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Gearing load spectra data collected under actual working conditions help a designer predict the fatigue life of power train components. Considerable time was required in the past to collect and reduce these data to a form suitable for design use. A vehicle mounted instrumentation system consisting of a strain gaged shaft, a shaft encoder-slip ring assembly, and an amplitude distribution analyzer, was developed which performs load measurements. At the test's conclusion, it provides a spectrum analysis in printed histogram form.

An eight-stage transonic axial flow compressor was scaled to three-tenths its original size. The scaled compressor was built and tested as a separate component, and as a component of a gas turbine engine. This paper summarizes the work done on this compressor, including the aerodynamic design considerations and overall performance results.

Analytic modeling and analog computer simulation techniques are presented for determining power train transient responses excited by clutch-actuated gear shifts. A method for describing the dynamics of a transmission arrangement having several clutches and interconnected planetary gear sets is considered in detail. Simulation model testing is directed toward optimizing system design parameters and evaluating power train component capability and vehicle shift-feel. Data reduction techniques applied to model responses of torque and speed will yield appropriate spectrums representative of simulated work cycle. The spectrum data are used to predict hours of life for gears, bearings, and driveshafts, according to cumulative fatigue damage theory.

THIS paper presents results which will answer many of the problems facing an engine manufacturer in the selection of the most suitable types and sizes of superchargers to use with a line of engines. Although performance curves of production model diesels are available, decisions are still needed in choosing peak supercharging pressures, drive means, and size and effectiveness of intercoolers, if any. The author describes the use of a typical model to determine response to variation in intake and exhaust conditions, resulting in data which will assist in evaluating engine potentials with any system of supercharging. Thus, supercharger selection for a particular line of engines is aided by knowledge of engine characteristics as a second-stage compressor.

THIS paper points out that the advantages of using light, nonadditive oils are often sacrificed because of lack of fundamental knowledge about gear-scoring problems. Most formulas that have been developed to determine the scoring resistance have been totally empirical and have proved inadequate for stringent design requirements. The author discusses the excellent correlation that exists between scoring test results and a hypothesis on the failure of straight mineral oils. This correlation also encompasses the test results of ball and roller scoring test machines, showing the probable universal application of the hypothesis. The method of approach to the scoring problem of gears as discussed in this paper is a fundamental one, which combines the factors affecting the conversion of frictional energy into surface temperature with gear tooth geometry, stiffness, and surface finish, and points a way to design gears of higher scoring resistance.

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.

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.

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.

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.

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.

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.

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.

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.

This paper demonstrates a way of applying an iterative computing technique to a typical engineering design problem, in such a way as to maximize a mathematical expression of the design criteria. Ways of writing this mathematical expression to express design criteria are explained through several illustrative examples. This technique of computer-aided design should allow the engineer to arrive at more than satisfactory designs in a minimum of engineering time.

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.

THE HYDRAULIC SYSTEMS for the Caterpillar “G” Series Motor Graders were designed to provide for maximum operator comfort, ease of operation, and optimum control of the vehicle and implements. The use of high pressure closed center systems on these machines produces rapid system response and high hydraulic horsepower to the implement cylinders and motors, and operates with minimum size control components. Components were designed to meet specific system requirements for functional performance, reliability of operation, size and placement on the machine. System goals were met through the use of a variable displacement pressure compensated pump, controlled flow four-way implement valves, and a hydrostatic steering system.

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.