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Selective Catalytic Reduction (SCR) of Nitrogen Oxide (NOx) emissions using ammonia or a 32.5%-urea solution has been used for many years in a variety of stationary applications. These applications include but are not limited to coal fired power plants, gas turbines, diesel locomotives, marine engines, as well as other stationary diesel and non-diesel engine applications. Global emission limits for mobile heavy-duty diesel engines are becoming increasingly rigid. In response to this trend the diesel industry has begun testing and applying various emission control technologies to mobile applications. SCR is one such technology. Europe is the first major market to introduce SCR into the heavy-duty (class 8) as well as medium-duty (class 4-7) truck applications. The EURO4 standards (effective Oct. 2005/2006) and the EURO5 standard (effective 2008) favor SCR as the NOx reduction technology of choice in the European Union (EU).

Changing diesel engine emission requirements for 2002 have led many diesel engine manufacturers to incorporate cooled Exhaust Gas Recirculation, EGR, as a means of reducing NOx. This has resulted in higher levels of soot being present in used oils. This paper builds on earlier work with fresh oils and describes a study of the effect of highly sooted oils on the low temperature pumpability in diesel engines. Four experimental diesel engine oils, of varying MRV TP-1 viscosities, were run in a Mack T-8 engine to obtain a soot level ranging between 6.1 and 6.6%. These sooted oils were then run in a Cummins M11 engine installed in a low temperature cell. Times to lubricate critical engine components were measured at temperatures ranging between -10 °C and -25 °C. A clear correlation was established between the MRV TP-1 viscosity of a sooted oil and the time needed to lubricate critical engine components at a given test temperature.

More stringent emission legislation has been a driver for changes in the design of Heavy Duty Diesel engines since the 1980s. Optimization of the combustion processes has lead to significant reductions of exhaust emission levels over the years. However, in the year 2002, diesel engines in the USA will have to meet an even more stringent set of emission requirements. Expectations are that this will force most engine builders to incorporate Exhaust Gas Recirculation (EGR). Several studies of the impact of EGR on lubricant degradation have shown increased levels of contamination with soot particles and acidic components. Both of these could lead to changes in lubricant requirements. The industry is developing a new specification for diesel engine lubricants, PC-9, using test procedures incorporating engines with EGR.

Commercial Heavy vehicles (CHVs) are an efficient and reliable link between marine, railroad, and air transportation nodes. The vehicle braking power imposes an important constraint in the allowable vehicle speed. The compression brake augments the vehicle retarding power and is currently typically used as an on-off device by experienced drivers. Hardware and software advances allow modulation of the compression brake power through variable valve timing, and thus, enable integration of the compression brake with service brakes. To analyze how much the compression brake affects vehicle speed during braking, we develop a crank angle engine model that describes the intrinsic transient interactions between individual cylinder intake and exhaust gas process, turbocharger dynamics, and vehicle dynamics during combustion and variable brake valve timing. The model is validated using experimental data.

Prototype selective catalytic reduction (SCR) systems using urea have been demonstrated on diesel trucks in Europe in recent years. In view of upcoming stringent emissions control standards for US HD diesel engines, urea-SCR is being evaluated by US engine and truck manufacturers. The authors and their companies have worked jointly on a project to develop, test, and demonstrate urea-SCR on a US HD diesel engine and Class-8 truck. A prototype urea-SCR system was applied to a 12-liter HD diesel engine. The engine model selected is rated at 350 bhp and is common for highway trucks. The only engine modifications were changes to the injection timing control map in order to better suit the application of the urea-SCR system. This paper details two demonstration phases of the project as follows. The first phase includes recent emissions cell tests using a new compact SCR catalyst and an engine calibration optimized for lower NOX.

Heavy-duty natural gas engines available today are typically derived from diesel engines. The biggest discrepancy in thermal efficiency between a natural gas engine and its diesel counterpart comes at low loads. This is particularly true for a lean-burn throttle-controlled refuse hauler. Field data shows that a refuse hauler operates at low speeds for the majority of the time, averaging between 3 to 7 miles per hour. As a result, many developers focus primarily on the improvement of thermal efficiency at light loads and low speeds. One way to improve efficiency at light loads is through the use of a late intake valve closing (IVC) technique. With the increase in electronic and hydraulic control technologies, the potential benefits of late IVC with unthrottled control are realizable in production engines.

This paper describes the procedures used to reduce the tonal noise of a class eight truck engine timing gear train that was initially found to be objectionable under idle operating conditions. Initial measurements showed that the objectionable sounds were related to the fundamental gear mesh frequency, and its second and third harmonics. Experimental and computational procedures used to study and trouble-shoot the problem include vibration and sound measurements, transmission error analysis of the gears under light load condition, and a dynamic analysis of the drive system. Detail applications of these techniques are described in this paper.

A new heavy duty chassis-cab, i.e., “chassis”, for refuse applications, has been designed to improve the productivity of its operator while minimizing his or her physical efforts. The chassis has its operating compartment and controls arranged such that required operator's motions are productive. The chassis features minimize the operator's exertion and maximize his or her comfort, thereby reducing fatigue associated with an otherwise strenuous occupation. This product was developed utilizing a new, structured process involving discrete phases, checkpoints and teams.

