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14 hours ago, melmerby said:

Surely you need to know the mass to know how much energy is contained therein?

I meant per kilogram. All my heat engines coursework was in SI units

 

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18 hours ago, Gibbo675 said:

Hi 62613,

 

You are quite correct in your description of how and why steam is such a good medium for energy transmission.

 

The two things I would add are that, the drier the steam is the more energy it has per unit mass at what ever pressure is being worked and also that, expanded steam at the point of the valve opening to exhaust must indeed have positive pressure.

 

Hot dry steam, (a relativistic term), is the reason for the use of high degree super-heat, this comes at a cost of greater difficulties in the lubrication of the liners, piston and valve heads and rings and also the gland packings.

 

The main reason for positive pressure is that the steam has work to do in drawing the fire via the draughting arrangements.

 

The usual maximum exhaust pressure at the blast cap for a simple expansion, single chimney is around 12 psi irrespective of either maximum boiler pressure or steam chest pressure at any given cut off.

 

Any driver that thinks that he may develop more power by increasing the cut off beyond what the draughting arrangements will allow will only succeed in making lots of noise bye way of of increasing the back pressure of the locomotive ultimately lowering the power produced with the added expense of disrupting the fire bed and using more water that is necessary. That said certain idiots still give it a good go all the same !

 

Ask yourself what would happen, unlikely as this is, if the steam condensed in the cylinder and caused a vacuum.

 

Gibbo.

The 'dryness' of the seam surely depends on how much of the latent heat has been added, as I recall. I always thought one of the reasons for superheating the  steam was to prevent condensation when the steam is fully expanded at exhaust; isn't one of the penalties of steam with water droplets in it that you get erosion of the valve faces?

 

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18 hours ago, Compound2632 said:

 

Also, in the SI, unit names are always spelled lower case: the unit of energy, named in honour of James Prescott Joule, symbol J, is written joule. This avoids the solecism of having a capital letter in the middle of a word when adding one of the SI prefixes, as, for example, kilojoule.

So what you're saying is when you give the full unit name, and it has one of the prefixes, it should be written it lower case throughout, but when it's on its own or abbreviated, if it's one of those named for scientist (Joule, Watt, Volt, etc.,) it's capitalised? I well remember, at one of the drawing offices I worked at, the d.o. supervisor sent round a sheet with the "Correct way to write down SI units, e.g. mm for millimetres and not MM, which is, of course, Mega Mega. 

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Are imaginary liveries OK here, too, or is there a better thread for that?   Also, is there a good match for BR Golden Ochre that is NOT Phoenix or Railmatch?   Can't get those here.

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I think there was an imaginary liveried thread once upon a time... there was definitely one for Models rather than photoshop (it specifically said so in the title) so I'd be suprised if there wasn't a photoshop version too.

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56 minutes ago, 62613 said:

So what you're saying is when you give the full unit name, and it has one of the prefixes, it should be written it lower case throughout, but when it's on its own or abbreviated, if it's one of those named for scientist (Joule, Watt, Volt, etc.,) it's capitalised? I well remember, at one of the drawing offices I worked at, the d.o. supervisor sent round a sheet with the "Correct way to write down SI units, e.g. mm for millimetres and not MM, which is, of course, Mega Mega. 

 

We may be going a teensy bit off topic here, but no, unit names aren't capitalised either when prefixed or solo but the symbols are when named after someone.

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4 hours ago, Satan's Goldfish said:

The Diesel Garratt... Diesel engine in the middle, big drive motors and cooling in the articulated noses...

 

1254502094_DieselGarrattcomp.jpg.bcf0bd3ae4ddec3f72729fcc8827e86d.jpg

 

It's hideous...

 

maybe making it a 2-6-0+0-6-2 would be a bit more track friendly?

The Dell!

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2 hours ago, 62613 said:

The 'dryness' of the seam surely depends on how much of the latent heat has been added, as I recall. I always thought one of the reasons for superheating the  steam was to prevent condensation when the steam is fully expanded at exhaust; isn't one of the penalties of steam with water droplets in it that you get erosion of the valve faces?

 

Hi 62613,

 

You are correct in what you say, the increase in heat energy does indeed remove the suspended water droplets, as small as they are, but the lubrication problems generally arise form the dryness of the steam.  Saturate steam does to some extent lubricate but at the elevated temperatures involved with high super-heat it does not and so the oils used must not fry off and carburise upon the metallic surfaces. Carburised oil deposits cause trouble with valve rings sticking in their grooves often causing them to break as they are not free to expand and contract as the should.

 

Erosion of valve faces due to cavitation corrosion is generally due to lack of oil upon metallic surfaces when the locomotive is either cooling or warming up. This is usually due to some sort of lubrication failure, the two most common being lack of oil supplied or incorrect grade of oil for the specified duty.

