A Question ( or two ! )

[Kiha_120]

Well, here I go again - I hope you like reading !

 

Firstly, a question I have been meaning to get an answer for for years. I ought to be ashamed to ask this as I once was employed on p/w work British main line.   Can anyone tell me WHAT is the reason for the roaring noise which is sometimes heard in tunnels - this is not train related per se but is something to do with track and/or tunnel construction but I have never found out WHY.

 

There are sections where train is running 'normally' and all of sudden, this deafening 'roaring' noise is heard in places.  OK, that's my first question posted in this comment  - I look forward to answers. Now this segues neatly into this :

When I was working on mainline p/way work (non electrified) I had

quite an experience,   when once a few of us engaged in track maintainance had to enter a shortish tunnel to carry out visual inspection when our 'lookout' warned us of an oncoming train - this being a 125 set at full line speed ( 125 mph - sorry I don't do kilometres !) we saw the headlights at the far end and heard the warning horn, so into the refuges we went.  I kid you not,  the noise of this train passing literally a few feet feet away from us with the blast of air was frightening - you can imagine the racket as engine and wheel noise rebounded off the confines of the tunnel walls !

 

I had the same experience of a 'close encounter' when working under a road overbridge - if I had ( been foolish enough ) and extended my arm, I could have touched the passing train - there are no refuges in bridges !

 

Now for question 2 ( or more accurately, comment ).

It seems Japanese steam locos always seem to throw out dense clouds of filthy black smoke as normal - I rarely see them with white steam exhausting as in most other nations steam locos.  Also, there seems a lack of exhaust blast, the smoke just seems to fall out of the chimney. Is this a lack of decent coal ? Lack of decent sized lumps ? ( nearly every video I have seen of the contents of tenders/bunkers of Japanese locos seems to be 'slack' or dust ! ) and/or bad draughting ?,  which would account for the seeming lack of power and black claggy exhaust.

Finally, why does the driver keep opening the cylinder drain cocks at intervals when the loco is running ? This operation is surely only applicable when loco has been standing for any length of time to clear condensation - I have never seen this mode of working on British steam locos.

 

Finally ( yipppeee!)

Has anyone watched one of 'Nimo 5's' video's of Hinobori tunnel on the Kisuki line ? 

It's so long it even has fog ( ! )  and it's own climate deep inside it !   Japan - The land of LONG railway tunnels - and seemingly hundreds of them too.  Amazing stuff !

[marknewton]

When you mention steam locos do you mean preserved engines running today, or back when they were in regular service?

 

Cheers,

 

Mark.

[kvp]

Question 1: It's called echo and in a small space, you can get multiple waves hitting and amplifying each other. The result is a roaring, thundering sound.

 

Question 2: Continous black smoke is a nice byproduct of a high ash content, high sulphur, low quality coal with not enough power to heat up the fire properly. Something really cheap that you can't even sell to private customers. Also if you combine high draft with coal dust instead of proper coal, you get fuel loss through the chimney. The proper solution would be pressed coal dust pellets, which is something that is just not economical to produce for a few preserved SL-s. At least they are not run on diesel fuel, like some of the european oil fired preserved steam locos.

 

Question 2/b: Drain cocks: On old black and white films, you don't see this, but on preserved steam locos this is one of the extra features, like the constant wistle sound, like the loco is actually pushed by the sound and the clouds of steam. If you want proper steam, then look for the old photographs and films, from the years when the locomotives ran in regular service.

 

Question 3: The same is true for all long tunnels without high capacity ventillation, including the Seikan and even the Channel tunnel.

 

ps: Here is an example that if you want to do it properly, then it's still possible:

http://www.youtube.com/watch?v=fL8ZFPNZdjg

[Kiha_120]

When you mention steam locos do you mean preserved engines running today, or back when they were in regular service?

 

Cheers,

 

Mark.

