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1970-02-01
Technical Paper
700057
J. N. Bradley
The development of the truck disc wheel from World War II through the present period is traced. Both the tubed and tubeless developments are discussed with a look at where we are today, and what some of the wheels will be in the immediate future. The duo rim is discussed in some detail as the answer to a requirement for an orderly development from tubed to tubeless.
1970-02-01
Technical Paper
700056
Lawrence F. Looby, Robert S. McKee
Race car designers have relied heavily upon mechanical creativity to gain a competitive edge in racing. The Armco/McKee Can-Am car is not short in its mechanical innovations, but the program objective was to demonstrate the merits of special aircraft steels and titanium in a road racing vehicle. The design advantages gained in the use of these very high specific strength and specific modulus materials are shown. Their use in future racing cars will be more in the area of highly stressed components, rather then complete vehicle concepts. Their use in passenger cars will also be in highly stressed components, and will depend upon the emphasis placed on power/weight ratios of specialty vehicles.
1970-02-01
Technical Paper
700157
G. B. Hickner, D. W. Howard
An analog computer simulation development for a passenger car foundation braking system is presented. A brake control system is added to the simulation. As the hardware for the brake control system is developed it is substituted into the simulation along with components of the foundation brake system. This mixture is a “physical simulation” where the analog simulation is reduced to represent only the vehicle and the road with appropriate interface elements for the actual brake and control system hardware. The discussion includes the studies conducted using physical simulation for tolerance study of vehicle characteristics as well as the foundation brake system and control system parameters. Results which validate the model are presented. In conclusion, the advantages of this approach which supports the development of an advanced brake control system are discussed.
1970-02-01
Technical Paper
700156
Richard W. Valentine
This paper discusses the use of hybrid analog-digital simulation in vehicle design analysis. A hybrid program for the design application of nonlinear directional control analysis is described. This program combines the nonlinear tire properties, suspension analysis, and vehicle dynamics into an efficient design analysis package.
1970-02-01
Technical Paper
700153
Dennis K. Fisher
The development of an automotive brake test stand has required the design of a highly responsive hydraulic system in order to provide acceptable dynamic control of brake line pressure. This paper describes the analysis, simulation, and performance optimization of the electrohydraulic pressure control system built for this application. A hybrid simulation employing a patterned search algorithm was used to determine the compensation network yielding the optimum system response to a step input. Solution time comparisons between hybrid, digital, and analog simulation methods are made, and the relative advantages of each are noted. Finally, a comparison between the simulation and some experimental results indicates the validity of the analytical procedures employed.
1970-02-01
Technical Paper
700137
R. M. Rusnak, H. W. Schwartz, W. P. Coleman
The effect of rotor alloy composition on thermal conditions in a disc brake system was determined analytically. The three alloys selected were gray cast iron, 356 aluminum, and copper -1% chromium. This study includes calculations of the temperature and heat storage in the various portions of the brake system, as well as the variations of convective heat transfer throughout the system. These computations were made for the transient conditions existing during a series of 60 mph stops (15 ft/sec2 deceleration). The steady-state rotor surface temperature and the thermal gradients were found to decrease with increasing thermal conductivity of the alloys. The rotor surface temperatures for the first two stops were relatively independent of thermal conductivity, but were strongly dependent on heat capacity. Convection was found to occur almost entirely (greater than 90%) from the rotor surface and ventilating passages.
1970-02-01
Technical Paper
700138
S. K. Rhee, J. L. Turak, W. M. Spurgeon
Drums made of a chromium copper alloy, an aluminum alloy/cast iron composite, and conventional cast iron were compared by inertial dynamometry, using full-size linings in a Non-Servo brake system. The tests were performed with three types of linings: nonabrasive, moderately abrasive, and highly abrasive. In each test, 30 stops were made from 40 mph and 30 stops from 60 mph, using a rotational inertia of 31.4 slug-ft2. Temperatures near the lining/drum interface, hydraulic line pressures, and lining wear, were measured and compared. For a given amount of work, the temperature rise near the drum surface was found to be lowest in the chromium copper drums, next lowest in the aluminum alloy/cast iron composite, and highest in the cast iron drums. This confirms earlier test results from drag dynamometry, using 1 X 1 in. samples. The average temperature rise decreased linearly with increasing thermal diffusivity of the drum material.
