Improving Mamod & MSS Performance

A very popular starting point for Live Steam. With their low cost comes a number of problems which can be discussed here
Abiogenesis
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Re: MSS loco on 4' diameter curves ?

Post by Abiogenesis » Sun Jul 08, 2018 2:37 pm

CSL,

Have you any further news about the hauling capabilities of your loco? Whilst the standard safety valve blows off at 15 psi, there is an upgraded version to 20-25 psi which should help matters.

https://www.dreamsteam.co.uk/mss-mamod- ... valve.html

Both my Mamods are gas fired (70% Butane 30% Propane) for safety concerns. Spilled flaming meths from multiple derailments taints the herbs planted alongside the track. :)

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Re: MSS loco on 4' diameter curves ?

Post by CSL » Mon Jul 09, 2018 5:05 pm

Abiogenesis,

Thanks. I fitted that safety valve last year, at the same time as replaced the meths wicks. That upgrade visibly improved performance, as did the Roy Wood wheels fitted this year (I'm not sure whether the original wheels were already loose on the axles last year, but they did get worse).

I think I need to do some more trials, but the latest steamings had the following results:
1. Two (original-type, now MSS) Mamod coaches + North Pilton brake van: too much. Brake van removed from consist: ran well (but seemed to have got tired from trying to haul the bigger load - poor thing!).
2. "New" Mamod tank wagon + Swift Sixteen square tanker: ran beautifully.

So two vehicles are fine, and indeed the regulator was part-closed with load two. I may have to choose my vehicles carefully for three (or possibly more) - the NP brake van is quite heavy.

Or a couple of other possible explanations:
- the long curves present excessive drag.
- the power output of the meths burner is roughly matched to load two-and-a-half.

Whatever I find, I'm actually really pleased with it. It's a joy to watch it chugging steadily round the circuit, slowing on the curves and then picking up a bit - but not too much - speed before hitting the next curve.

Under the right circumstances it can even be preferable to the Bertie: speed doesn't increase as it warms up, and running time is shorter (which is a plus sometimes!). And the meths gives no roar and a great smell!

I'm managing very few derailments too...

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Re: MSS loco on 4' diameter curves ?

Post by Abiogenesis » Mon Jul 09, 2018 7:00 pm

S2020152 (1).JPG


Aaron,

These are my two SL1s that I purchased April & May 2017. The red loco is only a Mamod because it retains the original frames, drag bar & smokebox. The rest is Janet specification. The green loco retains the original boiler, cylinders/pistons & wheels. The RWM regulator, lubricator & SV (set at 40psi) have proved very worthwhile in both cases. I've not had problems with loose wheels on the green loco, but the new RWM cylinders/pistons fitted to the red loco increased the piston thrust so much that the Mazak wheels moved on the axles & locked. As for hauling capacity, ten loaded Mamod wagons are no problem. I'll post a video sometime soon.

All the best.

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Re: MSS loco on 4' diameter curves ?

Post by CSL » Mon Jul 09, 2018 8:08 pm

Very nice. Look forward to seeing a video. Do they have the same performance, or is the one with new cylinders the better?

I'm sure I've read on these forums that 40psi might be rather too much for the original Mamod sight glass...?

I'd be interested to hear what kind of performance a c.30-year-old Mamod in the condition that mine is (original apart from 20-25psi safety valve and meths burner - the RWM wheels being like-for-like rather than an upgrade - might be able to offer...

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Re: MSS loco on 4' diameter curves ?

Post by Abiogenesis » Mon Jul 09, 2018 9:16 pm

The RMW cylinders/pistons were a necessity as they were missing on the left side of the first SL1 (now red) I purchased. The water sight glass in the Mamod brass boiler has not given me a problem, so far! With gas firing there is no margin for error if the Mamod boiler runs dry. Hence the Janet replacement from RMW. When I upgraded the boiler, Roy very kindly took back into stock the steam turret & SV I had purchased previously, as the tpi differed. I shall have no hesitation in acquiring a second boiler when a rebuild becomes due. They are top quality copper & are silver soldered with a decent water gauge glass. There is a take off for a syphon & pressure gauge as well.

