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WORK IN PROGRESS
I'm currently in the process of turning this work into a paper so this will be quite abridged.
A traction drive transmission is one that uses an electrohydrodynamic (think a fluid that freezes when pressed into a gap) layer between two moving surfaces to transmit torque. In our case we are using a planetary roller configuration, you could think of it as a tapered roller bearing being used as a planetary gearbox.Â
The novel part of this work is the method of preloading. Typically, one would use a spring to preload this sort of gearbox but in this case we are using the thrust already present from a ships propellor. Additionally, the drive can also potentially replace the thrust bearing itself.
A graduate student in my lab (Trevor Murphy) did much of the modeling for this design before I joined the project. Most of my work centers around finishing up the final odds and ends of that and then designing and conducting testing to validate various aspects of the model in reality.
A cutaway of a 3:1 planetary roller drive model.
Static Testing
This testing was done to confirm that the linear torque-thrust relationship our model showed was accurate.
Dynamic Testing
Dynamic testing was done to confirm the theory that thrust could help preload and extend the torque capacity of the drive. It also provided some qualitative indications that our modeling was correct.
An earlier model built for dynamic testing. (Photo from T. Murphy)
A later test setup for dynamic testing with integrated sensors.
Stiffness Testing
This would done to get a rough estimate of rotational stiffness.
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