Jan 3, 2003
When EMD designed the SD40-2, they literally designed the most reliable, cost-efficient, heavy-service locomotive ever built, creating a favorite among train crews and shop employees alike. Conrail purchased their first order of SD40-2's from EMD in 1977, seeking to replace the similar but cost-inefficient fleet of SD45's. A high-horsepower locomotive with a high tractive effort rating, the SD40-2 featured many innovations shared among the entire Dash 2 series, such as modular electronics and increased fuel efficiency. In short, the SD40-2 was the perfect locomotive for the emerging Conrail, perfectly suited for coal and heavy merchandise trains storming across the mountainous terrain of Pennsylvania and Massachusetts.
Because EMD saw the SD40-2 as a direct replacement for the older SD45, understanding the latter locomotive model is helpful. Briefly stated, the SD45 was an immense class of locomotive. They were powered with EMD's excellent 645E3 prime mover, though EMD pushed the design to its limits for the SD45. Twenty turbocharged cylinders could produce 3,600 horsepower, while still having good tractive effort. This mix perfectly suited Conrail's mountainous predecessors, such as the Reading Company, Pennsylvania Railroad, and Erie Lackawanna. With such high horsepower and traction, the SD45 could easily haul freights over these railroads.
Unfortunately, the SD45 was a maintenance and bottom-line nightmare. Its enormous, oversized prime mover sucked fuel like a kid sucks down candy. Plus the enormous engine required constant maintenance. Combine these problems with an antiquated electrical system and you have a locomotive that shop employees, engineers, and accountants disliked, a rare occurrence on any railroad, let alone Conrail. Working for a new railroad that was looking to streamline its bloated roster of inefficient locomotives, the SD45's future on Conrail looked bleak. The new Dash 2 series of locomotives simply sealed the SD45's doom.
A decade after they introduced the SD45 in the 1960s, EMD introduced the next generation of locomotive design, dubbed the Dash 2 line, which incorporated advancements in electrical systems and prime mover designs, creating a highly efficient and reliable series of locomotives. Because of the poor economy in the 1970s, EMD looked to control costs on Dash 2 designs. As a result, they used as many stock parts as possible. For example, the SD40-2's 4,000 gallon fuel tank is a stock SD45 4,000 gallon fuel tank.
While they shared some common parts with the previous series of locomotives, especially with the SD45, the SD40-2 really was an improved locomotive. For example, the SD40-2 used a turbocharged, 16-cylinder 645E3 prime mover, producing 3,000 horsepower, whereas the SD45 used a larger prime mover to produce 600 additional horsepower. Even though the SD40-2 produced 600 less horsepower, they could easily pull the same tonnage at the same speeds as an SD45, while weighing 1,000 pounds less and using much less fuel. How was that possible? The trick lies in tractive effort. While horsepower indicates the top speed a locomotive can achieve, tractive effort indicates how much tonnage a locomotive can pull. Tractive effort is the locomotive's ability to start progressively heavier trains from a dead start. The higher the locomotive's tractive effort, the heavier a train it can pull. Increase the weight applied to the locomotive's driving wheels and increase wheel-slip technology, then tractive effort dramatically increases. EMD did just this with the SD40-2, creating the equivalent of an SD45 that operates far more efficiently and reliably.
A brief side note about tractive effort. Because wheel-slippage is such an important issue, railroads like assigning locomotives of similar tractive efforts to a train. If a locomotive with a low tractive effort is coupled with locomotives having a substantially higher tractive effort, the wheels on the lower rated locomotive will begin slipping while accelerating a heavy train long before the other locomotives. This is why you will never see an SW1500, which has a tractive effort rating of only 42,000lbs, running in a consist of road units such as the SD40-2, which has a rating of 83,000lbs. In such a situation, the SW1500 will be shut down and in tow. So modelers, take this into consideration when assigning locomotives to your trains.
