Is there some reason why a urea exhaust treatment cannot be used on locomotives ? I am aware thatMarine EMDs have a much larger sump, and obviously there is more room in a ship than within the confines of a locomotive , to add auxiliaries that will improve fuel processing.
If the 710 can be made Tier 4 compliant then why is Progress Rail / Caterpillar ceasing US supply of 710s as was recently reported in Trains magazine ?
Best wishes and regards, Radioman
"Trains" is aimed at a North American reader, it caters to the rail fan market (a goodly percentage
of whom think that a foreign loco is one from the other side of the Mississippi), it is not a trade publication like "Railway Age". As far as the 710 goes, US railfans are convinced that it is dead. With a 16-710E23B costing north of US$1.25 million, there is no way that Caterpiller is going to walk away from ongoing sales of >1000 engines per year. Who outside of North America will purchase a rail traction Tier 4 compliant engine, unless compelled to by legislation? These engines are too heavy/high for the European loading gauges
The liquid exhaust after-treatment chemical freezes (Diesel exhaust fluid (DEF) is an aqueous urea solution made with 32.5% urea and 67.5% deionised water). Private sector US freight railroads did not want the expense of rolling out the heated infrastructure required to handle this product at each refueling point. Exhaust gas recirculation (EGR) was seen as a cheaper option. A second objection was decreased fuel capacity, due to the requirement of a second tank for the DEF, leading to around a 6% decrease in diesel capacity
The State owned commuter railroads in the USA service/refuel from centralised facilities, so are going down the selective catalytic reduction (SCR) path using DEF, with high speed diesels from Caterpillar and Cummins (EMD F125, Siemens SC-44 Charger, et al). The high speed diesel engine is initially cheaper than the medium speed, so this appeals to the bureaucratic mindset
Europe is now mainly high speed diesel, SCR treatment is used to achieve European Stage IV standard. ABC (Anglo Belgian Corporation) produce medium speed diesels for rail traction, which also use this method. ABC engines for countries like Iran delete this feature