Planetary gear systems are widely used in helicopter transmissions, aircraft turbine engine reduction gears, automotive automatic transmissions, and many industrial applications. Because of the multiple load paths of planetary gearing, the horsepower transmitted is divided between several planet meshes and the gear size can be reduced significantly, compared with parallel shaft designs. In addition, planetary stages can be linked together to achieve high ratios. Hence, the use of planetary gearing is an efficient method of achieving high reduction ratios in minimum space. Planetary gear systems are compact, resulting in significant envelope and weight savings; they have reduced noise and vibrations and improved efficiency because of smaller, stiffer components, and they have concentric input and output shaft axes and only transmit the torque.
Return to article
Last updated: July 21, 2005 11:01 AM
Responsible NASA Official:
Point of contact for NASA Glenn's Research & Technology reports:
Web page curator:
Wyle Information Systems, LLC