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Continuing with the theme in my previous email, I spent some time to dis-assemble my PSRU, to see what it was really made of. The design boils down to a planetary gear set welded to the wheel hub of a NASCAR racing car, and held to the engine with custom cast aluminum (LOTS of custom cast aluminum).
This was put together several years ago, and loosely based on the Ross unit. There have been several lessons learned since the Ross units started flying, and I want to make sure I incorporate those lessons into any modifications I make.
The first question I have concerns the reaction forces from the planetary gear set. If I understand the mechanism correctly, as the helix teeth on the sun gear engage and turn the planets, there is a considerable force trying to push the sun gear out the back of the unit. This force will be taken up by the eccentric shaft and destroy bearing in the engine unless steps are taken to handle it in the PSRU. Tracy's solution has been to add a properly rated bearing at the back of the sun gear, if I'm not mistaken.
The unit I have has a set of ball bearing at the rear of sun gear. They look to be really heavy duty bearings, but I couldn't find a part number and didn't want to take the chance of damaging them while removing them from the housing. Any guesses from the group on whether this setup will stand up to the reaction forces or not?
The first picture below shows the back of the PSRU with it's rear cover removed. The shaft engages the clutch plate. The second picture is from the other side, and depicts how the sun gear sits in the center of the ball bearing housing.
PSRURearThrustBearing.jpg
PSRUSunGear.jpg
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