What you, your employees and customers need to know
Tier 4 Interim (Tier 4i) is here. Now, rental stores and their customers are learning how to deal with any new cost and maintenance requirements of heavy construction equipment in the 174- to 750-hp range.
However, there may be less to fear from the machines employing new technologies as long as a rental store’s employees and customers are educated about the benefits and maintenance needs to avoid problems.
Manufacturers, for example, say that there are no major maintenance issues as the industry has moved to Tier 4i engines. One of the reasons for that smooth transition is that much of the technology has been in use since 2007 in on-road vehicles.
One of the main technologies that engine manufacturers have adopted to reach Tier 4i compliance is exhaust gas recirculation (EGR), which is a method for reducing nitrous oxide (NOx) exhaust levels. An EGR system recirculates exhaust gases, blends them with fresh air and returns the blend to the cylinder. This makes for lower combustion temperatures, which reduces NOx, but also will mean higher particulate matter (PM) levels than a hotter burning engine. As a result, a diesel particulate filter (DPF) is needed to lower the PM levels. The DPF is coated with a catalyst, so that hot exhaust can burn off particulate matter, releasing carbon dioxide.
With an EGR system, the basic engine technology remains the same. No engine additives are needed and the system doesn’t require any change in the way the equipment is operated, but the DPF will require attention.
The EGR system’s DPF requires periodic regeneration that will vary depending on engine load and the filter will need to be removed and professionally cleaned or replaced with a DPF that has been cleaned periodically. While there are DPF cleaner machines on the market, most engine manufacturers already have DPF exchange programs in place, which can be helpful as the ash in a DPF can be considered a hazardous waste, as it is in California.
Another technology used by manufacturers to reduce NOx levels is selective catalytic reduction (SCR). When an engine is adjusted for maximum efficiency, high combustion temperatures will reduce PM levels, but increase NOx levels.
SCR is an after-treatment system that injects diesel exhaust fluid (DEF), a mixture of urea — an organic compound — and water, into the exhaust stream to create a chemical reaction that transforms the NOx into nitrogen, carbon dioxide and water vapor.
Most manufacturers in the off-road diesel engine arena have preferred to use EGR and DPF to reach Tier 4i, but many probably will use SCR and DEF technology to reach the Tier 4 Final (Tier 4f) level beginning in 2014, when NOx exhaust has to be reduced by a further 80 percent.
In addition, equipment owners are seeing many changes in new engines when it comes to electronic control, which helps increase efficiency and warn equipment operators of potential issues.
“Just as when we went from carburetors to fuel injection systems on automobile engines, we see more computer controls on each successive generation of engine,” says Tim O’Brien, brand marketing manager for Case Construction, Racine, Wis.
The electronic engine controls monitor EGR sensors and other inputs to determine DPF system regeneration needs. As a normal course of operation, the electronic controls will trigger an automatic regeneration of the DPF system. In addition, the system can notify the machine operator to manually regenerate the DPF system occasionally when the soot load in the DPF exceeds the range defined for automatic regeneration.
“Automatic regeneration does not cause any adverse effect on vehicle power or performance,” O’Brien says. “The operator can continue to operate the vehicle normally during automatic regeneration.”
Since mechanics responsible for over the road (OTR) diesel truck fleets have been working with the challenges of these new technologies going back to 2007, when higher emissions standards began coming into the trucking industry, they are familiar with the challenges these technologies can bring.
“There is an electronic module to control EGR and another module to control DPF in these new engines,” says John Keiffer, diesel engine technician for Quad City Peterbilt, Davenport, Iowa.
“These modules each are connected to sensors and are similar to the older, more familiar modules that control fuel injection, for instance. So, just as mechanics have had to become familiar with diagnosing other sensor and module problems over the years as they have become used, this will be two more levels of sensors/modules to look at when you are diagnosing problems with a Tier 4i or Tier 4 engine,” Keiffer says.
With these advanced generation engines, it also becomes even more important to keep the maintenance that is typical on older engines up to date. “When there is a traumatic engine failure that puts oil or coolant through the engine, such as a ring or seal failure, or a turbo system failure, it will make an already expensive repair even more expensive. When oil or coolant goes through the engine, it will come out through the exhaust system and can quickly ruin the diesel exhaust filter,” Keiffer says.
“Any engine problem where you see black smoke coming out the exhaust becomes a DEF problem,” he says.
While the initial costs of Tier 4i and Tier 4f equipment are higher, manufacturers say that operating expenses for the new machines can actually decrease.
“Overall, operating costs for Cummins engines are lower at Tier 4i compared with Tier 3,” says Jennifer Rumsey, executive director for heavy-duty engineering at Cummins, Columbus, Ind.
“Depending on the work cycle and application, up to 5 percent better fuel efficiency is possible, which offsets the small increases of using ULSD [ultra-low sulfur diesel] fuel, low ash oil and having the DEF cleaned at 5,000 hours,” Rumsey says.
Manufacturers are working to lower the operating costs of Tier 4f engines as well. To meet Tier 4f in some power categories, John Deere, Moline, Ill., plans to optimize its after-treatment system to use less DEF and to optimize the SCR.
