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Super Modulator
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Greg, I am in contact with Dave. He is not sure he has any parts left but he said he would look. I've seen the bicycle speedometer type and I made up a spread sheet for several different scales that gives you the speed when you time a train over an 18ft (three 6ft sections of flex track) distance. What I would like is a portable unit that does not need to have a special car in the consist. Though I run mostly 1/32 scale I do have some 1/20.3 scale and 7/8 scale so I would like to be able to change the scale speed read out, which I understand Dave's unit can do.
The one I have from Dave has 1:20.3, 1:29, 1:32...
 

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Discussion Starter · #24 ·
Yes the same as what I have. I'm just building a "mount" for it that doesn't look to obvious.
 

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Some of the problem is dealing with physics that you cannot scale down. The expansive power of steam is huge, but our models lack the mass tonnage of the real locomotives. Which helps temper that expansive power at slow speeds. We crack open the throttle and its off to the races, real ones just start easing into motion(having cylinder cocks open helps as well do remove any condisation in a full size locomotive). The SSP Slomo inertia device comes the closest to making a model behave like a real locomotive. I have been on and fired both Cass Scenic Shay 2(many many years ago) and NKP 587 back when it was running. The Slomo gives the model the inertia of simulated weight by using a gear reduction unit with a flywheel. I am all for realistic running speeds. Nothing spoils the look of so many of these beautiful gauge 1 and G scale locomotives that watching them run at warp speed and looking like a runaway train. The engine drivers that learn their engines and keep speeds in check, have my deepest respect and admiration.
 

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Have to agree with Mike, while weight scales nicely, the frictional losses, and power and control does not. The gearing down and adding rotational mass to increase apparent momentum sure looks effective from all the videos I have seen.

I think turning the pressure down works on very high quality mechanisms, but try to make a ruby run slow!

Greg
 

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Rod locomotives are a bit more difficult but still doable. While adjusting speed the boiler pressure rose to 60. Still able to creep with only throttle control and no load. Don't own a Ruby, but have seen them creep at gatherings. None of my loco's have the fine throttle control modification.
 

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One also cannot just turn down the fire on most Alcohol fired engines, so just turning down the fire rate is not a cure all. One can mess with the wicks but there is a limited to what one can do there as well. The problem is usually worse with light engine or little to no load to pull. Putting a decent load on the draw bar is the only way to slow down some engines, such as my Bowman 234 4-4-0 in O gauge. Even with 2 of the 6 wicks capped off, its a race horse with lots of power if you try to run it by itself. Needs several heavy tinplate coaches to tame its power(there is NO throttle on these pre WWII tinplate live steamers). You only methods of speed control is capping wick tubes prior to the run or just keep adding coaches or wagons till the speed is under control.
 

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Mike, I agree, slower running locos do have a special charm. Alcohol and coal fired loco's do produce more heat, thus more steam vs gas. As can be seen in the video the boiler had 60lbs pressure, and release valve had started to activate. I don't have an alcohol or coal fired loco so don't know if they designed to run on more pressure, can someone help with that? If so speed control may be more difficult, and I never considered those with no throttle control. So I guess 'gas' fired loco's do have one advantage, easier to run closer to scale speed.
 

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Nick,
As far as alcohol locos, as you know, they will run at whatever pressure the safety valve is set at.
Of course if you have it set low, and the fire can produce enough heat for a higher pressure, you will be blowing off continuously.
As far as speed control, it all depends on the loco, and the load it is pulling.
Here is my 9F, with small wheels and a nice heavy train showing that alcohol fuelled locos can run nice and slow at a scale speed.
Cheers,
David Leech, Delta, Canada
 

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David, a great track set up, that loco is beautiful. And it can be run at scale speed with a load. Are those voluminous plumes due to the alcohol fuel or the weather at your location on that day?
EDIT: further research shows water vapor is a by product fo burning alcohol, a benefit of that type of loco.
 

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David, a great track set up, that loco is beautiful. And it can be run at scale speed with a load. Are those voluminous plumes due to the alcohol fuel or the weather at your location on that day?
EDIT: further research shows water vapor is a by product fo burning alcohol, a benefit of that type of loco.
Nick,
I am very fortunate to have had a garden that I can fit the railway in.
It was a cold January day, hence the nice plumes of exhaust.
Just above freezing, but in 'normal' summer weather you don't see any of it.
Too bad.
Cheers,
David Leech, Delta, Canada
 

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David, since I use a Butane/Propane mixture I should get out there more in the colder months. The beautiful plumes are sure worth the look. Thank you
 

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If you look at films of real locomotives in action, you usualy can see the rods turning over at a leisurly pace, if rods start to blurr you are running too fast. In the real world rods crosheads and pistons are so heavy that they will generate hammer blow. On tests of locomotives with throtles wide open lounched onto greassed track acheived running at incredible rotational speed and actually had their drivers lift of the rails; although they were charged with up to 35 tons per axle! This is what limits the speed at which an engine may run in the real world. Too often I see folks running a freight engine at 90 to 100 Mp/h speeds, which is awfull.Running trains at a realistic pace can be done though, it is usually like on the prototypes a question of adapting the train weight to the loco.
By the way the 9 F were with the Nord 150 B and P class notorious for being the fastest 2-10 -0 in history i beleive. You did get that wonderful smoke effect Davidand a beautiful run.
 
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