DCC LMS Compound

Heather Kay

Western Thunderer
According to my expert, if it's running in simple form it should be four chuffs per revolution. When running in compound form, probably two. The loco will start off in simple and then change to compound after reaching a certain speed - not sure what that would be, though.

I stand to be corrected!
 
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OzzyO

Western Thunderer
Or did they start as a simple three cylinder loco and then go into compounding? This should then give us six beets per. rev. then when the compounding kicks in you would only have three beets per. rev.? Or something like this, cough, cough, wheeze, cough, cough.

I must look in my books about this,

OzzyO.
 

simond

Western Thunderer
I looked a bit last evening, but have not found anything conclusive, but am hopeful that I will know more tonight, I have a tame expert...

I believe there were two "simpling" systems used on these locos. They were three cylinder, so it's reasonable to expect 120 degree cranks, which would suggest that when in simple mode, there would be 6 beats per revolution as Ozzy suggests. When they were in compound mode, the HP cylinders would exhaust into a chamber from which the LP cylinder would be fed, and the LP cylinder would then provide the blast, and this would be two per rev, as Heather's tame expert proposes.

So my guess is 6 & 2, and that the two might be quite "soft", in comparison to the six, which would be "chuff, chuff, CHUFF, chuff, chuff, CHUFF" as the LP cylinder was very much bigger than the HP cylinders. Or perhaps the other way round, "Bark, Bark, Woooof"...

Quite how you find a suitable sound project, I have no idea! Perhaps there are recordings, or cine film that would give enough info for a reconstruction?

Best
Simon
 

rusty

Active Member
This is a topic on which I have little information other than to suggest a look at the J T van Riemsdijk book on compound locomotives (Pendragon/Atlantic 1994) - from which the following extract on Midland and North Eastern 3 cylinder locomotives, comes:
"The (NE) engine was provided with separate control for the high and low pressure valve gears.......so insuring four equally-spaced exhaust beats for each turn of the driving wheel. It (NE loco) was provided with a starting gear which allowed for working the low pressure cylinders as a two cylinder simple, the high pressure cylinder being cut out (as far as power was concerned) by the fact that its piston had high pressure steam simultaneously on both faces." "The first two Midland compounds ..... were slightly larger (than the NE loco.) but copied that locomotive very closely. Like that engine they made provision for the direct admission of steam .... to the low pressure steam chests on starting or as a way of reinforcing power for a short while ....... reinforced working was a feature, though little used, of the de Glehn four cylinder compunds."
Lots of scope for DCC sound by the look of it!
Julian
 

JimG

Western Thunderer
looking at youtube I found this
1000 under restoration and in steam.
Might be of help.

Have a care about trusting the sound on this film. It has the hallmarks of being shot mute and having FX added from whatever FX disk was available. The last shot on the film shows distinct exhaust beats out of the chimney which would be a certain source of data.

Jim.
 

simond

Western Thunderer
I have it wrong in my post above - not sure why, but I had two HP and one LP cylinders, but it's T'other way about.

Sorry for any confusion. Hoping to see my pal this evening, will report if I have better info.

Best
Simon
 

OzzyO

Western Thunderer
I have it wrong in my post above - not sure why, but I had two HP and one LP cylinders, but it's T'other way about.

Sorry for any confusion. Hoping to see my pal this evening, will report if I have better info.

Best
Simon

That sounds wrong it's two LP cylinders on the outside and one HP cylinder between the frames the HP cylinder was about the same Dia. of the LP ones.

OzzyO.
 
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mth

Western Thunderer
Have a care about trusting the sound on this film. It has the hallmarks of being shot mute and having FX added from whatever FX disk was available. The last shot on the film shows distinct exhaust beats out of the chimney which would be a certain source of data.

Jim.

I agree with you but if you watch you can count the barks per wheel rotation.
 

OzzyO

Western Thunderer
Hello all,

the following pages may help us or get us all the more confused. The following is from an LMS book published in 1941 for steam railway locomotive engine-men. They turn up on Ebay every now and then but well worth getting a copy.
Valve gear.jpg

Valve gear 001.jpg

Valve gear 002.jpg

Valve gear 003.jpg

Valve gear 004.jpg

Valve gear 005.jpg

OzzyO.

PS. after doing a full read of the above it looks like the compound will allways give four beats per rev. Thats if I'm reading it right.
 
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simond

Western Thunderer
Thanks Ozzy

Curious crank arrangement.

Very strange not to make use of the HP cylinder at all for starting

Best
Simon
 
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