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Statistical measures of whole-body vibration from ambulation are shown to be higher than those from operation of earthmoving machinery and significantly higher than published guidelines for human exposure to whole-body vibration. The inconsistency of human response to low level vibration of technological origin as compared to human imperceptiveness to high level vibration from ambulation is discussed.

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 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 Cushion Hitch is a unique application of vibration absorber theory to a self-propelled tractor-scraper. The scraper mass is utilized as a damper for suppressing predominate bouncing motions of the tractor unit. A more comfortable and safer operator ride, with increased productivity, results from the Cushion Hitch application. This paper describes development of the early prototype design as well as the final production version. Particular emphasis is given to both the hydraulic and the structural characteristics of the system.

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.

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.

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.

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.

For some time, Caterpillar Tractor Co. has been marketing a new transmission control system for wheel-tractor scrapers and off-highway trucks. The new system is composed of an electronic microprocessor control box coupled with an individual clutch modulation hydraulic control. This system has resulted in increased vehicle productivity, improved reliability and serviceability, decreased complexity, and increased commonality of parts. This paper describes the concept, design, and test and evaluation process used to develop the new controls before production.

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.

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 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 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.

Inertia welding is a friction welding process using energy stored in a rotating mass as the source of heat and mechanical work. The process has been described in previous publications. The state of development of this manufacturing process, with respect to complexity of design and dissimilar metal welding, is the subject of this article. The successful applications of inertia welding now in production establish the utility of this versatile process while current developments portray exciting future possibilities.

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.

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.