Pulling power Coal v Meths

[INJIN]

Can a Meths fired pot boiler pull the same train as this coal fired Darj pacific? The last two shots show the final length.

http://www.youtube.com/watch?v=8iHduWhZ ... e=youtu.be

[laurence703]

Yes... Two mamods on 32 wagons. Both were meths fired.
Trying to find a photo and failing miserably...

[laalratty]

I would guess probably not, because coal burns hotter then meths. I suppose the only way to test the theory is to build an identical loco but with meths rather then coal firing. But it comes down to can the fuel be burnt in such a way to provide enough heat to sustain the steam pressure to haul the train.

[Keith S]

I would guess yes, simply because assuming the engines both weigh about the same, the wheels will slip on either before it gets to its maximum power output. These little engines seem to have more power than they can actually use.

[INJIN]

Keith S

You are of course right.............Here is a Meths fired pot boiler with the same train on the same day. The method of firing makes no difference whatsoever in our scale, it's more about putting the power onto the rails. After all a Roundhouse Millie has the same cylinders & if you put enough lead into it to make it weigh the same as these engines I'm sure it'd pull just as much as long as enough valve chest pressure can be maintained.

http://www.youtube.com/watch?v=U8GDa1Oh ... 8X6xxnTtow

I'll put up another video of a gas fired loco I used in the experiment, soon. All three loco's I used weigh about the same,  have the same number of drivers & the same cylinders & run under the same conditions with the same train.

[GTB]

The max. drawbar pull of a loco. will be about 1/5 of the weight on the drivers and the maximum pulling power will be independent of what is boiling the water.

Where a coal fired loco. may have an advantage over meths or gas (all other things being equal) is that a coal fire is self regulating and should cope better with heavy loads on long uphill runs, without operator intervention. The higher working pressure of most coal fired locos. will also give a greater reserve of steam when needed, but won't increase the drawbar pull.

I seem to remember you were building one of Brian Wilson's coal fired Briggs boilers a while ago. How did that work out?

Graeme

[INJIN]

Hi Graeme,
I can't agree with your statement.

" The higher working pressure of most coal fired locos will also give a greater reserve of steam when needed."

The Rheidol runs at 75psi the same as the "C" class.
The "pot" will just produce steam whatever it's doing. In the case of the Rheidol it's designed to pull whatever load you care to put behind it to the limit of adhesion. The loco is never short of steam on much more hilly lines that my own, it just ploughs on whatever the terrain.


Here is a video of the loco with a Briggs boiler "Young Luke's" engine.


http://www.youtube.com/watch?v=iYQoVOjC ... 8X6xxnTtow

Video of gas fired loco of similar weight/same train etc on it's way.

Cheers

Keith

[INJIN]

Part three is now uploaded...............gas...........

http://www.youtube.com/watch?v=fjzRgRkm ... 8X6xxnTtow

Cheers

Keith

[laalratty]

All very interesting, thanks for doing this comparison Injin. Must admit my only experience of this is comparing meths fired Mamods to gas fired Mamods, where the gas fired one out performed the meths fired one by about 5 or 6 wagons. Likewise, meths fired locos have always seemed to me to not give as good a steaming performance as gas fired locos. Of course, it could be that all of the meths locos I've seen running have been quite old (I'd imagine your Rheidol is in about as good a shape as a loco could be being nicely run in by now) or perhaps its more that the art of setting up a meths burner is something of a lost art...

[Peter Butler]

Regardless of the power source, the railway is just perfect.
Perhaps we could see more of the line, plus an explanation of how the 'Fireless' is charged?

[INJIN]

They say a picture is worth 1000 words. Does this explain OK





Cheers

Keith

[Peter Butler]

If that pump is designed for a pre-charged airgun, there is some serious pressure in there!

[INJIN]

125psi...........

I'll put some pix of the railway in the Photo section............