By Larry Stalcup
Tier 4 Interim Engines are performing well in the field. And the engines can remain highly efficient if tractor operators perform by-the-book preventive maintenance before hooking up planters or other equipment for the 2013 season, says an Iowa State University agricultural engineer and engine specialist.
Stuart Birrell, associate professor with ISU Ag and Biosystems Engineering, says the Tier 4i diesel engines resulted from new Environmental Protection Agency standards. Standards for agricultural diesel engines require a 90% reduction in particulate matter (PM) and a 50% drop in nitrous oxide (N2O), compared to its previous Tier 3 regulations.
A combination of emission compliance technologies are being used by engine manufacturers in Tier 4i production, They include Exhaust Gas Recirculation (EGR), Diesel Oxidation Catalyst (DOC), Diesel Particle Filters (DPF) and Selective Catalytic Reduction (SCR).
EGR diverts a percentage of the exhaust gas back into the cylinder, lowering combustion temperatures and thereby reducing NOx. A DPF in the exhaust system traps and holds the remaining PM, which are then oxidized in a process called regeneration.
SGR is an after-treatment technology that uses a chemical reductant, Diesel Exhaust Fluid (DEF), also known as urea (a solution containing 32.5% urea plus deionized water). Urea is injected into the exhaust stream where it transforms into ammonia and reacts with NOx on a catalyst, converting the NOx to harmless nitrogen gas, small amounts of CO2 and water vapor.
Preventative Maintenance Birrell says preventative maintenance of the Tier 4i engines has not changed significantly from other high-tech diesel engines. However, he said it is more important to follow the recommended maintenance schedule, particularly in keeping all filters and cooling systems clean and free of dust and dirt. If not, it could cause automatic power reduction.
“In most engines, the automated engine control and monitoring system will de-rate (reduce hp) the engine if the sensors show that the operational parameters are out of recommended ranges,” Birrell says.
“For instance, if a fuel filter has not been replaced and the fuel pressure drops, the engine control system will automatically de-rate the engine horsepower so much that you could not operate in the field.”
Birrell says EGR systems are highly dependent on the cooling system operating correctly — “so keeping the radiators and screens clean is very important.”
Since the SCR systems require the DEF, the DEF should be refilled periodically. “The urea solutions in DEF will gel and solidify at higher temperature than diesel,” Birrell says. “However, after the engines are running, there are systems to keep the DEF warm.
“In addition, DPF must be periodically serviced in an EGR system to remove accumulated ash. EPA requires that the interval between ash removal be greater than 3,000-4,500 hours, depending on engine size. But many original equipment manufacturers (OEM) indicate that many engines exceed this requirement and state that over 5,000 hours are possible.”
Prevent Fire Risks Birrell says the automated regeneration of DPF produces very high temperatures during regeneration. “This can be a fire risk in some instances,” he warns. “Although the DPF are very well insulated and protected, any accumulation of combustible material around the DPF can compromise the heat protection and cause a fire risk.
“This is particularly true in machines like combines that have a significant amount of fine particles that can ignite on a hot surface. Farmers need to be aware of this risk and make sure they do not do anything to increase these risks.”
Engine and machinery manufacturers stress the need for farmers and other operators to read their operators manual (OM) to know the specifics of their engines. Rachelle Thibert, spokesperson for John Deere, says a comprehensive listing of the actions needed are all listed in the OM. “For Deere, they will vary slightly depending on which model of vehicle the grower has,” she says. She cites several items growers should pay attention to regardless of their machine:
• Make sure all fuel used to power machinery is of good quality. This means free of contamination like water, rust, biological growths and other debris. “All of our engines come with water separation features on board that should be used,” she says.
• Ensure that fuel home storage systems have been upgraded and have adequate filtration systems to match the fleet of machinery being operated. Ensuring good turnover of fuel is also important to keep it fresh. This is particularly important if Bio-Fuels are being used. “Doing periodic checks of these systems and keeping them as up to date as the tractor will go a long way in avoiding issues,” Thibert says.
The OM will contain information about what oils are recommended and these can vary depending on location and seasonality. “Like fuel, using high quality oil of the correct grade is important to both the engine and hydraulics systems on board,” Thibert says. “Paying attention to the hydraulic implements to avoid contamination is a good idea to prevent downtime issues. Using the recommended coolant from the OM will ensure trouble free operation.”
Birrell notes that the new engines appear to be functioning well in field operations. “In general, OEMs have invested a significant amount of time and money to ensure the reliability and capacity of the tractors and combines,” he says. “They have not been affected by the introduction of the new Tier 4i engines.
“These upgrades have included significantly more sophisticated electronic controls on the engine and updated cooling systems to deal with engine temperature management which is critical to emissions control.”
“While the increase in control is necessary for better emissions management, it also has enabled OEMs to have greater capacity for automated engine control and monitoring, which have other benefits.”
Birrell suggest that farmers review their OM or consult their equipment dealer or manufacturer for additional information on Tier 4i engine operating tips.
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