Pacific231G Posted June 24, 2018 Share Posted June 24, 2018 (edited) This is a very simple quiestion but can anyone explain the very distinctive ying ying ying sound that Class 66s (sheds) make especially when idling? It's very clear in this clip. https://www.youtube.com/watch?v=5LiRy_noywo I've not heard any other diesel loco that makes this particular sound so Is it coming from some piece of auxiliary machinery or is it simply characteristic of the diesel engine employed? Edited June 24, 2018 by Pacific231G Link to post Share on other sites More sharing options...
Zomboid Posted June 25, 2018 Share Posted June 25, 2018 I believe it is the supercharger. I've never heard one in real life, but the GP60 sound chip I heard has a similar squeaking thing going on, which would make sense as the engines in eachv type are closely related. Link to post Share on other sites More sharing options...
Pacific231G Posted June 25, 2018 Author Share Posted June 25, 2018 (edited) I believe it is the supercharger. I've never heard one in real life, but the GP60 sound chip I heard has a similar squeaking thing going on, which would make sense as the engines in eachv type are closely related. Hi Zomboid The explanation I found elsewhere is that, because it's a two stroke engine, the inlet air needs to be at a sufficiently positive pressure to purge the exhaust when both inlet and exhaust ports are open. At higher revs it's the turbo charger, driven by exhaust gases (AFAIK) that maintains that inlet pressure but at low revs it needs to be mechanically driven. It's that mechanical drive that makes the characteristic "ying, ying" sound at idle and low speeds. I don't know how accurate that explanation is but it agrees with what I know about large two stroke diesels. I did find this clip of a UP (ex Central Pacific) GP60 that had been parked with its engines running in winter for about five days. https://www.youtube.com/watch?v=igW8QAlQgAg According to Wiki "All 710 engines are two-stroke 45 degree V-engines. The 710, and the earlier 645 and 567, are the only two-stroke engines commonly used today in locomotives." Edited June 25, 2018 by Pacific231G Link to post Share on other sites More sharing options...
RMweb Premium Davexoc Posted June 25, 2018 RMweb Premium Share Posted June 25, 2018 The supercharger is driven off the engine through a viscous coupling, which then disconnects it above a certain rpm as it then becomes an unnecessary load. By then the turbochargers are providing the charge air pressure driven off the exhaust gases. The road going version was the Lancia Delta Integrale, same principle but a four stroke. Dave Link to post Share on other sites More sharing options...
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