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The military requirement for a lightweight, air-cooled compression ignition engine family having two members, specifically 10 and 20 hp versions at the rated speed of 3600 rpm, is discussed in this paper. Design and preliminary development programs for such an engine family have been completed, and specifics are related. Development of a practical combustion system for the high rated speed was found to be feasible and is demonstrated on the basis of test data. Endurance data to date indicate that the design life of 6000 h between major overhauls will be attainable. The plan for the future includes additional testing of updated prototype engines as well as further investigations in the areas of noise reduction and control of harmful exhaust emissions.

The procedures used by Twin Disc in the design and application of a combined torque converter-powershift transmission system are described. In conjunction with digital computers, these procedures provide data on specific power train proposals which are then compared with known values of acceptable and unacceptable data for clutch design, vehicle acceleration, deceleration, jerk, and vehicle response.

Circumstances and results of tests of a three-chambered REDSOD built for attachment to a Caterpillar D9 tractor are discussed. The Caterpillar D9 tractor was chosen for its drawbar capability of 4000 lb/ft of width, bare weight of approximately 70,000 lb, and 10 ft width. Tests in straight trenching operations were performed at two sites: one in an area with a clay overburden, the other in sand. From the data presented, it is concluded that a REDSOD machine, with a 1200 ft3 min air compressor, handled by a skilled operator, can produce a 2 ft deep trench at approximately 2000 yd3/h. The noise level is not damaging to operator or adjacent structures or personnel. The use of higher air pressures increases production rates. The recoil produced by REDSOD has no appreciable effect on production rate or tractor reliability.

This paper describes the new 3000 Series MK II engines and their application in the Allis-Chalmers 7030 and 7050 farm tractors. This includes performance, reliability, noise reduction, and economy of operation to meet the environmental and performance specifications established for these farm tractors. Improvements were made to the cylinder block, cylinder sleeve, piston and ring, crankshaft and flywheel, water and oil pumps, cylinder head, exhaust manifold, lube oil cooler and filters, and intercooler and turbocharger (depending on the engine model). Endurance tests at full speed over fueling, load cycle testing, and field testing were conducted.

The major problems and some of their solutions in the application of pneumatic tires, principally off-road tires, to vehicular equipment are explored. Variables attributed to the user's operation, his equipment, and the off-road tires are considered in detail. Topics of standardization, abuse, mobility, and ton-mile-per-hour are included. Also discussed is the industry's need for a common vocabulary.

A system has been developed which fragments rock by high-pressure gas discharges near the point of ripper penetration of a rock formation. From development tests, it was demonstrated that the system markedly extends the rock fracturing performance of a D7 Caterpillar tractor. The paper is divided into three basic sections. First, a summary of the mathematical analyses and model testing of rock fracturing is presented. Next, the hardware design and development necessary to adapt the FARE principle to rock-ripping requirements is described. Finally, the results and evaluations of tests conducted at various limestone rock test sites are described.

Advances in digital computer technology have brought the application of on-line digital control systems to bear on the problem of exhaust gas pollution from the internal combustion engine. One application, adaptive digital control of fuel consumption based on a feedback of an analysis of exhaust gases, is explained. A small gasoline engine is modified with a fuel injection system, thus the engine, digital computer, and gas analyzer interface is developed. The engine's exhaust pollutants, based on real time operating conditions, are minimized while performance is retained. The delay time limitations experienced by the feedback transducer are demonstrated by a transient mode of operation. The relevance of this investigation and some future applications are discussed.

The emission characteristics of small industrial engines have not been as thoroughly documented as those used in vehicular applications. This paper presents emission data obtained for a variety of engines, under 120 hp, primarily used for Army field power generation. A more limited presentation concerns the effects of fuel composition on emissions. In general, the emissions from gasoline engines used in generator set applications are much higher than they would be in other uses. They are operated on the rich side to enable rapid response to load transients. Emission variability from engine to engine appears to mask out any major trends with engine size that might be observed. This variability as well as variance in test replication also masks out any changes that might be observed as a result of varying fuel composition.

To insure that all components of new design haulage vehicles can function to produce the daily work requirement, it is necessary to consider the specification limits of these parts. Tires have a specification limit called ton-mile/hour (tmph). The use of this tmph tool as well as the Tire & Rim Association load tables, in the initial design of new vehicles, is important to make sure that the tire's structural limits are not exceeded. The use of job tmph requirements in the field as a basis for tire selection will make certain that downtime due to tire heat problems will be minimal. There are limits in both load and speed for the use of the tmph concept which must be considered as well as the conditions of ambient temperature. The SAE has recognized the use of tmph ratings, and will publish tire test standards and recommendations in the SAE Handbook.

Allis-Chalmers has introduced a new family of tractors for 1973 in the 130-155 hp (96-116 kW) class. The unique design and development aspects are presented for the entire power train system - Power Director transmission, range transmission, park lock, differential and differential lock, brakes, final drive, and independent PTO. Durability, performance, low noise emission, safety, and convenience of operation were the key objectives.