 

Gibbo.

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20 hours ago, Compound2632 said:

 

I used to be involved with committees that discussed such things - railway modellers are easy-going, let-anything-pass types in comparison.

 

Now, I suppose it might be possible to heat the alloy in the fusible plug to a temperature at which it is sufficiently soft that the water, under the residual boiler pressure, will force it back into a tight fit in the housing but not so soft that the alloy will simply run out?

Hi Compound,

 

Here is what you do with leaking fusible plugs;

  1. Draw or drop the fire.
  2. Check size of plug that is leaking, the sizing number is stamped into head of plug.
  3. Open injector steam valves to allow steam pressure to fall to zero.
  4. Shut injector steam valves and make all other valves are firmly shut.
  5. Connect cold water hose to injector overflow and start to fill boiler, this causes the steam to condense and create a vacuum above the hot water.
  6. When the pressure gauge needle is suitably below zero make a secondary check by opening a gauge glass blow-down cock to see if the bubbles travel up the glass instead of the more usual downward direction. This shows that air is being drawn into the boiler rather than water either being draining or being forced out by pressure.
  7. With the replacement fusible plug at the ready, undo the fusible plug with the box key and quickly remove with a gloved hand and put the new plug in as fast as you are able. Tighten up the fusible plug with the box key. Job done.
  8. If you drop the plug or cross thread it, get out of the fire box as fast as you can ideally before the vacuum is destroyed and the hot water starts to boil for other wise water will be forced out of the plug hole and flash off to steam.

This job is best done by two men although should you drop the new plug it is even more fun trying to escape the firebox !

 

Gibbo.

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3 hours ago, 62613 said:

So what you're saying is when you give the full unit name, and it has one of the prefixes, it should be written it lower case throughout, but when it's on its own or abbreviated, if it's one of those named for scientist (Joule, Watt, Volt, etc.,) it's capitalised? I well remember, at one of the drawing offices I worked at, the d.o. supervisor sent round a sheet with the "Correct way to write down SI units, e.g. mm for millimetres and not MM, which is, of course, Mega Mega. 

 

Unit names written out are not capitalised, thus for the unit named after Newton, one writes 1 newton or 1 N - always with a space between the figure and the unit: 4 mm scale, not 4mm scale - and of course, strictly speaking 4 mm/ft scale, since a "scale" must have dimension 1.

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1 hour ago, Gibbo675 said:

Hi 62613,

 

You are correct in what you say, the increase in heat energy does indeed remove the suspended water droplets, as small as they are, but the lubrication problems generally arise form the dryness of the steam.  Saturate steam does to some extent lubricate but at the elevated temperatures involved with high super-heat it does not and so the oils used must not fry off and carburise upon the metallic surfaces. Carburised oil deposits cause trouble with valve rings sticking in their grooves often causing them to break as they are not free to expand and contract as the should.

 

Erosion of valve faces due to cavitation corrosion is generally due to lack of oil upon metallic surfaces when the locomotive is either cooling or warming up. This is usually due to some sort of lubrication failure, the two most common being lack of oil supplied or incorrect grade of oil for the specified duty.

 

Gibbo.

I've actually had to attempt to overhaul, and in the end replace, ordinary steam valves with severely wire-drawn seats, despite those seats having special finishes (stellited). Yes, superheating didn't really take off until special high-temperature oils had been developed.

 

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17 minutes ago, 62613 said:

I've actually had to attempt to overhaul, and in the end replace, ordinary steam valves with severely wire-drawn seats, despite those seats having special finishes (stellited). Yes, superheating didn't really take off until special high-temperature oils had been developed.

 

Interesting info there, I was once involved with the re-machining of the valves and seats of Seventy One Million, Duke of Gloucester and most of the problem was due to cavitation corrosion because of water between the faces when stored out of steam between jobs. It is also the same reason that Malesco poppet valve regulators must be left in the open position when stored out of steam, these have stainless valve spindles set into cast iron faces.

 

See below photo for a return to subject to those that don't like things to go too far off topic !

 

DSCF0542.JPG.c7a8d11ce7bfec309a64a007bf1d76ef.JPG

 

Gibbo.

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6 minutes ago, standardblue said:

Why not ensure you're mid gear and open the regulator?

 

Mark

Hi Mark,

 

Because dependant upon the type of regulator fitted, opening the regulator may cause it to not seat correctly upon closing after the steam had been blown down and then the boiler would not be able to hold a vacuum for sufficiently long to allow the plug tho be exchanged.

 

Not forgetting that should a locomotive be under the attention of fitters it would already be screwed down and scotched in both directions, and carrying either red flags or not to be moved boards.

 

Gibbo.

