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TVA is an interactive computer program which performs a Torsional Vibration Analysis on lumped mass systems which contain torsional degrees of freedom. This program has two fundamental analyses. The first is Normal Modes which analyzes the natural unforced undamped behavior of the system to give natural frequencies and mode shapes. The second analysis is Frequency Response which analyzes the forced response of a damped system to give response results. TVA is used to analyze engine-auxilary equipment systems as well as vehicle drivetrain systems.

A cooperative research program has been completed evaluating the impact of fuel composition (volatility, aromatics and sulfur) on the combustion and emissions performance of a Caterpillar 3406B turbo-charged diesel engine, which is representative of diesel truck engines of the late 1980s. Tests included both steady-state and transient operation measuring regulated and unregulated emissions. The fuel set was blended using only commercially available refinery stocks typical of those which could be considered for use in distillate fuel. The compositions of the blends were selected so that direct measurements of the individual effects of 10% and 90% distillation temperatures, aromatic content, and sulfur content could be made independently. Engine combustion performance data indicated that all fuels operated satisfactorily; aromatic content was as high as 50% and cetane number as low as 39. Further, the cetane number did not predict the engine measured ignition delay in this program.

This Paper: 1. Shows that the present spherical rod end manufacturer's rotational tests, which are intended to select the best bearing material, do not necessarily select the best materials for the push/pull linkage requirements of earthmoving machinery. 2. Emphasizes the need to perform push/pull comparative testing as defined in SAE J1367 on spherical rod ends to determine acceptable materials for earthmoving equipment application. This test is in contrast to rotational testing presently being performed by spherical rod end manufacturers.

The small wheel type loader has seen its application range extended such that it is now one of the most versatile machines in our industry. However, its effectiveness in tasks other than bucket loading is limited. In order to provide improved tool control characteristics that contribute to efficient multi-task capability, it is necessary to design these characteristics into the base vehicle. The Integrated Toolcarriers recently introduced by Caterpillar fulfill this requirement. This paper discusses the design objectives and summarizes the development program which preceded their introduction.

A system has been developed that provides real-time measurement of heavy-duty diesel engine particulates emitted during the EPA transient emission test cycle. This is accomplished by measuring the opacity of the exhaust/air mixture in an EPA type dilution tunnel with a light extinction opacity meter. Simultaneously, the temperature in the dilution tunnel is measured, and the ratio of the dilution tunnel temperature to a standard temperature is used to correct the opacity signal to standard conditions. The outstanding features of the system are that it produces a continuous record of when particulates were generated during the 20-minute transient cycle and that particulate cycle results are available immediately upon completion of the transient cycle without the requirement of conditioning and weighing filters. Results to date indicate correlation of the opacity-particulate monitor measured particulates to gravimetrically determined particulates to be within 10% for specific engines.

Chromatographic analysis of diesel exhaust indicates a number of low molecular weight hydrocarbons, below C6. Using reactivity index as a criterion, much of the diesel exhaust reactivity can be attributed to ethylene and propylene caused by the thermal decomposition of the fuel. Hydrocarbons in the C4-C7 range, including high relative reactivity olefins, are generally low in volume concentration and therefore contribute little to the overall exhaust reactivity. Hydrocarbons, in terms of parts per million carbon above C7 are low in present diesel engine designs, so individual volume concentrations are generally fractional parts per million. Reactivity per horsepower-hour from diesel engine exhaust is less than that from the one small industrial gasoline engine tested by the heavy-duty truck diesel engine cycle.

A new family of heavy duty diesel engines, the 3400 Series, has been developed by Caterpillar Tractor Co. The family includes Inline 6 cylinder, V-8 and V-12 engines covering the 270-750 horsepower range. Stringent program objectives were established in the areas of durability, reliability, commonality, flexibility and serviceability within defined limits of cost and weight. Design, development and manufacturing planning were closely coordinated to ensure economical manufacturing with high volume tooling. This paper deals with the design, development and certain aspects of engine applications.

The effect of altitude on the performance of two turbocharged prechamber diesel engines and one direct-injection diesel engine has been studied in a test cell. One prechamber engine was tested at altitudes up to 16,000 ft. The data from these tests are presented and compared with performance at standard conditions. Using the data, an analytical method of predicting the performance of turbocharged diesel engines at altitude has been developed. An iterative computer program, using part-load data taken at standard conditions, is used for the prediction. Comparison is made with the simulated altitude data and with other calculation methods.

A new 2-ring piston package has been developed which has proven successful in internal combustion engines. The need for a compact piston arrangement is discussed along with the steps followed to arrive at excellent oil economy. The paper presents other advantages related to cost savings, lower wear, and reduced engine friction. The paper discusses applications of the compact piston package along with its advantages in designing compact engines.

Modern data acquisition methods combined with new testing and analysis techniques are revolutionizing product design and development. Detailed analysis of recorded vehicle drive-line data has given today's engineer new insights into drive-line dynamics. This paper discusses how vehicles can be analyzed as a series of torsional springs and inertia masses. A two axle, 300 hp, 15 cu yd earthmoving tractor scraper (model 621) is used to illustrate significant factors. Main emphasis is on drive-line resonant torsional vibrations and shock loading. Diesel engines as torsional vibration exciters and transmission clutches as the major shock load producers are covered in some detail. How analog computers can effectively be used to facilitate vehicle development is briefly discussed.