A new and unique load-sensitive hydraulic system is now available on the new Allis-Chalmers Models 7030 and 7050 agricultural tractors. Although the system is considered very efficient and effective by experts, use of the system has been limited in the mobile equipment industry. This paper highlights the application of the load-sensitive circuit in the A-C 7030-7050 tractors. The circuit combines the advantages of the two basic types of systems used in tractors-fixed flow (open-center) and variable flow (constant-pressure, closed-center)-and avoids their major disadvantages.

Durability of planetary final drive gearsets for use in large agricultural tractors can be enhanced by modifying gear tooth profiles, adding sufficient rigidity to the system, and floating at least one of the members. Properly applied to the design, these procedures may also reduce the need for close manufacturing tolerances Their application was instrumental in providing a successful planetary final drive design for the Allis-Chalmers Models 7030 and 7050 agricultural tractors.

In an attempt to characterize emissions from small air-cooled utility engines, five gasoline-fueled models were operated over a variety of speeds and loads, and important exhaust constituents were measured. These emissions included hydrocarbons, CO, CO2, NO, O2, aldehydes, light hydrocarbons, particulates, and smoke. Emissions of SOx were estimated on the basis of the fuel consumed; evaporative losses of hydrocarbons were also estimated. The impact of small engine emissions was calculated on the basis of the test results and information on national engine populations and usage. From these data, it appears that the 50 million or more small engines currently being used account for only a small part of pollutants from all sources.

Satisfactory control of fluid power system noise is dependent upon accurate knowledge of component noise levels. One component which contributes to the total system noise level is the hydraulic pump. There are test methods available for measuring and reporting airborne pump noise. However, these test methods need to be carefully examined to insure that proper constraints are placed on the various hydraulic and mechanical factors which affect the accurate measurement of pump airborne noise. This paper describes the major hydraulic and mechanical factors that affect the measurement of pump airborne noise. Experimental data are presented to illustrate the variation that can result due to such factors as the pump mount, fluid lines, and the drive shaft. Techniques for reducing the variation due to these factors are presented for the reader's consideration.

Discussion and author closures on Viscometry and its Applications to Automotive Lubricants provides a supplement to SAE SP-382 which included all papers presented at the ASTM-SAE Symposium during the National Automotive Engineering Meeting held in Detroit, Michigan, May 14-18, 1973. The format of this paper follows that of the Symposium which was divided into two sessions: Effects of Low Temperature and Shear Rates on Lubrication, and Effects of High Shear Rates on Lubrication.

An aircraft maintenance program can be one of the most valuable economic tools available to a commercial air transport operator. It is the area that offers management the most opportunities to control costs. Current commercial aircraft design plus recent regulatory changes have combined to place an increasing burden on management, accompanied by the potential for an increasing economic return.

A program has been undertaken to develop new airfoil sections suitable for general aviation aircraft, utilizing theoretical and experimental advanced technology developed in recent years primarily for subsonic jet transport and military aircraft. The airfoil development program is one component of the Advanced Technology Light Twin (ATLIT) program sponsored by NASA Langley Research Center. Two-dimensional tests of a new airfoil at NASA and Wichita State University have demonstrated high cruising performance over a fairly wide C1 range, and a C1max value of 3.69 with Fowler flap and no leading-edge devices. Experimental and theoretical development of additional configurations is under way.

A totally integrated design-to-cost program was undertaken at Westinghouse to derive a basic, standardized line of spray oil-cooled generators having optimized performance and maximum reliability over a wide range of output ratings and customer applications. The development of the spray cooled generators resulted in unique design configurations that also warranted development of new manufacturing facilities.

An overview of avionics maintainability, as indicated from airline operating statistics, shows improvement in some elements and degradation in others, but a slowly degrading overall trend. Maintainability elements and trends are identified and discussed. Principal problems are the shop labor expended for the high proportion of removed equipment found to be in satisfactory condition, and the increasing line maintenance effort required by wide-body aircraft. Built-in test equipment (BITE) or monitoring within the system, if properly designed, appears to be a good approach to improve this situation. Design guidance for effective BITE or monitoring objectives is provided.

The question has been asked whether the airline industry is gaining or losing in the design of new aircraft for maintainability. The Lockheed L-1011 aircraft is examined by an operator resulting in two answers: yes-for routine maintenance; and no-for nonroutine maintenance. Areas for investigation for further improvement, particularly in the wide-body aircraft, include the care of passenger cabin and associated appliances and amenities. The airlines have increased interior maintenance by brightening up the interiors-trading dark colors, which do not show abuse, for the lighter, more attractive colors. The same principles and criteria need to be applied to cabin interior design as have been used to develop the reliable structures, systems, and powerplants now in operation.