Mamod Running Pressures

[DolwyddelanLightRail]

PPS boilers were stamped - mine has 'PPS74' on the back of mine.

As for RWM/WS now only testing to 80psi for 40psi running? Dude, downrating  :shock:

Off topic, however, is there actually any need for running at 60psi? Lets face it, anything above 40 and the Mamods can't really put the power down. If you are hauling a train that requires 60psi then you'll more likely loose grip before you can actually run the train at any decent speed, so thus you'll end up running the train with wheels spinning and adding additional wear to the loco. In the end you'll be running a train which will be rather ridiculous for running at 60psi as it doesn't need all that power as it can only really convert it to speed.

[dougrail]

Off topic and I'd say that the locos can put the power down to a degree. However there can be some wheelslip. If you have the transmission and the loco is suitably weighted down, why not.

[ace]

PPS boilers were stamped - mine has 'PPS74' on the back of mine.

As for RWM/WS now only testing to 80psi for 40psi running? Dude, downrating  :shock:

Off topic, however, is there actually any need for running at 60psi? Lets face it, anything above 40 and the Mamods can't really put the power down. If you are hauling a train that requires 60psi then you'll more likely loose grip before you can actually run the train at any decent speed, so thus you'll end up running the train with wheels spinning and adding additional wear to the loco. In the end you'll be running a train which will be rather ridiculous for running at 60psi as it doesn't need all that power as it can only really convert it to speed.

Just a little off topic, but....

Above 40 psi? My Titan (dream steam works loco from Alan at PPS days) cannot get the power down at 40. I don't see the point at running at 40 psi! I was thinking of knocking the SV back to 30 or even 25, 60 psi is just pointless. You are putting unnecessary stress on all parts involved!  In my experience a higher pressure makes slow running harder to do and you have to uprate every spring and working surface to even try. My Chevalier runs at 10-12 psi and runs like a Swiss watch on that, even with standard Mamod cylinders and pulls a modest load too. I can imagine that she would be blowing steam out of every orifice if 60 were involved, who runs at 60 psi ffs? My Roundhouse Billy runs at 30 psi and that can pull the house down, totally different model I know.

I think if you have to run at 60 psi, then there is something wrong somewhere......

Thinking about it 60 psi would be good for santa pod or even trying to keep up with Sebastian Vettel,

Just my 2p

[DolwyddelanLightRail]

I run both Britomart and Dolmur Goch at 40psi, the main reasons is that with a dry rail, Brit can put the power down with a train that weighs around 4kg. On wet rails however it just cannot put the power down until you are around 20psi, and in it's current state, it just cannot do anymore. Dolmur Goch was the guinea pig when it was built, mainly as I was getting annoyed at running Britomart at lines which are incredibly greasy or slippy, as I am pretty sure that the loco slipping a lot of the time has nackered it. Dolmur Goch has lead weight added to the side tanks, so that on dry rail it will be able to run off with a reasonable train, and also on moist rails as well, which so far seems to be working to some extent. However, for the time being Britomart will always have more potential traction over the two locomotives due to the tyres being very worn down.

[dougrail]

What you forget to tell everyone ace is that Chevalier is a brass boilered meth fired loco.

As for 60psi on mine? It's there, it happens [got to love efficient gas fired] but 40-60 is my usual running range. Usually more 40-50.

As for something wrong? 2013, several days out and exhibitions would say au contraire chap.

[laurence703]

Ofario runs at about 35 / 40 PSI... I ran it yesterday on my tipper train in wet conditions and to say it struggled is about right. Ofario is quite heavy with all the added extras but it just could not get grip and wheelspun like mad. In the dry weather it would walk around with the tippers all day long but as soon as the rail gets wet or oily then you might as well run it with a very short train otherwise it'll just spin and look rather silly...

For those that aren't familiar with my tipper rake its 9 tippers and one brake wagon. 4 tippers are about 7lb each in weight and the other 5 are about 3.5 /4lb's each. The brake wagon weighs next to nothing really...

[laurence703]

Also it don't matter what its fired by... its tractive effort given by the weight and the power in the cylinders...

If anything 60 PSI on a mamod is essentially turning a loco into a bomb...

[dougrail]

Weighting of which I've been looking into and the cylinders having that capability, Laurence. As for firing, it does matter. If you have a weak fire, there won't be any steam. Have a good primed wick meth burner or a good gas burner and it'll do the job.

As for a bomb, I'm not the one trying to build a tender that'll be full of flammable spirit.  :roll:  

Afterall, this is what I bought :http://web.archive.org/web/200810121118 ... /janet.htm Working pressure 65psi.

