EXPERIMENTAL ANALYSIS OF HIGH-SPEED GEARBOXES

With the rise of rotation speed of the gears in the gearboxes several phenomena that can significantly affect the gearbox energy efficiency and reliability occur. A lot of experimental data is available in literature for peripheral speeds below 40-60 m/s. But above this value some load parameters are changing their trends so this value can be classified as a limit between low and high-speed application. The main causes of power loss in gearboxes are tooth mesh losses, bearing losses, churning, windage, oil pocketing and gear drag. Some literature shows that windage losses which occur due to sliding friction of the high-speed gears in the oil-mist environment in the gearbox housing can be up to 30% or even more of the entire gear drive meshing losses. The phenomena of squeezing out the oil from the gear meshing area can also add more power losses in the system. In the worst case when the backlash is very small, these phenomena can even create oil blockage. Some problems with hydrodynamic losses due oil retaining in some housing pockets can also lead to lower energy efficiency. All of the mentioned hydrodynamic losses are negligible in the low-speed gearboxes, but in high-speed gearboxes they can exceed basic gear teeth meshing losses and even become larger.