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Technical Paper

Diesel Combustion Chamber Sampling - Hardware, Procedures, and Data Interpretation

1975-02-01
750849
In-cylinder sampling appears to be the only available means for obtaining detailed information of the diesel combustion process. This information is necessary to understand pollutant formation because of the intimate relationship between formation rates and local cylinder conditions. This paper discusses efforts to (1) examine and improve sampling valve design, (2) evaluate potential effects of the valve and the sampling system on sample composition, (3) find methods to extract useful information from sampling data. Sampling hardware is currently being used to study combustion in engines, but further work is needed to quantify the influence of hardware and procedures on sample composition and to design experiments to provide data containing maximum information.
Technical Paper

A Rotary Engine Test to Evaluate Lubricants for Control of Rotor Deposits

1974-02-01
740159
During development of the General Motors rotary engine, the lubricant was recognized as important to its success because certain lubricants produced deposits which tended to stick both side and apex seals. Consequently, it was decided to develop a rotary engine-dynamometer test, using a Mazda engine, which could be used for lubricant evaluation. In an investigation using an SE engine oil with which there was rotary engine experience, engine operating variables and engine modifications were studied until the greatest amount of deposits were obtained in 100 h of testing. The most significant engine modifications were: omission of inner side seals, plugging of half the rotor bearing holes, pinning of oil seals, grinding of end and intermediate housings, and using a separate oil reservoir for the metering pump. Using this 100 h test procedure, three engine oils and five automatic transmission fluids were evaluated.
Technical Paper

The Relationship of Low-Temperature Rheology to Engine Oil Pumpability

1973-02-01
730478
An analysis of oil pumpability reveals that engine oil pumping failures may occur because either the oil cannot flow under its own head to the oil screen inlet, or the oil is too viscous to flow through the screen and inlet tube fast enough to satisfy pump demands. To determine which factor is controlling, the behavior of commercial, multigraded oils was observed visually at temperatures from -40 to 0°F (-40 to - 17.8°C) in a laboratory oil pumpability test apparatus. Test results revealed that pumping failures occur by the first alternative: a hole is formed in the oil, and the surrounding oil is unable to flow into the hole fast enough to satisfy the pump. Of 14 oils tested, 7 failed to be pumped because of air binding or cavitation which developed in this manner. A model, which explains these failures in terms of yield point considerations and the low shear apparent viscosity of the oils, is proposed.
Technical Paper

Correlation of Physical Properties with Performance of Polyacrylate Radial Lip Seals at -30F

1973-02-01
730051
This paper evaluates the tendency of lip seals to fracture in a test apparatus in which dynamic runout is 0.010 in and the temperature is cycled between -30 and 0 F. Seals made of eight different polyacrylate polymers were soap-sulfur cured with various types and amounts of carbon black. Physical tests included room-temperature flexibility defined by Young's modulus at small strains, standard tensile tests at room temperature, flexibility at sub-zero temperatures determined by a Gehman test, and sub-zero starting torques of the seals. Primary determinant of successful fracture resistance is a low starting torque resulting from good low-temperature flexibility. The effect of adding graphite to some of these formulations is described and some current commercially available seals are evaluated.
Technical Paper

Mechanical Simulation of Human Thorax Under Impact

1973-02-01
730982
This paper summarizes an analysis, design, and test project in which a dummy chest structure was developed. The chest consisted of mechanical elements that had been characterized by computer simulations as giving responses to blunt frontal impacts necessary for biofidelity. An analysis of mechanical rib structures indicated that materials having a high ratio of yield stress to modulus of elasticity were required. Only metals having unusually high yield strengths, such as spring steels, qualified. A mechanical system was developed with steel ribs pivoted at each end as a primary spring. A secondary spring was a pair of commercially available die springs acting in parallel with the ribs after 25.4 mm (1.00 in) deflection. A fluid damper was developed to provide the damping. The chest structure was tested under conditions modified from those used by Kroell. The modifications were holding the spine rigidly and reducing the impact masses.
Technical Paper

The Turbine Interstage Diffuser

1971-02-01
710553
The incentive for use of an interstage diffuser in a free-shaft gas turbine engine is briefly examined and some pertinent published background data reviewed. Tests of two annular diffusers behind an upstream turbine show the deleterious effects of turbine exit flow nonuniformity on diffuser behavior. The flow acceleration provided by the area contraction of a power turbine nozzle located at the diffuser exit substantially improves the nature of the flow previously found to exist at the diffuser exit in the absence of the nozzle.
Technical Paper

