Slow speed performance

Joecaboose said:
How can I improve the slow speed performance on my Roundhouse Forney?
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SloMo is what you need, but not sure if you can get one for that loco. Have a look or chat to the owner of this site.

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smallsteamperformance.com.au smallsteamperformance.com.au
This link to my RH steam tram chassis under test shows the results, the slight whine you hear is the gearing in the device tends to only be noticeable at higher speeds.
 
Practice and as Tony said “Turn the gas down and run at 20psi”.
I have a good number of Roundhouse live steam locomotives and each has its own idiosyncratics. Plenty of practice and experience can lead to slow and smooth running.
 
Almost the same result can be achieved by good loco management, i.e. running at a pressure well below whatever the safety valve is set to blow. Much cheaper, and achievable without modifying the loco. Slomos are certainly clever and well-made, if a tad noisy for my personal liking. Are they unbeatable? Certainly not. I've installed several, and it is true to say that they make a major change to a loco's performance characteristics.
 
Rhos Helyg Loco Works said:
Almost the same result can be achieved by good loco management, i.e. running at a pressure well below whatever the safety valve is set to blow. Much cheaper, and achievable without modifying the loco. Slomos are certainly clever and well-made, if a tad noisy for my personal liking. Are they unbeatable? Certainly not. I've installed several, and it is true to say that they make a major change to a loco's performance characteristics.
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Tony, honestly, some very interesting points, which I cannot disagree with (mainly because I do not have Slomo), but you last line (it is true to say that they make a major change to a loco's performance characteristics.) almost seems to argue for their virtues. :)
 
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Rhos Helyg Loco Works said:
Almost the same result can be achieved by good loco management, i.e. running at a pressure well below whatever the safety valve is set to blow. Much cheaper, and achievable without modifying the loco. Slomos are certainly clever and well-made, if a tad noisy for my personal liking. Are they unbeatable? Certainly not. I've installed several, and it is true to say that they make a major change to a loco's performance characteristics.
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Well we must agree to disagree. i have no issue with that.

For my part running up to a set of stock and “kissing” the buffers without a nasty bang or shoving stock back a few inches is possible but difficult to achieve reliably without a lot of hard work and yes practice without a SloMo. I run my live steam rarely so am unpracticed with driving techniques. Thus I find that the SloMo gives me the unbeatable, reliable, believable control that I like and want when I use them
 
Unless you are prepared to install a Slo-mo device in each loco - something that might be painful to your pocket but will surely please the makers - the other option, taken up by some - is to install it in a wagon of some kind that will always be part of the consist.

Or, as Mr Rhos Helyg notes, effect more control over your locomotive by turning down the gas.
 
tac foley said:
Unless you are prepared to install a Slo-mo device in each loco - something that might be painful to your pocket but will surely please the makers - the other option, taken up by some - is to install it in a wagon of some kind that will always be part of the consist.

Or, as Mr Rhos Helyg notes, effect more control over your locomotive by turning down the gas.
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Agree Tac, I have 2 Roundhouse locs fitted the others are geared drive so slomo not required.
 
Joecaboose said:
How can I improve the slow speed performance on my Roundhouse Forney?
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For improving the performance do you mean it will not run slowly or does not have much power at slow throttle settings? My Roundhouse Forney has always been a good slow speed performer, excellent for shunting. Fitting a SLOMO is academic in this case, as the Forney has inboard eccentrics and valvegear, between the frames. Turning the gas down and run at 20-25psi would be worth a try. Also see if the valve events are okay. Roundhouse have some instructions on their website at Forney Valve Gear My Forney did require new o-rings on the pistons a while ago, the originals having become hard and worn. Your piston o-rings may have gone hard with time as 10 hours usage is fairly low.
 
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mike bickford said:
For improving the performance do you mean it will not run slowly or does not have much power at slow throttle settings? My Roundhouse Forney has always been a good slow speed performer, excellent for shunting. Fitting a SLOMO is academic in this case, as the Forney has inboard eccentrics and valvegear, between the frames. Turning the gas down and run at 20-25psi would be worth a try. Also see if the valve events are okay. Roundhouse have some instructions on their website at Forney Valve Gear My Forney did require new o-rings on the pistons a while ago, the originals having become hard and worn. Your piston o-rings may have gone hard with time as 10 hours usage is fairly low.
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Ah there is the rub, inside gear is the killer to any slomo conversion. Not had a look below a Forney so not aware of that as an issue. Some time back I was twitching on buying a Roundhouse Garratt, a SloMo for me was a must but when I looked below it would have been impossible to fit a SloMo due to the run of the main steam pipe. Hence I do not nor ever will have a Roundhouse Garratt.
 
My understanding of the principal of a Slo-Mo is that it uses an overdriven flywheel to smooth out the power delivery. But given that nothing is for free in this universe, doesn't the energy required to activate the device have an adverse effect on the available drawbar pull - and wouldn't exactly the same end result be achieved by simply loading up the loco with more rolling stock, rather than driving a flywheel with its associated gear train and bearing friction?

BTW - has anyone done a spring balance drawbar pull comparison - both with and without the device - all other conditions being equal?
 
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Yes, same thing by adding mass, but drawbar slack/wheel friction would not be as "smooth" as something directly geared to the power plant.

So from a theoretical standpoint yes, from an implementation/practical expression probably not.

But of course then the challenge of controlling the loco.

Be sure to remember that the flywheel is using momentum, not resistance to achieve this, so a slow application of power would most likely not affect drawbar pull significantly, in fact the added system momentum is what makes the slow speed performance "smoother".

Greg
 
Trainman 864 said:
My understanding of the principal of a Slo-Mo is that it uses an overdriven flywheel to smooth out the power delivery. But given that nothing is for free in this universe, doesn't the energy required to activate the device have an adverse effect on the available drawbar pull - and wouldn't exactly the same end result be achieved by simply loading up the loco with more rolling stock, rather than driving a flywheel with its associated gear train and bearing friction?

BTW - has anyone done a spring balance drawbar pull comparison - both with and without the device - all other conditions being equal?
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Have not done precise calculations but I have a short section of 1:25 grade on a 4ft radius curve and the pulling power of my Roundhouse Jack and Ted is much the same on the section before and after SloMo fitting.
 
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