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Eighteen percent nickel marage steel can be used to fabricate welded airframe structure. The weldability is excellent and the heat treatment is simple. The mechanical properties of marage steel sheet is presented at ambient and elevated temperatures. TIG welded properties are also determined. The adaptation of this alloy for use in a tubular truss weldment is discussed. The tensile, notch tensile, and compressive yield strengths are very good, but the fatigue strength is low compared to a weldable low alloy steel. Marage steel can be used to advantage for high strength, short life applications such as experimental aircraft structure.

A new family of steels, called maraging steels, is being used quite successfully as die casting dies for casting aluminum. The maraging steels were developed for high strength pressure vessel applications such as solid fuel rocket motor cases. These steels have high strength with excellent toughness. In addition, they are relatively easy to heat treat and have good dimensional stability. Repairs by welding are accomplished with relative ease.

Extensive use of mining haulage vehicles with capacities greater than 610,000 kg (120 tons) has created the need for larger front end loaders. This paper describes the design of the L-1200 LeTro-Loader, rated at 17 m3 (22 yd.3), which incorporates an electric propulsion system integrated with an implement hydraulic system.

Marathon LeTourneau’s D-800 rubber tire dozer was developed specifically to meet the high production demands associated with strip mining reclamation. The electric propulsion system (diesel engine, ac generator, wheel motors and solid state control system) design is the same as that used by the L-800, 11.5 M3 (15 yd.3), front end loader. Specific performance and design features of the various systems are discussed.

IN the first part of this paper, read at the March 3, 1938, meeting of the Baltimore Section of the Society, the author discussed the advantages of cab-over-engine trucks as compared with the engine-under-the-hood type, covering much of the same ground included in his earlier paper: “Cab-Over-Engine Trucks-Their Place in Transportation,” published on pages 421-427 of the September, 1937, S.A.E. TRANSACTIONS. At Baltimore Mr. Schon also traced the evolution of transportation by depicting examples of various forms of transportation at different stages in their development; portrayed the progress in allied industries; evaluated the uncontrollable expense increases from greater regulation, higher taxes, and increased pay-rolls; and touched upon dangerous practices and maintenance methods. In the remainder of the Baltimore Section paper, which follows in full, Mr. Schon interprets the trend of commercial-vehicle regulation in the various States, aided by tables showing 1937 changes.

A method for determining margins in conceptual-level design via probabilistic methods is described. The goal of this research is to develop a rigorous foundation for determining design margins in complex multidisciplinary systems. As an example application, the investigated method is applied to conceptual-level design of the Mars Exploration Rover (MER) cruise stage thermal control system. The method begins with identifying a set of tradable system-level parameters. Models that determine each of these tradable parameters are then created. The variables of the design are classified and assigned appropriate probability density functions. To characterize the resulting system, a Monte Carlo simulation is used. Probabilistic methods can then be used to represent uncertainties in the relevant models. Lastly, results of this simulation are combined with the risk tolerance of thermal engineers to guide in the determination of margin levels.

This research makes a new attempt to apply the activated seawater by electrolysis in the development of two-stage wet scrubber system to control the exhaust gas of large marine diesel engines. First, with using only seawater that is naturally alkaline (pH typically around 8.1), the SO2 and SO3 are absorbed by relatively high solubility compared to other components of exhaust pollutants, and PM (Particulate Matter) is removed through direct contact with sprayed seawater droplets. Besides, the electrolyzed alkaline seawater by electrolysis, which contains mainly NaOH together with alkali metal ions (i.e. Na+, Mg2+, Ca2+), is used as the absorption medium of NOx and CO2. Especially, to increase NOx absorption rate into the alkaline seawater, nitric oxide (NO) is adequately oxidized to nitrogen dioxide (NO2) in the acidic seawater, which means both volume fractions are adjusted to identical proportion.

The U. S. Marine Corps, in conjunction with the U. S. Army, is developing a marginal terrain vehicle, based on the airoll principle, to replace the M76 and Ml16 vehicles. The first phase of the XM759 development program established the overall vehicle configuration. Following approval of the basic design, detail design and pilot fabrication were developed. Initial testing was considered unsatisfactory. However, after tire modifications involving a Chevron tread design, slope climbing capability was achieved with no reduction in mobility. Extensive mobility tests have verified that the marginal terrain vehicle can negotiate the most extreme soft soil conditions.

Marine couplings are lubricated either by a continuous flow of oil, or by packing with grease. For an extended, trouble free performance, the selection of the lubricant, as well the maintenance procedures are of utmost importance. While for oil lubrication the main characteristics are viscosity and cleanliness, for grease lubrication the resistance to centrifugal separation is also a factor to be considered.

The basic reason for most marine diesel maintenance problems can be summed up briefly--lack of proper instrumentation. Preventive maintenance is the key to efficient and reliable operation of marine power plants, and this can be effected only by valuable safeguards such as torsion meters, lube pumps, proper inspection, and interpretation of consequent data. Instrumentation and inspection techniques are discussed and related to the responsibilities of both manufacturers and operators.

