View Full Version : Hit and Miss Steam Engine running with Variable Load
07-17-2009, 05:37 PM
I have been wondering ever since I built the hit and miss version of Chuck Fellows engine, what I could do to present a load that would increase and decrease to show the governors kicking in and out and affecting the "Hitting" and the "Missing" of the engine. I believe I have come up with the answer to that in the attached video. There is a slight offset delay between the load being presented to the engine and the change in the firing pattern, but I think that is either because the governor needs a bit of time to react to the engine speed, or possibly because when the engine "Hits" the drive belt slips a bit. It is an interesting video, and the package will show well at a steam fair when I run it and all of my other engines and the machines they drive.---Brian
07-17-2009, 06:00 PM
After years of attending the NAMES expo, seeing a multitude of steam, air, hit-n-miss engines, yours, with the variable load is impressive. Most of the NAMES exhibitors set their engines running at some steady speed, or start and rev it a few times then shut down. You present an excellent demonstration of governor action. Good job!
07-18-2009, 02:08 AM
I don't think yours is of the size I see at a "fair" I have been to that has full size, originals, that have maybe a corn sheller driven that DO see a load.
Freewheeling, they will run till governor says close valves, pop a couple times to satisfy governor, then run till needed to rev again.
I have not watched the video, so, what of a small generator and light bulbs for load? The lights dim, indicates the gen is running slower, pop a few times, get the flywheel back up to speed, and the lights are full bright again.
07-18-2009, 10:10 AM
i think the delays you're seeing are due to your load. as an example i'll use a water pump i have hooked to an old Fairbanks hit-n-miss engine. the engine hits until it gets up to speed and the water pump gets up to pressure. the engine then misses for several revs until the water pump puts a load on the engine again and it slows down and hits. the water pump is basically a constant load since it is always pumping (it is pumping water up a 30' incline through a 3/4" pipe). as soon as the engine starts missing it starts slowing down due to the constant load.
on your engine the unbalanced flywheel you are driving is actually driving the engine until the unbalanced side starts rotating upwards. my guess is what is happening is that as the weight rotates downwards, it is actually over-revving the engine (not a problem on your air-powered model engine, but could be a very real concern on a full-size engine) and the inertia from your driven unbalanced flywheel lets the engine keep missing until the weight gets partially through the upwards rotation. if you had a constant load on the engine it seems as though it would function closer to the way an actual hit-n-miss engine functions.
for a display engine to show the effect of the governor, i think it is a very good representation. most folks who have never played with a hit-n-miss engine wouldn't even notice the issue with your model. on your model it is very easy to see the governor weights locking in and out to control the speed. i think it looks pretty cool!