Large Tires Research Articles

On the spatial spread and oligopolistic behavior of large rubber companies

Little attention has been given to the spatial selectivity implicit in the decision-making processes of multinational companies. After reviewing the two major models explaining foreign direct investment, empirical regularities are detected in the spatial behavior of large rubber and tire companies, with regard to product lines, locational distribution and plant size. Some proof of “oligopolistic reaction” can also be seen in the spatial growth process of these firms over time.

Chronic Diseases in the Rubber Industry

An overview is presented of epidemiologic studies of chronic diseases in the rubber industry. Analyses of the mortality experience during the period 1964-1972 of workers age 40–64 and retirees age 65–84 of two large rubber and tire manufacturing companies consistently disclosed excesses of deaths attributed to leukemia and lymphosarcoma, and for cancers of the stomach, large intestine, and prostate. The relation of site-specific malignancies to work histories and grouped occupational titles as surrogate measures of work-related exposures to possible carcinogens is described. There was no evidence of company-wide, sizable, consistent excess for the other major chronic diseases causes of death. Although a total cohort deficit in the mortality rate for lung cancer was found, there was a history of increased frequency of exposure to certain work areas among lung cancer decedents. Morbidity studies, including analysis of disability retirements, and ad hoc questionnaire and health testing surveys, disclosed excesses of chronic pulmonary diseases. There was evidence of an interactive effect in the association of work and smoking histories with pulmonary disability retirement.

Chronic diseases in the rubber industry.

An overview is presented of epidemiologic studies of chronic diseases in the rubber industry. Analyses of the mortality experience during the period 1964-1972 of workers age 40-64 and retirees age 65-84 of two large rubber and tire manufacturing companies consistently disclosed excesses of deaths attributed to leukemia and lymphosarcoma, and for cancers of the stomach, large intestine, and prostate. The relation of site-specific malignancies to work histories and grouped occupational titles as surrogate measures of work-related exposures to possible carcinogens is described. There was no evidence of company-wide, sizable, consistent excess for the other major chronic diseases causes of death. Although a total cohort deficit in the mortality rate for lung cancer was found, there was a history of increased frequency of exposure to certain work areas among lung cancer decedents. Morbidity studies, including analysis of disability retirements, and ad hoc questionnaire and health testing surveys, disclosed excesses of chronic pulmonary diseases. There was evidence of an interactive effect in the association of work and smoking histories with pulmonary disability retirement.

Improved technological process for forming tread patterns in dies for vulcanizing large tyres

Improved technological process for forming tread patterns in dies for vulcanizing large tyres

29—FURTHER EVALUATION OF THE PROPERTIES AND PERFORMANCE OF LARGE NYLON 6.6 TYRE CORDS

An account is given of the properties and performance of large nylon tyre cords, and, as in an earlier paper, a description is given of laboratory experiments designed to increase knowledge of the performance of these cords in the light of experience of smaller, more conventional, cords. Various greige cords of up to 30,000 denier (3,333 tex) were produced, to a constant cord angle, on a conventional downtwisting machine. The strength, linear density, tenacity, extension, modulus, and heat contraction were determined for the greige cords, which were then dipped and hot-stretched on a Litzler Computreater by both the constant-tension and the constant-stretch principles. After this, the cord properties were again measured and compared for the two techniques. In addition, the tensions required to combat shrinkage at a range of temperatures were measured for these hot-stretched cords. The parameters specific adhesion, equivalent adhesion, and adhesion efficiency are defined, and values of these parameters for...

Fundamental Characteristics of Single-Track Vehicles in Steady Turning

In equations of equilibrium, amounts of the tyre tread radius, gyroscopic couples due to wheels and engine as well as special properties of conventional models which have a large angle of lean and a small steering angle in rounding a curve are taken into account. And both results of calculations and experiments are well agreeable with each other. The angle of lean is always greater than the balancing angle of gravitational and centrifugal force. This is due to effects of large tyre tread radius and low position of mass centre. Moreover, the gyroscopic effect of engine is considerably intensive, especially in lower gear. The main reason why the motor-cycle has the property of oversteering is in the geometrical relation of the steering system. The side slip angle of tyre in single-trackers takes a far smaller value than that of four-wheeled vehicles.

The Diffusion of Sulfur 35 in Rubber. Effect of Carbon Black Loading on Sulfur Migration from the Breakers in Large Tires

Abstract This work had two principal objectives; in the first place, to make a contribution to clarifying the dependence of the diffusion characteristics of sulfur in rubber upon the carbon black concentration in the compound and secondly, we attempted to study the process of diffusion in vulcanized large pneumatic tires, using two different procedures with special experimental conditions. It may be assumed that the physical processes which lead to the diffusion of one material in another are basically well known. Work by Fick and by Langmuir and Dushman, among others, is especially valuable in explaining the diffusion process. while the first studies of diffusion of sulfur in rubber used optical methods, the application of sulfur 35 has been stressed for this purpose in the last few years. Auerbach and Gehman were first to use such a procedure. They, as well as Bresler, Prjadilowa and Chainman, followed the migration of sulfur into rubber during the diffusion process. The latter authors worked at technically interesting temperatures, from 130° to 150° C. Diffusion coefficients calculated from the experimental data were in the range 1.9×10−7 to 1.6×10−6 cm2/s. Studies by Mozisek and also by Ludwig represent more recent work in the field of sulfur diffusion. Ludwig used a different method than the preceding authors. After the test specimens were vulcanized, they were cut into thin slices with the microtome and the radioactivity which was present in the slices was determined. The excellent and detailed books by Jost, may be consulted by anyone with either a general or special interest in securing information in the field of diffusion.

The "Little Curette''

The little curette has proved to be helpful in the curettage of epitheliomas, particularly of the basal-cell type. After the usual curettement with standard-sized instruments, it is well to curette carefully and firmly the base of the lesion with a curette having a 2 mm.-diameter cutting edge. A slightly increased pressure on the base of the wound is advisable, so that the instrument will fall into a pseudopod of friable tissue should one be present. A larger instrument will generally miss a narrow strand of malignant tissue, and chances of recurrence would be increased accordingly. If the little curette should penetrate deeply, then decision regarding the further management of the lesion could be made with the reasonable assumption that pathologic cells extended beyond the main treatment site. The principle involved is quite simple—it is observed daily when we note that the large truck tire rides over a pot-hole in the

Domestic Natural Rubbers

IN late 1941 and early 1942 the Japanese obtained control of 97% of our natural rubber supply. The United States was fully awakened to the realization that it was critically short of a vital resource. The tremendous growth of the American synthetic rubber industry from a paltry 22,000 tons in 1942 to over a million tons in 1945 is, without a doubt, one of the greatest chemical engineering achievements of all time. Without it we could not have won the war. Both military men and rubber men are agreed on that fact. Adequate supplies of domestic natural rubber could not have been developed in time. However, although synthetic rubber proved very successful for small tires, a substantial amount of natural rubber was and is mixed with synthetic rubber to produce truck, bus, and large airplane tires. Indeed, we scraped the bottom of the natural rubber barrel throughout the war. The presence of a natural ...

Hysteretic and Elastic Properties of Rubberlike Materials under Dynamic Shear Stresses

Abstract The principal problem of the rubber technologist and engineer today is that of applying the various types of synthetic rubber to products which undergo rapid repeated flexure. All commercially available synthetic rubbers possess a greater hysteresis defect than does natural rubber. Hence, the task of designing a product such as a large truck tire, where heat development has been no small problem even with natural rubber, is much more difficult. Consequently, the accompanying problem of evaluating the hysteretic properties of rubberlike materials has assumed new importance.