A very high output (VHO), compression ignition engine family has been designed for the Military by Caterpillar Tractor Co., under contract with the U.S. Army Tank-Automotive Center, Detroit Arsenal. The engines in this family have maximum parts interchangeability and feature a multifuel combustion system. The first model, the LVMS1050, has been built and tested. This engine develops 960 bhp, weighs 2.5 lb per hp, and produces 29.5 hp per cu ft of volume. This paper discusses the family design and LVMS1050 development.

After reviewing the present state of diesel engine design art as applied to vehicle applications, the paper analyzes future application requirements and outlines possible paths of engine development. In general, future requirements demand engines of higher output, lighter weight, better fuel economy, and smoke-free operation. A better understanding of vehicle load demands and careful matching of engine and drive-line will be required. Reference to extensive recent research developments shows that the diesel engine industry will be prepared to meet this challenge to provide the customer the best possible engine in terms of return on his investment.

Advance in earthmoving technology has made necessary a corresponding advance in cutting edge technology. In adopting the concepts of matching the cutting edge to the machine, or possibly the job requirements of the machine, in rare instances it is found that the cutting edges employed in the 1930's and 1940's are satisfactory; however, in general, the increase in horsepower and carrying capacity of earthmoving machinery has necessitated a vast increase in the strength and wear properties of the cutting edge. The development of these properties, based on academic, laboratory, and field precepts, has advanced hand-in-hand with machine developments.

Two high specific output diesel engines designed for the Military -- the LVDS-1100 and LDS-750 engines, which are of V-8 and 5-cyl in-line configuration, respectively -- were developed by Caterpillar Tractor Co. under contract with U.S. Army Tank Automotive Center at Detroit Arsenal. This paper covers the development work, also sponsored by ATAC, required to adapt these engines for operation using regular grade gasoline in addition to the diesel and CIE fuels for which they were originally designed. Test techniques used, a description of some interesting combustion systems tried, and data obtained with the selected arrangement are included. The engine has excellent performance and starting characteristics with any of the three fuels.

This paper first discusses the loads of major significance to various machines and machine parts, and second, considers available methods of measuring, analyzing, and presenting information on loads and stresses. Various engine and machine components are examined from standpoints of loading methods and which loads are likely to be critical on each component. Interrelations between components and machines are also discussed. Tools and methods available to the load and stress analyst are described, with particular emphasis on choices available in methods, instrumentation, and presentation of data. Reasons for preferences in particular situations are given.

AFTERCOOLING, coupled with higher pressure turbocharging can increase vehicle engine output. The author thinks that it is possible to anticipate diesel engines being run with compressors supplying air at pressure ratios higher than 2/1. Density ratio is the most important consideration in increasing pressure ratio, since the engine's output is dependent upon weight rather than volume of air supplied. Because the density of the compressed air is dependent upon its temperature at any pressure level, cooling the air after compression results in density increases. This paper describes various methods of after-cooling which increase engine output and fuel economy.

SETTING ratings for diesel engines takes laboratory testing and field experience for critical parameters such as smoke, piston temperature, and exhaust temperature. Rating is based upon theoretical considerations, plus the approval of the engine itself. Factors in rating considerations include a knowledge of the application of the engine, and whether its use is to be intermittent or continuous. Ratings by the manufacturer are not always accepted by the engine user, however. The user will run the engine at the load most profitable for him, which may be above or below that recommended by the manufacturer.

TRACTORS operate in a wide range of conditions, from desert to swamp. At all times, the final-drive seals must keep the oil in and the dirt out. In this paper, the authors discuss the latest developments in seal design and the resulting improvements in performance. Efficient performance of a tractor final-drive seal depends upon a number of factors, including: bellows and bellows-boot operation, seal load and area, seal material, wear washer, and gasket structures.

TESTS on two series of diesel engines were run. The first group, consisting of four engines, had the stroke changed only, while the second group had the stroke/bore ratio changed and the displacement held constant. Results of the tests indicate that the longer stroke engines had more power, higher torque, and lower fuel consumption. Friction was high for the short-stroke engines at low speeds and for the longest stroke engine at high speeds. Theoretical analysis indicates that the optimum stroke/bore ratio for best performance may vary as the compression ratio and bore diameter are changed.

HIGH load-carrying ability and fatigue strength, good embeddabiltty and conformability, and resistance to wear, seizure, and corrosion are factors that sold them on aluminum for bearings, the authors report. Bonded steel backing, they say, makes aluminum bearings even better. Retaining aluminum's good properties, it improves some of its bad points and gives such advantages as: Reduced bearing clearances, compared with those used with solid-aluminum bearings. No life limit in operation below 5000 psi fatigue stress value. Less sensitivity to high oil temperatures. Negligible wear (after 29,000 hr in one test). Simpler and less expensive bearing-locating designs. Special excellence for high-load, high-speed applications.