SD39-2U

I was just looking through a recent roster of BNSF and I noticed what used to be sd40-2s were sd39-2us. I take it it is a derated SD40-2. Whay did the railroad do this and were these rebuilds done in the last year?

The Santa Fe 4000 Class (4000-4019) were SD39s with 12 cylinder 645 turbocharged engines. A 16 cylinder engine out of an SD40 or SD40-2 could be modified into a 12 cylinder engine in a couple of ways. Or the BNSF could have gone to EMD and asked how much they'd charge for a 12 cylinder 645 turbocharged engine with a 16 cylinder for a trade or sold the 16 cylinder engine on the open market. For shoving the hump at Tulsa or Birmingham or Argentine that would be plenty of horsepower even with a slug.

Why would they do that? Because maintaining a 12 cylinder engine is cheaper than maintaining a 16 cylinder engine. The main generator and traction motors might even live longer.

Without you showing any road numbers, I'd say they're SD45-2's that have had their 20-645E3 prime movers replaced with 16-645E3B prime movers, dropping the horsepower rating from 3600 to 3000 and essentially turning them into a SD40-2.

BNSF classes at least some of these rebuilds as SD39-2R. The 39 is for administrative purposes since they're rated at 2,999hp to take them out of the locomotive utilization calculation for road power and the 39 denotes to employees that they're for local and yard service.

They also are doing 10 or so SD40-2 rebuilds for low speed RCO service and there might be others similarly designated (Depends on which roster you look at online). They're titled as SD39-2 by BNSF probably for the same reasons. I don't know their horsepower ratings. but I suspect it's just a computer change to show them as having 2,999hp so they're not mistakenly used in road service just like the reengined SD45-2's. If it was something as simple as turning them into normally aspirated units to drop their HP and reduce maintenance cost, I would've thought they'd be designated as SD38-2's. And I've heard nothing of a program by BNSF to turn SD40-2's into a true 12 cylinder Dash 2 version of a SD39.

Leo_Ames wrote:Without you showing any road numbers, I'd say they're SD45-2's that have had their 20-645E3 prime movers replaced with 16-645E3B prime movers, dropping the horsepower rating from 3600 to 3000 and essentially turning them into a SD40-2.
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Actually the entire SD40-2 fleet, including the recent group of rebuilt former SD45-2's, are being reclassed as SD39-2. All are still powered by turbocharged 16-645's.

Bryan Jones
Brooks,KY