Machine efficiency plummets during reverse-drive operation.

Other
1

Good morning.

I reversed the helical planetary gearbox (https://www.oyostepper.com/category-199-b0-Helical-Planetary-Gearbox.html) to use it as a speed increaser, connecting the low-speed end to the turbine and the high-speed end to the generator. The result was a 10% lower power generation efficiency than calculated, severe overheating of the gearbox, and oil temperatures easily exceeding 100°C.

I suspect that the helical gearbox is operating like a “turbine” during reverse drive, reversing the axial force direction. The bearings that originally bore the thrust are now bearing the reverse tension, leading to a dramatic increase in bearing friction loss.

The thrust bearing wasn’t selected to handle bidirectional forces, and replacing it now is too late.

Could adjusting the oil viscosity temporarily alleviate the problem, or could an auxiliary thrust disc be temporarily installed to share the reaction force?

2

Is using a gear reducer of some kind instead an option?

I’m kind of a simple creature for stuff like this but I might add a cooling apparatus or a large secondary oil tank (AKA the ‘German carmaker approach’) as a workaround until finding a more permanent solution

Using a coupler with a bushing/shock absorber might help a bit as well (to attempt relieving some off-center and velocity-change stress/strain)

3

I wouldn’t expect a helical gear reducer to be very efficient when reversed, and a web search revealed several manufacturer comments explaining why doing so is not a good idea.

See for example https://www.rjlink.com/speed-reducer-speed-increaser/