Abstract
Fluid motion has been investigated to give suggestions for more efficient lubrication feeding with respect to cooling tooth surfaces as early after finishing engagement. A pair of transparent helical gears made of PMMA was immersed in a water tank, which made the tooth space visible during engagement from the inside of the gear. The arrangement also made the speed of gears about 1/10 lower than that in practical gear operation owing to the Reynolds similarity principle. Flow behavior was three dimensionally visualized by using a high-speed camera which shot suspended polystyrene particles or nozzle injected milk. The observation clarified that there are marked sucked flow into tooth spaces just after engagement, which is mainly originated at around mesh ending region of leading side directed against the motion of gear movement and also directed axially toward the trailing side of mesh. However, another flow weakly exists at the trailing side axially getting into the spaces.
