Cat Engines with ACERTTM Technology:Designed and Built for Todays Global Environment

May 1, 2006

The variety of information and misinformation

circulating in the market about various

emissions technologies has made it

necessary to provide some details

regarding Caterpillars unique

emissions reduction solution

ACERTTM Technology. The following

briefly describes the components that

make up ACERT Technology for the on

highway market and offers an overview of the

competing technologies.

Originally developed to meet the United States EPA

04 emissions regulations, ACERT Technology is a

total systems solution comprised of four key areas:

air systems, fuel systems, integrated and enhanced

electronic engine controls, and a simple, effective

aftertreatment device. We believe this solution not only

enables Cat engines to meet todays EPA 04 emissions

regulations while delivering higher customer value

than the competitors EGR (Exhaust Gas Recirculation)

solution; it also establishes the building blocks for

meeting the more stringent Euro 4, Euro 5, EPA 07, Euro

6 and EPA 10 standards. Caterpillar carefully considered

the options when selecting which technology path to

follow to reduce NOx, particulates, hydrocarbons and

carbon dioxide to regulated levels for EPA 04 emissions

regulations. In fact, ACERT and EGR technologies aim

to achieve the same thing: control peak combustion

temperature to reduce NOx production in-cylinder. They

simply go about it in different ways. The EGR approach

recirculates cooled exhaust gases back into

the combustion cylinder to reduce peak

cylinder temperatures. In doing so,

however, it also injects soot and other

contaminates from the exhaust back

into the engine. Caterpillar considered

this technology option, but in evaluating

the effects it may have on maintenance

issues, component life, fuel economy and engine

durability, considered the outcome unsatisfactory to

meet emissions levels at the time.

The ACERT Technology approach achieves reduced peak

cylinder temperatures by utilizing series turbocharging,

flexible valve events, and carefully controlled fuel

injection and without the contamination caused by

EGR. Consequently, maintenance intervals were not

compromised, fuel economy has been maintained, there

has been no diminished effect on component life and

the durability of the engine is maintained. All in all, we

believe that ACERT Technology was a better solution to

meet EPA 04 regulations.

For the much tighter emissions regulations of Euro 4,

Euro 5 and EPA 07, a combination of technologies will

most likely be required. Caterpillar will introduce Clean

Gas Induction (CGI) into the 2007 models to gain some of

the reduced temperature gains provided by inert gas, but

will ensure exhaust contaminants are removed.

Cat Engines with ACERTTM Technology:Designed and Built for Todays Global Environment

Air SystemsAn important component of ACERT Technology is an advanced air system. Conventional single turbocharging is used on smaller displacement mid-range engines, while all Cat heavy duty products use series turbocharging to provide more air flow and higher boost levels. Our turbocharger technology puts cleaner air into the combustion chamber, said Greg Gauger, Director of On-Highway Engine Products, Caterpillar Power Systems Division. This provides the needed reduction in oxides of nitrogen, as well as better fuel economy, improved response and additional engine braking.

Heavy duty Cat engines with ACERT Technology use two standard turbochargers in series that turn slower, putting less stress on both for increased component life. These conventional turbochargers use proven wastegate technology for outstanding reliability and improved durability vs. competitive systems.

The advanced air system controls the air volume required at various loads and speeds, so the engine achieves complete combustion to reduce emissions, according to Gauger. The system automatically adjusts to the requirements of the engine, he said. The engine adapts to the airflow needed, allowing higher boost levels and more airflow for better performance and fuel economy.

The Caterpillar advanced air system also employs a technology called variable valve actuation. Controlled by Cat advanced electronics, this system allows just the right amount of air to be pulled into the inlet valve for efficient, clean combustion. The system uses components from proven Caterpillar technology. Benefits of variable valve actuation include low emissions and fuel economy equal to model year 2001 products.

For the C13 engine, a new cylinder head design provides inlet valve actuation, but also includes exhaust valve actuation, which allowed Caterpillar engineers to include an integral compression brake. As a result of this system, compression brake performance has been improved 25 percent over alternative compression brake options. The advanced system design to control exhaust valve actuation was used on all heavy duty Caterpillar engines beginning in 2004, Gauger said.

Fuel SystemsThe C7 and C9 engines with ACERT Technology feature a new Cat Common Rail Fuel System that optimizes the performance and fuel economy. It offers greater injection flexibility to facilitate compliance with more stringent emissions regulations and increases fuel economy by up to 4%.

The Common Rail Fuel System uses precise multiple injections to introduce a small amount of fuel at the appropriate times to achieve maximum fuel economy and lower emissions. The amount of fuel injected is determined by the engines electronic control module. The first injection is called the pilot injection, after which fuel is added as needed to achieve the best combustion.

Heavy duty engines, including the C13 and C15, use the Mechanically actuated Electronically controlled Unit Injector (MEUI) fuel system found on todays Caterpillar engines. MEUIs multiple injection technology is similar to that of the HEUI fuel system.

Multiple Injection Combustion Advanced Air Systems

Electronic Controls Diesel Particulate Filter

ACERTTMis a Systems Approach.