1970-02-01
Technical Paper
700112
Bruce E. Latvala, Robert J. Morse
A braking control system for air braked vehicles has been developed which prevents wheel lock under any braking condition and thereby improves vehicle stability and reduces stopping distance. The theory of operation and the specifications of the system are discussed and performance under several typical conditions is shown.
1970-02-01
Technical Paper
700113
Gordon W. Yarber, Franklin B. Airheart
Automatic skid control provides the rotation control needed to stop a wheeled vehicle safely through a control system which senses wheel speed, has control logic, and controls braking torque. This paper describes how these essential control functions are used on the vehicle. Skid or rotation control can be provided for all braked wheels, either on an individual or paired wheel control basis, if maximum safety of vehicle operation is the primary consideration. If the major objective is to prevent complete loss of vehicle control, rotation control on the rear wheels only, either individual or paired, will be satisfactory, realizing, however, that steering control is lost when the front wheels lock up. To determine the final configuration, the performance as related to vehicle stability, directional control, stopping distance, tire damage, and relative cost must be evaluated.
1970-02-01
Technical Paper
700114
Michael J. Denholm, Frederick E. Lueck, John W. Bush
This paper discusses the brake performance of air-braked trucks and combination vehicles relative to deceleration and stability The available means for improving the performance are covered, including recommendations based on maximum cost effectiveness. Methods discussed are the use of load-sensitive proportioning valves and skid control, with the study of tractor installations as a prelude to more widespread usage of either device. Related areas of interest are also considered, such as the vehicle modifications that may be required to permit the use of these brake controls, the benefits of tractor installations on interchange vehicles, and the relative merits of load-sensitive proportioning valves and skid control when so applied.
1970-02-01
Technical Paper
700001
D. Adams, R. S. Cassle
Chrysler Corp. has introduced two new features on their 1970 steering columns: an energy absorbing steering wheel which appears on the Barracuda and Challenger models; and an antitheft steering column which is standard on all car-lines. This paper describes the two engineering programs.
1970-02-01
Technical Paper
700002
Donald P. Marquis
The 1969 General Motors steering column involves a new system for absorbing energy from the body of the driver in the event of a frontal collision. This steering column also contains a locking system which permits the locking of steering shaft and and gear shift as well as the ignition switch. A comparison of the 1969 ball type energy absorber with the 1967 mesh type absorber shows gains in rigidity, consistency of load, and ease of changing design load. The discussion of the locking system development for various types of steering columns includes a description of the inhibiting system.
1970-02-01
Technical Paper
700179
Roy L. Orndorff, James Sidles
Changing a flat tire no longer need be a chore if the Newmatic jack is used. The Goodrich jack is a compact, inflatable, textile, and rubber cylinder capable of extending vertically to lift a vehicle wheel off the ground. It is stable and easy to operate. Inflation pressure for most standard-sized cars is in the range of 20-25 psig. The inflation source can be a compressed gas bottle, a compressor driven by the engine, or an electric motor driven compressor plugged into the cigarette lighter. The Newmatic jack can be stored within the spare wheel. In today's automobile with limited storage space and uncertain lifting methods, the Newmatic jack offers the chassis engineer considerable freedom of choice.
1970-02-01
Technical Paper
700423
Roger P. Daniel
1970-02-01
Technical Paper
700446
L. D. Gschwind
In the late 1940s a series of three laboratory fatigue tests for development of passenger car and light truck road wheels was experimentally developed. Each of these tests evaluate specific portions of the wheels and thereby reduce development time by allowing more concentrated effort. Rim and disc tests are performed by loading the test wheel through a tire against a drum to duplicate abusive wheel loadings on a vehicle. The value of these tests has been confirmed by good correlation between laboratory and proving grounds testing as predicted in the development of the test. Additional laboratory and vehicle wheel tests are also described. This family of tests is used for development of new wheel designs and not for production quality control testing.
1970-02-01
Technical Paper
700444
Roy Richter
The increased popularity of the cast nonferrous styled wheel has created a need for performance testing of these wheels. Styled wheels are normally used on the same applications as standard OEM steel wheels so they should be expected to pass the same test requirements. However, the difference in physical properties of the two materials dictates a change in test load as well as a redesign in some commonly accepted test equipment.
