TIER : New standards for reducing harmful emissions
The new standards for reducing harmful emissions apply to off-road engines and portable generator sets. To meet these new standards, Caterpillar has developed a new generation of engines.
Caterpillar®machines are rolling off assembly lines with the latest in engine technology. The first model to ship was the D8T. Several other models followed suit including the D9T, 365, 385, and four Articulated Trucks. A total of 26 machine models are now available!
Each of these machines use Caterpillar engines with ACERT™ Technology, the result of more than $500 million in research and development and more than 250 patents.
The engines are compliant with the United States EPA Tier 3 emissions regulations governing off-road machines, which took effect 1 January 2005 for engines of 300 to 750 horsepower. Standards for engines of 175 to 300 horsepower took effect 1 January 2006.
Emissions regulations for machine engines are not new. Tier 1 went into effect in 1996, and Tier 2 regulations were applied in 2001. Those standards were met by adapting existing technologies, but the aggressive Tier 3 requirements dictated breakthroughs.
Caterpillar introduced ACERT Technology to meet EPA ’04 regulations for on-highway trucks. Earlier, Caterpillar machine engines with ACERT Technology began field-testing across the United States, Canada and Europe. Now there are more than 350 such machines in the field. Combined, they have worked over 520,000 hours.
These machines are working in the multitude of applications typical for Cat equipment—from construction to mines to landfills. And they are working in a wide variety of conditions.
ACERT Technology represents a series of evolutionary and incremental improvements developed by Caterpillar. For example:
- The fuel system allows for multiple injections each combustion cycle. Small amounts of fuel are injected at precise times to achieve the combined goals of fuel economy and lower emissions.
- An advanced air system provides more cool air in the combustion chamber. A wastegate turbocharger provides excellent low-end response. In addition, crossflow cylinder heads provide a direct path of air to the engine.
Caterpillar engineers worked with approximately 125 variables to find the optimum balance. There are more than 10 million possible combustion combinations. Those engineers were challenged by the highly intertwined relationship of (1) reduced emissions, (2) engine performance, (3) fuel efficiency and (4) engine durability.
Those are not necessarily complimentary objectives. Improving emissions, for example, can have an adverse effect on fuel efficiency. Their overriding goal is no different than the goal Caterpillar has had since its inception—to provide customers with the lowest owning and operating costs, and the lowest cost per unit of material moved.