Where you can learn more?

Conduct simple internet search on EPA Tier 4 Emission Standards. There is plenty of material to help get you grounded in EPA Tier 4. The following links should help get you started:

Related Links

EPA Regulations for Non-road Diesel Equipment
www.epa.gov/nonroaddiesel/2004fr.htm

The Diesel Forum
www.dieselforum.org

General info on off-road diesel engines, equipment, retrofitting, etc.
www.clean-diesel.org

Association of Equipment Manufacturers
www.aem.org/SRT/Regulatory/Tier4/

Bobcat Website - Tier 4 Content
www.bobcat.com/excavators/tier4

Catepillar websites
www.cat.com/technology/acert-technology

Cummins Website
www.tier4.info
www.mtu-online.com/mtu-northamerica/products/diesel-engines-overview/

Diesel fuel standards and timeframes
www.epa.gov/nonroad-diesel/regulations.htm#5