Using sound decoders in UK Steam

Don't forget that the A3 is a three cylinder locomotive and it should sound a lot different to a two cylinder machine. You may have difficulty finding one that sounds right.

This was because when setting up the valves on the conjugated valve gear, they never got it absolutely right and the exhaust beats were not quite even, hence you got the characteristic Gresley syncopated exhaust with three beats to the bar. One of the three beats always sounded harder than the other two.

This was not so evident if the locomotive had recently been in the works and the valve gear had been set up by a really skilful fitter, but the beat developed thereafter.

In theory the same should apply to other three cylinder engines such as the LMS Jubilee.

Broadway Ltd have a sound sample of a Norfolk and Western Class A 2-6-4 which has a three cylinder beat, but the whistle is entirely wrong.

Colombo

There is a bit more to the 'Beat' story on Gresley's pacifics which I only became aware of a couple of months ago. I borrowed a book, I think by O S Nock, on the Gresley pacifics. This points out that the inner cylinder has to be inclined to the outside cylinders to clear the front driving wheel axle. Thus to get the right valve events with the conjugated valvegear the crank for the inside cylinder has to be moved away from being 120degrees with respect to the other two cylinders by the amount of slope of the cylinder. So that even with the valvegear being in tip-top condition there will be a slightly uneven exhaust beat because the cylinders don't exhaust at even points in each revolution.

So whoever comes up with the sound for an A3 or A4 is going to have fun sorting out the right beat!

Regards,
John Webb

The problem with sound decoders is they are quite large, so mounting them in the boiler of the A3 for example is probably not going to work. I normally mount a normal motor decoder in the body and then mount a sound only decoder in the tender.
The Soundtraxx SDX is great for this and the sound is impressive, for W/C B/B standards, and the like. They however do not have a chime whistle which would be a major draw back for LNERpacfic's. Mounting a ESU sound decoder in the tender will probably work or you can wait just a little bit for the new cheaper Digitrax sound decoder with recordable sound, this is the route I would take. If you do go the tender mounted route then perhaps it might pay to thinking of a perment coupling of the tender to the loco body. M3 cheese head screws work perfectly. I found ESU a difficult company to contact as there appears to be no one in the company who can read or respond in English.

Actually it's a N&W A class 2-6-6-4 which is a an articulated 4 cylinder simple and not to be confused with a Y class loco which is also an articulated 4 cylinder machine but is a compound rather than a simple. Loksound do a 3cylinder decoder which has the right beat but you would need to listen to the whistle to determine wether it would suit.

Ozzie21

QUOTE (Colombo @ 26 Mar 2006, 20:40) <{POST_SNAPBACK}>Don't forget that the A3 is a three cylinder locomotive and it should sound a lot different to a two cylinder machine. You may have difficulty finding one that sounds right.

This was because when setting up the valves on the conjugated valve gear, they never got it absolutely right and the exhaust beats were not quite even, hence you got the characteristic Gresley syncopated exhaust with three beats to the bar. One of the three beats always sounded harder than the other two.

This was not so evident if the locomotive had recently been in the works and the valve gear had been set up by a really skilful fitter, but the beat developed thereafter.

In theory the same should apply to other three cylinder engines such as the LMS Jubilee.

Broadway Ltd have a sound sample of a Norfolk and Western Class A 2-6-4 which has a three cylinder beat, but the whistle is entirely wrong.

Colombo