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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.

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 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 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.

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.

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.

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.

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 traces the development of lubricants for Diesel engine and heavy duty service from the time the mobile Diesel became a production entity in this country. Beginning with a background of lubricants found acceptable for large Diesel engines in marine and stationary service, the trend in the supply of lubricants in subsequent automotive practices in the early 1930's led to difficulties in ring sticking, bearing corrosion and cylinder scuffing in the moderate speed, heavy duty engine seeking commercial favor at that time. The attempts to solve these problems, both as to engine improvements and lubricant selection, are reviewed historically. The logical development of additive oils followed the pattern of alloy steel achievements.