Question for steam experts

[Moonraker]

We are doing some work on our small scale steam soundcards which are designed for use on 2, 3 and 4 cylinder locos. The question has come up...how many chuffs are there for each wheel revolution. My understanding is that two and four cylinder locos emit four chuffs per revolution and 3 cylinder Gresley locos emit six chuffs per revolution. Is this correct and are there any locos which emit 8 chuffs per revolution? Shays perhaps?

Thanks for any info
Peter

 

[Neil Robinson]

In addition to Tac's information I felt sure that the Southern's (in the U.K.) "Lord Nelsons" had eight beats to the bar.
The link below confirms this and states that was due to the cranks being set at 135 degrees.
http://www.erps.co.uk/Trains/E850/A-History-Of-Lord-Nelson.htm
It also mentions two other locos with this arrangement and that one of the Nelsons was modified with conventional 90 degree cranks. These locos are very much the exception to the general rule.
Tac also mentions the Gresley and Thompson three cylinder machines. For the record the Thompsons were rather different animals to the Gresleys as Thompson used three sets of valve gear, one per cylinder whist the Gresleys used only two sets, with the the third, middle, cylinder's valve shaft driven by Gresley's conjugated motion.

 

[Moonraker]

Thanks for the responses gentlemen. I have carefully watched several A4 videos on YouTube, etc and found it hard to detect the irregular chuff you mention.

Peter

 

[Doug]

In addition to Tac's information I felt sure that the Southern's (in the U.K.) "Lord Nelsons" had eight beats to the bar.
The link below confirms this and states that was due to the cranks being set at 135 degrees.
http://www.erps.co.uk/Trains/E850/A-History-Of-Lord-Nelson.htm
It also mentions two other locos with this arrangement and that one of the Nelsons was modified with conventional 90 degree cranks. These locos are very much the exception to the general rule.
Tac also mentions the Gresley and Thompson three cylinder machines. For the record the Thompsons were rather different animals to the Gresleys as Thompson used three sets of valve gear, one per cylinder whist the Gresleys used only two sets, with the the third, middle, cylinder's valve shaft driven by Gresley's conjugated motion.

I take your point about the SR loco,s but, AFAIK, nobody yet has made a model of one of the bigger SR region locos, apart from Aster [King Arthur], and that was only a two cylinder model. If you want to hear what a Thompson sounds like, then I guess that the nearest you are going to get to it would be the new 'Tornado'.

tac
http://www.ovgrs.org/ < Link To www.ovgrs.org
RLGSS Member

The utoob vids of Tornado at speed - it just makes a whooshing noise. The carriage wheels are louder!

 

[Rhinochugger]

In addition to Tac's information I felt sure that the Southern's (in the U.K.) "Lord Nelsons" had eight beats to the bar.
The link below confirms this and states that was due to the cranks being set at 135 degrees.

Interesting musical leanings there, Neil

Anything the Southern did would inevitably be far better than anything anybody else did, not that I am at all baised in any way. I had been under the impression that the Nelson's were unique in this respect ....but obviously not.

I seem to recall the one-off 90 degree experiment was someething to do about getting them to steam more eagerly - apparently it required a skilled fireman with some experience of the Nelsons to get them to perform well - but when they did, they did
Sadly, as tac's mentioned, nobody has seen fit to model one in large scale.

Back to the question of sound, I'm not a purist in this regard, more of an impressionist, and for what it's worth, the most evocative small loco sound that I have heard is from those Darjeeling 0-4-0s - they're something else

Edit: just read your link Neil - and see that I am regurgitating stuff that has already been given from a better authority - I'll go back to sleep

interesting though - how could I go about being 'almost unique'........................

 

[Rhinochugger]

apparently it required a skilled fireman with some experience of the Nelsons to get them to perform well

A strong contender for the 2010 understatement of the year methinks :thinking:

Not sure that I was actually proposing a shovelling contest

I think Neil's article said it required a throw of 10 ft to get coal to the back of the grate