How was the turbo on an Alco 539 prime mover powered? I have an Atlas H O S-2 with Loksound 4 and the turbo sound seeems almost independent of the engine sound. Also, did such diesels have to go back to notch one prior to reversing direction and was there a delay dependent on the turbo?
trnjHow was the turbo on an Alco 539 prime mover powered?
I believe the Alco 539T Buchi turbo was only powered by the pressure of the exhaust, no mechanical connection whatever.
trnjAlso, did such diesels have to go back to notch one prior to reversing direction and was there a delay dependent on the turbo?
Yes, the throttle had to return to idle before changing the reverser. The prime mover, thus the turbo did not actually have to wind down but electrically, the reversing relays would be damaged due to arcing if the locomotive itself was still moving when reversed.
Regards, Ed
Glad it helped. There are some very interesting locomotive operator manuals here:
http://www.rr-fallenflags.org/manual/manual.htm
They are helpful for such research.
Good Luck, Ed
I find some of Alco's assumptions right up through the early 244s regarding turbosuperchargers a bit surprising. I see no mention of externally-adjustable wastegating, which is about the only thing that would give a constant-speed 'whine' from a turbo that size; I would in fact expect the speed to vary directly with required charge-air mass, although with serious turbo lag on small engine speed changes. The only installation note regards bushing check when reinstalling to the air manifold, there is no mention of anything to do with oil management or 'turbo timing' on spindown, and the maintenance instructions only involve the air filters (other than to shut off if you observe weird turbo behavior).
Nothing I can see about letting the turbo spool down before reversing direction; presumably just cutting fuel would quickly enough knock down crank speed on a 539, and modulation of excitation would reduce any inertia flywheel' generator kick on too-prompt reverser operation. But again see the operators' manuals. Interestingly there are notes in the first-generation 244-engined manuals that explain where the Alco smoke shows come from...
The only other maintenance note I see is that the RD-1 is expected to run 300,000 miles before furst inspection and at 150,000-mile intervals thereafter. Perhaps the arrangement on the 539T was even more conservative... I see nothing special about oiling arrangements at all; presumably there was no more prelubing concern for the turbo bearings than there was for the mains and valve train in the startup ... there's plenty of concern for adequate fuel-oil pressure! (unsurprisingly many 'preservation' organizations seem to have put prelubing on their 539Ts and I would argue that some of the associated sounds should be put on decoder startup routines...).