1970-02-01
Technical Paper
700445
Elvin E. Tuttle
A high speed, natural frequency type, fatigue testing machine has been evaluated for testing automotive wheels. Rim stress correlation between service loading and machine loading is good and fatigue failures are produced in the predicted areas of the rim. Although fixtures were modified to test other parts of the wheel, no consistent patterns of failure were apparent. The value of this type of testing is that a large number of load cycles are applied in a short time. Its first use will be as a quality control check in manufacturing rims.
1970-02-01
Technical Paper
700462
R. H. Spelman, H. D. Tarpinian, D. E. Johnson, K. L. Campbell
This four-part study is based upon tests planned and conducted by the SAE Tire Committee. The introductory remarks are written to give a brief outline of the complexity of tire traction measuring procedures and to describe the methods used in this work. The second part of the study deals with the methods used. Three basic methods were used, based upon stopping distance, vehicle deceleration, and towed skid trailers. In the third section, the results are analyzed. Test data from various types and sizes of tires are presented which show the effect of tire wear, vehicle speed, and various test surfaces. The study is finalized with conclusions and recommendations. Conclusions permit us to offer a basis for establishing minimum values expressed as related to a standard for straight ahead motion for passenger tire traction on wet pavement. Recommendations are offered for future activity.
1970-02-01
Technical Paper
700568
Frank Ratliff
Controlling the cost of excavating and moving a yard of earth is the greatest challenge confronting the earthmoving industry today. This industry, in particular, faces both a shortage of skilled operators and an inflationary wage environment. To increase a skilled operator's efficiency and decrease learning time for new operators, the Tyrone Automatic Central Hydraulic System automatically directs the proper amount of hydraulic power at the proper time to the various functions of the front loader. Hydraulic valving coordinates pump flows for approximately constant lock-to-lock times throughout the cycle regardless of engine rpm and at the same time, controls the interaction of the lift cylinder, bucket cylinder, and transmission disconnect for the fastest possible full bucket loading in both stockpile and virgin bank.
1970-02-01
Technical Paper
700582
J. Forgione
This paper outlines the key elements in a laboratory reliability verification test program for an automotive sub-system. Many of these elements are described in some detail through the various stages of development from prototype concept to production. By means of an actual case study, verification testing of the 1970 Ford Anti-Theft Steering Column, steps required to design tests which yield meaningful information and the rationale used to analyze the results are presented. The steering column on a late model automobile is a complex system which combines several functions and features; steering, shifting, warning devices (turn signal and emergency flashers), ignition switch, anti-theft devices plus several safety features. The effectiveness of the overall verification program is evaluated through the presentation of actual field-feedback results.
1970-02-01
Technical Paper
700476
A. Marzocchi
The high modulus, dimensional stability and cross section properties of glass fibers have made possible the development of dimensionally stable power transmission belting. In addition, the use of glass fibers as a belt material for tires has improved abuse resistance, tread wear and handling characteristics. Chopped impregnated glass fiber bundles have also found application as reinforcements for tread stock in off-the-road tires. In this paper physical property characteristics of glass fiber and rubber stock containing chopped glass fiber will be discussed.
1970-02-01
Technical Paper
700475
F. S. Conant, G. L. Hall, J. D. Walter
An infrared line scanning system has been used to measure surface temperatures of automobile tires under operating conditions. A designed experiment was employed to demonstrate statistically the individual and interaction effects on tire temperature profiles of changes in tire speed, inflation pressure, and wheel load. These effects are different at different radial positions on a given tire and are quite dependent on tire construction, as illustrated by application to bias, belted-bias, and radial tires of comparable sizes.
1970-02-01
Technical Paper
700474
N. M. Trivisonno
A complete steady-state thermal analysis was made for a rolling passenger tire. A numerical network analysis was used which involved the solution of a set of simultaneous heat balance equations. Conduction within the tire, conduction to the road surface, convection to the contained air and to the surrounding air, and radiation from the outside and inside surfaces of the tire were taken into account. The experimentally measured infrared surface temperature distribution was used as input data. The results gave the complete distribution of temperatures and rates of heat generation in the tire. The calculated power loss and shoulder temperature of the tire agreed well with experimental results obtained on an indoor road wheel. Radial and bias ply rayon tires of equivalent size were compared. The radial tire ran cooler and had lower power loss.
