Tier 4 refers to the latest emission milestone established by the U.S. Environmental Protection Agency and the California Air Resources Board applicable to new engines found in off-road equipment including construction, mining and agricultural equipment, marine vessels and workboats, locomotives and stationary engines found in industrial and power generation applications. As of January 1, 2014, these emissions standards apply to new engines that power equipment commonly found in most construction and agricultural applications while new engines manufactured for much larger applications including marine, locomotives must have met the standard by January 1, 2015. These emissions standards apply to new and remanufactured engines and do not apply to older engines.
Tier 4 compliant engines significantly reduce emissions of particulate matter (PM) and oxides of nitrogen (NOx) to near zero levels. Relative to previous emissions standards, Tier 4 compliant engines reduce emissions by over 95 percent for most agricultural and construction equipment and just over 86 percent for much larger applications like locomotives and marine vessels.
The Tier 4 emission standards are roughly similar to emission reduction requirements for engines that power heavy-duty trucks. While engine manufacturers have developed a nearly uniform suite of clean diesel technologies to meet the truck emission standards, a wide variety of approaches to achieve emission reduction are evident in off-road applications given the wide variation in engine size and equipment use.
Despite the seemingly endless permutation of emission reduction technologies found in Tier 4 engines and equipment, most manufacturers also incorporate fuel savings capabilities and productivity enhancing features. Light-weight materials, fuel sipping engines, hybridization, advanced energy storage capabilities and the use of global positioning systems and telematics developed to make the most of expensive equipment are increasingly found in off-road equipment that help equipment owners reduce fuel use to control costs but also conserve energy resources and reduce greenhouse gas emissions, and, more importantly, improve air quality for everyone.