Conrail Cyclopedia

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Apr 11, 2002

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The Conrail Cyclopedia - Serving Conrail fans world-wide since 1998.

Conrail SD50 The SD50 was an interim locomotive design, a step up in performance and efficiency from the SD40-2 but not quite as good as the SD60. Conrail purchased a total of 135 units between 1983 and 1986, making them the second largest owner of the model next to CSX, which ordered a total of 144 units.

Why did Conrail become such a large buyer of a locomotive that was produced for only a few years? The answer is quite simple. Shortly before Conrail went on their SD50 buying binge, Congress and the President had passed the Staggers Act into law. This freed all US railroads from the red tape that had been smothering them into bankruptcy for decades.

The law could not have come at a better time. The US economy as finally digging itself out of the recession that had been plaguing it for years. Rail traffic in many areas was beginning a slight upturn. And Conrail for the first time was beginning to turn a profit. More and more goods were being manufactured in the Northeast and being shipped via the freed Big Blue. Trucks, once the predicted doom of the railroad industry, were now appearing more and more on Conrail trains. Power plants were consuming larger quantities of the cleaner burning coal found in Conrail's Pennsylvania mines. The end of the 'transition' years of bombed out predecessor locomotives and abused rail lines was finally coming to an end. In late 1983 and 1984, Conrail was finally becoming its own railroad--and they needed more locomotives!

Conrail turned to it's good friend, EMD, which had produced the reliable SD40-2, which Conrail had purchased back in 1977 to haul coal and heavy merchandise trains over the mountainous terrain of Pennsylvania and Massachusetts. But the reliable SD40-2 that Conrail loved so much was no longer in production. By 1983 a new model was on the market: the SD50.

The SD50 marks several significant changes over the prior "Dash 2" series. The most noticeable change is the plainer look of the SD50 compared to the SD40-2. Gone were the SD40-2's distinctive dynamic brake blisters on the long hood and the long front and rear "porches."

Why did EMD streamline the SD50? To improve performance and reduce maintenance costs. EMD stretched the basic SD40-2 frame by a little over two feet for a total of 71'2", providing more room for the electrical cabinet and relocation of the dynamic brakes from the traditional blister in the center of the long hood to a more cooler and cleaner location directly behind the cab. Remember that dynamic brakes produce great amounts of heat and take in large amounts of air to cool them. Probably the worst spot to house the dynamics is directly over the hot prime mover and next to the filthy exhaust fans as found on the Dash 2 line! By moving the brakes forward in the SD50, EMD reduced maintenance costs and increased performance. Overall, the SD50 is a more efficient locomotive than its Conrail predecessor, the SD40-2, in every area, and is capable of pulling heavier trains over difficult terrain.

Flexicoil That being said, we can take a look at some of the difference among Conrail's four SD50 orders between 1983 and 1986. The most noticeable difference is that Conrail received its first three orders (6700-6804) with the older, reliable Flexicoil trucks as pictured to the left. They did order the fourth order (6805-6834) with the newer HT-C trucks, though EMD had been manufacturing these trucks since the SD40-2. Another difference among units is that Conrail received its first two orders (6700-6779) with 4,000 gallon fuel tanks, which had been standard on the SD40-2/SD45. However, Conrail received its final two orders (6780-6834) with larger 4,500 gallon tanks, one of the largest fuel tanks EMD made at the time Only the SD45-2 was larger with 5,000 gallons.

FRA Another unique spotting feature of the Conrail SD50 are the FRA-approved classification lights on the nose and rear. While other US railroads in the 1980s were abandoning the use of class lights all together, Conrail still insisted on using them for light engine moves and when units were awaiting assignment in engine terminals. The FRA-approved lights are what I like to call 'bug-eyed' affairs that shine a red beam of light directly down the rails, instead of outward along the angle of the nose like older 'standard' class lights did. All Conrail SD50's were to be equipped with such lights, but I have photographed three units that are equipped with the standard class lights: CR 6756 and 6819. There may be more that I have yet to photograph. This is a point to remember for those wishing to model the Conrail SD50.

Like all Conrail locomotives delivered prior to 1989, the SD50's came with black numberboards and white numbering. From 1989 until 1998, Conrail began replacing these with white numberboards with black numbering. Conrail received their SD50's in the standard scheme that they had been applying since Day One, but over the years variations have occurred. I have noticed that several styles of number boards have been freely used over the years, plus other minor details such as warning stickers. Originally, all units came with snow plows on the front pilot, but this has also changed over the years. Check photos to find that one unit that has just the right, bizarre mix of variations! From bombed out bodies to enormous rust patches, the Conrail SD50 is variety on wheels--even if some railfans/modelers find the body style boring.

One last quick thing I want to mention about variations. Directly behind the cab on the long hood sit a set of filter screens called simply enough "inertial filter screens." These screens filter air for the dynamic brakes. The standard screens are inset into the long hood. But I have noticed that on some units these screens are more like external wire grids. When looking at photos of these locomotive, see if you can spot this variation.