1970-02-01
Technical Paper
700473
John E. Corl, Chester F. Schwall
Recently, a unique image derotator has been developed which will permit a continuous stationary view of a tire actually moving at very high angular velocities. This device, called Spinvision, has been combined with a special infrared camera and monitor which allows engineers to observe instantaneous change in the heat patterns on the surface of a rotating tire. With conical mirrors around the tire, almost the complete surface may be studied, under loaded conditions, at speeds in excess of 150 mph. The intended application of this equipment is to locate potential faults in tires, while they are originating, instead of depending upon post-failure examination for analysis. It may also be possible to explore the relationship between heat patterns and tire wear, and tire uniformity.
1970-02-01
Technical Paper
700513
R. R. Svenson
Truck air brake performance at low operating pressures is important to the owner because it represents the service range representative of the greatest amount of use. This paper presents the factors involved and the results to be expected from the most commonly used brakes on line haul trucks in current use. Included are representative input-output curves of the brakes. From a safety standpoint maximum performance at rated load is of paramount importance but service life is determined by balance at low operating pressures.
1970-02-01
Technical Paper
700512
Robert J. Morse
The role of air brake system pneumatic pressure and time differentials in total vehicle brake system performance is discussed. The magnitude of pressure differentials for typical air brake system valves is shown and the significance of both ascending and descending differential discussed. Transmission times for typical combination vehicles are shown and the effect of both pressure and time differentials at various axles on the proportioning of brake system work is developed. A number of means to deliberately unbalance pneumatic systems to compensate for unbalance in other components and thereby achieve better total brake system balance are discussed.
1970-02-01
Technical Paper
700515
Bohyun Yim, George R. Olsson, Peter G. Fielding, Glenn G. Balmer
The dynamic equations for an automobile in braking maneuvers are simplified in two steps. First, a nominal rectilinear trajectory is considered, with a constant deceleration rate. Secondly, a small perturbation in sideslip angle is examined, and the small disturbance equations of motion are derived. Solutions are obtained in terms of Bessel functions. The vehicle response is deemed stable when initial perturbations to the nominal trajectory are damped, and the perturbed motion is oscillatory. Algebraic expressions for the stability criteria are derived, illustrating the effects of speed, road frictions, tire slip-ratio, and vehicle design characteristics on vehicle response in braking maneuvers.
1970-02-01
Technical Paper
700514
James E. Nelson
An effort was made to evaluate accurately truck air brake performance balance at low application pressures by means of comparing drum temperatures. This procedure produced excellent results, and is a fast, practical method for evaluating brake performance of combination vehicles. The drum, hub, and wheel assemblies used in this evaluation were all the same type and weight. The s-cam used was a 16-1/2 X 7 in. and the wedge was 15 X 7 in. Mixed combinations of these types were tested. It was found that s-cam brakes are more effective when used on drive axles than when used on trailing axles. A tractor protection valve with a built-in pressure increase of 33% to the trailer brakes was installed to compensate for the more effective drive axle brakes and this provided the desired braking balance.
1970-02-01
Technical Paper
700516
George R. Olsson, Peter G. Fielding, Glenn G. Balmer
An evaluation of the applicability of braking control systems for highway vehicles was carried out. Elements of the study included development of a theory of vehicle response in braking maneuvers, design of logic for a braking control system, incorporation of the control in a hybrid computer simulation of a motor vehicle, and evaluation of control system performance. Benefits of braking control systems are illustrated in terms of improvement in stability characteristics (rear-wheel control) and in directional control (four-wheel system).
1970-02-01
Technical Paper
700504
RICHARD W. HILDEBRANDT
The braking system presented in this article represents a new and forward thinking philosophy regarding commercial vehicle air brake systems. A concept that provides responsive service and emergency brake applications with optimum vehicle control, by the same driver action on the brake pedal. The uniqueness of the total system, and each circuit's function thereof, is explained in basic detail. In addition, the engineering, quality control, and assembly techniques to manufacture the vehicle with assurance that design intent is achieved, are discussed.
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