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Hydraulic excavators perform numerous tasks in the construction and mining industry. Although ground grading is a common task, proper grading cannot easily be achieved. Grading requires an experienced operator to control the boom, arm, and bucket cylinders in a rapid and coordinated manner. Due to this reason, automated grade control is being considered as an effective alternative to conventional human-operated ground grading. In this paper, a path-planning method based on a 2D kinematic model and inverse kinematics is used to determine the desired trajectory of an excavator's boom, arm, and bucket cylinders. Then, the developed path planning method and PI control algorithms for the three cylinders are verified by a simple excavator model developed in Simulink®. The simulation results show that the automated grade control algorithm can grade level or with reduced operation time and error.

A liquid fuelled, fuel cell auxiliary power unit (APU) can provide efficient, quiet and low pollution power for a variety of applications including commercial and military vehicles. Truck idling regulation, customer comfort or military “stealth” operation by using electrical power, require a device disconnected from the main diesel engine. The power can be utilized for air conditioning as well as other auxiliary systems found on board commercial trucks for driver comfort. In a military vehicle, this regulated power could be supplied to telecommunication and other computer equipment required for military operations. A system designed to be an add-on or retrofit solution using alternative fuel can have the potential to meet these requirements on the hundreds of thousands of existing vehicles currently in service or as optional equipment on a newly procured vehicle.

The main issues related to the vibration response and acoustic noise emission of a new liquid fuelled fuel cell APU (auxiliary power unit) system are discussed and analyzed. These problems are being addressed in an on-going research project. The APU is comprised of several critical subsystems including the fuel processing system, fuel stack, heat exchanger, compressor, as well as high-pressure and low-pressure components. The vibration concern deals with the design of a two-stage isolation mount system to shield these critical parts from the shock and steady-state dynamics coming through the truck frame during on-road traveling conditions. A lumped parameter dynamic model is formulated for use in optimizing the mount stiffnesses and locations. Acoustic concerns are primarily related to exterior noise levels when the truck is at a rest stop. To address those issues, experimental studies are conducted to quantify the main sources and paths for noise.

Vehicle NVH performance is significantly affected by the dynamics of various primary systems. In the automotive industry, different design activities or vendors are responsible for designing various different systems simultaneously. Therefore, it is highly desirable to gain a better understanding of the individual system characteristics and the interaction between the primary systems to achieve a desirable overall NVH performance. Unfortunately, it is usually quite difficult to construct a proper fixture to accurately measure and quantify the actual uncoupled system characteristics. This paper examines an alternate approach of applying the FRF-based substructuring method to back-calculate the system response characteristics from the full vehicle system measurements. The results are then used to forward-compute the dynamic response of the vehicle, which are also validated by comparison to the direct response function measurements.

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.

In this paper, we discuss methods used to investigate a clearly audible gear whine problem in a modern automobile. Currently available PC-based computer software, coupled with more traditional engineering tools, such as spectrum analyzers, are employed to efficiently observe noise and vibration phenomena. Jury evaluations are conducted, using in-vehicle noise data, to rank actual gear whine levels. Additional jury studies using synthesized gear whine help us further understand listener preferences. Unloaded gear transmission error testing is explored as a means of predicting gear whine levels under light loads, such as those seen during highway cruising. We finally correlate many results to better understand the source and paths of the gear noise, and make recommendations for further exploration of this type of problem.

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.

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.

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.

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.

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.

The truck flywheel power takeoff has proven itself as a reliable means of supplying continuous power to a variety of mounted equipment. The features of available units are described in detail in an effort to provide the design and application engineer with complete information regarding their function and application, and to stimulate expanded usage of this constant power source.