Search Results

An interdivisional organization has been formed within General Motors to supply special information to assist in the development of friction materials. People with special talents from nine different divisions of the corporation have been active contributors in the exploration of 33 special projects by this organization, which has been called the “Beta” Group. From these projects have come new procedures, new devices, and new information which should be helpful to chassis engineers and development people who are interested in brake lining improvements.

The experimental program described here was conducted in order to determine the effect of fixed and variable steering gear ratio on driver task performance. Three fixed gearbox ratios and two variable ratios of the Bendix Varamatic type were tested, using a single vehicle. Four steady turn driving tasks were used, each producing the same lateral “g” (0.2g) and a transient maneuver task, induced by applying a step change in front wheel angle to the vehicle, was also used. The pool of test subjects consisted of student drivers with an average of 39 hr of on-the-road driving experience.

Disc brakes and modulating valves work together to improve the stability of a car during braking. This fact, as well as the increased possibility of braking control, comprise the main reasons for the tendency of European manufacturers to employ four disc brakes and modulating valves in their cars. Floating and fixed calipers are both used, but the first category has advantages which seem conclusive for the future. The next step could be the use of antiskid devices, the object of considerable research efforts, none of which has given any conclusive results to date.

An experimental-analytic method of determining the stress distribution in narrow faced spur gear teeth is presented. The successful application of photostress to this contact problem is reported. It utilizes a digital computer routine developed for separating stresses in any general two-dimensional region. Results for two pairs of gears are presented. Comparison is made with values predicted by the modified Lewis formula, the Kelley and Pedersen equation, and by the Belajef solution of the Hertz contact problem for two cylinders.

It is necessary to consider the brake lining and brake drum as a mating pair for optimum performance. Some of the characteristics of brake linings, the interrelationship of the brake drum, and their combined effect on certain aspects of brake performance are discussed. Temperature, rubbing speed, unit pressure, and mating surface material are factors affecting the coefficient of friction of the lining. Brake maintenance also affects the operation of the lining as well as the entire brake system. By understanding the various properties of linings and drums and the concept of mating pairs, certain compromises can be reached which offer optimum performance for a specific set of operating conditions.

Brake drums and brake linings work together to control vehicle deceleration. The best brake drum material is fully compatible with the various linings made by reputable manufacturers. Brake drum size and shape can be varied to provide adequate resistance to mechanical and thermal stresses while effectively storing and transferring heat to the atmosphere.

Five test devices were developed to aid in the development of new friction materials. A friction machine has been equipped with disc brake apparatus and the data compared with standard drum friction machine data. A method has been developed which utilized fast response thermocouples to measure interface temperature distribution during dynamometer tests. Extremely high temperatures have been noted. Three laboratory tests were developed to evaluate brake materials' susceptibility to produce noise: vibration tests to measure dynamic characteristics; friction machine tests to measure negative damping; slip-stick machine tests which use the lining's noise producing tendency to excite a resonant system. Correlation of these tests with vehicle data were investigated and are discussed in the paper.

Findings obtained through mass diagnosis provide a practical insight, useful in the development of: multiple personnel work procedures, efficient facility layout, testing techniques that answer field service problems, equipment and personnel education that implement these techniques, and solutions to novel architectural problems inherent with indoor vehicle operation. New lower cost equipment permits reasonable amortization with lesser vehicle through put. Capabilities of the Lane and Bay type facility are also compared. A highly coordinated system, including management, personnel, building area, and machines offer a solution to the routine detection of the exact cause of existing or potential vehicle problems in both small to large operations. Reliable diagnosis provides the opportunity to recommend specific repairs and in an order of urgency.

Infrared and gas chromatographic techniques are capable of yielding compositional data on the organic constituents of brake linings. Examples will be given relating such compositional data to the state of cure of the resin binder, to the presence or absence of specific organic friction modifiers, and to determining whether or not the proper resin binder system was used. The success of the above techniques in the solution of specific brake lining problems does not necessarily recommend them as quality control tools.

This paper explains the background of the Concord engines and how a design specifically for civil operation has been derived from a military supersonic engine. It reports a study of the failure pattern of current engines, which shows that the traditional approach to reliability must be extended by all means available. Reference is made to the application of the disciplines of reliability engineering and the special design features to assure safety and reliability. The test program and some of the special test equipment required for a supersonic engine are described.

The benefits provided by phosphate coatings in reducing wear are ascribed to the controlled etching of the surface subjected to wear. Through tests it appears that the manganese phosphate coating is the most effective application, the reason being the number of larger pits formed by manganese phosphate and the greater amount of phosphate retained in these pits. Chemical reactions involved in the production of these coatings are reviewed together with a comparison of the reactions involved in some of the common phosphate coating baths. The effect of treatment of metal surface prior to coating and the type of coating bath used are compared by examining the coatings as produced and after burnishing. These coatings have been reported to provide wear resistance by removing surface irregularities after machining and lapping, increasing lubricating efficiency, and preventing welding under loads.

