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This paper is a brief survey of the various methods in existence today for weighing heavy earthmoving construction equipment. Also considered are the problems, solutions of problems, and practices involved in the weighing of heavy construction equipment; and the progress made by LeTourneau-Westinghouse Co. in field weighing techniques.

The four-wheel brake system with separate parking brake was made available as standard equipment on the Chevrolet Corvette. This new system developed by Chevrolet and Delco Moraine meets specific sports car requirements such as increasing total braking effectiveness, giving more stopping power, and improving vehicle control through increased braking feel. The disc brake gives virtual fade free performance which is achieved through use of a ventilated disc which dissipates heat rapidly and keeps brake linings within their working temperature range. Intensive proving ground and road tests, as discussed in this paper, prove the overall performance of the disc brake system.

A brief review of the two classes of plastics, thermoplastic and thermo-setting resins, is presented. The physical and chemical properties of each class are described, and respective molding techniques detailed. Plastics in combination with metals are discussed, and production examples of this combination are described and illustrated.

The haulage cycle as a factor in successful operation of a mining property is described. At Kennecott a change over was made from rail to truck haulage as the best means for over burden removal. Factors determining efficient utilization of equipment in a haulage operation such as tonnage to be moved, grade and length of hauls, equipment capacity, maintenance, and weather conditions were evaluated. The method whereby computers were used to analyze these variables and to provide guide lines for optimum utilization of equipment is presented.

When properly designed and produced by the best known techniques, products made of Fiberglas Reinforced plastic (FRP)* offer performance features superior to metals, wood and non-reinforced plastic, and at a cost per unit of value less than that of other materials. The authors report on the nature of reinforced plastics, some successful applications in general in transportation equipment and specifically in earth moving equipment. In addition, the authors report on recently completed process studies which are best suited for the unit volumes existent in earth moving equipment. The report is concluded by outlining structural analysis and prototype activity planned for the near future.

The forces of interaction between smooth silica surfaces in contact has been investigated in order to contribute to an understanding of soil behavior in the lunar environment. The normal cohesion between two fused silica spheres (0.1 cm diameter) was measured under ultra-high vaccum conditions (10−9 torr) and in the presence of water vapor (10−9 to 18 torr). The values obtained (5-25 dynes) are essentially independent of the environmental conditions and may be accounted for in terms of the van der Waals “body” forces. In the absence of physically adsorbed water the force required to separate two smooth fused silica spheres in tangential contact is significantly higher than the normal cohesion. The formation of chemical bonds across the unprotected contact interface as a result of micro-sliding is suggested by this observation.

In 1964, at the request of the Federal Aviation Agency, an Ad Hoc Group on Aviation Fuel Safety was organized by the Coordinating Research Council, Inc. This Group assembled and reviewed the technical information available concerning the safe handling and usage of aviation gasolines, jet A (kerosene), and jet B (JP-4), which are currently used as commercial aviation fuels. After reviewing the available information, the consensus of the Ad Hoc Group was that, while there are differences among the fuels, adoption of a single type of aviation turbine fuel by the entire industry would not significantly improve the overall excellent safety record of commercial aviation, and that safety is more a function of equipment design, proper handling techniques, and rigorous precautions than of the particular fuel type employed.

The new 82% low section height passenger tire has been developed to attain the tire performance and durability requirements of present day automobiles. A new tire mold shape had to be devised to obtain an improved inflated tire flatness that had been difficult to accomplish in previous attempts to design low section height tires. With this development it was then possible to take advantage of inherent features such as stability and handling, high speed capability, power consumption, and brake clearance. Additional improvements were found in tire tread wear, traction, and tire uniformity.

The Ford 705, 600hp, supercharged gas turbine is utilized to maximum advantage in the super-transport truck. This power package meets the requirements of power, fuel economy, noise level, and minimum package size for a successful vehicle installation. A detailed description of the component and engine development is covered in this paper. Rig test, dynamometer, and chassis engine performance is discussed. The application of the Ford 705 supercharged gas turbine engine to the super-transport type vehicle is unique. Experience in successful cross-country operation of the vehicle confirms the selection of the powerplant for this type of service.

Trucking in countries around the world are in various stages of development and fleet operation and maintenance practices vary with the conditions in the individual countries. Extreme conditions of temperature, altitude, dust, humidity, and in the quality of service available influence the equipment and accessories necessary for operation in different countries. The heavy duty American truck has earned an excellent acceptance in rugged work but flexibility of production is necessary to provide the accessories required for unusual operating conditions. Examples of the service facilities of both the end users and the Cummins distributors in selected countries are included in the paper.

The structural designer of automotive components often is faced with a problem of paint application for which paint technology has not provided solutions. Hence he must solve his problem by changes in his design rather than by using an applicable painting system. The electrocoating system described in this paper clearly allows the designer greater latitude because it provides greater protection for inaccessible or severely exposed components. Moreover, it provides more uniform coatings than can be obtained by older methods.