“Lower DEF consumption means DEF tank size can be smaller — minimizing the impact on vehicle applications, extending DEF filter service intervals and reducing operator involvement,” says John Piasecki, director of worldwide marketing, sales and customer support for John Deere Power Systems, Moline, Ill.
Deere also finished testing this year on its Power Tech Tier 4i construction equipment engines in the 175-hp and above range and found that the DPF could go for up to 15,000 hours before it needed to be exchanged.
Educating customers about these sorts of operational benefits also is a way to sell Tier 4i and Tier 4 machines as the best alternative as well as justify any increase in rates to customers renting the technologically advanced equipment.
Another consideration with EGR and DPF technology is the need to use newer formulated CJ-4 engine oils that are designed to produce less soot, which is important as there is more exhaust that is being pumped back through the engine than on earlier engines.
CJ-4 is the American Petroleum Institute’s specification for lower ash content oil and using CJ-4 also allows the DPF to run for an EPA-mandated 4,500 hours before cleaning.
Oil change intervals remain the same and, while non-CJ-4 oil should not be used in EGR/DPF-equipped engines, CJ-4 can be used in lower-Tier engines without a problem, so fleet managers may opt to switch over to all CJ-4 for all of their diesel engines rather than keeping two types of oil on hand for their mixed fleets.
“There are several reasons you need to use CJ-4 in Tier 4i and 4f engines,” says Piasecki. “No. 1 is DPF service life. Using oils with high levels of ash, phosphorus and sulfur will greatly reduce the life of the DPF and negatively affect the catalyst action that lets the engine meets the higher standard of emissions. A second factor is heat. Off-highway engines work in tougher conditions and more heat is generated. The oxidation rate of oil goes up with heat and CJ-4 is formulated to inhibit oxidation,” he says. “Engine wear is less with CJ-4 and there are soot-handling additives in CJ-4 to prevent excessive soot build-up and wear.”
Diesel on-highway trucks models made in 2007 and later already use CJ-4 engine oil, so this requirement is nothing new for many fleet managers; it is just one that needs to be applied to new off-road equipment.
With EGR/DPF-equipped engines, it also becomes more important to use ultra-low sulfur diesel (ULSD) fuel, not only to meet the EPA’s requirements and keep warranties, but to maintain the after-treatment system functioning properly. Since ULSD is the only diesel widely available to on-road and off-road users in North America, this requirement should not be a factor for most equipment owners unless equipment is taken outside the country, or if railroad or marine diesel is used.
Because of questions regarding Tier 4i engine maintenance and a slight increase in the cost of maintenance, Komatsu America Corp., Rolling Meadows, Ill., is offering Komatsu Care, a service standard with all its Tier 4i equipment.
Komatsu Care includes factory scheduled maintenance for the first three years or 2,000 hours and two complimentary Komatsu Diesel Particulate Filter exchanges by a factory certified technician during the first five years of ownership. The maintenance program also includes fluids, fluid filters, oil analyses and multi-point inspections.
“We’ve introduced Komatsu Care at this time to ease the cost of buying or leasing a Tier 4 machine,” said Dave Grzelak, CEO, Komatsu America Corp.
While the Tier 4i and Tier 4f regulations apply directly to the manufacturers of engines and equipment, they can have an effect on the final user, especially in California where the California Air Resources Board (CARB) rules for fleet composition can be more restrictive and require the latest emissions technologies. Also, in lower Manhattan in New York, contractors are required to use latest technologies in their off-road diesel equipment.
“Tier 4 is a regulation that is directed toward the manufacture of new equipment. It does not apply to used or in-use equipment,” says John McClelland, American Rental Association (ARA) vice president for government affairs. “That means that you can buy or sell used equipment that is not Tier 4 without any problems. However, if you want to buy new equipment after the Tier 4 requirements are phased in for the particular engine size in the equipment you are buying, you will have to purchase Tier 4 equipment.”
The road to Tier 4
Throughout 2011, manufacturers debuted new Tier 4 Interim (Tier 4i) off-highway engines in the 174- to 750-hp range. All diesel engines in that range produced last year in the U.S. were held to that standard and were transitioned into equipment throughout the year.
Tier 4i is the U.S. Environmental Protection Agency (EPA) emissions regulations for off-highway diesel engines in North America. Stage IIIB is nearly the equivalent emissions regulations for the European Union (EU) member states. In terms of effective dates and emissions levels, the EPA and EU are closely aligned.
Tier 4i requires that diesel engines reduce particulate matter (PM) exhaust emissions by 90 percent and nitrous oxides (NOx) exhaust emissions by 45 percent compared with the current Tier 3 and Stage IIIA emissions standards.
Tier 4 Final (Tier 4f) standards will come into play in off-highway diesel engines in this power range beginning in 2014. At the Tier 4f level, new engines must reduce NOx emissions by a further 80 percent compared to Tier 4i levels.
For engines within the 75-hp to 173-hp power range, Tier 4i regulations commenced in January 2012. The Tier 4f regulations will be applied in January 2015. The emissions levels for this power category are much less severe than at the higher power ranges and will likely see less and simpler after-treatment in the engines.