Okay, for those really into railroad operations, all Conrail SD50's are equipped with cab signals. Cab signals are similar to signals you might see along the tracks, except they are located in the cabs of the locomotives. They are basically a safety feature. There were areas on Conrail where locomotives were required to be equipped with cab signals. This could be an important detail if you were into realistically modeling Conrail operations on your layout. The cab signal electronics are located in a box that sits on the engineer-side of the short-hood walkway, but some units have a different style box mounted on the conductor-side running board between the blower and the cab. Yep, another variation!

Conrail's SD50 fleet has definitely seen better days. Most units are covered in rust, dirt, and dents, with peeling and faded paint to boot. They are definitely an interesting unit to catch if you like your locomotives down and dirty. Back in the 1980s I found the units extremely boring to photograph. It took me nearly a decade to "rediscover" their variety and character. Next to the aging SD40-2's, they remain one my favorite Conrail EMD locomotives from the good old days. I already miss them.

(Note: I wrote this piece before the end of Conrail on May 31, 1999, and have decided to keep it as a memory of those days.)

6741's Shock Absorbers How The 6741 Got Its Shocks by Don Oltmann
Don Oltmann, Conrail locomotive expert without peer, spins an amazing yarn about corporate paranoia, suspicious coincidences, and plain old fashioned Conrail thinking that it's a tale so bizzare that it just has to be true! So sit back and enjoy the story of how little engines can do big things...and how one Conrail engine got a special pair of shock absorbers. We begin in the beginning with... Amtrak?

1. In the late 1970s the nation learns that Amtrak SDP40Fs derail too often.
2. Everyone suspects the locomotive's HTC trucks to be the cause, but no proof is ever found.
3. Conrail's Vice President of Transportation decides to limit all HTC-trucked locos to 40 mph and decides to purchase all new locos with the older Flexicoil trucks.
4. All other railroads continue to buy the newer HTC trucks, making Conrail unique in this regard, though being unique is rather common on Conrail.
5. Then something bad is discovered. The bolster to the truck frame snubber in Flexicoil trucks contains asbestos, but the HTC trucks have no such snubber (their rubber "springs" are self-damped).
6. Now Conrail begins retiring a whole mess of old SD9s, SD35s, SD45s and SD40s that are wearing out.
7. We now go to the MT-6 slugs, whose tri-mount trucks slugs make changing their brake shoes difficult and whose trucks are an all-around pain in the neck in general. (Slugs go through brake shoes at a great rate, so this is no small deal.)
8. So Conrail decides to use retired SDs to replace MT-6 slugs. It is cheaper to do a carbody transplant from the MT-6 to SD frame, but Juniata is short of electricians and has plenty of welders, so MT6s are retrucked instead. (And it took a LOT of welding to replace those trucks!) Retired U-boats were also considered, but rejected for reasons I forget. Maybe it was that the GEs were still whole and the SD45s cut up already--the carbody transplant would have been to the GEs? Anyway...
9. There are two styles of Flexicoil truck. Those on the SD9s and SD35s are the older variety. They have clasp brake rigging that takes cast iron shoes, which slugs need, and a bolster that takes a round snubber. The newer style has a single shoe rigging, a square bolster snubber, and are generally more desirable (same as new purchases, somewhat stronger casting, etc.) Still with us?
10. Trucks from SD40/45s selected and clasp rigging applied to the MT-6; again, LOTS of welding.
11. MT6s are now retrucked with new-style Flexicoil trucks. There is much rejoicing.
12. Conrail orders SD50's in 1983.
13. EMD says that the new Flexicoil trucks will cost big bucks because they hadn't sold one for nearly 5 years at this point, but they were selling lots of HTC trucks.
14. Conrail doesn't have enough SD40/45s trucks alone left to trade into EMD, so they use SD9s and SD35s as well to complete the order.
15. EMD converts the SD9/35 trucks to single shoe rigging, which is much easier to do than the other way around, and delivers the SD50's with the trade-in trucks.
16. The Conrail VP Transportation who distrusted HTC trucks retires. The Mechanical Department acts nearly immediately to remove speed restrictions on HTC trucks, and a few other restrictions, like the pilot plow profile!
17. Then EMD decides to stop selling parts with asbestos.
18. While nearly all parts in EMD's catalog were replaced with asbestos-free equivalents, the snubber for the old Flexicoil truck is not, leaving Conrail to search for an alternative.
19. EMD offers a modification to replace the friction snubber with a hydraulic arrangement. Hydraulic dampers are mounted between the truck frame and bolster at a 45 degree angle so that they damp both lateral and vertical motion.
20. It is tried on 6741 and tested at Mifflin PA at speeds up to 70 mph. It works rather marginally. It is safe, but the ride quality is somewhat sub-par, so Conrail decides against the modification, eventually finding a non-OEM vendor who can manufacture a suitable asbestos-free snubber for the old Flexicoil trucks. The 6741 probably should have been modified back to standard, but since that cost big money and the snubbers worked well enough to keep things safe, it was left as-is.

And that, ladies and gentlemen, is the story of how one little, blue engine got a special set of shock absorbers. Thanks for the info, Don!

Comprehensive Roster
The roster below is comprehensive for these units, which were purchased beginning in 1983 and survived on roster until 1999. This roster based on information from CR Locomotive Data books.

 CR          Built
 6700-6739   1983
 6740-6779   1984
 6780-6804   1985
 6805-6834   1986

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