Numerically Controlled Milling for Making Experimental Turbomachinery

1967-02-01
670096
Utilization of numerically controlled milling has been found particularly attractive in producing, in limited quantities, the three-dimensional curved surfaces characteristic of turbomachinery. In experimental and developmental programs its use can result in decreased fabrication cost, reduced lead time, and improved dimensional accuracy. Following a review of the general classifications of numerically controlled milling machines available for manufacture of such parts, illustrations are given of some of the procedures and techniques employed in their use. A variety of parts made using numerical control serve as examples.
Technical Paper

The GMR Sealometer A New Machine for Oil Seal Evaluation

1966-02-01
660381
The Sealometer is used for evaluating the performance of lip type oil seals and provides a dimensionless number derived from measuring the increase in temperature of a test shaft operating in a lip seal for a given time interval. With the Sealometer it is possible to study parameters that affect seal performance. As a quality control instrument, the machine provides accurate data for design. Sealometer evaluation offers a quick method of determining the life expectancy of a particular design for a particular application and eliminates the need for long life test programs.
Technical Paper

Evaluating the Effect of Fluids on Automatic Transmission Rotating Shaft Seal Elastomers

1966-02-01
660396
The Total Immersion Test (ASTM D 471) for seal elastomers, used in evaluating the compatibility of fluids and seals for automatic transmissions, does not, produce hardness and volume change results similar to those found for rotating shaft seals in service. The Tip Cycle Test was devised to provide better agreement with service results. In the test, one side of the seal is exposed to air, and the other alternately to fluid and to air-fluid vapor. Rotating shaft seals were evaluated in both car and dynamometer transmission tests, and in various bench tests. Agreement was poor between transmission tests and both the Total Immersion and the Dip Cycle Tests. Good agreement was found with the Tip Cycle Test.
Technical Paper

Fluid Composition Affects Leakage from Automatic Transmissions

1966-02-01
660397
Tests were conducted using older model cars with automatic transmissions to determine the effect of fluid composition on leakage past the rotating shaft seals. It was found that seal leakage was reduced or stopped by changing to seal-swelling fluids, and increased with seal-shrinking fluids. Leakage was also reduced by adding aromatic additives to existing fluids in the transmissions. Seal volume and hardness change results from bench tests support the car data.
Technical Paper

Hydrodynamic Sealing with Radial Lip Seals

1966-02-01
660379
Conventional radial lip oil seals can be made more effective by utilizing helical grooving beneath the contact lip surface. Miniature hydrodynamic pumps so formed aid the radial lip seal in containing the oil by generating fluid forces opposite in direction to the leakage flow forces. This seal-shaft combination has been termed the Hydroseal. Four factorial experiments were conducted to evaluate the effect of helix angle, groove depth, groove width, and number of grooves on sealing performance. The criterion used as a basis for selecting the optimum design were leakage, wear, hardening of the sealing surface, and pumping capacity. These data indicated that the best hydroseal design was one with three grooves, 0.0003 in. deep, 0.014 in. wide, having a helix angle of 45 deg.
Technical Paper

A Study of the Effects of Automotive Fluids on Elastomer Seal Materials Using Immersion Tests*

1966-02-01
660395
Effective performance of functional automotive components requires fluid sealing under compatible conditions. One method of determining this compatibility is through the use of immersion testing under a variety of conditions that simulate those experienced in actual use. By measuring the changes in the physical properties of the seal materials after immersion a judgment can be made regarding seal/fluid compatibility which will be encountered later in actual use. A series of immersion tests using representative seal materials and automotive fluids; namely, gear oils, transmission fluids, and motor oils were conducted within the framework of the Technical Committee on Automotive Rubber, jointly sponsored by SAE-ASTM.
Technical Paper

Factors Influencing the Measurement of Tire Uniformity

1965-02-01
650734
Tire nonuniformities are a major source of vibration problems in vehicles. There is considerable disagreement on which tire uniformity parameters are important to vehicle noise and vibration problems, and on how these uniformity parameters should be measured. This paper is concerned primarily with the effects of the nonuniformities of the tire structure which cause contact patch force variations as the tire is rolled in a straight line at constant axle height. Experimental results showing the effects of mean radial load and roll size on these structural, or static, nonuniformities are presented which indicate that these force variations should be measured on a large roll at rated load. Mathematical analyses of certain vehicle vibrations show that radial and lateral force variation are important uniformity parameters. The amplitude of the first harmonic of these force variations contributes to vehicle shake.
Technical Paper

