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This paper provides an overview of the current state of knowledge on medium and heavy truck safety and reviews the results of truck safety research sponsored by the Motor Vehicle Manufacturers Association. A number of issues have been raised about the accident experience of trucks, and the injuries and fatalities sustained by occupants. The diverse viewpoints and perceptions which exist on the reasons for these accidents and what countermeasures should be taken are reviewed. The evolutionary nature of truck accident research is presented, pointing out that sufficient detailed accident and injury data are lacking. Corresponding information on truck configuration, size, weight and exposure data remain inadequate. The role of the vehicle, driver, and highway environment in accident causation must be known and methods to achieve this goal are examined. Despite these limitations, there is progress in understanding the causes of truck accidents.

From various sources of information it is clear that truck noise is a definite public nuisance. Early noise control efforts were very productive in that many heavy duty trucks did not have mufflers, and the addition of this device made clear improvements. Further improvement requires treatment of many sources significant to the overall level. It is felt that today's “tight but attainable” 88 dBA for heavy trucks can reduce to 86 dBA by 1975 and 8k dBA by 1978 with a lot of hard work. There is promise for meaningful noise regulation in the “real world” as indicated by “calibratability” of non-standard sites.

DURING the period between the two World Wars the track-type vehicle was stimulated into a position of prime importance both in military and civilian applications. This paper reviews the vast strides made in the design of tracks and suspensions, which in turn have led to higher road speed and more efficient utilization of power. However, with the increase of speed, the importance of controllability and power transmission becomes more evident, necessitating careful consideration of the problems of steering mechanism design. The author describes an ideal system which, when and if designed would undoubtedly be universally adopted. But only those who have attempted to come to grips with the problem in a practical manner realize that the final solution will not be a simple one. The present result is that there are almost as many steering systems as there are different types of vehicles. The many reasons leading to such wide-range developments are covered in this paper.

The Vehicle Maintenance Reporting Standards of the American Trucking Associations can be used by manufacturers to improve heavy-duty vehicles. After verifying the accuracy and significance of the data the manufacturing, engineering, technical service and marketing departments can all use the information to improve vehicles and provide better service to the user.

THIS paper outlines the advantages and disadvantages of present-day hydraulic systems. Included in the discussion are: the blocked return line system for single-acting cylinders, the blocked pump inlet, and the basic open-center-valve system. More advanced designs mentioned are: open-center-valve systems with cylinders in series and with parallel cylinders, close-centered valve systems with pressure regulator, and the central hydraulic and accumulator systems. The author points out that the advantages and disadvantages of each system depend to a great extent upon the design in which it is used.

Field performance of tractors with various transmission designs can be determined and compared under identical test conditions. A relatively simple mathematical model of the tractor and implement system provides information like productivity in acres per hour and fuel consumption in gallons per hour. The program provides information for management decision without the costly, time-consuming activity of designing, building, and testing each prototype.

The addition of the radiotracer method of wear measurement to the tools available to the development engineer is a great aid, but not a pancea. Its use in conjunction with the conventional approaches can expedite development testing. If the test techniques are properly selected and combined, the ultimate answer can be partially predicted, alternatives screened, and backup engine tests made in a smooth flowing test sequence. Data from two unrelated product development programs are given as illustration. Indications are that piston ring wear predictability can be measurably improved.

Discussed are two high-speed, 4-cycle, turbocharged, compact, lightweight engines recently introduced by International Harvester. These new diesels were designed to meet the requirements of a wide variety of applications ranging from mobile to fixed installations. An analysis is made of the design features and experimental test results of the DVT-573 and DT-429 engines.

A study to define accurately and discover new parameters of productivity for the contractor has resulted in a new design concept in off-highway trucks. This new concept has been first applied in the International Model 180 Payhauler, a rear dump vehicle of 45 ton rated capacity. The function and form criteria are discussed by components and systems in terms of the complete vehicle and on the job applications.

Application of the hydrostatic transmission to a farm and light industrial tractor involved many special design and manufacturing considerations. A brief description of the transmission is given, and some of the special considerations along with their solutions are discussed. Emphasis is placed on the importance of having the proper control system to provide desirable performance and endurance characteristic for the tractor. Because the controls of a hydrostatic by necessity are quite different than for a conventional tractor, particular emphasis is placed on the control portion of the overall development program.

A semirational method is developed for predicting steady-state power, smoke, exhaust temperature, and turbocharger speed of diesel engines (naturally aspirated (NA), turbocharged or turbo-intercooled) over a range of ambient conditions at constant fuel rate and engine speed. The equations are shown and prediction calculations can be performed on a slide rule. The basic assumptions, derivations, and a comparison of calculated predictions with test data are presented. A method of including the effect of fuel temperature on engine power is also given. The derivations and fundamental approach have been detailed in Appendixes B and C to assist other investigators. The addition of other factors not included by the authors may improve the accuracy or extend the useful range of the prediction equations.

Prior to World War II, most heavy duty highway trucks and tractors were built as Conventionals, i. e., with the cab mounted behind the engine. In the late 1940's cab-over-engine types gained acceptance and in the 1950's the tilt cab COE was developed in its present form including sleeper cabs. The new concept is to combine the best features of conventionals and tilt cab COEs to develop a superior non-sleeper tractor that makes no compromises for sleeper cab types.

THE NEW DIESEL ENGINES developed recently by International Harvester are adaptations of existing carbureted truck engines. The manufacturing economies possible by employing existing machine tools were the governing consideration in their design. This paper discusses solutions found to the many problems presented by this approach to engine design: crankshaft, crankcase, connecting rods, pistons, lubricating system, and the like. Extensive interchangeability of parts was a result of the design concept. The engines have been successfully adapted to farm tractors, crawler tractors, stationary motors, and various automotive applications.*

INDUCTION heating, the authors show, has been successfully applied to the hardening of many types of gears. Over a million transmission gears have been produced with its aid and thousands of induction-hardened final-drive gears and pinions are giving satisfactory field service. It has resulted in lower costs (due to the substitution of carbon for alloy steel, fewer machining operations, and lower heat-treating costs) and improved quality (due to a lack of distortion and better stress distribution). The first part of this paper, by Mr. Kincaid, covers the equipment and methods used in handling various gear jobs. Then Mr. Knowlton covers the engineering tests and service performance of various types of induction-hardened gears.

Splash and spray conditions created by tractor-trailer combinations operating on the Federal highway system have been studied and tested for many years with mixed results. Past events are reviewed briefly in this paper. In additional testing during 1983, using new state-of- the-art splash/spray suppressant devices, some encouragement was provided that these devices could work. The 1984 Motor Vehicle Manufacturers Association (MVMA) test program was designed to develop practicable and reliable test procedures to measure effectiveness of splash and spray reduction methods applied to tractor-trailer combination vehicles. Over 40 different combinations of splash/spray suppression devices on five different tractors and three van trailer types were tested. The spray-cloud densities for some 400 test runs were measured by laser transmissometers and also recorded by still photography, motion pictures, and videotape. On-site observers made subjective ratings of spray density.