To meet the increased power demands for special vehicles, Daimler-Benz started the development of a compact, liquid-cooled diesel engine family some 12 years ago. The objective of this development was to obtain a maximum output from a given bulk volume while maintaining well-known diesel engine characteristics. The basic layout of this family was such as to offer a high degree of versatility and to allow continued development. Based on this existing engine family, the development of a 1500 hp engine was started about three years ago. Reducing the bulk volume and, at the same time, increasing the specific output, resulted in a very compact engine, producing 28.4 hp per cu ft of bulk volume. This paper presents some of the considerations made in the design of these engines and some interesting technical data.

The radiator in today’s internal combustion engine has many functions in addition to its primary job of cooling the engine. The name “radiator” is a misnomer since its function is that of a heat exchanger that transfers heat by means of forced convection. Considerations involved in radiator design depend upon functions performed by the radiator, space available for its installation, the environment in which it must operate, and basic economics. Presented in this paper are design details pertaining to methods of construction, kinds of materials used, and types of fins and core designs. Other factors to be considered are necessary coolant reserve, deaeration, use of pressure caps, and types of mountings. All these factors must be considered but practical limits as to space and cost often cause decisions to be made to the detriment of any one particular function.

The author presents a brief description of a present day automotive ignition system with an explanation of its various components. The moving parts of the ignition system such as the distributor shaft which is driven from the cam shaft, centrifugal weights which move the cam, vacuum advance mechanism, and rubbing block with breaker points and rotor can and will be eliminated with the aid of solid state electronics. An analysis of the ignition coil and factors influencing its design as well as its vital part in the present-day system is reviewed. Also mentioned briefly are the transistor system and capacitor discharge ignition system and their current state of application. It is believed that solid state devices and integrated circuits will develop greater reliability and greater cost advantages for the consumer.

In the case of small, lightweight aircooled engines the fin design is of utmost importance. The basic consideration is to make maximum use of the material in the cylinder to obtain maximum heat transfer for minimum material used. The trapezoidal fin approaches the ideal construction and is more effective than either the rectangular or triangular types. The author illustrates how thinner fins mean better utilization of material, together with an additional advantage in that cooling surfaces are doubled and the amount of heat transferred is increased. An important point to be considered is the spacing of the fins so that airflow is not reduced between them. Finally, provisions must be made for the disposition of foreign materials, which may block airflow, if the engine is to operate in a dirty environment.

The rapidly increasing number of passenger car trailers using public highways has focused attention on trailer brake systems. One of these systems, the surge or momentum actuated type, has received particular attention because it offers automatic trailer braking inherently synchronized with different deceleration rates of the towing vehicle as well as with different gross trailer weights. This system presents new considerations that must be evaluated in establishing overall system performance and extent of application. This evaluation is described here.

The laboratory evaluation of brake lining materials at General Motors Engineering Staff is discussed. Physical aspects that may occur during test which were of concern are swell, shrinkage, blistering, extrusion, and sloughing. The friction materials test machine and test procedures are described. Frictional characteristics considered in the testing are friction level, uniformity of output, shape of family curves, fade, fade and recovery, and resistance to moisture. Test results are presented in the form of sample plot sheets of good and poor lining performance. Good linings showed fairly uniform coefficient of friction and consistent grouping of the family curves, in contrast to the excessive spread and erratic values of the poor lining example.

In order to maintain designed mating compatibility of brake drum and lining, we rely on assistance from the field maintenance personnel and the vehicle operators. Specifically, they must recognize environmental and mechanical conditions that prevent the compatibility of the brake lining and brake drums and based on their all around knowledge of braking fundamentals and experience correct these conditions. This paper covers: theoretical braking concept; internal conditions contributing to noncompatibility of drum and linings; foreign conditions contributing to noncompatibility of drums and linings; corrections.

A new concept in nickel plating is described. The process produces a low gloss finish through the co-deposition of inorganic particles in the nickel deposit. The process is discussed from the standpoint of bath composition, process control, corrosion protection, instrumentation for quality control, and special processing techniques. The low gloss nickel coating provides a method of meeting the requirement for a low specular gloss electroplated finish on certain automotive

This paper explains the reflectance characteristics of anodized aluminum and describes the finishing treatments which produce the desired low glow appearance required by The Proposed Federal Motor Vehicles Safety Standards. Certain of these low gloss producing treatments are easily incorporated into existing finishing lines and in many cases are more economical to apply than the present bright specular finish. The materials and processes used to satisfy this proposed standard are discussed fully.