Force and Moment Characteristics of Rolling Tires

1964-01-01
640028
The primary forces and moments which affect the directional control properties of wheeled vehicles are those between the road and the rolling tire. These forces and moments are nonlinear functions of a large number of parameters including slip angle, camber angle, vertical load, tire-road friction coefficient, and traction forces, among others. A new apparatus particularly suited to the measurement of the steady state tire properties most significant in handling studies is described. The forces and moments of interest are defined and typical results fora7.60-15 tire are presented to illustrate the effects of slip angle, camber angle, vertical load, inflation pressure, and wheel torque on lateral force and aligning torque.
Technical Paper

Weibull Renewal Analysis

1964-01-01
640624
Renewal theory concerns itself with the replacement of randomly failing parts. In the simplest case we have a one component system which is kept running continuously by replacing a failed component at the instant of failure with an identical “new” component. The random variable N(t) = the number of failures (or replacements) to time t is then of interest in many types of reliability analysis. In this paper the distribution of N(t) is considered when the underlying failure law is a Weibull distribution. Tables of the mean and standard deviation of N(t) for various values of the Weibull slope parameter are presented. Applications to warranty and spare parts analyses are also noted.
Technical Paper

Corrosion Resistance of Trim Materials

1963-01-01
630110
As the design of automobiles changed over the past seventy years, manufacturers have increased the usage of decorative trim to further enhance the beauty of styling concepts. As new trim materials were introduced and parts became more complicated in design, producers have continued their efforts to produce decorative trim parts which remain attractive during the service life of the automobile. The service performance of trim materials in several geographic locations, the use of accelerated tests to predict service performance, recent developments in improving the durability of plated parts, and requirements for producing quality exterior decorative trim are reviewed in this paper.
Technical Paper

Evaluating the Effect of Fluids on Automatic Transmission Piston Seal Materials

1962-01-01
620231
A brief review of the testing of automatic transmission fluid for compatibility with seals is presented. The total immersion test used in fluid qualification, while apparently effective in predicting the compatibility of fluids and seals in service, does not correlate well with transmission tests with respect to hardness change of piston seals. The Dip-Cycle Test, developed to overcome this limitation, is a procedure for alternately immersing seal specimens in the test fluid and suspending them in the hot air-fluid vapor atmosphere above the fluid. Correlation of the Dip-Cycle Test with transmission piston seal results is much improved over that with the total immersion test. It is the purpose of this paper to review these developments and to present an improved test procedure (dip cycle test) for evaluating the effect of fluids on transmission piston seal materials.
Technical Paper

A Laboratory Method for Testing Moisture Sensitivity of Brake Lining Materials

1962-01-01
620128
A laboratory test method has been devised to measure the variation in coefficient of friction values of a brake lining as it passes through the various degrees of wetness. The results of tests on two linings are shown: the first one of the most sensitive lining material tested to date; the second an improved material.
Technical Paper

DEVELOPING TRANSAXLE FLUID

1960-01-01
600069
EXTENSIVE TESTING by GM Research Laboratories has screened five promising transaxle fluids out of 32 mineral-oil-base fluids, 10 synthetic-base fluids, and numerous additive-base stock combination fluids. This paper discusses the findings of the testing and the continuing program on the five fluids. Transaxle fluids have a number of properties affecting performance, including: High-temperature viscosity. Low-temperature fluidity. Shear resistance. Friction properties. Oxidation resistance. Antifoam quality. Effect on seals. Fluid-clutch plate compatibility. Antiwear quality. Extreme-pressure quality. Antirust and anticorrosion qualities.*
Technical Paper

Seal Testing to establish quality control specifications Can Reduce “LEAKERS”

1960-01-01
600047
THIS REPORT deals with the major parameters of a seal application which affect its efficiency and life, as determined by controlled laboratory testing in CM Research Laboratories.* A. Shaft 1. Surface Roughness 2. Machining Lead B. Assembly C. Seal 1. Seal Diameter Control Trim Interference Spring Rate 2. Seal Lip Pressure Trim Interference Spring Rate Rubber Hardness Eccentricity 3. Seal Eccentricity Mold Register Assembly Trim
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