 Well Mark,  As far as British steam locos go - both now and then.  I grew up when steam was THE main tractive power on BR - the diesels were just beginning a major push into steam duties with the ill fated Hymeks, NBL's and 'Westerns' (in my region ). I know nothing of Japanese steam prior to becoming 'hooked' on Japan ( fairly recently) so I cannot comment about how they were run back then except to say, I feel sure the smoke wouldn't have been such a problem - certainly the overuse of the whistle and drain cocks would not have been either - as KVP puts it in his comment, most of the noise is done for 'effect' for tourist and railfans benefit.

[Kiha_120]

Question 1: It's called echo and in a small space, you can get multiple waves hitting and amplifying each other. The result is a roaring, thundering sound.

 

Question 2: Continous black smoke is a nice byproduct of a high ash content, high sulphur, low quality coal with not enough power to heat up the fire properly. Something really cheap that you can't even sell to private customers. Also if you combine high draft with coal dust instead of proper coal, you get fuel loss through the chimney. The proper solution would be pressed coal dust pellets, which is something that is just not economical to produce for a few preserved SL-s. At least they are not run on diesel fuel, like some of the european oil fired preserved steam locos.

 

Question 2/b: Drain cocks: On old black and white films, you don't see this, but on preserved steam locos this is one of the extra features, like the constant wistle sound, like the loco is actually pushed by the sound and the clouds of steam. If you want proper steam, then look for the old photographs and films, from the years when the locomotives ran in regular service.

 

Question 3: The same is true for all long tunnels without high capacity ventillation, including the Seikan and even the Channel tunnel.

 

ps: Here is an example that if you want to do it properly, then it's still possible:

http://www.youtube.com/watch?v=fL8ZFPNZdjg

Some great feedback there KVP, thanks.

The answers you give are detailed, but as to Q 1, this noise is not heard constantly, only at certain places as trains traverse tunnels ( and sometimes rock cuttings as well ),  that's why I asked about this odd phenomena - it seems to have a bearing on the track and/or formation in certain locations.

Q 2.   Yes, it's easy to see from the poor fuel why these locos can't get up and sprint !  I wouldn't mind betting the shed crew have regular flue brushings after each day or two out with the amount of clag produced, but on the other hand, I bet the firebars last for ages !!!! 

I have worked on steam locos in preservation here - everything from boiler washouts, wire brushing the firebox stays, brushing through the tubes, dropping the ash pans and generally getting covered in water, oil and dirt.

I loved every minute of it ! I even managed a short firing turn on 'Nunney Castle' one Boxing day past.

[kvp]

 

it seems to have a bearing on the track and/or formation in certain locations.

Yes, since the effect depends on the distance and angle of the echoing surfaces. If the echo phase is correct, you get the amplified rumbling noise, if not, the sound waves just cancel each other out. For example the 3rd avenue elevated in New York had the perfect distance between completly parallel buildings. The right surface distance (and thus the right delay) is also dependent on the speed, frequency and rhythm of the noise source. In case of wheel noise based rumbling, the latter is usually a function of the rail joint distances and the distances between successive axles. Noise engineering is quite a complex area, so i'm sure a specialist would have more information.

[bikkuri bahn]

Coal quality is poor in Japan, and hard to get to- typically in very deep seams, and many undersea.  I read somewhere that during the age of revenue steam, some of the coal was processed into briquettes for use on steam locomotives. 

[Ochanomizu]

Hello,

 

A1: bridge!  Bridge in a tunnel?  Yes, bridge in a tunnel.  Bridge over water drainage pit, for example, or soft ground or water course or another rail line.  Perhaps you are hearing this noise near the low point on the line?

[katoftw]

Good coal doesn't exhaust pure black.  Japans coal comes from Australia, the best coal in the world.  And the Japanese are will to pay top dollar for it.  Opposite for UK steam engines and coal sources.

[Kiha_120]

Hello,

 

A1: bridge!  Bridge in a tunnel?  Yes, bridge in a tunnel.  Bridge over water drainage pit, for example, or soft ground or water course or another rail line.  Perhaps you are hearing this noise near the low point on the line?

