To achieve compliance with Interim Tier 4 off-highway emissions requirements required in 2011 for engines 174 horsepower and up, John Deere Power Systems will not use selective catalytic reduction, but rather will add a diesel oxidation catalyst/diesel particulate filter unit to its Tier-3-compliant PowerTech engine to achieve the 90-percent diesel particulate reduction required. Selective catalytic reduction, says Deere, requires the vehicle be fitted with a separate tank, a urea injection system and a legislatively-required tamper-proof diagnostic system. For the required 50-percent reduction in oxides of nitrogen, Deere will increase the percentage of cooled exhaust gas recirculation.
