Case Construction recently introduced four models with Tier 4 Final engines. The company takes a different approach based on the size. “Our goal has always been to go beyond compliance and do what is in the interest of our customers,” says Stemper. “Our choice in technologies is driven by machine design, operating characteristics and customer needs.”
The Case SR175 and SV185 medium-frame skid steers use a DOC-only solution to meet Tier 4 Final. “These machines are commonly used by contractors with large fleets, as well as rental fleets,” says Stemper. “In these applications, the machines may have various operators and move around between jobsites regularly. Using the maintenance-free, DOC-only solution for these models creates greater convenience and more efficient operation.”
The Case SR130 and SR160 compact-frame skid steers use cooled exhaust gas recirculation (CEGR) technology with a DPF to meet Tier 4 Final.
Caution: High Pressure
High-pressure common rail (HPCR) fuel injection is critical to meeting the emissions standards. But the higher fuel injection pressures also make it necessary to use sound fuel management practices.
“Fuel quality can definitely affect the fuel system in a Tier 4 engine,” says Wright. “Very low sulfur content is recommended with Tier 4 Final engines. Dirty fuel does not burn as clean and can plug fuel injection nozzles as well as the DPFs more quickly, potentially increasing operational costs and losing productivity due to downtime.”
Impurities found in diesel come in many forms. “Particulate matter such as dirt, sand and rust are some of the most destructive because they act as abrasives inside the fuel system,” says Norwood. “Pressures found in HPCR fuel systems can reach upwards of 2,000 bar or 30,000 psi. This has the effect of turning even the smallest particle into scouring agents that can, over time, damage fuel system components such as fuel pumps and injectors. Well-serviced fuel filters can remove much of this contamination, but not all.”
The higher fuel injection pressures associated with the common rail fuel injection systems mean you should pay careful attention to maintenance practices. “Customers should already be diligent about their fuel handling and cleanliness, as this can have a direct effect on component life and thus owning and operating costs,” says Kevin Hershberger, Caterpillar. “HPCR fuel systems are more sensitive to contamination from dirt or water, which means you will need to continue to monitor the fuel water separator and drain water when present, as well as change your fuel filter element per the owner’s manual.
“Probably one of the most important steps for a customer to follow is to not pre-fill the fuel filter element in an attempt to ‘prime’ the fuel system,” Hershberger continues. “This practice can allow unfiltered fuel into the fuel system. The Cat SSL/MTL/CTL products provide an electric priming pump/auto air bleed combination fuel system. This fuel system design allows the customer to simply replace the fuel element, turn the key switch to the ‘on’ position and the fuel system primes and the air is bled out automatically.”
The concern with fuel goes beyond cleanliness. “Our fuel supplies in North America are relatively clean and reliable,” says Stemper. “A bigger concern is ensuring that fuel supplies are kept fresh and that any chance of putting degraded fuel in the machine is eliminated. This is not a concern in most construction applications, where fuel supplies are regularly turned over. Customers should always be aware of this.”
In addition, pay careful attention to the engine oil recommendations from the manufacturer. “Some CEGR systems require the use of higher-spec, more expensive oil to deal with the effects of higher soot levels that result from lower combustion temperatures,” Stemper explains. “Most manufacturers recommend using oil that meets the API CJ-4 oil specification. CJ-4 oil exceeds previous performance requirements and is specifically designed to protect emission control systems, help comply with emissions standards, reduce engine wear and control piston deposits and oil consumption.”
He adds, “CEGR engines with a DPF should also use ultra-low-sulfur diesel fuel (15-ppm maximum sulfur), because small amounts of sulfur can impair the filter's effectiveness.”