To achieve compliance with Interim Tier 4/Stage IIIB mobile off-highway emissions regulations for engines 130 kW (174 hp) and above, John Deere Power Systems plans to use its Tier 3 PowerTech Plus engine platform, add a diesel oxidation catalyst/diesel particulate filter (DOC/DPF) unit for reducing particulates, and increase the percentage of cooled exhaust gas recirculation for NOx control. The DOC/DPF unit meets the demands of rugged off-highway applications, including extreme vibration and temperature. The DOC component reduces carbon monoxide, hydrocarbons, and some particulate matter, while the downstream DPF traps and holds particulates remaining in the exhaust stream. Trapped particles are eventually incinerated within the DPF through regeneration, and the DOC/DPF replaces the need for a muffler in most applications. Next-generation engines also will be equipped with either a closed or open crankcase ventilation system to manage crankcase emissions.