Lets examine each of the four systems of ACERT Technology in more detail.

ElectronicsThe advanced Cat ADEM electronics package used in ACERT Technology integrates the engines systems, guiding them to work together to achieve reduced emissions while maintaining excellent fuel economy and performance.

First, the system senses the engines ever-changing operating conditions. Thenin much the same way the engine adapts automatically to airflow needs by increasing or decreasing turbo boostthe electronic control module sends out signals that variable valve actuators and fuel injectors convert into mechanical responses.

The electronics provide the software, hardware and sensors that manage ACERT Technology, Gauger said. Like the brain that runs the human body, the electronics ensure that all systems of ACERT Technology work together to run the engine cleanly and efficiently.

Caterpillars dedicated engine division of more than 600 engineers has been particularly successful in achieving industry recognition for their work in electronics. For 13 years running, Caterpillar has received the prestigious Mentor Graphics award for excellence in circuit board design.

AftertreatmentWhile the combustion processes (fuel and air systems) function to reduce NOx emissions, regulated exhaust emissions also include particulates, hydrocarbons and carbon monoxide. So a simple, effective aftertreatment device completes the systems solution of ACERT Technology. For the EPA 04 models, a diesel oxidation catalyst was required to reduce hydrocarbons and carbon dioxide. As we move further down the emissions spectrum, a diesel particulate filter will be required to meet Euro 4, Euro 5, EPA 07, Euro 6 and EPA 10 regulations.

When ACERT Technology was introduced to the U.S. market in October 2002, Caterpillar promised that customer value would not be reducedas appeared to be the case with the EGR alternative. True to that promise, fleets across North America are reporting that Cat engines with ACERT Technology are delivering fuel economy equal to or better than pre-October 2002 engines and reliability equal to pre-October 2002 engines. Why? In part, because ACERT Technology required very few NEW developments. It simply utilized existing proven technology and systems more effectively. From a customer perspective, the utilization of proven systems and components means fewer problems.

In Europe, regulations differ in respect to the technology options that are acceptable. Consequently, SCR

(Selective Catalytic Reduction) is an option that was not available in the United States. So how do the ACERT and EGR technologies measure up to SCR? SCR attacks the emissions reduction goal from a different standpoint. It aims to reduce the production of particulates in the combustion process, and treat NOx after the fact in the exhaust. The proponents of SCR have used fuel economy and performance gains as the primary argument supporting the technology. In comparison to a Euro 3 engine, it was originally proposed that a 3% to 5% improvement could be obtained. Later information suggests that there is no real improvement in fuel economy, particularly when the implications and cost of urea are taken into account.

In order for SCR to meet the emissions regulation, the NOx that is created in the combustion process needs to be treated. The solution to this is to inject a urea solution into the exhaust stream to convert the NOx to carbon dioxide and water. This requires an aftertreatment container of similar size to what is required to treat particulates under the EGR and ACERT Technology approachbut also requires a tank to hold the urea. And the urea tank needs to be refilled, requiring a new distribution system. In addition, there needs to be some way to assure regulators that the tank is filled with the correct liquid. This requires the addition of On-Board Diagnostics (OBD), technology that is still being developed. Moreover, because urea freezes at 11C, an on-board heating facility is necessary for operation in many countries. So while the SCR approach maintains a fuel economy level at Euro 3, it requires a significant number of extra components to be added to the truck. This reduces payload capacity and adds to overall costs.

Availability of urea is also a critical issue. Again, consider the implications of ensuring the availability of urea throughout the vast regions of China and Russia, the isolation of Africa, the Middle East and even outback Australia. Will it really happen? In short, ACERT Technology delivers not just cleaner air, but in our view also better bottom-line value over competing technologies. It is a safe, secure method of delivering the cleaner air mandated by the increasingly stringent emissions regulations of Europe, the United States and other regions of the world. And the process happens without any external input; the engine does it.

As we move further down the emissions path in the United States and Europe, a mix of the technologies may well be required to meet the exceedingly low levels permitted by the regulations. You can be assured that Cat engines with ACERT Technology will continue to meet the ever-tightening emissions standards around the world while setting the standard for customer value.

For more than 80 years, Caterpillar Inc. has been helping to build the worlds infrastructure and, in partnership with Cat dealers, is driving positive and sustainable change on every continent. With 2005 sales and revenues of $36.339 billion, Caterpillar is the worlds leading manufacturer of construction and mining equipment, diesel and natural gas engines and industrial gas turbines. The company is a technology leader in construction, transportation, mining, forestry, energy, logistics, financing and electric power generation. Caterpillar is also the leading manufacturer and supplier of truck and bus engines in the combined medium and heavy duty categories in North America, holding the leading position in engine shipments to vehicle manufacturers since 1999.

More information is available at: http://www.cattruckengines.com.

C7 C9

C13 C15

Cat offers a complete lineup of mid-range and heavy duty engines featuring ACERT Technology.

Caterpillar 2006. All rights reserved. CAT, CATERPILLAR, ACERT, their respective logos and Caterpillar Yellow,as well as corporate and product identity used herein, are trademarks of Caterpillar and may not be used without permission.