Search Results

Acoustic emission technology has developed to the state where broad applications to materials testing and evaluation are evident. The unique characteristics of acoustic emission as they bear on applicability to nondestructive testing are emphasized. Among the advantages anticipated for the acoustic emission method, two are especially noteworthy: 1. Moving inspection upstream in the production process so that bad production can be eliminated before large fabrication and assembly costs are accumulated. 2. Economical 100% NDT inspection of finished components or products.

The record of the nation's cities in implementing plans for significant changes in their public transportation systems is strikingly poor. However, there is substantial evidence to suggest that all the important pieces necessary for major programs are available. This paper covers forces of change in urban transport development-sources of financing, institutional arrangements and their impact on decisionmaking; also discussed is urban transportation technology-options for the future, and transit implementation projects in cities.

This paper deals with a new concept of transportation system development based on well-established psychophysical principles. It reviews briefly the traditional method of transportation system development and modification. The point is made that it now becomes necessary to reverse the usual trend of declining public transportation system usage. The “new philosophy” of system development utilizing user-oriented techniques in the form of attitude surveys is presented as a possible aid in enhancing public transit use. As an exemplar to illustrate four techniques (paired comparison, semantic scaling, branch-and-bounds interview, and document attitude analysis) the methods and some representative data of General Motors Research Laboratories' Transportation Research Department case study of a door-to-door (demand-actuated) public transportation system are discussed.

The evaluation of new friction materials at Caterpillar includes small scale, full scale, and field tests. These tests and the equipment used for them are discussed, as well as the philosophy behind the program. The quality assurance of production materials, the equipment used, and the tests run are directed at measuring the performance of incoming materials to be sure they meet our standards. New tools being developed to improve the program are described.

The kind of powder selected for use in the P/M forging process depends on the requirements of the finished part. Most of the commercially available P/M powders can be used to make parts by P/M forging, and a majority of these applications do not require properties as high as those achieved by conventional forging. However, the most likely candidate for use in manufacturing parts that require the properties of conventional forgings is atomized low-alloy steel powder. When processed correctly, parts made from the atomized powders will duplicate the microstructure and hence the mechanical properties of conventional wrought steels. Initial interest in alloys centered around the nickel-molybdenum steels (AISI 4600). However, because of economic factors there has been a shift to alloys leaner in nickel and to those that contain the less expensive elements such as manganese and chromium.

Gylon is a proprietary family of filled fluorocarbons that are the new, high-speed, high-performance friction materials of now and the future. The energy absorption, life, and power transmission capabilities it contributes to heavy-duty, wet clutches in both over-the-road and off-the-road vehicles have been demonstrated to be markedly superior to those of metallic and semimetallic friction materials currently available. Gylon friction material is providing substantive commercial solutions for current problem clutches as well as for new-generation, high-speed clutches now on the drawing board.

Application of the powder or particle metallurgical (P/M) method to the production of high-speed tool steels is an effective means of controlling segregation problems. Macro- and microsegregation are virtually eliminated. The characteristics of carbides in the microstructure are appreciably changed; this has important effects on the pertinent properties. The P/M high-speed steel products offer significant advantages in the manufacture and performance of tools. The advantages include superior grindability, machinability, size change uniformity, cross-sectional hardness uniformity, hardening response, and tool life under intermittent cutting conditions. The observed property and performance advantages are rationalized in terms of the rapid solidification rate inherent in powder making, as well as in terms of basic microstructural characteristics of the P/M products.

During design, development, and testing, the engineer is continually confronted with the task of transforming a large volume of freshly gathered, undigested data into a meaningful representation of “what's going on.” This paper discusses several types of analyses that have proved to be both useful and flexible. The necessary data processing tools, also described, vary in complexity from a desk calculator system to a large computer system.

This paper discusses the use of powder metallurgy to produce gas turbine components. Various methods of manufacture are mentioned, with particular emphasis on hot isostatic pressing. Because rippling, buckling, and similar problems are associated with HIP, the use of glass or vitreous containers was attempted and found very satisfactory. The use of Astrology, Inco 718, IN-100, and Rene 95 in this technique is described. The success of these alloys, the wide shape flexibility, and the wide operating temperature range prompt the authors to feel many materials can be produced by this process.

Demands for quick, sure answers to field problems; shorter development times; an ever-increasing amount of social and political pressures; and increasing foreign competition present a tremendous challenge to construction equipment engineers. To meet this challenge, we must economize by more fully and effectively using developed technology. One area where considerable improvement can be made is in obtaining and utilizing recorded instrumented data. This paper first discusses the types of instrumentation that are being used to record data; then gives practical examples of how the data can be used in establishing loadings for full-scale structural fatigue testing and laboratory component testing, or in establishing test courses for complete vehicles. Emphasis is placed on the team effort required to obtain, analyze, and use recorded data successfully for vehicle development.