Tier 4 terminology
Part of dealing with the latest technologies and emissions regulations is keeping all of the shorthand straight. Here’s a short glossary of the most used abbreviations:
DEF — Diesel exhaust fluid. Referred to as “urea,” its main component. This fluid is used as an after-treatment to the exhaust used in selective catalytic reduction (SCR) to remove nitrous oxide (NOx).
DOC — Diesel oxidation catalyst. This is the part of the diesel particulate filter (DPF) system where soot is burned off during regeneration.
DPF — Diesel particulate filter. This is a filter with a catalyst that filters ash from the exhaust.
EGR — Exhaust gas recirculation. This is the process where some cooled exhaust, mixed with fresh air, is diverted back through the engine. This also is sometimes referred to as CEGR, which stands for “cooled exhaust gas recirculation.”
NOx — Nitrous oxides. These are a group of nitrogen/oxygen compounds that in the Tier 4i standard must be reduced by 90 percent from the previous standard and by a further 80 percent in the Tier 4f standard.
PM — Particulate matter is a regulated diesel emission made up of soot and ash. Soot is made up of unburned diesel fuel and engine oil. Ash comes from a variety of engine oil additives that didn’t burn. A catalyst in the DPF system burns off the ash and the soot needs to be periodically cleaned from the DPF.
SCR — Selective catalytic reduction. This is the process that uses DEF to separate NOx into nitrogen, water vapor and carbon dioxide.
ULSD — Ultra-low sulfur diesel is the only widely available diesel fuel available in North America, Europe and Japan. Using higher
sulfur fuel will foul the systems of Tier 4i and Tier 4f engines, so manufacturers still produce and will continue to produce lower Tier engines for overseas markets where ULSD is not available.
Diesel exhaust fluid (DEF) is available throughout the nation and is becoming available at more locations as the demand increases.
Pilot Flying J, the company that owns and operates Pilot Travel Centers and Flying J truck stops, offers DEF at the pump at more than 300 of its locations. For a listing of the company’s DEF locations, go to pilotflyingj.com/pump-def.
“If you have a problem finding DEF in your area at a truck stop, for instance, I would recommend contacting a local trucking company and finding out where they get their DEF and find out if they have it delivered,” says John Keiffer, diesel engine technician for Quad City Peterbilt, Davenport, Iowa.
Avoid crystallization and allow regeneration
One of the more common problems with the latest generation of Tier 4 engines can be crystallization of the diesel exhaust fuel (DEF).
“Exposure to air seems to be the big culprit with this crystallization, so it is always best to keep the DEF tank full. Like a gas engine works most efficiently when the gas tank is full, a DEF system is least prone to fluid crystallization when the tank is full,” says John Keiffer, diesel engine technician for Quad City Peterbilt, Davenport, Iowa.
Keiffer says that crystallization is such a common problem with DEF systems that it should be a point of inspection. “If a technician or operator of this equipment notices a leak, it is important to address that quickly. As long as the system remains sealed, it is reliable, but construction equipment is used in harsh conditions, so things can happen. If you address a leak when you first notice it, you can avoid a troubling crystallization problem later,” he says.
Other than keeping an eye on selective catalytic reduction (SCR), the normal additional maintenance requirement for newer engines is minimal. “Within the DEF controller there is a small filter that ensures that it cleans the diesel exhaust fluid before it is injected into the exhaust,” Keiffer says. “That filter should be checked and periodically replaced.”
Keiffer says the other problem he has seen in the trucking industry is operators defeating the regeneration process. “The engine will automatically start regeneration of the exhaust filter. It is a fine, honeycombed filter where soot will build up and the engine periodically revs up to burn off built-up soot, so the filter does not become clogged. The driver can override the process with the push of a button, but when they do this too often, it causes the engine to overwork and can kill the engine because the exhaust becomes trapped. Operators of construction equipment need to realize that the engine might need to start idling higher and they need to let it do its thing and not try to shut down the engine, thinking that there is something wrong with it. It is a matter of training and awareness more than anything,” he says.
“The diesel particulate filters may require special operator actions to initiate a cleaning cycle,” says Roy Brookhart, senior marketing specialist for Caterpillar, Peoria, Ill.
“However, on many of the recently introduced Caterpillar machines, this cleaning process is done passively and does not require any special actions or activities by the operator. Since this is different from brand to brand and machine to machine, make sure you understand your equipment and pass that information on to the people that operate these machines,” Brookhart says.
Your manufacturer can help
The manufacturers of diesel engines and off-road diesel equipment have been working to put into place systems that make it easier for owners of their equipment to buy and maintain their equipment and the major engine and equipment manufacturers have been working to educate their customers on Tier 4, both in their latest product literature and on the Internet.
- Caterpillar - cat.com/technology/tier-4
- Cummins - cumminsengines.com, click on the Tier 4 Technology icon.
- John Deere - johndeereemissionshub.com
Many manufacturers also have put maintenance programs and diesel exhaust fluid (DEF) exchange programs into place to make buying Tier 4i and Tier 4f equipment less intimidating.