John Deere officials have announced they plan to meet Tier 4/Stage III B off-road diesel emission requirements due in 2011 on engines 174 horsepower and larger.
Deere says it will use an upgraded exhaust gas recirculation (EGR) system, a diesel oxidation catalyst (DOC) and a diesel particulate filter (DPF) to meet the more stringent Tier 4 requirements calling for a 90% reduction in diesel particulates and a 50% cut in oxides of nitrogen. The company also noted it was avoiding the use of "selective catalytic reduction" (SCR) for engines in the Tier 4 regulations. SCR is a urea-injection system used by some European engine builders to control nitrous oxide in the exhaust stream.
Deere officials say their system of upgrading the existing Tier 3 Power Tech Plus engines and their control computers with DOC/DPF technology, along with proven techniques of using cooled EGR is simpler and less costly to operate than SCR systems. The urea-injection technology involves a separate urea container, injection system, heating system for cold weather use, and a tamper-proof diagnostic system.
The Power Tech Plus engines mentioned in the announcement are the 6.8L, 9.0L and 13.5L in-line, six-cylinder engines, all of which breathe through four valves per cylinder and a variable geometry turbocharger, and are fed by a high-pressure fuel injection system. Engine control systems on the new engines will be updated to provide twice the processing speed and internal memory to handle the increased sensor data and control logic needed for the cleaner exhaust.
For engines below the 174 hp. rating, Interim Tier 4 emissions regulations are effective in 2012, and Deere says it is looking at similar changes for those powerplants (75 hp. to 173 hp.) as what is being announced for the larger engines, as well as "other technologies."
"While we're not ready to make any announcements (on the smaller engines), our technology decision will be based on what we feel the best overall value for the customer," says John Piasecki, director of Deere's worldwide marketing, marketing, sales and customer support.
Deere's under-75 hp. engines already meet Interim Tier 4 and Stage III A emission requirements.