The Night Mail

[Happy Hippo]

Just in case the brown stuff gets rotivated. A last resort snack. 

[Tony_S]

8 minutes ago, Happy Hippo said:

A last resort snack. 

Our equivalent seems to be pasta and baked beans. And lentils. 

Edited November 24, 2020 by Tony_S
Forgot lentils.

[roundhouse]

No chocolate here. Just beer bonfire and trains in the garden this evening.

 

Yes that is a beer despite being blue.

[Tony_S]

41 minutes ago, Tony_S said:

Our equivalent seems to be pasta and baked beans. And lentils. 

I just showed Aditi your (Happy Hippo’s) snacks and she thought it was more suited to the “four minute warnings” we were told to expect once upon a time. 

Edited November 24, 2020 by Tony_S

[Florence Locomotive Works]

1 hour ago, Happy Hippo said:

Just in case the brown stuff gets rotivated. A last resort snack. 

Do I sense a lack of Mince Pies?

[polybear]

1 hour ago, roundhouse said:

Yes that is a beer despite being blue.

 

Beer?  Looks more like very soapy pond water.....

[roundhouse]

17 minutes ago, polybear said:

 

Beer?  Looks more like very soapy pond water.....

It reminds me of the blue Wkd drink that a late friends other half used to drink. However this beer was a very nice sour fruited weisse beer from Haarlem in the Netherlands picked up at a local-ish craft beer shop between lockdowns. We caught the train there then walked the 8 or so miles back home carrying that can and others via a number of country pubs on a pleasant late Summers day. Would be a bit muddy to do that now.

[Tony_S]

25 minutes ago, polybear said:

 

Beer?  Looks more like very soapy pond water.....

Are you related to the Cresta “it’s frothy, man” bear?

[simontaylor484]

5 hours ago, Happy Hippo said:

Just in case the brown stuff gets rotivated. A last resort snack. 

This picture just had me reaching for the diabetic medication

[simontaylor484]

Blue wkd always reminded me of screenwash in both colour and taste 

 

A pint of proper Yorkshire bitter anyday would have sufficed at one time haven't had a alcoholic drinks for 18 months 

[J. S. Bach]

3 hours ago, polybear said:

 

Beer?  Looks more like very soapy pond water.....

Looks like the dish soap that I use!

[SM42]

Tried this over the summer. 

It tasted of nothing in particular

 

Yes it is green

 

 

Andy

Edited November 24, 2020 by SM42

[Happy Hippo]

Just now, SM42 said:

Tried this over the summer. 

It tasted of nothing in particular

 

Andy

I thought that was loobrushsickie

[SM42]

Just now, Happy Hippo said:

I thought that was loobrushsickie

 

That a good description of the approximate taste,  but with less sickie

 

Andy

[SM42]

7 hours ago, Happy Hippo said:

Just in case the brown stuff gets rotivated. A last resort snack. 

 

 To me that's  a healthy evening snack

 

To Mrs SM42 it's a two year supply of treats

 

I hope your cake doesn't get stollen

 

Andy

[Florence Locomotive Works]

More Mogul musings, feel free to ignore, unless your a Hippo...

 

Richard, I have a problem.

 

I realized tonight that my engine, while it does run, is chronically underpowered and short on steam. I mainly saw this after watching a video of a mogul of the same vintage as mine pulling 6 tinplate BR mk1s at speed on an oval. Mine struggles to make one rotation with a single coach.
 

Here’s the video, skip to 2:59.

 

So it would appear to either be a “steam volume” issue, or a blockage somewhere in a pipe. But a blockage seems unlikely, lest it’s solder, which I was very careful to make sure none got inside. If it is solder, than I’m not sure what I will do.
 

However if it is steam volume, than would the amount of water in the boiler have something to do with that? I fill it typically with between 100 and 125 cc, which I read online was a suitable amount to alleviate major priming.
 

The engine (after sitting for 45 sec) can make about 3-4 circles of the oval before running out of steam, which seems unlike what it should be doing. There is of course the problem that perhaps I am overfilling the lubricator, most of which as you know spills out onto the front bogie. Could this have something to do with everything? 
 

Apologies for the slight barrage of questions.

 

as always,

thanks,

 

Douglas

[rockershovel]

That’s a fascinating video. What radius are those live streamers running on? 

 

Also, what’s the occasion? 

Edited November 25, 2020 by rockershovel

[Happy Hippo]

Hi Douglas,

 

Let's start at the very beginning:

 

A steam engine requires a boiler which is only a kettle.  Water boils and evaporates to form steam.  By trapping it and keeping it hot, the pressure increases.  Think of a saucepan with a lid.  when there is sufficient pressure under the lid, the lid lifts up and dumps the pressure.  The process then repeats itself until you either turn down the heat source or there is no water left.

 

Notice I stated 'turn down the heat source.'

 

Now without going into a long story about early steam boilers and factory chimneys being tall so as to create a draught, and the picture that Neil posted with the GGR locos with hoses out of the chimney; plus talk of dampers and ash pans and forced draft and the Stephenson principle, let us accept that for model railway purposes there are two types of boiler.

 

The first is a Stephenson principle boiler where the fire is enclosed in a firebox at one end of the loco, there are tubes that connect the firebox to the smokebox at the other end of the boiler, which is also home to the exhaust.  when the locomotive is working, the used steam exhausting through the smokebox and up the chimney created a partial vacuum in the smokebox and that sucks the fire through the tubes which increases the heat transfer and therefore the ability to generate more steam.  The harder it is worked the more steam it will try to generate, although there is an upper limit.  Providing you have an endless supply of fuel and water, it will continue to function...... Until you lose the ability to keep the fire burning.

