The upside-down axle causes a major problem. The entire drivetrain was rotating backwards because of it. Since this application was an electric drive, the problem wasn't easily discovered. With the electric motors, if the bus moves backwards when commanded to move forwards, it is merely a simple switch in the controller to remedy the problem. Had this been an engine-driven vehicle, the axle problem would have had to be solved properly for the vehicle move in the correct direction.
The implications of this oversight to the transmission were critical. The transmission was designed to run in only one direction. It could handle reverse only for short durations, due to its oiling system. As the transmission spins the proper direction, some oil from the sump is deposited onto the chain for oiling, but this is not the primary source for lubrication.
The centrifugal force would fling the oil off the chain without ever penetrating the joints. It is this phenomena that is used by the transmission manufacturer to properly oil the chain. As the oil would fling off the chain, it would be channeled into a gutter in the middle of the chain. From the gutter, the oil would drip onto the inside of the chain, and the centrifugal force would push the oil into the chain, properly lubricating it. This oil would the fling back out of the chain, and the process would continue for as long as the chain was spinning. It was very similar to the "bath and disc lubrication."
While running in reverse, the chains simply weren't being oiled properly and were failing in short order. All of the shuttles with this drivetrain had to have their axles flipped over, and the problem was solved.
Sadly, the company no longer exists. Several factors such as the higher price for green technology, internal financial bumbling, and external political factors led to an eventual shutdown. I'm glad to say it wasn't because of the failing transmissions.
This entry was submitted by Chris Clouser and edited by Rob Spiegel.
In the early 90s, Chris Clouser spent three years in the US Air Force, designing and building gas chromatography and nuclear measurement equipment in support of Desert Storm and the Nuclear Test Ban Treaty. After that, he attended Cal Poly SLO and graduated as a mechanical engineer, also studying electrical engineering. He has been heavily involved in aerospace, alternative energy, and ground vehicle design. He specializes in designing large, multi-disciplinary systems involving complex mechanisms.
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