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A couple of years ago I started on an LBSCR E1 body, however it got stalled, I recently got a chassis for it, but wanting to place it on wheels, and discovering I can't find the ones for the E1, I decided to have some fun with something different. Please excuse the state of the body, it has taken a bit of a battering in it's time in storage and needs some repair work, never mind the fact it was never properly finished in the first place.

 

So following the LB&SCR's Atlantics it was decided that tender engines were not really necessary for the Brighton, and having to turn them was more effort than was needed.

 

What if this had been decided sooner? What if it was in fact William Stroudley that made the decision to rid the line of tender engines? I present to you what I have dubbed the G Tank, a tank engine form of Stroudley's G Class Single wheeler!

 

162799824_2019-03-0216_49_27.jpg.2a59b5e27362769ee114a2ba082ccf4a.jpg

 

Being that this is based on the E1 I can roughly work out the difference in fuel from a G. I am claiming that this has the same internals as the G since it is supposed to be a tank engine version of that.

 

The G could carry 2250 gallons of water, and 2 tons of coal. The E1 could carry 900 gallons of water, and 1.75 tons of coal.

 

I will have lost some water capacity in this design due to the large driver taking up the tank space, however I have added a well tank to the back, I have calculated these at 304 gallons lost to the wheels, but 438 gallons gained in the well tank. this brings me up to 1035 gallons, So I assume about half the range of the G, but taking on water can be done at most stations without leaving the platform, so this probably isn't an issue, bit would be nice if I could add more

 

For the difference in coal load I think I could probably make up most of that by extending the bunker upwards and adding some coal rails.

 

All in all I am rather happy with this imaginary loco, I would love to hear what other people think, although at the moment there is no guarantee the model will continue.

 

Gary

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Hi all,

Quotation from http://sbiii.com/bwapoc20.html: “The Olsen Electric - Fred Olsen came up with this one and the BW jumped on it. Using a pair of surplus ALCo Centipede tenders with GE electric components and salvaged cabs from SP Baldwin AC-12 cab-forward steamers, the BW made up this very-heavy electric (which looks vaguely like an electric version of the British Southern Railway Leader Class)”: http://sbiii.com/bwrkapix/olsnelec.gif

 

Quite wrong, he should write, British Soutern Region Bulleid no 2001. Anyway maybe source of inspiration for British modellers?

 

The Signal Box Cat

 

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On 28/02/2019 at 21:45, Compound2632 said:

 

The Babylonians counted in base 60. I suppose this to be an anti-fraud measure, ensuring that there are always at least three people present at audit.

 

I was told that the Babylonians invented the base twelve by using the 3 knuckles x 4 fingers on each hand.

How they then came up with the idea of multiplying by 5 to get the 60 we use for so many things (seconds,

minutes, degrees and seconds, minutes, hours) I'm not sure, but it's a very versatile number.

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On 28/02/2019 at 21:45, Compound2632 said:

 

The Babylonians counted in base 60. I suppose this to be an anti-fraud measure, ensuring that there are always at least three people present at audit.

 

I was told that the Babylonians invented the base twelve by using the 3 knuckles x 4 fingers on each hand.

How they then came up with the idea of multiplying by 5 to get the 60 we use for so many things (seconds,

minutes, degrees and seconds, minutes, hours) I'm not sure, but it's a very versatile number.

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23 minutes ago, [email protected] said:

 

How they then came up with the idea of multiplying by 5 to get the 60 we use for so many things (seconds,

minutes, degrees and seconds, minutes, hours) I'm not sure, but it's a very versatile number.

It's only versatile because we use it!

There is no real reason why things couldn't be divided up differently.

10 hour day with 100 mins per hour and a 100 second minute

(Or maybe 20 hour day divided into 10 day & 10 night, based on average, with a 100 minute hour )

Then measuring degrees would fall into line as well.

 

The measurement of degrees has already included the "centigrade" which had 100 degrees in a right angle.

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22 minutes ago, melmerby said:

It's only versatile because we use it!

There is no real reason why things couldn't be divided up differently.

10 hour day with 100 mins per hour and a 100 second minute

(Or maybe 20 hour day divided into 10 day & 10 night, based on average, with a 100 minute hour )

Then measuring degrees would fall into line as well.

 

The measurement of degrees has already included the "centigrade" which had 100 degrees in a right angle.

 

No, it's versatile because it's divisible by 2, 3, 4, 5, & 6, whereas 10 is divisible by 2, and 5!

Divide 10 by 4, and you have a fraction (or point five!), also, you can't accurately get a third

of 10, or 100.

By 'dumbing down' the ability to do proper maths (ie, not just moving the decimal point),

you increase the chances of 'schoolboy' errors. There was a planning application a few

years ago, somewhere in the midlands, where nobody noticed the decimal point was in

the wrong place, and the permission was (nearly) given to a garden wall 600 m high!

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