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A look at Tier 4 Engines
By Aaron Cozart, OEM Acounty Manager, Cummins Bridgeway
January 1, 2014 marks an important milestone for the forestry industry; the much anticipated arrival of the world’s cleanest diesel engines. Environmental Protection Agency’s (EPA) Tier 4 Final off-highway emissions standards take effect in 2014 for engines with power output of 174 - 751 hp (130 - 560 kW).
While engine manufacturers may offer variations with the technology approach to meet the stringent Particulate Matter (PM) and NOx regulations, from Cummins point of view, one thing is for sure; our Tier 4 Final engines are the smartest, cleanest and quietest engines seen to date.
Reducing diesel engine emissions has been a long journey; first focusing on on-road vehicles before restricting emissions for off-road applications, Tier 1 regulations took effect in 1996 — the agency’s first emissions regulations. In almost 20 years of gradual reduction, Tier 4 Final brings emissions levels of PM and NOx down to near zero levels, as clean as any on-road regulation in the world today. What does this mean for the environment? The emissions output of a single Tier 4 Final machine is equivalent to the emissions output of 25 Tier 1 machines.
Clean diesel benefits also virtually eliminate visible smoke and the use of more advanced fuel injection systems means that the engine operates much quieter and with less vibration than users will have experienced before. This all adds up to a more comfortable, and more productive, working environment for the equipment operator.
As engine manufacturers produce the clean diesel engines with exhaust aftertreatment, forestry equipment manufacturers are working to integrate the new Tier 4 Final power systems into equipment. The rollout of equipment with Tier 4 Final engines will, of course, be gradual, as new equipment enters the forest ramping up over the course of the next 18 months. As the new equipment arrives, the substantial improvements in performance will soon become obvious.
While cleaner diesel engines are great for the environment, there are also a number of more tangible benefits for Tier 4 Final users. To make engines that produce emissions levels near zero, the engine must be smart and highly efficient. Increased efficiency within engine combustion means better fuel efficiency. The fuel efficiency comparison between Tier 4 Final and Tier 3 engines is dramatic. For example, Cummins Tier 4 Final engines typically use eight to 10 percent less diesel fuel, enabling a significant reduction in operating costs.
The Tier 4 engines are also more powerful. For example, compared to their Tier 3 predecessors, Cummins Tier 4 Final QSB6.7 and QSL9 engines each produce more torque, with ratings of 770 and 1200 lb-ft respectively. The Cummins QSX15 goes up 75 hp, with a peak rating of 675 hp. So while the engine is cleaner, it has also been maximized to deliver the dependability, reliability and durability needed for the rugged environment and duty cycles.
Cleaner diesel engine combustion alone cannot take emissions down to near-zero levels. Engines require exhaust aftertreatment to reach the Tier 4 Final standard. Cummins integrated exhaust aftertreatment is made up of a simple, service-free Diesel Oxidation Catalyst (DOC) with Selective Catalytic Reduction (SCR).
SCR requires Diesel Exhaust Fluid (DEF) for operation, which functions as a reactant in the catalytic process to lower NOx. DEF is not a new fluid to North America, and has been used in on-road vehicles since 2010. By 2015, North American consumption of DEF is expected to be over 400 million gallons per year and is available from many suppliers. The DEF required for off-road equipment is the same as that used in on-highway vehicles and is available in a wide variety of packaging sizes: 1 or 2.5 gallon jugs, 55 gallon drums, and 330 gallon totes. DEF is cheaper than diesel fuel. Cummins has designed and manufactured the Tier 4 Final engine and exhaust aftertreatment as a single, integrated system, minimizing DEF consumption.
Tier 4 Final technology will keep the equipment operating at optimum power and fuel-efficiency, responding to the differing load and duty cycle conditions experienced by forestry equipment.
For those who still have questions about the advent of Tier 4 engines, Aaron invites you to contact Cummins Care, located in Nashville, Tenn.
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