scope:

A planetary gearset is composed of sun gear, planet gears, ring gear, carrier and bearings. As the gearset is in motion under torque, heat is generated at all sliding and rolling contacts for gear meshes and bearing surfaces as lubricant is supplied. Without lubrication the gearset cannot operate properly because all contact surfaces are influended by heat and subsequent damages. On the other hand, excessive lubrication could cause a significant heat generation as churning or dragging losses increase. It is very important to predict a right amount of lubrication required for each component and to supply a necessary amount of lubricant in an effective way. Empirical data of temperature increase inside a planetary gearset at different inlet lubrication temperature, torque and speed are presented with physical explanation. It has been attempted to utilize heat generation data as an indicator for required lubrication measure and also for gearset efficiency measure. Heat generation sources are classified to examine largest and smallest contributors and then project a better way to effective lubrication for the planetary gearset. Some published gear efficiency equations are examined with power loss calculations based on gearset heat generations which are empirically measured in the present study.