No sir, I think you misunderstood, I was quoting two separate 'incidents' - One was in a tunnel,  the second I was working under a road overbridge (where there are no refuges as most bridges are only a few feet in width.)

 

I will add,  that even now , at my age,  I would still enjoy working lineside.

Edited July 17, 2015 by Kiha_120

[Kiha_120]

Good coal doesn't exhaust pure black.  Japans coal comes from Australia, the best coal in the world.  And the Japanese are will to pay top dollar for it.  Opposite for UK steam engines and coal sources.

ANY coal will produce black smoke if it's reduced to slack !  Loco fireboxes are designed to burn lumps of coal, not dust.

[Kiha_120]

Coal quality is poor in Japan, and hard to get to- typically in very deep seams, and many undersea.  I read somewhere that during the age of revenue steam, some of the coal was processed into briquettes for use on steam locomotives. 

 Yes these briquettes were used in Britain as well - they were made to use up the otherwise useless 'slack' and make it burnable.

These briquettes were not popular amongst firemen, and from what I have been told by ex enginemen, they were reserved for mainly freight and secondary routes where maximum steam raising was not quite so critical.

[Kiha_120]

Yes, since the effect depends on the distance and angle of the echoing surfaces. If the echo phase is correct, you get the amplified rumbling noise, if not, the sound waves just cancel each other out. For example the 3rd avenue elevated in New York had the perfect distance between completly parallel buildings. The right surface distance (and thus the right delay) is also dependent on the speed, frequency and rhythm of the noise source. In case of wheel noise based rumbling, the latter is usually a function of the rail joint distances and the distances between successive axles. Noise engineering is quite a complex area, so i'm sure a specialist would have more information.

 

Many thanks for your in depth answer.  It answers a virtually lifelong question !

[marknewton]

Question 2: Continous black smoke is a nice byproduct of a high ash content, high sulphur, low quality coal with not enough power to heat up the fire properly. Something really cheap that you can't even sell to private customers. Also if you combine high draft with coal dust instead of proper coal, you get fuel loss through the chimney...

 

Question 2/b: Drain cocks: On old black and white films, you don't see this, but on preserved steam locos this is one of the extra features, like the constant wistle sound, like the loco is actually pushed by the sound and the clouds of steam...

Re question 2: Firing technique is the main factor behind the amount of smoke being produced, regardless of coal quality. A good fireman can keep a clean fire with poor coal, and a poor fireman can make lots of clag with good coal. I've been both, and done both. Key factors are experience, road knowledge and a good driver who works with you, not against you. And speaking from experience, if you're firing with fines and your firebed is being lifted by the draught, what you'll get is the spark arrester being blanketed and the lower rows of tubes being blocked. The coal won't ever get as far as being ejected from the chimney.

 

As for running with the drain cocks open, I agree that to a certain extent it's done for effect, but I've been on engines that were priming badly due to untreated or contaminated feed-water, and the only short-term solution was to run with the drain cocks open. I was running engines in the UK back when the all the dramas involving water treatment were happening so it was a technique that got used a lot.

 

Cheers,

 

Mark.

[marknewton]

If anything I would say that the draughting of modern Japanese locos - C57, C58, C61 and D51 - is very good. All these types have well designed front ends with generous exhaust passages and multiple orifice blastpipes designed to minimise back pressure.

 

But it's late, I'm ready for bed, so I'd like to continue this discussion when I'm more awake. :)

 

Cheers,

 

Mark.

[marknewton]

It seems Japanese steam locos always seem to throw out dense clouds of filthy black smoke as normal - I rarely see them with white steam exhausting as in most other nations steam locos.  Also, there seems a lack of exhaust blast, the smoke just seems to fall out of the chimney. Is this a lack of decent coal ? Lack of decent sized lumps ? ( nearly every video I have seen of the contents of tenders/bunkers of Japanese locos seems to be 'slack' or dust ! ) and/or bad draughting ?,  which would account for the seeming lack of power and black claggy exhaust.

