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Technical Paper


The larger the equipment for a specific job in the earth-moving field, the more quickly and efficiently that job can be done. Unfortunately, the very size and weight of many present units means that the transportation of them involves a ponderous task. If increased capacity could be obtained with no increase in gross vehicle weight, and with only negligible differences in dimensions, major progress could be made in the equipment field. Even if physical dimensions involved no problem, the weight and placement of such essentials as tires, wheels, brakes, drive chains and engines, all tend to limit the payload capacity of a given vehicle. Through the judicious use of aluminum alloys in proved applications, a 10 to 15 per cent increase in payload capacity can readily be achieved at no increase in gross vehicle weight. The aluminum applications referred to have been proved both in over-the-road and in off-highway service.
Technical Paper

Temperature-Strength-Time Relationships in Mufflers and for Truck Muffler Materials

DATA presented in this paper show temperature-time diagrams obtained from mufflers mounted on trucks which were traveling over their regular routes. Using these temperature data, specimens made of possible muffler materials were subjected to laboratory tests. A wide range of possible muffler materials and gas composition were covered in these tests. Results of the tests indicate that under long-run heavy-duty truck service, muffler failure occurs primarily because of high metal temperatures and that coated mild steel showed the most promise of longer muffler life.
Technical Paper

Winterization Of Construction Equipment - Report of CIMTC Subcommittee XV—Winterization

SINCE 1954 the CIMTC Subcommittee has been engaged in a program to meet military requirements through industry's production of construction equipment which can give satisfactory cold weather performance down to temperatures of −65 F. Individual contracts for three crawler tractors and one motor grader were negotiated by ERDL for these projects, and their performance is discussed. Industry participation was subsequently expanded to include engineering tests in the cold weather conditions of the Mesabi Iron Range. This joint report of the Winterization Sub-committee of the CIMTC and ERDL Winterization Section consists of separate papers by various members and consultants of this Sub-committee and ERDL personnel.
Technical Paper

Symposium — Plastics for Truck Bodies

EXPERIENCE with new plastics for truck bodies reported by these five authors yields a complexity of pros and cons. Among advantages claimed are: 1. High strength-weight ratio. 2. High impact strength and ability to absorb punishment and return to original condition without permanent damage. 3. Ease of maintenance, repair, and cleaning. 4. Good thermal insulation. 5. Resistance to chemical or electrolytic attack or deterioration. 6. Ease of bonding. 7. Adaptability to mass production techniques. Disappointments reported by various users include: 1. High cost of raw materials. 2. Low modulus of elasticity. 3. Low endurance limit. 4. Fractures from internal abrading of reinforcement. 5. Weakening and failure of structures because of poor adhesion between plastic and its reinforcement. 6. Inadequate and faulty engineering knowledge of the subject.Agreement is general, however, that plastics for trucks have a bright future, once the many problems have been ironed out.
Technical Paper

Manufacturing Phases of Metal-Aircraft Construction

THE introduction to this paper includes definitions of the major items under discussion, and is followed by a discussion of the materials most widely used in metal-aircraft construction and their important physical properties. In the remainder of the paper are described some of the problems encountered in metal construction and the processes that have been developed to facilitate manufacture. The following specific items are discussed: (1) Design, (2) Tooling, including lofting, (3) Fabrication, (4) Assembly, (5) Inspection, and (6) Protective coating. Special equipment and tools are illustrated.
Technical Paper

Safety in Body Design Through Chassisless Construction

THE successful development of the chassisless motorcoach and its relation to safety, weight reduction and automotive design are discussed by the author. Pioneer design of this type, made back in 1927 after encountering various difficulties with conventional frames, was followed by successive improvements in design, resulting in the highly developed unit of today. A study is included of the engineering fundamentals primarily involved in the integral or chassisless design versus conventional-frame design from a strength and weight standpoint. This study involves a comparison with other more concrete objects to establish a definite insight to the why and wherefore of these structural changes. The relation to body safety design and its interconnection to weight distribution, vehicle balance, and resistance to crushing are also covered by the author.
Technical Paper


Railroads are facing a crisis in operating costs, the urge toward reduction of unnecessary weight has become widespread and the crusade for noise abatement is no longer to be denied, according to the author. The pneumatic-tired railroad-coach not only answers these requirements, he says, but anticipates a demand for a new traveling comfort. The desire to rubberize railroad equipment is old but much fruitless research has resulted from directing it chiefly toward solid-rubber or cushion tires. Road and rail surfaces present entirely different problems so far as the tire is concerned. No uniformity of conditions obtains on highways but rails are even and smooth. A badly aligned joint such as would wreck a metal wheel makes no impression on a pneumatic tire. As simple as the tire problem may seem, its solution represents years of courageous and skillful research on the part of the Michelin company in France.
Technical Paper

Duralumin All-Metal Airplane Construction

PSYCHOLOGY of the public, as well as engineering structure and aerodynamics, is involved in commercial aviation. The public has confidence in metal. With quantity production in view, the author and his associates considered costs of production as related to quantity and also costs of maintenance at airports and in the field, and chose metal as the material of construction. Structural members are fashioned from sheet duralumin rather than from tubes and a type of construction was evolved that can be made with the minimum investment in tools, that is cheap to put together and that can be repaired with the smallest amount of equipment and labor. For compression loads, duralumin has a great deal more strength for a given weight than has steel. It cannot be used, however, for compression members in combination with steel in tension members because of the difference in coefficient of expansion.
Technical Paper


The author quotes statistics relating to the proportion of closed to open bodies and outlines the changes that have taken place in body construction in recent years. He sketches the advances that have been made and states that the question to be answered now relates to what all this improvement in manufacturing methods has accomplished toward reducing the price of a closed-car body to the consumer. He compares the percentage of public benefit in 1922 with that of 1914, excluding the period of inflated prices immediately following the war, and states that it is 10 to 15 per cent, but says also that this is an unfair comparison because of the excessive increases in the cost of labor, lumber, sheet steel and trimming cloth. An unconventional type of body, covered entirely with fabric over a foundation of wire-mesh and buckram fastened to the conventional wood-framing, is illustrated and described in detail, together with a statement of its advantages.
Technical Paper


Stating that asphalt, brick and concrete-slab road-surfaces are the only pavements that have given satisfaction for automobile traffic, the author believes further that thus far the concrete-slab surface is the only one worthy of consideration for such traffic. He discusses the merits and demerits of these surfaces and includes an enumeration of the factors that combine to produce a thoroughly satisfactory road surface. Passing to a detailed review of the bearing value of soils and the correction of road failures, the author presents data and illustrations in substantiation of his statements and follows this with a consideration of the reinforcing of a concrete road-slab with steel.
Technical Paper


In the past the majority of trucks have been equipped with wood wheels. These gave good service, but the results demanded under strenuous modern conditions seem, the author states, to make the substitution of steel wheels on medium and heavy-duty trucks imperative. Truck engineers and builders seem to recognize the fact, but to hesitate to make the change, chiefly because a metal wheel is somewhat higher in first cost and because some designs have not as yet rendered the service expected of them. The service return of metal wheels is given from the records and reports of the London General Omnibus Co. and the Fifth Avenue Coach Co., both of which use steel wheels exclusively. The added mileage is in excess of wood-wheel service and exceptional tire mileage is shown. The author states briefly the arguments for the hollow-spoke, hollow-rim, the hollow full-flaring spoke and the integral-hub metal wheels.