Now back to our SD40-2 vs SD45 performance debate. As mentioned earlier, both locomotive classes shared many of the same performance criteria, but the SD40-2 comes up the overall winner. For example, both classes produced 83,000lbs of continuous tractive effort. Both operated at nearly identical minimum continuous speeds of 11mph with identical gear ratios of 15:62. Both classes had a maximum single unit speed of 30mph, maximum multi-unit light engine speed of 60mph, and maximum train speed of 65mph. The SD40-2 wins the performance battle because it did all this with a smaller, 16-cylinder engine that used less fuel while requiring less maintenance. Because of its smaller size, the SD40-2's prime mover also suffered less wear and tear, allowing it to last far longer than the massive 20 cylinder version, which tended to die rather quickly. As a result, the SD40-2 is still operating today, whereas the SD45 has long since become scrap metal.
One final note that seems to come up often in discussions. While the SD40 and SD40-2 shared the same long hoods, they did not share the same frame. Actually, the SD40 and the SD45 shared the same frame, whereas the SD40-2 shared the longer frame of the SD45-2, which is why the SD40-2 had such long front walkways, commonly nicknamed porches, compared to the shorter SD40 walkways. EMD lengthened the SD45-2 frame so that the locomotive's hood could accommodate the larger, non-angled radiators along with the 20 cylinder engine. Because the SD45-2 was in production contemporary to the SD40-2, EMD decided to use the SD45-2 frame to save costs, even though it was much longer than needed. Little did they know that they had created one of the most appealing spotting feature for the locomotive! Heck, one hot summer day when the SD40-2’s were new on the system, I actually saw a stopped crew pull out lawn chairs and set them up on the porches while waiting for a long delayed signal!
Uniquely Conrail: HTC v Flexicoil Trucks
While EMD tried using as many stock parts as possible to reduce overall costs and make the Dash 2 series as appealing to cash-strapped railroads as possible, Conrail ordered their SD40-2 locomotives with some uniquely Conrail features, making the modeler's life difficult. For example, even though EMD designed the SD40-2 with a newer and more sophisticated high adhesion truck design, labeled the HT-C, Conrail specifically requested that EMD equip all of the railroad's SD40-2's on order with the older Flexicoil trucks because Conrail feared that the newer trucks might cause derailments, as had been happening on Amtrak, which operated locomotives with the newer design HT-C. Even though investigations proved that the HT-C trucks were perfectly safe, Conrail still insisted EMD install the older but reliable Flexicoils.
Pictured to the left is a thumbnail image of a larger comparison photo available for download, featuring a shot on the top of a Flexicoil truck from a Conrail SD40-2 and a shot on the bottom of an HT-C truck from a Conrail SD60M. The main difference between the two trucks is the sideframe itself. After comparing the photo, not much discussion is really needed. Not so visible is the 40" wheel diameter on the Flexicoil truck compared to the larger wheel diameter of the HT-C truck. The axle centering and spacing on the two truck designs is also different. The Flexicoil truck has a 13' 7" spacing between axle #1 and axle #3 on each truck, while the middle axle is centered. The HT-C truck has a 13' 7-3/8" centering between axle #1 and axle #3, but the middle axle is offset 1-1/4" from center. You can almost see the offset center axle, if you look at it long enough, but you'll never see the 3/8" overall difference compared to the Flexicoil.
According to Conrail expert Don Oltmann, what made the HTC a "high adhesion" design was that all the traction motors were oriented the same direction so that their torque reaction didn't cause uneven axle loading. It also had softer primary (axle to truck frame) suspension and stiffer secondary (truck frame to bolster) suspension as well as a larger center plate. This kept the truck from trying to "pop a wheelie" under the locomotive.
Flexicoil Truck Modeling
Because no one makes a Flexicoil truck add-on detail part for the Athearn SD40-2--they would never sell enough to justify the development costs--modelers must make do. However, there are two approaches you can take if using the HO Athearn SD40-2 for your project. You can follow the Athearn Recommended Way or the Good Enough Way. We'll first look at the Athearn Recommended Way, which requires you to use the entire truck assembly from their Dash 9 model, replacing the wheels with 40" sets and adding on Flexicoil sideframes from an SD45, which are Athearn part number #40066. The wheelbase isn't completely correct, as Don Oltmann once pointed out on my Conrail email list, but we are dealing here with only a difference of the width of a few pieces of paper! The Athearn Recommended Way is the preferred method of Conrail modeler Ken Freeman, who says, "Yes, the wheelbase isn't completely right, but they fit, and look soooooooo cool for Conrail."
