Basicly, after taking a short introductory class at the local tech college, I was allowed to use the machines but was kinda (voluntarily) on my own. Reason being the teacher there was an increadable character... a mad genious of a machinest who couldn't approach a question with a straight answer to save his life, but rather had a penchant for laying out miles of colorful, metaphore filled stories before getting to the point. It was always very intertain. That was on his good days. On his bad, he had a tendensy to throw down his hat and stop around by way of an answer. So most of my machining questions were answered by myself smiply by conteplateing deeply into a coffee cup.
One of the early challenges I had to solve for was designing a slip eccentric. A Stephinson link designe is pure genious, but not without complicated trade-offs of it's own. To me, there's just too much metal flopping around to get the job done and I reasoned that the relationship of this particular engine to the hull would tend to require the engine to opperate at a long cut-off most of the time anyway. Being as the type of slip eccentric that I had in mind required having to stop the engine in order to shift, presented a delima.
The problem is that the side paddle wheel would not want to stop while underway without the complication of a brake mechinism so I had to contrive an eccentric that would shift on the fly.The solution presented itself with the idea of going about things in reverse. Rather then stopping the engine and slipping the eccentric around to reverse position, the eccentric is stopped and the crank rotates around to position .
The motion of the slip eccentric is simple although it's components look complex and it's lines harken back to the victorian moteif. Basicly the eccentric attaches onto the back of a large valve hand wheel which freewheeles around the crank shaft. The hand wheel / eccentric is all held in place by a pivoting , spring loaded A-shaped pin-capturing piece that looks like the Eifel Tower ( The spelling of which is probably as far off as France is to Quebec ) The Eifel Tower (shall we say) pivots on the axel that is held in place by a piviting arm fixed to the crank shaft. This in turn captures either one of two pins that cause the eccentric to be in forward or reverse relationship to the valve. By actuating a lever off to the side, two things happen: 1. A wooden brake shoe ingages the hand wheel and stops it spinning just at the exact moment that.... 2. An adjacent nylon striking wheel trips the eifel tower and causes it to dump a pin fixed to a plate that is attached to the hand wheel. Once the pin is dumped, the eccentric simply stops in place while the crank rotates the rest of the show around to the reversing pin. The one drawback is that the engine has to be throttled. But that's o.k. Throwing a bunch of heavy motion at full ahead suddenly back in to reverse is kind of a mean way to treat metal anyway.
