New relationships for involute spur gear geometry are introduced and integrated with new methods of orclating
lubricant traction and windage test data. Compact math models for lubricant density and viscosity under contact pressure
are proposed. A modem approach to dimensional analysis is iotroduced to cbaracterize lubricant traction data and gear
windage data with dimensionless terms which apply to gear systems which may have aconfguration and/or size different
from tbose tested. Finally, system considerations for optimal gearbox effciency are proposed.