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January 2011

Mechanical Article
Today's diesel engine technology


Compiled by Walter Weart

The diesel engine long has been the power-generating mainstay for locomotives and many types of rail maintenance equipment. Yet, engine designs haven't remained the same for very long — and likely will continue to evolve.

Locomotive and rail equipment users want more durable engines that can withstand difficult working environments and operate efficiently in remote locations. They're also placing a higher value on customer service and product support to maximize equipment uptime.

Meanwhile, stricter government emission regulations are dictating the development of more environmentally friendly diesel engines. The U.S. Environmental Protection Agency's (EPA) interim Tier 4 regulation took effect Jan. 1, requiring engines rated at 174 horsepower or more to reduce diesel particulate matter (PM) emissions by 50 percent to 90 percent and nitrogen oxide (NOx) emissions up to 90 percent. Tier 3 requirements that take effect in 2012 and full Tier 4 regulations that take effect in 2015 will further restrict PM and NOx emissions, depending on the engine rating.

How are engine suppliers responding to emerging customer needs and governmental developments? Progressive Railroading contacted several of the companies last month to find out. The e-mailed responses from four of the engine makers follow.

Electro-Motive Diesel

Railroads are seeking control of total ownership costs. So, Electro-Motive Diesel Inc. (EMD) is responding by providing its two-stroke 710 engine that provides reliability and durability, as well as low fuel consumption and ease of maintenance, according to EMD.

The company has received "dozens of patents" on new 710 engine technologies designed to reduce emissions and boost fuel efficiency, EMD officials said. The company has developed a combination of product enhancements for its diesel-engine families, including such features as an advanced cylinder head design, induction hardened valve seats, and improved cylinder liners and pistons.

EMD also offers the 710ECO™ Repower solution to update older low- and medium-horsepower locomotives with updated engine technology and extend locomotive life by 20 to 30 years. Repowers, which are eligible for federal clean-air funding, can cut emissions 50 percent to 70 percent, increase fuel efficiency up to 25 percent, provide lube oil savings up to 50 percent and offer 90 percent parts commonality with existing fleets to ease maintenance and improve reliability, EMD officials said.

In addition, the company markets more than 100 EPA-certified emissions kits for the entire spectrum of 645 and 710 locomotive-engine families, according to EMD. The kits are the result of "extensive development and testing" in the same engineering and manufacturing facilities used to produce new engines, officials said.

"This focus ensures the performance, reliability and durability that EMD customers require," they said.

Engines and subsystems are "carefully calibrated" to optimize performance, reduce emissions and minimize fuel consumption, and fuel injectors are "manufactured to precise internal specifications" to ensure sustained fuel economy and emissions performance over the engine's useful life, company officials said.

EMD has completed an emissions verification program for Tier 3-compliant engines and launched field tests. The company plans to begin shipping Tier 3-certified locomotives in January 2012.

However, Tier 4 is a "major challenge," and EMD is engaged in a multi-year emissions development and validation program to meet it, company officials said. So far, EMD has reached Tier 4 levels in its research facilities.

GE Transportation

Railroads are continuing to focus on lowering the total lifecycle cost of the locomotives they purchase, as well as seeking compliance with all regulatory requirements, safety in operation and maintenance, and improved fuel efficiency and reliability, GE Transportation officials said.

In response, the company has focused its investments on meeting railroads' locomotive demands, "led by our efforts to deliver Tier 3-compliant locomotives in 2012 and Tier 4-compliant locomotives in 2015," GE officials said.

The company is conducting research and development in emissions reduction, fuel improvement and alternative fuels, as well as in many more areas, they said.

The introduction of a Tier 3-compliant locomotive in 2012 will prompt the next major modifications to the Evolution® Series, which will incorporate changes to both the engine and control system to meet EPA requirements and lower a locomotive's lifecycle cost. Major engine changes will include improvements to the power assembly to reduce oil consumption, and to the fueling system to provide more flexibility in combustion management.

Because of Tier 3 and Tier 4 requirements, GE plans to make changes to the control system and engine to comply with Tier 3 standards in 2012. 

To meet Tier 4 standards, GE still is evaluating various technologies to provide the lowest engine emissions and minimize after-treatment requirements. The company also is "aggressively" working on after-treatment solutions that do not use urea — an organic compound added to fuel to reduce emissions that generally can't withstand cold air temperatures — and minimize the impact on locomotives' lifecycle costs, GE officials said.

John Deere Power Systems

In 2010, John Deere Power Systems released a full lineup of "Interim Tier 4" (IT4) diesel engines, which are designed to be fuel-efficient and meet more stringent emission regulations without sacrificing performance, reliability, durability or operator convenience, according to the company. In addition, two of the IT4 models received EPA certification.

As part of the IT4 introduction, John Deere added an exhaust filter comprising a diesel oxidation catalyst and diesel particulate filter to reduce PM emissions.

The company chose a "single-fluid approach," which calls for using cooled exhaust gas recirculation and exhaust filter technology, John Deere officials said. The technique provides a "proven solution that doesn't require the use of diesel exhaust fluid (DEF)," they said.

"This does not require operator intervention, making it ideal for a rail industry that frequently operates in remote locations," John Deere officials wrote. "Operators will not have to incur the cost of diesel plus the additional cost for DEF that is required by Selective Catalytic Reduction (SCR) systems."

SCR systems require a separate tank, "sophisticated" DEF injection system and a tamper-proof diagnostic system required by federal regulations, according to John Deere. Because DEF freezes, heating systems for the tank and delivery lines are required, as well.

The company designed the IT4 engine platform to minimize the need for original equipment manufacturers (OEMs) to alter their equipment design to meet railroads' and part suppliers' needs, John Deere officials said. The most notable change to the engine envelope: the addition of an exhaust filter.

MTU Detroit Diesel

MTU Detroit Diesel Inc. also is taking steps to address fuel economy, emissions compliance, reliability and service support. Although new engine development currently is driven by emission regulations, engine manufacturers still are trying to optimize fuel efficiency with as little impact as possible on an engine's installation size and support equipment, MTU Detroit Diesel officials said.

The company's current generation of Series 4000 diesel engines: the S4000 R43. The firm recently unveiled the latest generation, the S4000 R84, which features two-stage turbocharging, intercooling and cooled Exhaust Gas Recirculation (EGR), according to MTU Detroit Diesel.

The company is developing the S4000 R84 engine to meet strict NOx emission limits stipulated in the EPA's Tier 4 locomotive standards without requiring SCR, company officials said.

MTU Detroit Diesel already has introduced Miller cycle valve timing and two-stage charge air-cooling features for its product line to reduce NOx emissions while maintaining power density and fuel efficiency, company officials said.

Other available engines range from the Series 900 rated at 100 horsepower through the Series 4000 rated at 4,000 horsepower. MTU Detroit Diesel plans to release a "range of technologies," company officials said.

Each engine family was analyzed to select the emission-reduction strategy that's best suited for a particular engine, they said.

MTU Detroit Diesel also plans to introduce SCR to control NOx emissions on engines generating less than 1,000 horsepower, subject to the EPA's Tier 4 standards. The engines would include those used on maintenance-of-way equipment and diesel multiple units.

The company is "making larger expenditures" on research and development to comply with emission requirements and "needs to balance compliance with value for customers," MTU Detroit Diesel officials said.

For example, to reduce NOx emissions, EGR can eliminate the need to carry an extra fluid, but SCR provides greater fuel efficiency and avoids increased radiator size, they said.

Wally Weart is a Denver-based free-lance writer.


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