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Comparing Dolly Rollover Testing to Steer-Induced Rollover Events for an Enhanced Understanding of Off-Road Rollover Dynamics

The field of motor vehicle rollover research and testing has been one of multiple and varied approaches, dating back to at least the 1930's. The approach has been as simple as tipping a vehicle over at the top of a steep hill ( Wilson et al., 1972 ), to as complex as releasing a vehicle from an elevated roll spit mounted to the rear of a moving tractor and trailer ( Cooper et al., 2001 and Carter et al., 2002 ). Presenter Peter Luepke, P Luepke Consulting

Occupant and Vehicle Responses in Rollovers

During the past decade, there has been a steady increase in studies addressing rollover crashes and injuries. Though rollovers are not the most frequent crash type, they are significant with respect to serious injury and interest in rollovers has grown with the introduction of SUVs, vans, and light trucks. A review of Occupant and Vehicle Responses in Rollovers examines relevant conditions for field roll overs, vehicle responses, and occupant kinetics in the vehicle. This book edited by Dr. David C. Viano and Dr. Chantal S. Parenteau includes 62 technical documents covering 15 years of rollover crash safety, including field crash statistics, pre- and rollover dynamics, test procedures and dummy responses.
Technical Paper

Load-Carrying Capacity of Extreme-Pressure Lubricants

THE choice of a suitable lubricant for a given mechanism involves a study of the relation between the various factors of design, operation and lubricant characteristics. One of the most important phases of the extreme-pressure-lubricant problem is the development of laboratory apparatus and test methods for the determination of the characteristics of a lubricant that are significant measures of its service performance. During the last year the U. S. Bureau of Standards has undertaken a comprehensive study of the problem of extreme-pressure lubricants in cooperation with the S.A.E. Lubricants Research Subcommittee. Since the primary requisite for an extreme-pressure lubricant is that “it lubricate under high load,” it was decided that a start on this program be made with an investigation of the load-carrying capacity. The preliminary tests are described, the effect of speed and temperature is considered, and the apparatus and procedure are explained.
Technical Paper

An Analysis of Tires and Wheels as Causes of “Tramp”

THIS paper presents the solution of the factors in tires and wheels that cause a particular type of front-end vibration termed “tramp,” which is a vertical vibration of the front axle accompanied by a small degree of simultaneous oscillation of the wheel assembly about the king pin. This vibration in turn sets up the disturbance of the body and chassis. The front-axle vibration is caused by the unbalance and variation in rolling radius of the rotating front-wheel assemblies. The theoretical action of these two factors is developed in detail and supported by experimental results. The foregoing two factors act independently. The resultant of the two periodic forces which they set up depends on their phase relationship.
Technical Paper

Practical Tractive-Ability Methods

THE TRACTIVE ability of a motor-vehicle, as stated by the author, is the measure of its power to overcome outside resistances to its translation, based on the tangential force exerted by the driving wheels at their points of contact with the road. The propelling force is derived from the engine. To compute the “tangential force” of the foregoing definition it is engine torque that interests us rather than the horsepower, he states. If the horsepower is given, it can be converted into torque. After analyzing this point mathematically, the author discusses typical tractive-factors of modern motor-trucks so that he is enabled to develop an economic factor mathematically and thus be prepared to discuss tractive resistance as opposed to tractive effort. Air resistance is considered in detail as a particularly important factor concerning motorcoaches, and the author's points are backed up by diagrams and charts as well as by numerous tables of statistical and computed data.
Technical Paper

