Nearly all the major equipment manufacturers—including Caterpillar, Case/New Holland/Kobelco, Komatsu, Deere, Volvo, Terex and engine specialist Cummins—plan to use a combination of exhaust-gas recirculation (EGR) and a diesel particulate filter (DPF), to meet Interim Tier 4.

EGR + DPF
Image: CNH
EGR + DPF
SCR
Photo: CNH
SCR
Three Ways Manufacturers Will Meet the Tier 4 Standards
Photo: JCB

The other major technology for Interim Tier 4 is selective-catalytic reduction (SCR), which converts nitrogen oxides to harmless nitrogen and water by dosing exhaust fumes with small amounts of diesel exhaust fluid, an aqueous urea solution, sprayed downstream of the engine. Only JCB will meet the Tier 4 Interim rule without a DPF or SCR.