Office of Steam Forum for Model & Toy Steam Gas & Hot Air Engines

I said in an earlier video I would do an S10 Mill Steam Engine update and some more information on the Governor in another video.

Yo Jim

What you are fighting is simple physics here. The flyballs on the Polish School Engine probably weigh about 100 times what those tiny flyballs on the S-10 weigh, so your S-10's governor is lacking enough centripetal thrust to overcome the friction in the linkage, along with the governor spring compression modulus, which combined is likely only a small fraction less than the total friction of the Polish School Engine's linkage and return spring loading.

Lightening the spring compression on your governor would certainly help some, and break-in working (lapping as Gil suggests) of all the linkage joints to the best advantage will help gain some chance for your governor to do its job. But in reality, you are working against the "Scale Effect" that is so often encountered when either reducing or increasing the size of something that does work in a given size range, but may not in another scale.

@Jim

Well, alrighty then, I'm thinkin' it's time for a bit of a physics lesson that might help to get that little S10's governor functioning as it is intended ..... or not?!?!

Here's the base line deal on that little puppy. It is just too small to overcome the friction in the system to be able to perform properly.

Where it is too small is in its mass. The flyballs simply do not weigh enough to "throw out" and actuate the throttle control linkage, over the spring compression resistance and linkage friction.

So perhaps there are a couple of approaches to this issue that can "cheat" the scale effect that is preventing the governor from doing its job.

The first one that comes to mind is to somehow make the flyballs heavier. Make them out of gold, platinum or even spent uranium. Doing so would about double their current weight, which would certainly help them to perform better, but might not be quite enough to crack the nut. Perhaps a better idea would be to add weight to the existing balls by drilling them and attaching larger, heavier and far cheaper brass balls, via threaded rod or rod and solder to the outside of the existing flyballs. Actually, the added material wouldn't necessarily have to be in the form of a ball, just so as a significant increase in weight was realized at the flyball linkage hinge joint, to assist in helping what minor centripetal force is generated by the governor's rotation, to throw the balls out and thus activate the linkage to the throttle.

The next concept that could work to improve the governor's function would be to increase the leverage by lengthening the "arm" that the flyball is attached to, as is the case with the governor on the Polish School engine. To be very successful at this approach, it might be best to modify the S10's governor so that the extended arms went up to allow more room for increased length, as opposed to down where room is at a premium as it is currently configured. In other words, it would be best if the flyball was on an elongated arm that extended far beyond the scissor hinge point that is currently the flyball itself. In that way you could combine these first two suggestions of having a much heavier ball, or other shape, that was farther out on the pivot arm thus multiplying its leverage significantly. This option would require an extensive rebuild of the governor as provided but would likely offer a real chance at making it work!

Finally, if you don't wish to make the above-mentioned major modification, there is one other possibility that might be considered. Perhaps making a different, larger pulley to drive the governor so that it spins much faster could provide the extra force needed to overcome the inherent friction in the too small scaled system to gain operability. If you will recall Einstein famously stated E=MC² such that if you can double the speed at which those flyballs are spinning, you will have effectively increased their weight by a factor of four! By using a set of pulleys that would up-gear the RPM three times, you will have effectively increased the apparent weight of the flyballs by a factor of nine!!!

Perhaps a combination of all three of these techniques would actually make that governor function properly and reliably, but the bottom line remains, you really can't cheat physics through perfectly scaling something that seem like it ought to work otherwise.

Hope this provides some food for thought!?!?