The Effect of Wheel-Setting on Wear of Pneumatic Tires

THE author compares tread-wear of front and rear tires. Considering wear of rear tires as normal wear he analyses the abnormal wear observed on front tires and traces it to its causes, which are found to be camber, toe-in and imperfect geometrical layout of steering-arms and linkages. A theory of the scuffing action is developed. It is due partly to various rolling diameters at different parts of the tire tread and partly to the setting of the two front wheels so they tend to roll in slightly different directions. Reducing the camber angle to ¾ deg. and the toe-in to 1/16 in., reduces both these errors and results in longer tire-wear. No definite theory for camber is found. Toe-in depends on camber, counteracting the tendency of cambered wheels to diverge. A method is described for testing accuracy of rolling action by means of paper on a greased floor. Service stations must be put in a position to test and correct toe-in and camber.
Technical Paper

The Electrodeposition of Rubber

AFTER giving a brief description of the nature of rubber latex and a review of investigations made in Europe of its physico-chemical properties, the author tells of experiments made in Rochester to develop a method for the electrodeposition of rubber particles. These proved that the process was possible but the problem of producing a coating containing all the ingredients requisite in a compound suitable for vulcanizing remained to be solved. The nature of the rubber particles and of rubber after coagulation of the particles is described and the method of rubber-plating as developed is explained. It is stated that the deposit can be built up almost indefinitely and at a very rapid rate; that the composition remains substantially unchanged during coating, and that the current efficiency is remarkably high.
Technical Paper

The Relation of Riding-Quality to Angular Car-Acceleration

THIS paper describes the use of the gyro-accelerometer, an instrument capable of recording angular velocity, angular acceleration and the total angle turned. The design and development of this instrument came as a result of research into the riding-quality of automobiles, which work demonstrated the necessity of measuring angular motions in a moving car under road conditions, a task that was impossible to accomplish with the equipment that was then available. To avoid taking a great number of readings and obtain a basis of comparison, a standard test, consisting of driving a car over a special bump at different speeds and plotting curves of the resulting angular quantities as given by the gyro-accelerometer, was devised. This test is known as the standard-bump test, and the values of maximum angular acceleration obtained at different speeds are evidently closely related to riding-quality.
Technical Paper

Spinning Characteristics of Airplanes

THE causes and nature of the spinning of an airplane, and measures for the prevention of and recovery from a spin, are discussed. Tests and analysis are said to have shown that spinning is a stable motion of rotation, and that the real dangers are in its instability. Recovery from a spin is held to be more important than prevention, as complete knowledge of means of recovery will lead to mastery of the whole phenomenon. The spinning motion is a combination and balance of aerodynamic and purely dynamic forces and couples, asserts the author. Full-scale experiments prove beyond doubt that side-slip may be very pronounced in a spin, which changes considerably the rate of roll of the simple autorotational kind. The rolling of the wings leads to the establishing of a yawning couple which may become dangerous, tending to keep the craft in a spin because of the increased shielding of the tail surfaces.
Technical Paper


The early wheels merely rolled, carried weight and resisted side strains; later they were called upon to transmit braking forces and still later the driving force. Prior to the automobile, wire wheels were not called upon to support much weight and the usual type was that used for bicycles. When automobiles were first built, bicycle-type wire-wheels were employed and used until the demand for larger wheels presented unsurmountable obstacles. From that time a development was in progress in this country and in England that resulted in the triple-spoke wire-wheel which has grown in popularity since 1912. The different types of wheels are discussed and the advantages and disadvantages of wire wheels stated; three diagrams are shown. As the wire wheel is a “suspension” wheel, the car weight is hung or “cradled” from scores of resilient, flexible spokes, and the pull is always on three-quarters of the spokes.
Technical Paper


Even though friction brakes are very necessary, they have certain limitations as to heat capacity that is especially noticeable on hills, but is also a factor in congested fast moving traffic. A 45,000 lb tractor and semi will generate about 300 hp going down an 8% grade at about 45 mph and less than one third of this if taken up by windage, rolling, and engine friction. The brakes must get rid of the rest as heat. This is where a supplementary brake, or retarder, comes in. An eddy current retarder will not stop or hold a vehicle but it can dissipate a lot of heat and so save the wheel brakes for the emergency, and also eliminate “engine braking” and so reduce wear and tear on engine and transmission. Even with retarders, however, it is advisable to distribute the force over the principally loaded axles.
Technical Paper


