Search Results

The Army has an ever-increasing need for electric power units, the most important capability of which is silent operation. In addition multifuel operation, light weight, remote operation, and versatility are required. This paper describes the development of three such units (10, 20, and 30 amp) which are expected to fill this need. The units are about 3.5% efficient, but improved thermoelectric materials are expected to improve this figure. The units run on gasoline, diesel, JP-4, JP-5, and fuel oil at temperatures of −25 to 125 F and altitudes of 8000 ft with a voltage of 28 V d-c. The units range in weight 25–50 lb.

The basic concepts involved in a technically correct reproduction of the charging system of a vehicle are reviewed. Simplified techniques and procedures are explained for measuring the customary battery variables plus others such as composition and evolution rates of the battery gases as a function of time, temperature, and battery type. The use of only simple and relatively inexpensive battery laboratory equipment and the application of uncomplicated experimental techniques are stressed.

The Battery Subcommittee of the SAE Electrical Committee has developed a new standard for rating automotive batteries. The proposed standard is detailed and discussed in light of its sufficiency in describing battery performance, its usefulness to application engineers in specifying original equipment batteries, and to vehicle users in selecting replacement batteries.

Various noise causes are characterized by means of noise sources and noise paths. Engine noise is differentiated from that of the plant. Well-known phenomena and empirical data gained from noise measurements are dealt with briefly. Statistically confirmed interrelations are used to predict engine noise with sufficient accuracy, in particular from the mean piston speed. It is also shown that noise generated by cooling blowers can be accurately estimated from pressure and delivery volume (blower capacity), and that circumferential speed is not an adequate criterion. Typical examples show the effects of various measures on mechanical, combustion, and blower noise.

The basic thermodynamic and operating advantages of using turbocharging with diesel engines are summarized and the question is posed as to whether turbocharging is the best method from an acoustic point of view. The generation, transmission, and radiation of noise in turbocharged engines are described and the interaction of the reciprocating engine and turbocharging system is discussed. An indication is given as to how acoustic improvements are possible by taking suitable measures at the drawing board. The conclusion is drawn that for increases in output, turbocharging is the most favorable method for creating a “quiet engine.”

This paper discusses some of the optical problems associated with the conventional rear view mirror, convex mirrors, combinations of plane mirrors, and periscopes. Two kinds of periscopes are described in some detail. The first is called a view finder and the second a folded telescope. The first presents an image inside the automobile on which the driver must focus his eyes. The second presents an image which seems to lie far away so that the driver can look into it without changing the focus of his eyes. Finally, an unconventional system is described built of parallel cylindrical lenses and mirrors and operating as a unit magnification telescope. Models of the latter system have been successfully installed in a variety of automobiles.

The success with which vehicle operators are able to utilize periscopic rear-viewing optical systems may well depend upon the extent to which the optical scientists, who are designing such systems, and the automotive engineers and automotive stylists, with whom they are working, consider the physiological and perceptual capabilities in performing the driving task as we know it today. This paper discusses where the operator's eyes are located in the vehicle, his visual capabilities, and how he utilizes them under today's driving conditions. These factors are then related to periscopic design and engineering. Also discussed are the advantages and disadvantages inherent in the location of the periscopic system in relation to the location of the vehicle operator's eyes.

Exhaust emissions were measured from a Chrysler gas turbine automobile operating on the road and on the dynamometer. Two different fuels were used, and tests were made after both hot and cold starts. Exhaust emissions, measured both as mass and as concentration, were considerably lower than those from a conventional automobile. Composition of the hydrocarbon emissions generally reflected the structure of the fuel being burned.

A single cylinder investigation was conducted to determine concentration of oxides of nitrogen resulting from combustion of ammonia and air in a spark ignition engine over a range of fuel-air ratios typical of normal engine operation with ammonia. Nitric oxide concentrations exceeded that with hydrocarbons. Spectroscopic observations during the expansion process gave concentrations in some instances an order of magnitude greater than exhaust gas determinations. The results imply a different mechanism for nitric oxide formation with ammonia fuel than with hydrocarbons and that some equilibrating process may take place between combustion and exhaust to reduce otherwise even greater than measured exhaust gas concentrations.

Oil economy is the one quality of a new engine oil that can be most readily observed by the customer. Studies have been made of the relative oil economies of a series of test oils using three different testing environments. These were laboratory engines, a tire test fleet, and an 80 car employee fleet test. All three methods generally ranked oils in the same order, but the size of the differences varied somewhat from method to method. These tests were then used to demonstrate the effects viscosity index improvers and detergent-dispersant packages have on the consumption characteristics of engine oils. They showed that increasing the concentration of viscosity index improvers did not return a proportionate improvement in oil economy. Simple reblending of older multigrade oils to meet the new SAE requirement for measuring the oil’s viscosity at 0 F may result in an oil with significantly poorer economy.

A spark ignition engine concept employing sonic throttling intake valves has demonstrated that the rapid, turbulent combustion process so produced permits extremely lean part-load operation. Light load mixture ratios in excess of 20:1 are possible without incurring the consequences of cyclic variations in cylinder pressure development and torque. A resulting improvement in fuel consumption is achieved. The impetus for throttling the engine by means of the intake valves originated in the hypothesis that increasing the intensity of the small scale turbulence within the combustion chamber would effect an acceleration of combustion propagation rates during the initial period immediately after ignition. Throttling the engine by means of the intake valves results in sonic inflow velocity throughout the idle, road load, and acceleration operating ranges up to approximately two-thirds load.

