Search Results

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.

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.

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.

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.

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.

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.

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.

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.

A new friction welding process, Caterpillar Inertia Welding, is described in this paper. The two distinguishing characteristics of this form of welding are a continuously decreasing rotational velocity and a continuously changing torque at the weld interface. This enables the forging of many previously “difficult-to-weld” materials, such as superalloys. Such welds also exhibit excellent fatigue properties. Because this process produces high strength bonds in dissimilar materials, the designer is able to create composite parts using the special properties of each material in response to the needs of the 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.

The causes of turbine blade excitation are described, and the factors that influence amplitudes of vibration are discussed. Blade rotation in an asymmetrical pressure field produces a periodic force on the blade. Harmonics of this periodic force excite the blades at their natural frequencies. Gas disturbances created by nozzle vanes also can excite the blades. Amplitudes are affected by the type of exhaust system combined with the type of turbine housing, turbine housing design, engine speed, vane design, and any local gas disturbance or condition that creates asymmetrical gas flow through the turbine housing.

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.

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 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.

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.

Fatigue failure of machine components subjected to high contact pressures is rapidly becoming recognized as a serious design limitation. Confusion has resulted from grouping three distinct types of contact fatigue failure under the term “pitting” A Geared Roller Test Machine is described that reproduced each of the three modes of failure. The stress-life relationships obtained for rollers tested under conditions of rolling plus sliding correlated well with actual gear performance. The sensitivity of the test to changes in material, micorstructure, and processing variables is demonstrated.

THE CATERPILLAR FOLDED CORE RADIATOR IS A NEW RADIATOR FOR VEHICLES AND STATIONARY ENGINE APPLICATIONS. THE MAJOR OBJECTIVES OF THIS DESIGN ARE TO GIVE THE USER AN INCREASED VALUE COOLING SYSTEM BY REDUCING RADIATOR REPAIR COSTS AND IMPROVING AIR-SIDE PLUGGING RESISTANCE. AS WELL AS PROVIDE THE VEHICLE DESIGNER WITH INCREASED APPLICATION DESIGN FLEXIBILITY. THIS IS TO BE ACCOMPLISHED WHILE MAINTAINING PERFORMANCE AND LIFE GOALS ASSOCIATED WITH THE CONVENTIONAL RADIATOR. THE FOLDED CORE IS A MODULAR DESIGN HAVING THE MODULES INSTALLED AT AN ANGLE TO THE FAN AIR STREAM RESULTING IN THE FOLDED APPEARANCE. COMMON MODULE SIZES ARE USED ACROSS THE MANY RADIATOR APPLICATIONS REDUCING INVENTORY REQUIREMENTS AT THE ASSEMBLY PLANT AND PARTS DEPOTS AND INCREASING INDIVIDUAL MODULE PRODUCTION VOLUME. THIS RADIATOR DESIGN IS REVIEWED FROM CONCEPT TO PRODUCTION.