 

Q 2.   Yes, it's easy to see from the poor fuel why these locos can't get up and sprint !  I wouldn't mind betting the shed crew have regular flue brushings after each day or two out with the amount of clag produced, but on the other hand, I bet the firebars last for ages !!!!

 

As I mentioned earlier, all the modern JNR engines had multiple orifice blastpipes to minimise back pressure. The disadvantage to that is the soft exhaust you've noticed. That's why JNR put a lot of time and effort into developing and testing effective smoke deflectors, to deal with smoke trailing due to the soft exhaust. In 2004 through to 2005 Japan Railfan Magazine published a 12-part article about the design, development and use of the various designs of smoke deflectors used on JNR steam locos. It makes very interesting reading.

 

I agree that on occasions you will see Japanese engines burning fines, but in my experience on most mainline trips the engines are burning washed and screened coal of a size I know as nut coal. It's also worth remembering that the preserved C61 and C62 class 4-6-4 engines have mechanical stokers, so they will tend to be fired with coal that is finer than hand-fired locos. And unless the fireman is really good on the stoker it's very easy to dump excess coal onto the grates and make lots of smoke.

 

I disagree with your suggestion that Japanese engines "can't get up and sprint" due to poor fuel. When they have to, the mainline locos can and do run quite smartly. I've seen C6120 starching along at 115-120kph quite comfortably, with a good clean fire too. But track speed is often relatively low due to curves and grades, and the crews I've seen and experienced don't thrash the locos. Japanese enginemen habitually link the engine up as soon as they can and run on short cut-offs whenever possible. I think that has always been the practice there, and the engines remain in good mechanical condition longer as a result. They also benefit from having bar frames, self-adjusting axlebox wedges, disck driving wheels and roller bearings.

 

I doubt whether the modern locos ever require much in the way of tube brushing. Apart fom anything else the modern designs all have Master Mechanics-type self-cleaning smokeboxes, which means you'd have to spend a day dismantling the entire spark arrester to get at the tubes. As for the grates, all the modern engines had rocking grates, with powered grate shakers on the bigger engines, and US-style Waugh segmental firebars. I know these well, they're very durable. Even with a very hot fire, or after knocking a clinkered fire out, they perform well.

 

Interesting that you've had a play on Nunney Castle. I worked on and fired Pendennis Castle when she ran on the standard gauge in Western Australia with Flying Scotsman in 1989. After that experience I can't say I'm a fan of GWR engines.  :)

 

All the best,

 

Mark.

[Kiha_120]

An interesting detailed reply Mark - thanks for that.

Well, not knowing anything about Japanese steam, I had no idea the classes most regularly seen have mechanical stokers ( that idea was tried here, but was not successful ) whether for 'political' reasons - i.e. unions, OR accountants ( and I know THEIR 'input' makes or breaks railways ! ) OR they were just not effective or even a combination of all three.

As for rocking grates - these are fitted on all British 'standard' locos, and I for one, love them ! ( especially on 'disposal' after a hard, dirty and wet day when the crew brings it back on shed ).

I have spent too many hours in pits between the frames having to rake out ash pans, banging my head on axles which were most inconveniently placed ! :)  and having (hot ) water dripping down the back of my neck also the not inconsiderable amounts of ash flying about, even with the hose on to keep the dust down.

I note you say are not a 'fan of GWR engines'  - Too many oiling points ? :) , well no problem there ,  I have an acquaintance who was a fireman on the infamous Somerset & Dorset.  He was based at Green Park, Bath,  and he told me he didn't like 'westerns' for various reasons, one of them being the difficulty operating the regulator whilst sat down........He said you needed arms like a gibbon to drive a western engine !

And loco nuts ?   Yes, I remember them - I even had one I picked up off the track bed at Shillingstone ( S & D ) it had survived intact for over 40 years !

Just to address the overuse (seemingly) of the drain cocks - as you point out, it could be from priming which points to the water used being very hard or even brackish ? I would have though the opposite judging by the abundance of mountain streams and rivers in Japan - but what do I know ?  I have never been to Japan, and unfortunately, am never likely to either, but I can hope !