Two-shaft planetary gear drives are power-branching transmissions, which lead the power from input to output shaft on several parallel ways. A part of the power is transferred loss-free as clutch power. That results in high efficiency and high power density. Those advantages can be used optimally only if an even distribution of load on the individual branches of power is ensured. Static over-constraint, manufacturing deviations and the internal dynamics of those transmission gears obstruct the load balance. With the help of complex simulation programs, it is possible today to predict the dynamic behavior of such gears. The results of those investigations consolidate the approximation equations for the calculation of the load factors...

One of the hot items on the public agenda these days is "The Environment." Suddenly everyone wants to save the whales and the rain forest. Politicians, rock stars, and big business have all discovered that you can't get anything but good press for saying that you're in favor of trees and marine mammals.

Mechanical efficiency is an important index of gearing, especially for epicyclic gearing. Because of its compact size, light weight, the capability of a high speed ratio, and the ability to provide differential action, epicyclic gearing is very versatile, and its use is increasing. However, attention should be paid to efficiency not only to save energy, but sometimes also to make the transmission run smoothly or to avoid a self-locking condition.

The effect of various lubricant factors on wormgear efficiency has been evaluated using a variety of gear types and conditions. In particular, the significant efficiency improvements afforded by certain types of synthetic lubricants have been investigated to determine the cause of these improvements. This paper describes broad wormgear testing, both in the laboratory and in service, and describes the extent to which efficiency can be affected by changes in the lubricant; the effects of viscosity, viscosity index improvers and, finally, synthetic lubricants are discussed. The work concludes that lubricant tractional properties can play a significant role in determining gear efficiency characteristics.