Cummins Inc.'s Tier 4 Final/Stage IV field-test program has accumulated over 140,000 hours with operators working in commercial service. The field-test program, initiated two years ago, includes nearly 70 different machines, encompassing the broadest range of applications and the toughest duty cycles. The equipment is operating on sites selected specifically to cover the most challenging conditions and extremes of temperatures. Overall results from the field-test program indicate that Cummins Tier 4 Final technology lowers fuel consumption by up to 10 percent compared with that of an equivalent Tier 3 machine, dependent on duty cycle and application.
A combination of remote monitoring and frequent site visits by Cummins engineers to interview the field-test operators has provided valuable insight into Tier 4 Final performance ahead of engines and exhaust aftertreatment entering full production. As a result, engine calibrations and operating characteristics have been fully optimized to achieve the highest fuel economy and better torque delivery.
The field-test program went beyond typical wheel-loader and excavator endurance test cycles to cover a wide variety of specialized equipment. That includes a snow groomer at very high altitude in the Alps, a container handler working high hours on the port side and a rock drill working on a mine site in very dusty, abrasive conditions. Equipment was operated in the high humidity of Florida and the extreme cold of a Canadian winter.
"With a very wide range of machine types working at challenging on-site locations, Cummins application engineers were able to build up the most comprehensive mapping of equipment duty cycles, load factors and operating conditions we have ever created," said Jennifer Rumsey, vice president, engineering - Cummins Engine Business.
One of the other key deliverables of the Tier 4 Final field-test program was an assessment of system reliability compared with that of previous engines. Operators report that Tier 4 Final equipment uptime is every bit as impressive as what they experienced with their Cummins Tier 3-powered machines. Operators found that cleaner, quieter and smoother performance with Tier 4 Final engines makes a real difference to their working environment.
Cummins field-test work has paid close attention to minimizing Diesel Exhaust Fluid (DEF) consumption by employing the most effective spray pattern techniques to encourage better decomposition of the fluid. Cummins results show that DEF is typically dosed at just 3 percent to 4 percent of diesel by volume.
Initially focused on the QSB6.7, QSL9 and QSX15 6-cylinder engine range across the 174- to 675-hp power range, the field-test program then expanded to incorporate the new heavy-duty QSG12 and compact QSF2.8. Field-testing is also well underway with the 4-cylinder QSF3.8 and QSB4.5 engines, ready for the January 1, 2015, Tier 4 Final emissions effect date for the 75- to 173-hp power category.
Field-testing of Cummins QSK high-horsepower engine range for mining is well advanced, including the QSK19 engine rated at 800 hp.