Or you can follow the "good enough for me" approach pioneered by Conrail modeler and expert, Don Oltmann, who found that the solution for him is to modify the HT-C sideframe to look more like a Flexicoil. He does this by filling in the center hole of the three in the frame casting, then cutting off the part of the frame that supports the "nose" of the inboard traction motors. He also omits the center axle "shock," filing flat where the top of the shock mounts on the sidefram. He also adda a Hyatt bearing cap where the bottom of the shock mounts, but he can’t remember the detail part number. What's still amiss when you do this modifications, he says, is that the center axle on an HT-C truck is still about .017" off center and the bolster-to-frame connection is wrong. Because these are such minor issues—remember the widths of paper discussion above--Neither of these bother him enough to do anything about them.
So there you have it. Two solutions to problems that have been plaguing Conrail SD40-2 modelers for ages. Which you decide to choose is up to you, and depends how much effort and money you want to expend. Either way, you will not get an exact replica of a Conrail truck and will have to settle for close enough.
Other Conrail Features
Another little Conrail detail involves their snow plows. When delivered, the first order of Conrail SD40-2's (6358-6440) had plows on the front pilots. The following two orders of SD40-2's (6441-6524) arrived without plows. Of course, all of this changed over the years and photos of individual units from specific times should be checked. Though not visible on the model, for those modeling sections of Conrail where cab signaling was in effect, you'll be happy to know that all of Conrail's SD40-2's were equipped with cab signal equipment, allowing them to lead any train anywhere on the system. Furthermore, Conrail specifically ordered their SD40-2's for heavy merchandise and coal service over its mountainous lines, but during the 1990’s Conrail equipped 6358-6413 for pusher service over Horseshoe Curve in Pennsylvania.
SD40-2 Paint Schemes
When modeling any locomotive, it's always best to track down photos of specific units for the period you're modeling. This is especially true of older units, such as Conrail's SD40-2's. Since they began arriving in 1977, Conrail’s SD40-2's have worn a number of paint schemes and variations. For example, units repainted since 1989 received white numberboards, while other units got the white safety stripe along the sidesill. The Quality scheme also has its fair share of oddities. At least three different sized Quality logos were used, with 6450 getting the Dash 8 Quality logo!. Plus some units got the Quality logo on the front nose, but not on the rear. While others got the logo on the rear but not the nose. And so on. I'll try and mention any known variations in the caption for each locomotive on the photo page.
While keeping track of the minor paint scheme variations can give the Conrail modeler fits in his sleep, there are some rather nifty schemes you might be interested in modeling. First, in 1977, CR 6431-6440, along with the new C30-7's 6600-6609, underwent an operational cost comparison program, receiving a white star under their cab numbers to denote engines participating in the program. One SD40-2, however, did get a special scheme. In 1992 Conrail's Altoona Juniata paint shop painted CR 6373 into a special 'Olympic Road Trial' scheme for Olympic cyclist time trials taking place in Altoona, PA, from June 11th to the 21st. In March 1993 the unit was still fully painted and running in the Altoona area, but by August of that year its logo along the long hood had been covered over in white paint. A photo of 6373 with the painted out logo is on the SD40-2 Photo page. By August 5, 1995, 6373 had been repainted into the Quality scheme.
A special thanks to all the people who have helped make this page a reality with their expert advice and input. I'd like to thank in no particular order: Don Oltmann, Ken Freeman, Jeremy Helms, Veli-Pekka Pelttari, and Brian Clough, all members of my Conrail-Classic email list.
The roster below is comprehensive for these units, which were purchased beginning in 1977 and survived on roster until 1999. The roster does not contain retirement dates and dispositions. This roster based on information from A Colorful Look At Conrail's SD40 and SD40-2's and CR Locomotive Data books. If you happen to spot an error in the roster or have additional information, please contact me.
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