Tier 4 regulations for off-road diesel engines in order to create cleaner air is not a new issue. We’ve all watched the agricultural equipment industry – specifically tractor manufacturers – change their engine packages drastically over the past few years to meet the stringent regulations from the U.S. Environmental Protection Agency (EPA) and the European Union.

Lowery mark
Director of Commercial Marketing / New Holland

Since 1996, the aim of these regulations has been to reduce nitrogen oxides (NOx) and particulate matter (PM).

Over the past 17 years, the industry has reduced outputs of PM by 90 percent and NOx by 50 percent. As agriculturalists, we understand the importance of being good stewards of the land for the next generation. Improvements in air quality from our tractors’ exhaust can give us confidence that we’re doing our part to keep the air cleaner for our children.

So what’s next? You’ve seen many different strategies from tractor manufacturers to meet the aggressive air quality regulations from the EPA. Companies have all launched new engines that are commonly referred to as Tier 4A/Interim engines to make the progressive steps toward compliance.

The rapidly approaching 2014 model year will mark another important step as the industry moves toward the final Tier 4 or Tier 4B solution.


While maintaining the Tier 4A/Interim PM levels, NOx levels will need to be decreased by 80 percent to meet the Tier 4B solution. Major manufacturers have already started to announce their engine packages to meet the final step in the EPA’s air quality rules. Let’s take a brief look at the two different approaches:

Selective catalytic reduction
(SCR) only

If you’ve purchased a highway diesel truck in the past one to two years, chances are pretty good that you’ve already encountered this system. It is easily identified by the separate blue cap close to the diesel fill.

This indicates the requirement for diesel exhaust fluid (DEF). SCR is an after-treatment system that utilizes a dosing module to treat the exhaust after it leaves the engine and before it leaves the exhaust stack.

This allows the engine to “breathe” clean, unrestricted air which, in turn, improves fuel economy by approximately 10 percent as compared to Tier 3 solutions.

The market has adapted to the second fluid, and it has become readily available at fuel suppliers and agricultural machinery dealerships across North America. SCR and DEF will be a permanent solution to meet Tier 4B/Final regulations.

Cooled exhaust gas recirculation (CEGR) and SCR
For Tier 4A/Interim, some manufacturers were able to achieve the EPA benchmark with just CEGR technology. This system recirculates some of the exhaust, and the pollutants it contains, back into the intake of the engine.

The exhaust travels through the diesel particulate filter (DPF), which traps pollutants in the form of soot. The DPF is a serviceable item that will require replacement or refurbishment at some time during the life of the tractor.

CEGR alone can’t quite meet Tier 4B or Final regulations, so the addition of a smaller SCR system will allow the system to achieve the EPA-required PM and NOx maximum levels. This smaller system will require less DEF than the independent SCR-only solution but will not realize the same fuel savings as an SCR-only system.

However, advanced common rail technology for these types of engines will allow for more precise fuel application and better transient engine response as compared to Tier 3 models.

Click here to visit the EPA’s website to get a better understanding of key dates for emissions compliance.

These are exciting times as we witness innovations in the agricultural equipment industry. The result will be smarter solutions to farmers and ranchers that save fuel and improve air quality. Stay tuned as manufacturers share more details about Tier 4B/Final solutions throughout 2013. PD


Mark Lowery
Marketing Specialist
New Holland Agriculture