Using 1966 and later model vehicles equipped with crankcase and exhaust hydrocarbon and carbon monoxide controls, prototype systems were installed to control evaporative emissions from the tank and carburetor and nitrogen oxides in the exhaust. The systems selected were the ARCO vehicle vapor recovery, and the nitric oxide reduction. Baseline evaporative emissions were determined for two of the vehicles operated over-the-road and on the chassis dynamometer. The proposed federal evaporation loss test technique was used for evaluating the performance of the vehicle vapor recovery system. Evaporation losses from the equipped vehicles were less than 1 g per test -- well below the proposed federal standard of 6g. However, carbon monoxide in the exhaust from one car increased by approximately 0.1%. The system had no effect on exhaust hydrocarbons. The mechanism by which the vehicle vapor recovery system functions was investigated briefly.

Recent advances in polymeric Viscosity Index improver technology have led to the development of premium quality, broadly crossgraded passenger car engine lubricants with unique physical properties. “True” SAE 10W-40 products can be made, where measured SAE 10W performance is obtained together with shear stability characteristics which enable the oil to remain in the SAE 40 viscosity range even after service in normal passenger car engines. “True” SAE 10W-40 lubricants provide oil economy characteristics significantly superior to those afforded by conventional SAE 10W-30 and SAE 10W-40 oils, and equal the performance of available SAE 20W-50 oils, while also offering excellent low temperature cranking and starting ability. Positive benefits of improved engine hot starting capability and reduced engine noise levels are also provided.

Sections approximately the size and shape of the load bearing portions of a standard track shoe for military track laying vehicles have been produced by an ausforging process. These sections were ausforged from H-11 consumable vacuum melt, H-11 conventional melt, and SAE 4340 conventional melt steel. Tensile strength ranged to 330,000 psi. Reduction of area ranged to 40%. Limited fatigue testing indicated a considerable increase in fatigue life over SAE 4340 steel. This paper covers the development program undertaken in preparation for the ausforging of complete track shoes.

A modified Ausform process has been developed which improves the fatigue properties of spring steels. In brief, the process combines metal deformation with heat treatment. The fatigue resistance of SAE 5150 and 1052 steels is greatly improved by this treatment. The amount of deformation directly influences the fatigue resistance; and with more than 50% deformation, the fatigue life is improved by 700% over that of SAE 5160 spring steel. For a 100,000 cycle minimum life, both maximum stress and stress range can be increased by 30,000 psi over that of conventionally heat treated SAE 5160 steel. Superior fatigue properties have been obtained in sections with thicknesses of 0.200-0.500 in. Surface treatments such as sandblasting, shot peening, and glass bead peening are effective in prolonging fatigue life; glass bead peening was by far the most effective. Modified Ausformed steels display an unusual fracture behavior which is beneficial in fatigue and notch toughness.

Spring rate is one of several factors that affect the ride performance of passenger car tires. A technique has been developed for obtaining precise spring rate measurements in the laboratory under conditions approximating road operation. The spring rate properties of many different tire designs have been measured. The effect of wear and several tire construction variables on spring rate is presented. A correlation between the laboratory measurement of spring rate and vehicle ride evaluations is discussed. It is necessary to measure tire spring rate for the rolling condition with a resonance test technique in order to generate data that are useful for ride performance analyses.

The transition temperature of Mn-Mo armor steels, quenched and tempered in either the temper embrittling or tempered martensite embrittling range, can be significantly lowered by warm working. The improved toughness, however, is developed only when the direction of prestraining and testing is identical. Deformation in one direction followed by testing in the opposite direction produced an increased transition temperature.

The exhaust emissions of the 6V-71E and 6V-71N engines, used in transit coaches, are compared to illustrate that design revisions can affect diesel exhaust. Carbon monoxide and sulfur dioxide are discussed and the effect of design revisions on aldehydes, oxides of nitrogen, and hydrocarbons are illustrated. The effects of the design revisions on exhaust smoke and odor are compared using three different measurement techniques. Smoke is compared using a filtering meter on engine dynamometer tests, a sampling light extinction meter on road tests, and a full flow light extinction meter on chassis dynamometer tests. Odor is compared using a sniff-box technique and a psychological scale, a threshold technique using natural dilution in a large building, and a sniff tube-dilution technique using the Turk bottle rating.

This paper describes a newly constructed research facility which was specifically designed for noise reduction work on internal combustion engines. Various approaches for reducing engine noise are discussed, and a method which permits locating individual sources of structure-borne sound is reviewed. A measuring system for airborne sound, radiated from the engine surfaces, is described. Some new findings and new problems encountered in noise reduction work are discussed.

The exhaust emission characteristics of 4-stroke, direct-injection diesel engines, naturally aspirated and turbocharged, have been investigated. Data on the emissions of carbon monoxide, oxides of nitrogen, and unburned hydrocarbons are presented. It is shown that concentrations of these emissions increase with increasing fuel-air ratio. Turbocharged engines, by virtue of running at generally lower fuel-air ratio, tend to produce lower concentrations at equivalent loads and speeds.