Briefcase-sized analyzers, originally designed for monitoring emissions from land-based smokestack gases, have been adapted to shipboard use. The results are comparable to those of much larger, rack-mounted devices used on shore, or the multiple instruments used by Lloyd's Register on shipboard. Portable monitors are particularly useful for small vessels, and have been applied to hot exhausts directly out of turbochargers, instead of the usual smokestack measurements. The test protocol evolved during this study will be useful in monitoring diesel engine exhaust emissions, before and after application of emission reduction techniques to assess their efficacy. Initial shipboard testing was conducted on three 82-ft U.S. Coast Guard Cutters (WPBs). The test protocol used was one based on the ISO 8178 procedure (1), taking into account the speeds actually used by the vessels - their operating profile.

Controlling emissions is becompping a more and more important task in the development of diesel engines. So far the most stringent emission limits are valid for landbased power plants. But today the International Maritime Organization (IMO) [1] is close to completing regulations prescribing the upper limits for nitrogen oxides (NOx) emissions from engines running on ships. The new limits are based on the rated engine speed. This paper mainly discusses the results of the research efforts made by New Sulzer Diesel Ltd to achieve the required NOx reductions. The solutions comprise both primary and secondary measures. The various primary measures aim at reducing NOx at the source - the combustion process - whereas secondary measures reduce the NOx emissions produced from the engine by exhaust aftertreatment. The results show that by the year 2000, it is expected NOx limits imposed by the IMO can be met by using well chosen primary methods that are more economical than secondary methods.

The U.S. EPA and the California Air Resources Board have adopted standards to reduce emissions from recreational marine vessels. Existing regulations focus on reducing hydrocarbons. There are no regulations on particulate emissions; particulate is expected to be reduced as a side benefit of hydrocarbon control. The goal of this study was to develop a sampling methodology to measure particulate emissions from marine outboard and personal watercraft engines. Eight marine engines of various engine technologies and power output were tested. Emissions measured in this program included hydrocarbons, carbon monoxide, oxides of nitrogen. Particulate emissions will be presented in a follow-up paper.

Through a market analysis, PETROBRAS identified an opportunity to launch a new product dedicated to diesel boats market. This paper describes the activities performed by PETROBRAS research center (CENPES) during the new diesel development: new or improved methodologies to ensure reliable comparative performance, fuel consumption and smoke emissions analysis, with appropriate precision to elucidate differences between the new fuel and the conventional marine diesel. Performance tests were conducted by using radar monitoring. For fuel consumption, constant engine speed tests were made, with fuel flow measurement and acquisition. Smoke tests were performed using a total flow smokemeter, installed directly on the exhaust gas pipe. Results showed that, because of its special characteristics, the new diesel allows performance gains up to 6% and smoke emissions reduction up to 83%. Fuel consumption remains in the same level of regular marine diesel.

In spite of the apparent simplicity of marine propellers, their selection for small craft is complicated because of the possible interactions of numerous pertinent variables. It is not the intent of this paper to discuss propeller design, but rather to present procedures for selecting the most efficient propeller commercially available. A secondary objective is to point out the importance of gear reduction and its effect on propeller efficiency. To achieve these objectives, this paper will discuss those variables which must be considered in determining propeller dimensions and the modifications of these dimensions necessary for satisfactory performance under cavitating conditions.

As a designer and licensor of both two-stroke crosshead and medium speed trunk piston diesel engines, MAN B&W offers the industry engines in the power range from approx. 600 HP up to some 64,000 HP per unit. Whereas the four-stroke engine programme embodies engines with power outputs of up to some 19,000 HP per unit, the two-stroke programme starts at approx. 2000 HP per unit giving a considerable overlap in the medium power range so as to enhance the application possibilities. Over the years the distribution on two-stroke and four-stroke engine production has been fairly constant, whether counted as a whole or for MAN B&W engines only. This paper will, in particular, discuss the ongoing development and application potential of the MC-range of two-stroke engines which were introduced in 1982, and which have proved to be our Company's most successful engine programme so far, both in respect to engine sales and actual experience.

In the last four of the past twenty-eight year history of marine propulsion gas turbine engines, their numbers have doubled. Specific types of gas turbine engines in certain areas of compatibility with both military and commercial vessel power plant design have become recognized as being well beyond the prototype stage. The appearance of the establishment of some application trends and niches is described and rationalized from the technical and historical/statistical viewpoints. Demonstrated Engineering, Economic and Operational advantages are presented with emphasis in the large commercial marine services.

It is the responsibility of the boating industry to make certain that its marine products are designed and manufactured to operate safely and under almost all conceivable conditions. It is also the industry's responsibility to educate boat operators and the general public in common sense boating practices. However, in attempting to improve boating's safety record, it must be remembered that in the final analysis if the boat operator does not use good judgment or comply with the law, then all the engineering improvements, educational programs, and efficient law enforcement will not prevent boating accidents.