Most of the engine problems on the 645F series have been traced to 3 things. 1 the increase in rpm from 900 to 950 to get the hp out of the engine. 2nd but this was retrofitted fairly quickly by most shops. The bean counters at EMD decided that using a steel drain line for the turbo wasn't worth the cost. So they used copper instead. These tended to break and spray oil all over the place. The railroads just replaced it with steel. 3rd was the requirement for those tin plated cylinders. It meant a separate parts source for this line of engine rather than the same one's common for the 645 series.

I remember a tour of C&O's Huntington Shop when it was full of SD50's. I asked what they were doing there, as they were fairly new then. I was told they were "under engineered."

I assume the post production modifications made them into reliable locomotives.

Phil Mulligan

While the CRRM in Golden has a GP30 and SD40T-2 in the collection, a former Rio Grande SD-50 would be a nice addition, if not there, perhaps at another location on the former Rio Grande system in preservation. The SD-50's were unique on the D&RGW as being just about the only 2nd or 3rd Gen EMD's on the road that lacked dynamic brakes.

Rob Gardner

EMD transitioned to the "Pie" or "Radial" style dynamic brake grids on the 50 series. They were located directly behind the electrical panel and in front of the clean inertial blower/clean air room.

The location was a big improvement than the traditional blister over the engine and got the grids and associated wiring and shorting contactors away from the exhaust manifold.

EBL

The Rio Grande units came from a cancelled Chessie System order (see above, they were unhappy with their performance). Rio Grande wanted more tunnel motors but needed power fast and EMD made them an offer they couldn't refuse. I believe they had dynamics, I can't imagine the Rio Grande buying any units without dynamic brakes.

One thing I always noticed around 1992 when I lived 50' from the main line about ten miles below the Moffat Tunnel, the 5500s/ SD50s would often be bunched on the head end of empty westbounds going upgrade, especially empty coal trains, but generally were mixed in on loaded trains or eastbounds, I was never sure why. I suspect they were a bit quicker to track speed than the SD40-T2s.

Part of the reason why the SD50 wasn't as popular as the 40ts on the Rio Grande especially on the Moffat line going west with tonnage was they tended to overheat at full tonnage as they drew their cooling air from up high.

As I explained to you a few years ago, the Rio Grande struck a deal. There was no cancelled order.

The Rio Grande were in a power crunch, had been impressed by the Seaboard SD50's that they had tested, and cancelled plans for 20 additional SD40T-2's for late 1984 delivery (they had signed a letter of intent with EMD for the order). But the SD50 production line was booked solid and Rio Grande was going to have to wait until late 1985.

Since the Rio Grande needed SD50's quickly and didn't want to wait until La Grange could deliver months later, they made a deal with Chessie (which was experiencing a traffic slump in the east and could afford to defer a portion of their order by several months).

The 20 B&O assigned units were built and delivered as originally planned, but the 20 C&O units that were due to be built and delivered at the same time were deferred to 1985 (being delivered late that year, doubling the C&O fleet to 40 SD50's). All of this opened up their late summer/early fall 1984 SD50 construction slot for the Rio Grande's order.

They were built to Chessie specifications identical to the B&O units that immediately preceded them in July & August. This meant that EMD didn't have to retool for the order. Otherwise it would've delayed the SD50's previously ordered by Missouri Pacific, Seaboard, and Conrail for late 1984/early 1985 delivery.

And not only were these 20 "cancelled" C&O units built a few months later and delivered that you allege they wanted out of, but as I stated above, the CSX family afterwards also received 21 Seaboard assigned units in early 1985.