The paper provides mechanical and performance specifications for a giant 650 PS bulldozer and cites the outstanding features of this machine. The new bulldozer offers improvements in dozing, ripping, and pushing. It has an electropneumatic system employing solenoid valves and air cylinders, and it can be controlled by radio for unmanned operation in dangerous sites.

The development of an innovative electric transport vehicle of self-supporting plastic sandwich construction (FRP/PUR sandwich) is described. The specific advantages inherent in this plastics technology as applied to electric transport vehicles are illustrated. A short survey of the production technology as well as of the materials behavior is given. The propulsion and control concept in addition to the design of the source of energy are clarified. The test results obtained with the prototype, undergoing testing since one year, are given, and an automated data processing system for evaluating the test results described. The battery change technique is outlined and the important features discussed. Vehicle and operating costs of the innovative electric transport vehicle are indicated in brief.

A recently introduced Japanese electric light truck, the Daihatsu S-37, is described. Its dimensions are: length 9.84, width 4.25, and height 4.25 ft. The truck's maximum speed is 40 mph. The driving range per charge with a payload of 450 lb and two persons is 40-50 miles. The vehicle contains a series-wound traction motor of 10 hp peak power rating, an SCR chopper speed control unit, and six 12 V batteries of 150 AH capacity. In Japan many Daihatsu S-37 vehicles are in commercial use as delivery trucks for milk and other goods and have acquired a good reputation.

The development of modern heavy earthmoving equipment requires up-to-date laboratory facilities employing current computer technology to aid test engineers in acquiring, reducing, and analyzing laboratory test data. This paper describes one manufacturer's approach to the problem. Included are descriptions of the laboratory data area, signal flow, computer hardware, and computer programs to implement the system.

Analysis of used lubricating oil for products of wear can indicate the mechanical condition of engines, transmissions, final drives, and hydraulic systems. Laboratory equipment is available and techniques have been developed which allow the servicing dealer to perform this analysis in the field. Test results can also be interpreted by the servicing dealer. The time lag between sampling and reporting is reduced, and the servicing dealer can utilize guide lines available from the manufacturer while taking full advantage of familiarity with machine history and local operating conditions. Maximum results are achieved only when sampling is done on a continuing basis.

This paper describes the design of the Ford gas turbine engine. The discussion includes basic design parameters, mechanical arrangement, functional and material requirements, and the aerodynamic and mechanical design of the major components and associated systems. Component and engine test results are discussed briefly, together with some of the major problems encountered and their solutions.

Oil analysis is a maintenance tool that shows great promise in the construction and aggregate industries. Properly administered, it can save the user much money through reduced maintenance costs and improved machine availability. The paper describes an analysis program based on the reporting of periodic samplings taken in order to determine the presence of contaminants in the lubricants of various compartments of heavy-duty equipment. Locations of excessive wear can also be identified. When the oil sample program is operational, a monitor maintenance program serves to let the customer recognize and treat minor problems before they become major problems. Preliminary statistics are cited, indicating the new program's performance to date, and difficulties encountered are noted.

The Wabco Model 150-B mining truck was announced in late 1970, and during 1971, over 40 of them were delivered to various customers in this hemisphere. It employs various powerplants up to 1600 hp, which gives it a very favorable horsepower-to-weight ratio for vehicles in this size category. The 36 X 51 in tires provided are more than adequate for this vehicle, as the low air pressure at which these tires can be operated minimizes tire failures from road obstructions and provides extremely long life. The d-c drive system recently developed by General Electric for vehicles of this size class utilizes operational principles and design features that were successfully employed in smaller drive systems of this type, currently installed in over 1300 vehicles with engines up to 1000 hp. This paper describes the features of construction of this vehicle and the unique attributes of the pneumatic and hydraulic system.

The need for a compact, lightweight rear dump truck of large capacity has generated a new concept in the 200 ton class truck market. The dimensions of the load-carrying body and tires for the given capacity were set forth at the basic parameters inside of which the structure of the truck was to be accommodated. Recent development of an exceptionally small 7500 lb, 1850 hp, gas turbine-alternator package permits ideal amidship installation of the powerplant. Dual tires on the front and rear axles gives low body loading height and 50-50 weight distribution, both empty and loaded. Electric motors allow simple, convenient drive to all wheels for 100% traction capability in propulsion and dynamic braking.

The introduction of the gas turbine engine into automotive transport will depend, to some extent, on the achievement of an efficient working cycle. Implicit in this requirement is the operation of the turbine at inlet temperatures in excess of 1500 K where metallic alloys have insufficient strength and corrosion resistance. Of the ceramic materials being considered for this environment, silicon nitride is the most attractive because of its low coefficient of thermal expansion, good thermal shock resistance, and high strength at these temperatures. The techniques and processes used in the production of reaction-bonded and hot-pressed silicon nitride are sufficiently advanced to enable predictions of material costs to be made. Consistent material is now available with well-established physical properties and having potential for further development.