I usually keep 40-60, more like 40-50 to work with, 60 tops' and beyond that it's dampen off the fire and open all ports asap. No fool needs 70+ period. [Pressure gauge goes upto 80, for reference on pressure gauge builds.]

Was this ragged thread really necessary or was it just another exercise?

[ace]

I suppose with non greasy rails (of which mine are quite greasy being under trees and running lubricated models all the time and the lack of cleaning) there would be the purchase there to put the power down, hence my comments about my Titan (dream steam work loco).

Doug, I was not having a go about your running pressures, I didn't know you did run at 40 - 50 psi and was not attacking you directly. What I was alluding to was the fact that yes a Mamod gene pool model may function at 60 psi all day long, what is the point in doing so when 40 psi is more than plenty in my experience. Yes Chevalier is brass boilered and meths fired, should it make a difference to how efficient, well and smooth she runs with standard parts and near on standard operating pressure? If anything it should be an achilles heel. If I wound the safety valve in, Chevalier can run like an absolute idiot if I allow it at 30 psi, really that is credit to the running gear of the model.

At the end of the day a boiler is a boiler, a good fire is a good fire and pressure is pressure no matter what components they are put together in, it is just the durability and quality of the components that changes. The ultimate key is smooth efficient (low effort) running mechanical gear.

In my own opinion, 60 psi is just too much.

[dougrail]

I suppose with non greasy rails (of which mine are quite greasy being under trees and running lubricated models all the time and the lack of cleaning) there would be the purchase there to put the power down, hence my comments about my Titan (dream steam work loco).

Leaves on the line? You do better than the big railway does, from your videos

Doug, I was not having a go about your running pressures, I didn't know you did run at 40 - 50 psi and was not attacking you directly. What I was alluding to was the fact that yes a Mamod gene pool model may function at 60 psi all day long, what is the point in doing so when 40 psi is more than plenty in my experience.

With all due respect, it would seem this thread was set up so every John, Dick and Harry could come and have a pop. Afterall, it's been the running tone sofar and once again I find myself having to explain everything, summoned like some corrupt energy baron CEO before an inquiry of equally-corrupt government ministers. This isn't the first time it's happened here either.

Yes Chevalier is brass boilered and meths fired, should it make a difference to how efficient, well and smooth she runs with standard parts and near on standard operating pressure? If anything it should be an achilles heel. If I wound the safety valve in, Chevalier can run like an absolute idiot if I allow it at 30 psi, really that is credit to the running gear of the model.

In terms of tractive, possibly, but in terms of efficient, smooth running? No it shouldn't make a difference. A good engine is one that runs well and that is the top of the menu in my opinion. Having been to Butterley one day where a young lad and his uncle were running a perfectly good SLK straight out the box [hadn't been built before them for 20 years] it summed up the point we both agree on ace. 30psi on a standard model would be asking for suicide as I suspect the plastic sight might start to go? The speed factor we all know about. Credit indeed.

At the end of the day a boiler is a boiler, a good fire is a good fire and pressure is pressure no matter what components they are put together in, it is just the durability and quality of the components that changes. The ultimate key is smooth efficient (low effort) running mechanical gear.

In my own opinion, 60 psi is just too much.[/i]

Oui. For the most part - 60psi would be a special occasion but rarely used. 40psi on a good day will do fine. Anything over 60 as has been seen is gas off, open reg, add water to dampen it down as one is conscious of safety and surroundings.

[laurence703]

PostPosted: Sun Nov 10, 2013 9:03 pm Post subject:
Weighting of which I've been looking into and the cylinders having that capability, Laurence. As for firing, it does matter. If you have a weak fire, there won't be any steam. Have a good primed wick meth burner or a good gas burner and it'll do the job.

As for a bomb, I'm not the one trying to build a tender that'll be full of flammable spirit.

Afterall, this is what I bought :http://web.archive.org/web/200810121118 ... /janet.htm Working pressure 65psi.

I usually keep 40-60, more like 40-50 to work with, 60 tops' and beyond that it's dampen off the fire and open all ports asap. No fool needs 70+ period. [Pressure gauge goes upto 80, for reference on pressure gauge builds.]

Was this ragged thread really necessary or was it just another exercise?

For starters the Meth tender has now been redesigned to not explode and not set fire to my cab... do you really think Dan would build an actual bomb and let me loose with it?

Firing doesn't matter... the weather affects our little locos more than the firing does... At least a Meths burner won't melt a standard boiler to the extend that the joins fail...