Mack Trucks' E7 direct injection heavy-duty diesel engine is a four cycle, in-line six cylinder design. The 728 cu in. (12 1) engine is turbocharged and chassis mounted air-to-air aftercooled. The E7 is being introduced in 1989 with power ratings of 250 hp to 400 hp (186 kW to 298 kW) at 1700 to 1800 rpm, calibrated to 1990 EPA standards. Highlights of the E7 engine's design, development and performance are presented. Information is included which illustrates the strategies utilized to attain program goals of controlling weight and cost while extending power ratings, reducing emissions levels, and improving fuel economy, serviceability, durability and reliability.

Product design cycle time can be significantly reduced with the utilization of Computer Aided Engineering. (CAE) techniques. Computer modeling and analyses can eliminate portions of the lengthy procedure required by traditionally accepted Product Development Methods. This paper examines and compares a CAE application to a conventional method in the redesign of a structural component of a heavy-duty truck. The procedures to achieve design objectives: Modeling through stress analysis iterations and verification of analyses by prototype testing will be addressed together with the impact of such approach on cost and quality of engineering.

Two ceramic monolith wall flow diesel particulate traps, incorporating a new split flow design with a base metal catalytic coating were tested on line haul highway trucks to investigate their performance characteristics. The trucks were equipped with a 300 HP turbocharged and after-cooled engine. After-cooler by-pass was used to effect the regeneration of the trap and an elapsed-time scheme was employed to control the regeneration process. Tests were terminated after one trap completed 147,500 miles of operation on the truck for in-depth examination of the trap to determine the cause of substantial increase in back pressure. Tests with the second trap of identical design was also terminated due to filtering efficiency loss, the cause of which was traced to a flaw in the canning arrangement. This arrangement permitted exhaust flow to by-pass the element and led to melt down of the trap, due to reduced flow during regeneration.

Mack Trucks design and analysis capabilities have enhanced considerably with in-house computer aided engineering (CAE) systems. The CAE system includes Solids and 3-D Geometric Modeling, Graphic Finite Element Model Generator and general purpose Finite Element Analysis software. Finite element analysis of the cast Transverse Torque Rod Bracket was done as a product improvement to the existing fabricated design. Correlation of the Finite Element results with experimental stress analysis results for the proposed design was achieved to confirm the analysis procedure. Improved structural strength and substantial weight and cost reduction over the existing design was achieved with significant reduction in design cycle time.

A foundation of highway truck ride and cab suspension historical evolution is laid describing the influence of marketplace demands, highway conditions, and government laws. Ride quality test methods are revealed along with variables tried and conclusions drawn. These data and techniques are then used to design cab suspension systems for a new line of truck products including both conventional and COE cabs.

In an ongoing effort to further improve engine durability, effects on ring wear of various engine operating variables were measured utilizing a radioactive wear test, Due to findings in this wear testing, developments were initiated in air filtration, fluid filtration and oil quality level. Implementation of these changes has improved engine durability.

This paper describes development of a full-scale laboratory truck axle test used to predict the field performance of gear lubricants in heavy truck use. The relationship between laboratory results and known field performance will be described, as will a unique way of analyzing laboratory results. Data will also be presented which will show the laboratory test to be both repeatable and reproducible. Finally, data will be presented which shows lubricant additive type to play a vital role in defining field performance.

A new 998 CID V8 engine series has been developed by Mack Trucks, Inc. to supplement its line of heavy duty diesel engines. These engines, the E9 Series, are available in two configurations--a 400 bhp (298 kW) high torque rise version and a 440 bhp (328 kW) conventional torque backup version. Increased horsepower and improved fuel economy were achieved through the development of a chassis mounted charge air cooler and a new four-valve cylinder head. In addition, significant durability improvements were obtained due to the reduced thermal loadings resulting from the lower charge air temperatures. Additional noteworthy features include a new injection pump, improved lube oil system, advanced piston design, and proper selection of seals and gasket materials.

To establish a criteria for engine oil requirements for Mack diesel engines, a program was conducted to establish a specification based on the use of a production multicylinder engine. Laboratory engine tests were supplemented by field tests to assure correlation. Subsequently modifications were made to the engine test procedures to accommodate modifications in engines being marketed. Oil monitoring and oil analysis programs were also implemented to further assist in assuring adequate engine lubrication.

Employing the systems approach, an extended maintenance interval has been developed for the entire truck. Included are engine oil, gear oil, chassis grease, and the various filters required. Extensive laboratory and field testing was conducted in developing the various specifications and component configurations required to assure satisfactory performance and durability.

Field experience, together with engine laboratory testing, indicated the need for upgrading of Mack's diesel engine lubricant specifications. Field testing and laboratory testing indicated the superiority of several of the newer oil formulations for the Mack engine requirements. The newer type multi-viscosity oils were found to be particularly suited. A modified multi-cylinder engine test (T-5) was developed together with an oil specification based on the use of this test procedure (EO-J).

The application of an advanced state-of-the-art air inlet system has produced a high specific output, high torque rise, heavy-duty diesel truck engine. By integrating a compact plate-fin air-to-air heat exchanger with the cooling air driven by a novel tip turbine fan, a 25% increase in power output has been achieved with minimal increase in mechanical engine loads. The use of an aluminum two-piece piston which prevents side thrust loading on the ring-carrying head section results in improved ring life and reduced oil consumption.