What sort of work is required to add dynamic braking to a diesel-electric locomotive that was not built with it?

Enough work so that if you need a unit with dynamic braking you may be better off buying one that had it to begin with. Grids, blowers, DB hatch, contactors, HV cable modifications, additional control relays and regulator, wiring harness changes, control stand modifications, alarm devices, MU control modifications, etc.

I am not currently aware of any time that EMD issued a modernization recommendation for adding dynamic braking to any type of unit that did not originally have it. MK Boise and other rebuilders could add dynamic braking on a complete rebuilding if a customer wanted it, but that was usually done along with an electrical cabinet replacement, so they were usually building a clean frame locomotive up as a DB unit rather than adding the DB system to an existing non-DB locomotive.

PC

Well for starters I’d try to get a print of a locomotive of that make/model and see how the electrical high and low voltage for DB was done. On an EMD I know you’re going to need to modify the high voltage circuit. Adding another power contactor (BK) and two more reversing contactors (BKP1 & BKP2). High voltage wiring (535 MCM should be sufficient), appropriate grids/grid values. A grid blower and dynamic brake regulator. There are a couple other low voltage control items (such as a DBR, BWR, LRP, etc) you’ll need but depends on your setup. Of course you’ll also need a new master controller and ammeter as well if not equipped for db…

You’ll need to fabricate a new place for the grids to sit or buy a used grid hatch from someone like big Larry (LTEX)

Depending on how you approach this, it can be pricey parts wise. My recommendation would be to find a parts unit or a unit being scrapped by a rebuilder who will sell you parts cheap. I was able to get grids for 175 a pop from a loco being scrapped and they normally go for significantly more than that.

It’s doable for sure, just need someone who knows what they’re doing. It’s not impossible just time consuming

While DB might just be no more than a option box to check on the locomotive order forms, it is not a simple 'bolt on' option like many automotive options.

As DeAndre said… Can you do it? Probably. If you can find the bits and pieces and the manhours to do it. But should you do it? Unless you have a like model with DB to cannibalize at hand, that could be a long expensive slog. And it depends on what age/model you’re wanting to retrofit. We’ve been looking for the right 0.66 ohm grid to replace one that blew in a self load test in our GP7 (DB was a retrofit added back in the ‘60s and one of the grid resisters was replaced sometime after that with a .86 ohm which popped - bad move). Unless you have a fully equipped shop and a big pile of 5 lb. bags of $10 bills, I don’t think I would attempt it. Your mileage may vary, though.

Canadian Pacific retrofitted dynamics to their pair of ex-CN FP9s they bought for executive train service.

Iowa Pacific bought an F-10 from a commuter operation back east and sent it to the SLRG in Alamosa to pull passenger trains. They were somewhat dismayed when I (as system DSLE) refused to let it run over La Veta Pass (with 2.5-3% grades) because the passenger equipment was not equipped with retainer valves and the engine had no dynamic brakes.

I told EEE he ought to consult with the guys who had to run trains before buying things like this.

The F10 (#1100) got sent off to RELCO for repainting and fitting with extended range dynamic brakes (Sure! we can do that! Just send us money! - Relco). When the 1100 finally returned a year or so later, it was a disaster. If you put the dynamics into any position beyond "set up" it went into full dynamics. We brought our ace diesel medics out there and they quickly determined a whole bunch of electrical gear was not installed in order to throttle the dynamics.

Relco also was responsible for converting a few F40's into road slugs to be paired with a like number of F40's mother ships. All of the slugs immediately tripped their ground relays whenever they were placed on line.

Due to lack of payment RELCO refused to fix their ailing masterpieces, and we were stuck with them

Ah, yes but with a fully equipped locomotive shop, an experienced employee labor force and money to invest to do it right the first time. I'd bet there's not much under the hood that looks like an original FP9.

Not sayin' it can't be done, it certainly can be. Just sayin' that a typical tourist line might be getting into it a little over their head unless you have the facility and knowledge. That there 'lectric stuff quickly gets darned expensive, too.

Same as a modern car engine swap. Buy another one that has dynamic brakes, park it right next to yours, and swap everything that is different. Expect this to be much more than you'd hoped.

Trying to buy the needed parts on a piece-by-piece basis is going to be a non-starter and a bank-breaker. Even if a scrap company would sell them to you piece by piece, they'd likely come off the same unit *anyway* just at a much higher cost for labor and markup. So you might as well do it yourself.

Spectacular waste of time unless you're *really, really* married to a particular frame number or VIN.

Thanks for the replies and stories.

This wasn't for any particular project or locomotive, just a thought that had been bouncing around in my skull for a little while.