 

This usually happens when the primary air source required to keep the fire alight is compromised, either by a blocked ashpan or clinker forming on the firebars inside the firebox.  To keep the fire going it needs to be 'cleaned'.  A staple of one of many of the fireman's task but we'll leave it at that for the Stephenson principle boiler. As a quick aside, Neil has already pointed out that a marine boiler is different, it works on the same Stephenson principle but due to the design requires different management from the fireman.

 

Now let's look at the model locomotive boilers.  Basically two types, the Stephenson type of which there are a number of derivatives, and the pot boiler, beloved of toy manufacturers.

 

The Stephenson type on a model, works on exactly the same principle as the full sized prototype; it's only difference being that it does require an artificial draft on starting as the firebox and fire tube combination are not enough to create a natural draft.

 

Now onto the pot boiler!

 

Originally, a sealed tube, fitted with some form of safety valve and a method of steam regulation (on/off tap) it has an external heat source, usually in the form of a 'firebox' which is a series of metal sheets around the fire to direct the heat generated by the flames.  The fire burns naturally and there is no control over the rate of combustion, it's either burning or it's not.  You cannot  increase the fuel flow*, so your boiler has a single rate of generation.

 

At the moment let's assume your loco's pipe work is ok.  It should be because the loco does run so we'll look at two other areas that may be wanting.

 

Ssince you have pointed out that your loco is not pulling as much as others of a similar vintage and type, it would suggest that you have one of two problems.

 

First, the boiler may not be holding sufficient pressure.  The safety valve may be set too low or is leaking and you are losing much of your steam to atmosphere rather than being worked through the cylinders.  A steam loco will run by itself on  a couple of pounds of pressure, but it will require more pressure to pull a load.

 

DO NOT immediately go out and start screwing the spring down on the safety valve.  By all means do it, but ONLY AFTER you have had a hydraulic test carried out on the boiler so that you will know what the safe working pressure is.

 

The second issue may be in the fire itself.  You need to check that you are getting sufficient fuel through and that the burner is generating enough heat.

 

If it is not then this effects the steaming rate of the boiler, which is critical as being a pot boiler you only have the one rate, which is dictated by how good your heat source is.

 

So my suggested course of action is:

 

1.  Remove the safety valve and inspect it carefully, see if it is functioning properly and there is nothing that might be causing a leak, however slight, such as a damaged seal or perhaps some grit or scale that is trapped inside.

 

2.  Remove the burner form the locomotive and clean it.  Then test run the burner outside of the loco and make sure that once the burner is lit you have a blueish flame.  This indicates the meths/spirit is burning at it's optimum rate.

 

Try 1 and 2 first, and if there is not improvement then get back to me again.

 

 

* Gas fired single flue boilers are effectively pot boilers, but do have some regulation over the rate of steam generation, but that's another story.

 

 

Edited November 25, 2020 by Happy Hippo

[Dave Hunt]

I see that Morrisons in Telford is now permanently closed. Was it too much up-market for Telfs?

 

That's a very erudite post concerning Douglas's steaming woes Richard but you missed out the first investigative step of having some cake to stimulate the thought processes.

 

Dave

[Chris116]

1 minute ago, Dave Hunt said:

 

That's a very erudite post concerning Douglas's steaming woes Richard but you missed out the first investigative step of having some cake to stimulate the thought processes.

 

Dave

You forgot the last part as well! 

 

If all else fail have another cake and repeat until full. 

[Happy Hippo]

Douglas,

 

Just a further point to your initial query.

 

I suspect you've already realised this, but it is not the cubic capacity of the boiler or the ratio of steam to water within that affects the pulling power of the loco, but the ability of the boiler to replace the steam that has been used.  You need to make as much or slightly more steam than you require. So as an example your mogul pulling 3 coaches should be pulling possibly with some steam escaping through the safety valve, but runs constantly with 6 up without any safety valve usage.   Put another coach on and you'll find that the loco will run initially, but will eventually slow down and stop.  The power requirement to pull the seven coaches having overcome the ability of the boiler to generate steam.

 

You literally do 'run out of steam'.

[Happy Hippo]

21 minutes ago, Dave Hunt said:

I see that Morrisons in Telford is now permanently closed. Was it too much up-market for Telfs?

 

 

Which one?

 

If you mean the one in Turreff Avenue, Donnington, it closed years ago.

 

It was too upmarket for the donors that live in the area.  They already had Asda, Aldi and Co-op all with walking distance.

[Tony_S]

34 minutes ago, Dave Hunt said:

having some cake to stimulate the thought processes.

Surely you can’t have cake and heat it?

[New Haven Neil]

I agree with HH in that Douglas' problem is most likely burner related - meths wicks are something of a black art.  I detest pot boilers, too much Mamod trauma in my past.

 

The other thing is that the pistons don't have an adequate seal and the steam is wasted to exhaust, but that is HH's step 3 I suspect!

Edited November 25, 2020 by New Haven Neil
add an 'o'

[Happy Hippo]

14 minutes ago, Tony_S said:

Surely you can’t have cake and heat it?

PB and I are joint custodians of a  secret cake mountain hidden deep in the hills of.......................