The RMW cylinders/pistons deliver far greater performance. On the West Herts 16mm group indoor track, it's pulled 10 wagons loaded with stone ballast & a momentum wagon to keep the speed within decent bounds & the drivers were spinning madly on the oily Peco track. Great fun!

Steam oil 460 is essential to achieve a good seal between cylinders & pistons. Meths can contain too much water. You could consider trying 99.9% Isopropanol as a comparison. https://www.amazon.co.uk/BRAND-ISOPROPA ... B003D8SDSW

Addendum: I can replace original water sight glass in the Mamod brass boiler with polycarbonate. Polycarbonate has a glass transition temperature of about 147 °C (297 °F), so it softens gradually above this point and flows above about 155 °C (311 °F). Saturated steam at 40 psi has a temperature of 130.68 °C (267.224 °F)

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Re: MSS loco on 4' diameter curves ?

Post by CSL » Tue Jul 10, 2018 12:16 pm

It's fascinating how finding out more about what is possible crystallises your thinking about what you actually want. For me personally:

Must have (and already achieved)
- continuous running round my garden circuit
- working whistle
- meths firing
- confidence that the boiler will not run dry

Nice to have
- higher haulage capability

Acceptable as is
- running time
- haulage capability (a two-coach train is still a train)

Don't much like
- cluttered cab as in the photos above (the Bertie's bad enough in this respect!)

So some things are ruled out for me, including gas firing and cab regulator, while new cylinders are an unnecessary expense provided the originals continue to work as they currently do. Higher boiler pressure might not do anything if it's the the meths burn rate that limits the power output to something that is already acceptable.

But it looks like a front-end lubricator might give less steam loss and so better haulage capability...

Any recommendations?!

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Re: MSS loco on 4' diameter curves ?

Post by Abiogenesis » Tue Jul 10, 2018 3:09 pm

In order to keep the boiler topped up, whilst still in steam, I would recommend the Goodall filler & the "Superior" water bottle, if you don't already have them? You soon learn how many squirts are needed for circuits of your layout. A dead leg lubricator is available. See below.

https://www.dreamsteam.co.uk/mss-mamod- ... cator.html

https://www.dreamsteam.co.uk/mss-mamod- ... valve.html

https://www.track-shack.com/acatalog/Su ... JMPLF.html

Try the Isopropanol. Its heat of combustion is 50% greater than meths.

Alcohols MJ/Kg
Methanol 19.930
Ethanol 26.70
1-Propanol 30.680
Isopropanol 30.447

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Re: MSS loco on 4' diameter curves ?

Post by CSL » Tue Jul 10, 2018 4:45 pm

Thanks for the links.

I might go for the lubricator... Presumably it should improve pulling power by reducing steam losses, but will mot affect run time which is dependent on the meths burn duration.

Regarding the isopropanol, I'm trying to work out what effect I would see if I used the same volume and same burner as the meths. Would it burn longer, or for a shorter time? Would it give a longer run time after burning out if the whole system is hotter? Would it risk drying out the boiler if the same volume* of fuel gives more heat (no risk of that with the current meths set-up, and I value the certainty that brings).

*You quote energy per unit mass, rather than volume, although I rather assume the densities are similar.

Unless I've completely misunderstood, fitting the filler requires the removal of the whistle and so would cross one of my red lines. But I don't really want to extend run time anyway - a short run is convenient sometimes: and it feels a waste to shut down part-way through!

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Re: MSS loco on 4' diameter curves ?

Post by Abiogenesis » Tue Jul 10, 2018 6:24 pm

The Goodall filler screws into the boiler in place of the standard filler cap. It helps preserve the integrity of the soft soldered, Mamod brass boiler. The brass dome will sit firmly over the Goodall with a brass insert from RMW that fits inside the dome. The whistle is only replaced if a RWM steam turret for the regulator & displacement lubricator is fitted in it place. The whistle wastes steam & is too high pitched for my ears. I prefer these. :lol: https://www.youtube.com/watch?v=utg0tK7cDbE

The densities are close, but with 8 atoms of Hydrogen in Isopropanol rather than just 1 in Methanol, I'm guessing that's where Isopropanol gets its 50% extra heat of combustion. The power of a steam locomotive relies on its ability to boil water.

