Flyball governor plans

[Brian Rupnow]

This is kinda what I had in mind (no valve yet).--The 2 red cylinders are 3/8" sealed ball bearings

 

[tel]

Tel--Only for you, I put the spring in ;D

There's no reason that shouldn't work - just make sure your belt pulleys increase the speed at the governor by at least 3:1. AND you get away from cutting the dreaded bevel gears.

 

[tel]

Now the innards of the valve section should look something like this - lousy drawing, I know, but I can't be good at everything

And, after pondering those castings - here's about 5 mins worth of roughing out on a valve body. they'd be quicker and easier to build from scratch, I feel.

 

[Brian Rupnow]

Okay Tel--There we go--Valve block added, pulleys changed to give 2.5:1 ratio---The slightly larger balls (1/2") will compensate for the ratio not being 3:1

 

[tel]

Now yer cookin' mate! The 2.5:1 ratio will probably be quite ok, especially with the heavier balls. Just don't be tempted to make 'em out of aluminium

 

[mklotz]

Color me clueless but, if this is going to be a working governor (as opposed to purely decorative), won't you need a means of adjusting the spring preload so you can set the speed at which the engine runs?

 

[tel]

A bit of trial and error with a small pair of side cutters does that part nicely Marv.

 

[potman]

Cool addition to your engine Brian. Really adds to the mechanics but, I see a potential problem...

In your drawing it looks like the belt is coming off the governor pulley at quite a steep angle. It may not want to stay on the pulley. Perhaps an idler pulley or belt guides or something might be in order.

BTW: I really appreciate the effort you have gone through to share this design and build with us. I know it's took a lot of extra work and I thank you for it.

 

[Brian Rupnow]

Color me clueless but, if this is going to be a working governor (as opposed to purely decorative), won't you need a means of adjusting the spring preload so you can set the speed at which the engine runs?

You make a very good point Marv. Its just that at this stage of the game, I'm not certain how I would go about doing that.--However--If you would like to share some wisdom, I'm listening----Brian

 

[jack404]

Brian

if its any help

a real governor near me on a traction engine has a threaded shaft with a ball on top and a small lock nut ( very thin) under the ball to adjust it they loosen the thin lock nut and turn the ball on the thread up or down to suit.

maybe this can be scaled to fit your model , i dunno

this is from a 1909 herculese traction engine thats in the museum near me

cheers

jack

 

[tel]

To quote H.Muncaster, in his 1912 treatise on Model Stationary Engines -

.... the governor is fitted with a spring. This can be made to give the required power, within reason. It will be best to make a trial with springs of various strengths .....

In essence, experiment with springs of various length and wire gauge until you get a pleasing output speed at the engine. It is not as if the governor on the model can serve it's 'real' purpose of preventing the engine from over-running and shattering itself to flinders - 99% of it's function will be decorative, as the speed can more readily be controlled by the use of the steam valve, or shutoff. The couple of 'working' governors I have made have worked - that is, you can open the steam valve right up and still have the engine running at a sensible speed, however, in our sizes, this achieves little, other than to look really impressive when the thing is running.

 

[Brian Rupnow]

Tel---You bring up a very good point. I have nothing to compare this to other than experimenting with the engines I have built in the past year. I know that when I turn my pressure regulater down very low, (6 to 10 PSI) my engines will run very slowly and quietly, but they have very little power and can be "stalled" by finger pressure against the flywheel. If I crank the regulator higher, the engines have proportionally more power, but tend to rev their guts out, to the point where I am afraid they will "throw a rod". Where am I ultimately going with my quest??? Well, I would like to use my horizontal twin engine to run SOMETHING which presents a variable repeating load. When there is low load, I want the engine to run at a fairly constant, "medium" speed. Any load at all will slow these engines down considerably, so I would probably run 30 PSI, but the throttle restrictor valve (part of the governor mechanism) would restrict the FLOW so that the engine wouldn't "run away". In this state, the governor would be "balls out". When the load on the engine begins to increase, the engine will slow down, the balls will begin to take a "balls in" attitude, and this will cause the throttle restrictor mechanism to open, thus supplying a greater flow of air to the engine, thus making it speed up to a point where the balls fly "out" again and restore the speed back to my "medium" speed that I want to achieve as a constant. I layed in bed last night trying to visualize all of the sequences involved here. It seems that when starting one of these engines controlled by a governor, they would immediately rev up untill the balls flew "out" and restricted the flow to keep them from running away. I am doing some preliminary design "imagineering" where the engine belt drives a Geneva mechanism with a fairly massive ratio thru an o-ring drive. When only the constant revolving portion of the Geneva mechanisn was revolving, that would be the "low load" scenario. When the constant revolving portion of the Geneva mechanism engages the star wheel to turn it, I would have a friction brake on the star wheel portion of the Geneva mechanism , and this would be the 'high load" scenario. It would be nice to have a sensitive enough governor that you would be able to see it function and see the effect it has on the engine as it cycles through repeated revolutions of the star wheel.

 

[Maryak]

Brian,

With the scenario you are describing and using a flyball governor, I have a gut feel that what will be achieved is strong "hunting" of the governor mechanism, out of sync with the Geneva mechanism. These types of governors are not designed to cope with rapidly changing loads due to the inertia inherent in the system. : :

Sorry mate, I hope I haven't put a damper on things and I hope I am wrong.

Best Regards
Bob

 

[Brian Rupnow]

If you ever wondered how a Muncaster flyball governor worked, they were a bit different. There was a pivot point right at the balls themselves, and when the balls flew out under centrifugal force the sliding yoke at the bottom moved quite a lot--about 5/8" on this unit, which has 1/2" diameter balls on it. This was originally designed, by Muncaster, I assume, to work on model steam engines. The lever would pivot as shown, and a control rod ran from it to a butterfly valve which opened and shut to turn the steam supply on and off. I find that by by modelling these things, it gives me a much better understanding of exactly how they work. My information for modeling this governor came from an article published in 1957 in "Model Engineer".

 

[Brian Rupnow]

There are some great pictures available of a "Silver Angel" hit and miss engine, and it shows the flyball governor which moves a lever to hold the exhaust valve open so that the engine will not fire untill it slows down a bit and the govenor will collapse and allow the exhaust valve to close, thus causing compression so that it will fire.

 

[Stan]

Brian: It sounds like you want to get into engine design is a serious way. You have to know the load before you design the engine. Big bore - short stroke for quick response and small bore - long stroke for high torque. Then you design the flywheels to work with the pistons.

At this stage, to compensate for small changes in load, just increase the flywheel weight. The governor is just to hold the speed over the average load.

 

[tel]

Here's an interesting, and to my mind practical, variant of the Muncaster - one that screws directly to the end of the crankshaft.