Engines for the Interim

To meet upcoming Tier 4 Interim diesel emissions regulations, John Deere Power Systems (JDPS) will use cooled exhaust gas recirculation (EGR) and an exhaust filter rather than selective catalytic reduction (SCR) in its engines.

For CMI Mulching’s Yves St. Onge, that is good news that can be summed up with two words: single fluid. “Our customers will not have to carry additional fluids to the remote areas where they are working. That is very important to us,” he says.

The single-fluid approach of cooled EGR means owners and operators won’t have to incur the cost of diesel fuel plus the additional cost for diesel exhaust fluid (DEF) required by SCR systems. “For Tier 4 Interim, we’re not only looking at fuel economy, we’re taking into consideration total fluid consumption,” says Brian Brown, manager of worldwide marketing support for JDPS.

Engineered and manufactured in St. Cyrille, QC, Canada, CMI’s self-propelled mulcher offering starts with the 125-hp C125 and goes up to the 600-hp C600, known as “The Bull.” CMI’s machines clear right-of-ways and fire lanes, and the hydraulically operated head can work below grade to mix the woody debris into the dirt.

“What differentiates our machines from typical construction equipment is the load factor,” says St. Onge. “Our machines have higher loads than an excavator, for example. In a large landscaping operation, the engine in a mulcher will be under load for a long period of time, especially when working in the ground mixing chipped wood with dirt.”

Another difference that can pose a challenge when CMI engineers are spec’ing engines and components is the mulcher head. It generates enough hydraulic heat to require its own cooling system. “Because the Tier 4 Interim engine’s cooling requirements are greater, Deere improved coolant flows, top tank temperatures and adopted new radiator designs and variable speed fan drives to help manage increased heat rejection. This helps, but there is a little less room for our hydraulic heat exchanger.” Room for adding new components is getting tight, especially if doing so could potentially impact visibility. CMI’s engineers made the machine’s frame larger to provide more room.

CMI buys its Deere engines through a distributor in Quebec, and relies on it as well as JDPS for engine expertise. “We like buying engines from Deere because they are also building off-road machines and use their own engines,” says St. Onge. “They know the engines and how they fit, and they share a lot of engineering information with us.”

Much has been written about higher underhood temperatures as a result of emissions regulations. St. Onge acknowledges they must take hot components into account with all of the flammable airborne material the machines are working in, “but the machines already have very hot components. We’re not seeing hotter surfaces, just more of them,” he says. “For the most part, exhaust filters and the turbo are designed so that their skin temperature remains cool enough to prevent issues with debris. The operator should still continue to be diligent about removing any debris that may accumulate in the engine compartment, too.”

For St. Onge, the fact that CMI’s customers won’t have to worry about cold temperatures affecting the operation of their machine is another advantage to Deere’s approach. “A large part of our market is in the oil field industry in northern Canada, where freezing is a big issue,” he says. “Keeping DEF warm adds cost and complexity, and it’s a change that will not only be required to our machines, but to the fuel and fluid supply equipment, as well. We will reach that point in 2014, when SCR systems will probably be required industry-wide. But for the short term, we will hold off.”

Although it’s working in different applications from CMI’s mulchers, “Deere has yellow equipment out there using Tier 4 Interim engines,” says St. Onge. “Every OEM will know what the impact of Tier 4 Interim technology is within a year.”