General design philosophy and development stages are reviewed and related to the PT6 turboprop/turboshaft engine. Specific examples of problem areas encountered in field operation are given which have led to further development of the engine and its systems. An outline of current engine installations and the production program is given.

The large scale slush hydrogen facility at Wright Patterson Air Force Base is the largest of its kind in the Country. The purpose of the facility is to simulate operational scale equipment while maintaining the flexibility of small scale research apparatus. Although, ideally, this is impossible, various compromises in design have allowed for a generous portion of both to be achieved. The discussion, herein, will describe the equipment in the Air Force facility, the use of the equipment and some equipment design considerations based on small scale observations. Before going further it should be stated that the program is a joint Air Force-NASA effort with Air Force personnel conducting the research. The purpose of this joint project is to obtain as much information as possible on the handling characteristics of slush hydrogen. The information will then be integrated into functional and future design considerations for hydrogen using vehicles.

The parameters governing the leakage rate across metal-to-metal and metal gasketed seals are discussed qualitatively and quantitatively based on experimental evidence. The sensitivity of the sealing phenomenon to the surface finish of the mating components is illustrated. The results of several experiments in which flat annular sealing surfaces of both 347 stainless steel and 2024 aluminum were mated together, either directly or with intermediate flat annular gaskets of indium, lead, aluminum, copper, or nickel are presented. It is concluded in this paper that, in order to ignore the surface finish as a parameter in the design of a fluid connector (or the quality control of the surface finish), the normally applied stress to effect sealing must be approximately 2.75 times the yield strength of the weaker material in the system. For surfaces controlled, both in asperity magnitude and direction, the required stress level may be considerably less.

The hydrofluorocarbon elastomers have been a bright spot in recent elastomer technology, particularly in the area of high temperature hydraulic seals. However, significant limitations have existed: poor low temperature characteristics, and poor compression set at elevated temperatures. This latter deficiency severely limits the usefulness of these materials as seals at temperatures well below their thermal capabilities. The paper is concerned with presenting the latest advances in the experimental compounding directed toward improving the compression set of these elastomers. Compound recipes for low compression set and the data for short and long term aging at room temperatures and 400°F will be presented.

This discussion reviews connector design considerations including load conditions, thermal reactions, metallurgical compatability, design restrictions for both flanges and seals. A basic design approach is then set forth indicating the most effective way to meet the conditions existing for various common connector applications in today's aerospace industry. Sample hypothetical design requirements are solved by using formulae and a nomograph. The data contained herein has not been published previously nor has it been rejected by any other national conference. It is not being processed for publication elsewhere.

The search to improve the operational life of fluid power servosystems has led to a better understanding of the conditions which cause degradation of performance. A principal factor involved is the dimensional stability of the critical elements within the servovalve itself. A combination of the application of all-fluid techniques with that of superior materials offers promise. This paper discusses work accomplished in the application of tungsten-carbide to critical metering elements in a servovalve. Laboratory tests indicate an improvement of better than 50 times the life of conventional materials. The application of all-fluid techniques mitigates the critical nature of mechanical elements within the valve. A discussion of a closed loop all-fluid servo is presented.

In many applications, control system equations are being processed in a digital computer. Digital-to-analog (D/A) converters are then used to make command signals compatible with analog final control elements. It is more desirable to design a highly integrated system which uses a digital servo and does not require D/A conversion. However, digital hydraulic servo valves have not yet been highly developed, and some types are quite complex. It was the object of this program to design a hydraulic digital servo which uses the standard, proven two-stage electrohydraulic servo valve. This was done by having the servo valve itself perform the function of a D/A converter. It accepts digital signals in computer format and quantizes actuator velocity. Initial design studies were performed, followed by analog and digital computer studies. A breadboard unit was built and evaluated. Two main conclusions have thus far been reached: 1.

This paper presents a recent development in single-stage servovalve design. The new concept offers unique performance capabilities which overcome some of the serious shortcomings of conventional single-stage servovalves. In addition to the physical description of the new design, a performance comparison is made with existing single-stage and two-stage servovalves. Emphasized in this comparison are closed-loop system accuracy and hydraulic power utilization; performance areas where conventional single-stage valves have been notoriously deficient. Hydraulic flow forces acting on a nozzle-flapper valve are utilized to advantage in the new design. A section of this paper discusses these forces and presents empirical data on typical servovalve configurations.

The new type of fluid device described in this paper is closely analogous to a vacuum tube cathode follower amplifier. It provides an output pressure equal to an input control pressure, but with a high input impedance and low output impedance providing a power gain. A string of balls moving in response to pressures acting on the ball surfaces provides the basic valve action. Because of its structure and the use of balls as the control elements, this device is relatively easy to manufacture, does not require a lubricating fluid and can be operated at high temperatures.