Why do Class 66s ying?

[Strathclyder]

https://www.youtube.com/watch?v=a3FD-228ZvQ

That should work for the last link. I think you did http://https://... by accident.

D'oh! The perils of working with several web-pages while sleep deprived illustrated.

Now corrected, thanks.

 

[delticdave]

It's a two stroke engine which, unlike 4 stroke, does not naturally pump the gasses through. The inlet air needs to be maintained at a positive pressure so the charge air purges the exhaust when both inlet and exhaust ports are open.

The turbo maintains this inlet pressure at high revs but at low revs this is augmented by mechanical drive to the turbocharger (as per traditional supercharger). I think it is this mechanical drive to the blower that makes the prime - ahem, engine - "ying" at low speed.

Interesting.......

If you can find (youtube?) a recording of an idling non-turbocharged EMD locomotive, then their soundtrack is totally different.

As for when on load, even more awesome / different!

DC

PS I'd suggest searching for F7,GP7, GP7 or GP9 in North America, or "Nohab" diesels as sold / built in Scandinavia or Belgium.
There are also some good recordings from Australia, featuring some quite ancient units being caned to death in their last years in private ownership!

 

[Taunton]

Almost all locomotive types fitted with a specific variant of the EMD 710 powerplant (12N-710G3B-EC, to be precise) make the 'ying-ying' noise when at idle.

Not only those. This characteristic GM noise has been there since the original diesels they built in the 1940s-50s. The streamlined F-units with the old 567 engine make the same noise when standing.

Their main competitor from the same era, Alco, also had their own, different, noise. The "Alco chortle". They make a Ha-ha-ha-ha noise when standing.

 

[Strathclyder]

Not only those. This characteristic GM noise has been there since the original diesels they built in the 1940s-50s. The streamlined F-units with the old 567 engine make the same noise when standing.

That may be the case, but it seems to be especially prevalent in most of the locos fitted with that specific variant of the 710. If nothing else, it marks them out aurally from other EMD-powered locomotives.

 

[NSWGR 3827]

Interesting.......

If you can find (youtube?) a recording of an idling non-turbocharged EMD locomotive, then their soundtrack is totally different.

As for when on load, even more awesome / different!

DC

PS I'd suggest searching for F7,GP7, GP7 or GP9 in North America, or "Nohab" diesels as sold / built in Scandinavia or Belgium.
There are also some good recordings from Australia, featuring some quite ancient units being caned to death in their last years in private ownership!

For some good 567 sound try this link https://www.youtube.com/watch?v=sSMhj__LlOk

 

[spookywestie]

Some real quality threads on here.

 

[CosherB]

Some real quality threads on here.

Care to start one?