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[quote user="Overmod"]I frankly don't understand why even now there is no coherent discussion of the DEF issues on the F-125. Whether or not this originated in some supplier or specification error has long been immaterial: Progress has had its engineers working on this for many months, long past the time I or perhaps anyone in a position of authority at, say, Metrolink is prepared to wait before ceasing to accept an 'it's proprietary but we're fixing it' kind of excuse. [/quote] According to the minutes of Metrolink Board meetings the SCR problem is solved. #908 had 21 runs after necessary modifications without failure (minutes 02/09/2018). There were two failures: failure of "gating solenoids" to open thereby restricting urea flow to day tank, and "loss of prime" preventing transfer pump frum pumping DEF to day tank. (minutes of 12/08/2017) [quote user="Overmod"]You may recall that they came within something like 0.2 % of making the nominal NOx standard ........... I thought then, ....., it would make far better sense to slip that arbitrarily-generated NOx spec enough to allow the EMD EGR-only approach to qualify. Instead Progress/EMD has had their profitability slammed and the 'alternative' programs and approaches related to EMD power have put many times more NO into the atmosphere.[/quote] We had this argument before. It might have been better for the environment. EPA set the NOx limits expecting the manufacturers to use SCR. Read the EPA's 1998 final rule making. EMD started testing the 710 using EGR for the off-road NOx limit of 3.0 g/bhp-hr and succeded. From Railway Gazette International December 2015 "Tier 4 locomotives take to the tracks": ‘The 710 loved it’, recalls Lenz. But the euphoria was short lived. ‘The EPA came out with 1·3 g/bhp-h for Tier 4, not the 3·0 we were hoping for.’ Not to be defeated, the engineers looked at adding more EGR and installing giant particulate matter filters on existing locomotives. Using a pair of borrowed Union Pacific SD70ACes fitted with large roof boxes for emissions testing, Lenz says EMD successfully got the 710 engine up to Tier 4 requirements. But while the tests were successful, the resulting design was too heavy, too cumbersome and not cost competitive enough to be marketable. In particular, the fuel economy was worse than for Tier 3. You can't change law just to help one company so far into the design process. GE sent the first Tier 4 locomotices for field testing in 2013. I difference to EMD had realized early that the FDL was at its limits and designed the Gevo for Tier 2. [quote user="Overmod"]In my opinion, the whole GM and then Berkshire debacle has incredibly little to do with the actual Tier 4 final issue that whacked Progress over the head.[/quote] I think it has a lot to do with the GM and Berkshire. GE Transportation had a parent company willing to provide technical expertise and money while EMD lacked both. Regards, Volker
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