Environmental sustainability is an important consideration for mining companies and regulators, with U.S. legislation for diesel engines rated above 751 horsepower recently taking effect. That legislation requires very low limits for particulate matter and oxides of nitrogen (NOx), a significant technical challenge for high horsepower (HHP) engine manufacturers.
Cummins’ Tier 4 Final HHP technology exceeds expectations, providing fuel savings of up to four percent, extending life-to-overhaul by 10 percent, and enabling engine uptime availability equal to any Cummins HHP engine in service today. These results have enabled Cummins to remain consistent in keeping its promise to deliver more productive engines on schedule for original equipment manufacturers’ introductions.
Cummins’ Tier 4 Final engines achieve very low emission levels with no increase in engine displacement, no change to engine ratings and equivalent or improved power delivery. Each Cummins Tier 4 HHP engine also offers a near identical envelope to that of its Tier 2 predecessor.
Cummins Tier 4 Final engine systems provide other important advantages. Service intervals are extended to 500 hours, twice that of the Tier 2 engines. Engine life-to-overhaul is increased by 10 percent, which, for a Tier 4 Final QSK60 rated at 2850 horsepower, can mean a remarkable fuel burn of 1,100,000 gallons depending on duty cycle.
As part of the drive to enhance reliability, Cummins’ design teams analyzed every point on the Tier 4 Final engines that could lead to unscheduled downtime and took measures to prevent it. The new NanoNet filter media, which is used in fuel filters, is designed to ensure superior fuel cleanliness and protect the fuel system from dust or dirt ingress. Thanks to a more uniform pore size compared to traditional media, NanoNet captures and retains more harmful particles.
Like their Tier 2 predecessors, Cummins’ Tier 4 Final engines are designed with rebuild potential in mind, and are easily capable of three overhauls. They also do not require any major intervention at mid-life.
Removing particulate matter in-cylinder and NOx out-of-engine simplifies the emissions reduction strategy and allows the engine’s full potential to be realized. Without the need to remove NOx in-cylinder, the engine can operate at higher load factors while staying within a more comfortable range of cylinder pressure and piston speed.
Selective Catalytic Reduction (SCR) is now the key technology employed for all Tier 4 Final engines in the 75-to-751 horsepower category, and for every on-highway truck engine in North America. Cummins’ SCR population in North America has already passed the one million systems mark.
“No other approach offers such significant performance and fuel saving benefits with very low emissions.”
SCR uses diesel exhaust fluid (DEF) to initiate the chemical reaction over the catalyst. DEF is easy to use, easy to store and widely available. It is also an important means for saving fuel; one gallon of DEF can result in up to two gallons less fuel consumed by Cummins Tier 4 engines per 40 gallons of fuel used. Tier 4 engines employ advanced combustion optimization techniques to improve engine efficiency and reduce tailpipe NOx through the SCR aftertreatment. The resulting optimized product consumes less total fuel and DEF, saving customers roughly three percent on total fluid cost. No other approach offers such significant performance and fuel saving benefits with very low emissions.