- Jul 2, 2021
- Reaction score
- MidSouth, USA
Well that clears it up........NOT !Yes, The Cutoff function was only used in forward motion.
when the engine was reversed, the cutoff bypass valve would be opened and
that effectively meant the cutoff eccentrics and cutoff valve were inoperative.
So at the 1 minute mark, the main eccentrics are being rotated 180 degrees for reverse and if you look at the cutoff valve rods right behind, you see no motion. The cutoff eccentrics are fastened (keyed) to the reversing shaft, while the main valve eccentrics are really "slip eccentrics".
You could adjust the main valves somewhat and give them "Lead" . The quadrant gears turned the main eccentric ( pinion) and stopped when the key was met/engaged with the pinion gear fastened to the main eccentrics. ( see 1.00 to 1.20) -
Now "if" the quadrant gears rotated the pinion , but stopped short of the key, the engine would reverse and run , but then had lead on the timing. Of course the penalty for doing that was the reversing shaft transmitted power to throwout bearing which then passed it to the quadrant gears ,which then transmitted it to the Pinion gear fastened to the eccentric . That does work but involving the whole mechanism means excessive wear of all those components. Normally, the pahse changing mechanism has no load on any component during running operation, only during the actual changing of direction do they see load
Hope this helps
Its not that Rich didn't explain it, it is that my limited brainpower is having a lot of trouble seeing it in a comprehensive fashion.
This is not a simple valve gear mechanism/engine operation, in my opinion.
I will start a new thread about my general approach to understanding valve gear, so as to not clutter up this thread.
I became interested in steam engines at a young age, as I assume as many folks did, by operating a Wilesco steam plant and engine, which was a single-action oscillating engine. I went so far as to build a boiler and single-acting steam engine for a 12 grade science project. Most folks who saw...