Dynamic vs. extended range dynamic brakes

[Erik W]

I'm new to being interested in the spotting features of anything built after the transition era.  That said, what is the difference between EMDs dynamic and expended range dynamic brakes?  Photos would help.

Thanks,
Erik

[asciibaron]

I'm new to being interested in the spotting features of anything built after the transition era.  That said, what is the difference between EMDs dynamic and expended range dynamic brakes?  Photos would help.

the newer traction motors can handle higher current draws feeding more "effective" loads to increase the amount of braking effect.

that would be my guess.

-Steve

[Hyperion]

You've got to really be on the look-out to spot a unit that has them.

The only visual difference is a small hatch in front of the dynamic brake housing.  Some equpped units also have slightly different DB bulges on the sides, noticeable by slight differences in the angle between the grid housing and the hood.  Since more stuff had to be fit into the same space, the angles on the bulge were made 'steeper'.

[Walkercolt]

Yeah, but now the've gone to more efficent dynamic brakes, and now you can't tell the difference. I've seen re-built former UP SD-40-2 that have been upgraded to Dash 3 electronic controls and extended range dynamic brakes. How do I know? Trains Magazine article, and the little numbers on the side sill. In the cab, they have desk top controls like new locomotives too, all done by the rebuilders. It's like BNSF's GP-39-2's. It looks like a GP-30, GP-35 or GP-38-2, but inside it's all solid-state electronics and 645 prime movers(to keep down the inventory of spare parts), the traction motors have been replaced with up-graded ones, and little on them is what came from EMD when new. Just the frame and the shell, and they even modify those. ???

[jmlaboda - RIP]

"The only visual difference is a small hatch in front of the dynamic brake housing."

EMD GP38s/SD38s had the hatch behind the housing when an unit was equipped with a paper air filter, GP38ACs and GP38-2s/SD38-2s always had the hatch on the back side of the housing, even when they were built without paper air filters (as on SOU 5000 - 5054, which were the only -2s built without paper air filters, later retrofitted).

[Allentown Hump]

38-2 w/o extended range DB


38-2 w/ extended range DB