POWER LOSS OF SPUR GEAR DRIVE LUBRICATED WITH TRACTION OIL

ABSTRACT This paper describes the effect of traction oil on the power loss of spur gear drive. In this study, we measured the power loss of super gear drive using several traction oils. We separated the power loss into gear friction loss and oil churning loss. Furthermore, we measured the surface temperature on the gear tooth by the dynamic thermocouple method, and observed the lubrication condition between meshing teeth by the electrical resistance method. Then, we investigated the relationships between the power loss of the gear drive lubricated with the traction oil, the surface temperature on the gear tooth, and the lubrication condition. INTRODUCTION Traction drive is a mechanism which transmits a power by a shear force of an EHL film between two rolling elements. A lubricating oil used in the traction drive is required to have a high traction coefficient. Therefore, the exclusive lubricating oil, called traction oil, was developed for the traction drive. The traction drive is used as a continuously variable transmission (CVT) combining with a gear drive. In the CVT with traction drive and gear drive, the gear drive is lubricated with the traction oil. Since the traction oil has a high traction coefficient, the power loss of gear drive lubricated with traction oil may be larger than that with the ordinary gear oil. In this study, we measured the power loss of spur gear drive using four traction oils and a turbine oil by the method, which is based on the oil temperature rise due to the power loss in the gear drive. We separated the power loss into the gear friction loss and the oil churning loss. Furthermore, we measured the surface temperature on the gear tooth by the dynamic thermocouple method, and observed the lubrication condition between meshing teeth by the electrical resistance method. Then, we investigated the relationships between the power loss of the gear drive lubricated with the traction oil, the surface temperature on the gear tooth, and the lubrication condition