12-645 T "Roughness"

Recall one of the ex-RDG GP-39-2's being stripped of its' engine at Colonie
(D&H) shop on account a broken crankshaft.

Did this version of the engine have some vibration problems ?

The ARR has the 12-645F's in their GP49s, they haven't had any problems. I don't know the difference on the Fs and Ts, though

I don't know about the 12-645T: I've never seen anything about it having problems. (The 39 and 49 series were comparatively uncommon in the U.S., but enough GT22 and other export models have been built with the 12-645T that if there was a problem SOMEONE ought to know about it. Iarnrod Eireann in Ireland and V-Line in Victoria (Australia) both have sizeable fleets of 12-645T engined locomotives, to name just two.)
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I HAVE, however, seen a report of problems with the 12-710T. The October 1999 issue of the Australian magazine "Railway Digest" has an article on the 12-710T powered NSW 82 class containing the following paragraph:
"However, the change to the longer piston stroke upset the balance of the 12-cylinder engine in particular and both the Australian National (now National Rail) DL class and the 82 class have suffered from this problem, as have locomotives in other parts of the world. The vibration is not so serious for the crew, owing to the fully isolate cab (though it was an issue with crews in the early days) but results in a torsional (twisting) vibration in the crankshaft. A separate problem, caused by faulty welding of balance weights resulted in fatigue failures of a number of crankshafts in the 82 class While this was not the result of the torsional vibration, that probably reduced the time to failure. In comparison, the 16-cylinder 90 class has no problem in this regard. EMD have[*] faced up to the problem and designed a new crankshaft, which results in the cylinders firing in a different order. But this also requires new camshafts, and is basically too expensive to apply as a retrofit. However, the newer Westrail S class received the modified 12N-710G3B-ES engine (N for New firing order) when manufactured. Interestingly, the same torsional vibration problem occurred with the early 567C eight-cylinder engines but in Australia, only the very earliest Victorian T class had this engine. All later eight cylinder 567 units (including all the [NSWGR] 49 class) had the 567CR engine (R for Revised firing order)."
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* Linguistic note: note that in Australian English, names of corporations take a plural verb: an American writing this sentence would have said "EMD has...".

Allen and OLG, the twelve cylinder versions of the EMD engines have always had a "rough" feel on the platform at certain speeds which is indeed the result of a firing order induced torsional vibration. This is a function of having a crankshaft with throws indexed at 60 degree angles in an engine with a 45 degree angle between the banks of cylinders. The vibration characteristics of these units generate a lot of attention from their operators, particularly in marine installations where the engine supporting structure (usually designed by a naval architect) may vibrate in sympathy with the engine.

Having said that, I should also observe that twelve cylinder EMD's usually do not have significant failure problems with bearings or crankshafts, so the event OLG witnessed is rather unusual. The twelve cylinder crankcase is very stiff and provides very solid support for the crankshaft. In the rare instances where a twelve has a crankshaft failure it is usually a result of a triggering factor, like water contamination or fuel dilution of the lube oil, dirt cutting of the bearings from filters operating in bypass, or loss of lubrication.

Historically one of the biggest contributors to failure of crankshafts in EMD engines was improperly performed bearing inspections, where the bearing shell got put back in the cap the opposite of the way it came out. This is one of the reasons that they took the periodic bearing inspection out of the maintenance instructions back in the late 1970s.

I'm suprised to read that after all the years of EMD producing V-12's (no turbocharged and not) there would be any problems with them.

Stuart

I seem to recall that a very talented designer of diesel engines who worked for a very large US company once said: "Every engine is a great engine until you run it".