetary and Split Drives Design philosophies The conventional parallel shaft gear drive works well for most purposes and is easily the most economical method of reducing speeds and increasing torques or vice versa . The approach starts running into problems when size and weight are critical or when wheels start to become too large for easy manufacture. If we take the torques of the order of 1 MN m 750000 Ibf ft that are needed for 6000 kw 8000 HP at 60 rpm we can estimate the wheel size for a 5 to 1 final reduction. The standard rule of thumb allows US about 100 N mm1 per mm module so assuming 20 mm module DP gives us a wheel face width of about 450 mm and diameter of m. This is not a problem but if the torque increases we rapidly reach the point where sizes are too large for manufacture and satisfactory heat treatment especially as the carburised case requữed thickness also increases. The solution is to split the power between two pinions so that loadings per unit facewidth remain the same but the torque is doubled. The further stage in this approach is to split the power between four pinions to give roughly quadruple increase in torque without significant increase in size. This fits in well if there is a double turbine power drive which is often wanted for reliability. The design is as sketched in Fig. . Power comes in via the two pinions labelled IP splits four ways to the four intermediate wheels IW which in turn drive the four final pinions which mesh with the final bull wheel. The resulting design is accessible and reasonably compact though at the expense of extra complexity in shafts and bearings. To achieve the gains desired with power splitting it is absolutely essential that equal power flows through each mesh in parallel so as there are