Isopropanol Specific Gravity 0.7851 g/cm C3H8O

Methanol Specific Gravity 0.792 g/cm CH3OH

You might find these useful.

http://www.eagleassist.com/hglw/mamod.html

http://www.eagleassist.com/hglw/PeterJo ... 0Mamod.pdf

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Re: MSS loco on 4' diameter curves ?

Post by CSL » Tue Jul 10, 2018 9:29 pm

Sorry but I'm keeping my whistle! The children like it, for one thing. And I do, for another!
Abiogenesis wrote:
Tue Jul 10, 2018 6:24 pm
The Goodall filler screws into the boiler in place of the standard filler cap. It helps preserve the integrity of the soft soldered, Mamod brass boiler. The brass dome will sit firmly over the Goodall with a brass insert from RMW that fits inside the dome.
Not sure I understand. There are three apertures for live steam in the boiler - as built, they are steam dome, safety valve and whistle. If you fit a refill valve and keep the whistle, where does the safety valve go?

With the Dream Steam components, the 40psi safety valve replaces the whistle and the refill valve replaces the original safety valve, with no change to the steam dome (that's what I was thinking of earlier).

You refer to a "standard filler cap" - I presume that's the original safety valve.

Yours, puzzled...

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Re: MSS loco on 4' diameter curves ?

Post by CSL » Tue Jul 10, 2018 9:32 pm

Note to moderators - is it possible for posts including and since the one at 14.37 on 08/07/18 to be put in a new thread called something like "Improving Mamod/MSS Performance"? (Possibly with a link back to the source thread.)

This interesting discussion would then be easier for everyone to refer to in future

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Re: MSS loco on 4' diameter curves ?

Post by Abiogenesis » Tue Jul 10, 2018 11:17 pm

Yes, you are correct. I has forgotten that the steam feed to the cylinders is under the the solid cap beneath the brass cover. My two locos are much modified & I had a senior moment. :oops: The standard fuller is indeed the SV. HGLW have the instructions for fitting the lubricator.

http://www.hglw.co.uk/Fitting%20a%20Dea ... motive.pdf

I believe Mamod sell boiler inserts, so you could install a Goodall in place of the SV & then place the SV between the dome & the whistle?

http://www.hglw.co.uk/mamod%20stretching.pdf

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Improving Mamod & MSS Performance

Post by tom_tom_go » Wed Jul 11, 2018 11:28 am

CSL wrote:
Tue Jul 10, 2018 9:32 pm
Note to moderators - is it possible for posts including and since the one at 14.37 on 08/07/18 to be put in a new thread called something like "Improving Mamod/MSS Performance"? (Possibly with a link back to the source thread.)

This interesting discussion would then be easier for everyone to refer to in future
New thread started as requested.

Please keep threads on topic so information is easier to find for current and future members.

CSL
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Re: Improving Mamod & MSS Performance

Post by CSL » Wed Jul 11, 2018 12:45 pm

tom_tom_go wrote:
Wed Jul 11, 2018 11:28 am
New thread started as requested.

Please keep threads on topic so information is easier to find for current and future members.
Thank you - guilty as charged. With hindsight I should have created a new thread with a link to the original, but at the time I didn't know it would develop this way.

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Re: Improving Mamod & MSS Performance

Post by CSL » Wed Jul 11, 2018 12:55 pm

Abiogenesis wrote:
Tue Jul 10, 2018 11:17 pm
I believe Mamod sell boiler inserts, so you could install a Goodall in place of the SV & then place the SV between the dome & the whistle?
Had to research what a boiler insert is! You are suggesting drilling a new hole in the boiler - interesting, and also well beyond my home engineering capabilities...

Now this is probably a dumb question, but the Dream Steam lubricator description says that it improves O ring fitted cylinders, while I cannot see inside my Mamod's cylinders (originals, as factory fitted circa 1990) so am not sure if this applies. Is it definite that the lubricator should improve performance with the same cylinders retained?

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