A DESCRIPTION of two tests for car control, with results showing the effect of such variables as roll rate, load distribution, and tire pressure, is presented in this paper. Car control is defined by the author as the security with which the driver can maneuver his car over the highway, where he wants to and as he wants to, with precision and care. The two tests discussed were designed to find out what actually happens when a car goes around a curve, what factors are variables, and to set up a test procedure whereby these variables can be measured objectively, their relative importance determined, and the laws of their variation found. In the first of these tests, the skid-pad roadability test, the specific problem is to measure the aspect of the car in relation to the pavement plane and the relative motion of various parts of the car under conditions of constant speed and travel in a circular path.
Technical Paper

Development of the ERCOUPE … An Airplane for Simplified Private Flying

EVELOPMENT of a two-place airplane particularly suited to the needs of the private flyer was the aim of the design of the “Ercoupe.” This was done by making it unusually simple and easy to fly, quick to learn to fly, and free from the difficulties associated with stalling and spinning; it was also to have a good field of view for the pilot, and a cruising speed of 100 mph with a low-powered engine. The development of such a plane began ten years ago, Mr. Weick reports, when a small group of engineers at the NACA Laboratories at Langley Field started a private study that resulted in the construction of the W-1 and W-1A experimental airplanes having the following unconventional features: 1. The tricycle landing gear with castering nose wheel, steerable if desired. 2. Suitable longitudinal and lateral stability with definitely limited upward elevator travel to prevent loss of control due to stalling and spinning. 3. A glide-control flap. 4.
Technical Paper


WHAT would happen if an atomic bomb were to explode at noon tomorrow without warning of any kind? Would the automobile turn out to be a death trap for many of us or would it offer as much protection as the ordinary building? Would there be any advantage in having the car turned away from the center of the blast or to having the windows rolled down? Would it be safer to crouch down on the floor of the car at the first sign of an atomic explosion? Would it be safe to enter our cars as soon as the first effects of the explosion have subsided? Would the cars run? It was to find the answers to some of these questions that a group was invited to observe an experiment at the Nevada Proving Ground of the Atomic Energy Commission. This group - which became the SAE-FCDA Advisory Committee - wrote the accompanying report, which tells about the experiment and some of the things that were learned. A. L. Haynes of Ford is chairman of the committee. Other members are: R. B.
Technical Paper

Stress Testing Methods in Body Structures

SINCE theoretical and empirical engineering formulas do not always apply to automobile body structure, reliance must be put on structural testing to supplement available information. In this paper the author presents a technique for complete car structural and road testing in conjunction with body tests for such purposes as: 1. Aiding development of experimental body designs. 2. Assisting in the standardization of quality control methods. 3. Solving special problems in fabrication. 4. Furthering the improvement of body-frame unit structural efficiency. 5. Investigating the use of new materials. 6. Determining safety factor of body. The search for adequate methods of determining the safety factor led to the development of the roll-over test. It is accomplished by towing a car so that the wheels on one side go up a ramp at a 15-deg angle, and at a speed of 50 mph. The car is rolled in such a manner that the windshield header receives the greatest impact.
Technical Paper


THE roller bearing has been a peacetime development, particularly since the close of World War I in 1918. Since that time it has been introduced into a multiplicity of industries that now find application on a tremendous scale on defense projects. This paper traces the introduction of tapered roller bearings into all phases of industry, manufacturing, and transportation - particularly the automotive industry, the railroad industry, steel mills, oil industry, and machine tools. Discussing design principles, the author brings out that one of the fundamental concepts of tapered roller bearing usage is that they must be mounted in pairs and a second is that the bearings accommodate any combination of thrust and load; for high thrust reactions, the bearing is made with a steep taper. He points out that tapered roller bearings are rated in accordance with a speed factor, life factor, and application factor, explaining how each of these factors is derived.