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The 528 wheel skidder represents a second-generation machine designed and tested to satisfy the requirements of the large wood areas of the world. Numerous unique features were incorporated in the design to meet the special needs of the logging customer; these are described, along with the development program that yielded the present vehicle.

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.

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.

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.

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.

ISO and SAE static sound power test methods are currently used for construction machinery. The European Economic Community sound committee has been developing a drive-by or simulated work cycle test method using a hemispherical array of microphones. The EEC method is inconsistent due to the changing test surface (moist sand) and the variables of outdoor testing: temperature, wind, and precipitation. The in-place-dynamic test method described provides a disciplined way to evaluate machines with moving track or wheels and operating hydraulic systems. The machine is slightly elevated, resting on stands, so that the wheels are off the ground or the tractor weight is off the track chain. Data obtained from track-type tractor, track-type loader, and wheel loader machines supports the validity of using an indoor, in-place-dynamic test instead of a moving, outdoor test. Results also show that using sound intensity instrumentation permits the option of testing in an untreated, indoor facility.

Two new Caterpillar Wheel Loaders have been developed in the 1.2 cubic meter (1.5 cubic yd.) and 1.5 cubic meter (2.0 cubic yd.) bucket capacity categories. This paper provides a review of the design objectives and summarizes the design features included to meet worldwide manufacturing and marketing requirements.

This paper details the design and features of the 651E, 657E, and 657E Push-Pull Wheel Tractor Scraper. Emphasis was placed on the availability, reliability, and serviceability of these units.

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 new Caterpillar Wheel Loader has been developed to provide a loader in the 2 cubic meter (2.5 cubic yard) bucket capacity-category. This paper provides a review of the machine design objectives and summarizes the design features included to meet worldwide manufacturing and marketing requirements.

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.

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.