I'd say this thread was necessary as its a topic that can have an effect on Mss/Mamods/Janets/Janes/Etc... But too much pressure e.g 40 upwards is just silly as it will just make them speed demons and more accident prone thus tarnishing the good reputation that other mamod type loco owners who are careful, be it Meths or Gas, have.

[Chris Cairns]

My comments moved across from the other Topic: -

"As to running upgraded Mamod type locos at 60 PSI each to their own I guess. I quite happy running my various Mamod type locos at up to 40 PSI, and the Cheddar Iver & Cheddar/GRS Tram which use a similar sized oscillating cylinder (as their cylinders are no longer available as spares you can replace them with the upgraded Mamod type ones quite easily) are designed to run at 45 PSI (max operating 60 PSI) and are significantly heaver (they will continue to slide along for a bit after you have stopped the wheels turning, which you need to factor in to your driving technique)."

Another useless piece of trivia. Although one set of my Dream Steam steel wheels have a larger diameter outer part on the flange (the bit that contacts Mamod combustion chambers) the part of the flange that is actually in contact with the railhead is just smaller in diameter than the corresponding part of the flange on standard Mamod/MSS wheels. The wheels on the much heavier Cheddar models (effectively using the same size cylinders) are much bigger in diameter having no combustion chamber restricting their size.

Chris Cairns.

[dougrail]

Laurence - I'd expect no less from Dan the Man to thoroughly examine any plans, see the bomb and go NO. As for the weather - to a degree. Depends on one's fireguard and frames. Was it really, really needed to have another 'lol meths is better' pop? It;s been a year and more and to be honest, I got bored of it a long time ago, after reading several GR articles and finding pros and cons for both. Nowadays, its just sad - especially if it's kicks you and t'other still get out of it.

As said, 40-50, depends on the train. I try and avoid the speed demon thing if nothing else, repainting a crashed loco is a bitch were it to occur.

[Chris Cairns]

At least a Meths burner won't melt a standard boiler to the extend that the joins fail...

Except for my MSS Saddle Tank where the joint on the bottom of the boiler failed despite keeping a sufficient water level. Standard IP Eng 3 wick burner where the middle wick is directly underneath that joint.

Chris Cairns.

[ace]

Leaves on the line? You do better than the big railway does, from your videos

I didn't mean leaves you silly sod, I meant algae and green slime.

With all due respect, it would seem this thread was set up so every John, Dick and Harry could come and have a pop. Afterall, it's been the running tone sofar and once again I find myself having to explain everything, summoned like some corrupt energy baron CEO before an inquiry of equally-corrupt government ministers. This isn't the first time it's happened here either.

Why the hell is anyone having a go at you? People are here freely conversing about the operating pressures on Mamod gene pool locos, its not all about you Doug... As for you to explain anything about operating pressures to me, I have my opinions, you have yours and I am sticking to mine. We are going to have to agree to disagree my friend.

In terms of tractive, possibly, but in terms of efficient, smooth running? No it shouldn't make a difference. A good engine is one that runs well and that is the top of the menu in my opinion. Having been to Butterley one day where a young lad and his uncle were running a perfectly good SLK straight out the box [hadn't been built before them for 20 years] it summed up the point we both agree on ace. 30psi on a standard model would be asking for suicide as I suspect the plastic sight might start to go? The speed factor we all know about. Credit indeed.

I think you missed my point, if you have an efficient running rolling chassis, why would you need to shove 60 psi through it, when 40 psi is plenty? I am not having a direct go at you, I have only just found out you even ventured this 40 - 60 psi territory. In theory if a model has a stiff hard to work rolling chassis then one may find that 60 psi is required to turn the wheels at all. Again, this is not aimed at you or your model, it is just a point in this example. To conclude, a smooth running model does not need higher pressure to work well, unless (like I said before) there was something up, as described above.

Oui. For the most part - 60psi would be a special occasion but rarely used. 40psi on a good day will do fine. Anything over 60 as has been seen is gas off, open reg, add water to dampen it down as one is conscious of safety and surroundings.

That is fine, I have no problem with you using 60 and (god forbid) any higher, doesn't your safety valve work?

I am not looking to fall out with anyone, just passing my opinion across that I think 60 psi is too much, how that maybe construed is up to the individual.

laurence703, that tender sounds interesting. Do you have the meths tank below the floor of the tender to keep the levels the same?

Again Doug, I am not having a comparing this and that moment. I said that Chevalier having a methes burner was an achillies heel, I didn't say it was better. Gas is far superior for control on the fly and is a brilliant fire maker. I chose meths for Chevalier because of the open cab and me not wanting a gas tank on view, as you know the meths tank is stowed away under the floor.

[DolwyddelanLightRail]

Right, I think this has run it's course....