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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.

A report on a detailed evaluation of cylinder pressure measurement was made in 1967 by the author. At the beginning of that paper, the primary importance of cylinder pressure measurement was pointed out. Pressure is the means by which work is extracted from the gases; the cycle is known only to the extent that this work function ∫PdV is known. At the end of that paper, it was concluded that cylinder pressure could be measured accurately enough to determine imep and that complete electronic determination of imep was needed. A system for determining imep electronically with excellent accuracy has been developed and has been in use for several years. This paper describes the Caterpillar indicated mean effective pressure (imep) meter and gives a sample of the information it can provide.

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 authors sees a need, in the near future, for commercial vehicles with engines of 1000 to 1200 hp - powerplants that yield high outputs but require limited space. He sees an immediate need for more and more horsepower per cubic inch of piston displacement and per unit of space for the engine. He directs attention to six design potentials which may supply the answer: (1) the gas turbine; (2) supercharging; (3) aircooled diesels; (4) higher engine speeds; (5) 2-stroke diesel improvement; (6) compound engines. He also links the future development of the internal-combustion engine with basic improvement of components through simplification, calling for the elimination of extraneous gadgetry.

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.

The heavy-duty truck industry has seen the need for a change in the concept of transmission design for many years. Several improvements have been made and others attempted, but greater improvement is needed to match the engine's delivery to the vehicle's demand. Driver performance can be improved and fatigue reduced by lowering the effort and skill required to make smooth, consistent starts and ratio changes. This paper discusses a solution to this need in the design and development of a semi-automatic, pneumatically controlled, constant mesh transmission.

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.

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.

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.

A new two-speed converter drive, six-speed mechanical drive transmission was designed for a 14 cu yd tractor scraper to provide an efficient and easily controlled power train. Included with a description of the system is a review of the development history, along with a summary of some new features utilized in this design.

The requirements for cylinder pressure measurement for mechanical load, imep, and cycle analysis are developed. Methods for determining errors in transducers are presented, and the results are shown. The tests include passage error, hysteresis, nonlinearity, mounting strains, thermal strain, and twist in the crankshaft. Theories are developed to predict errors due to time or phase delay, passage, and thermal strain. The theory of the balanced pressure indicator is developed and the minimum delay and pressure error are calculated. Read-out systems are evaluated. Areas needing improvement are pointed out and specifications for the ideal pressure transducer are presented.

A single-shaft, simple-cycle gas turbine engine has been developed to power 200 kw alternators for standby power and for applications where heat is needed. The engine was designed to be sold and serviced by distributors of earthmoving and industrial machinery. Where feasible, design practices of industrial piston engine powered generator sets were incorporated to facilitate installations of combinations of engine types, and to limit novel and unfamiliar features of the basic turbine engine to those that were considered essential. Individual components and complete engines, initially developed by a research group, have been subjected to a wide variety of laboratory tests to measure performance and develop reliability.

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 new family of lightweight, high speed, direct injection, diesel truck engines has been developed for medium duty applications. These 4.5 in. bore, 90 deg vee, 8 cyl, naturally aspirated engines are rated at 150, 175, 200, and 225 hp. Three displacements are utilized within a common engine package size to produce these ratings. Several unique design features, including a two ring piston and a specially angled main bearing cap are incorporated in these engines.

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.