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The question as to whether a part should be made or bought is one that must be settled by the individual maker according to the value of his product, the nature of the part, his capital available for manufacturing purposes and the price at which his product is sold. The author describes the practice followed by some of the large companies, showing that in spite of their being quantity producers, they have found it desirable to buy a number of important parts. Certain parts are rarely made by automobile manufacturers, either because they can be bought more cheaply or because the machinery to produce them is intricate. The author sums up the problem by stating that a manufacturer makes the unit on account of not getting deliveries or because he does not get a fair price from the parts maker or an article good enough to satisfy his conditions. In order to give individuality to the product, the car maker often produces certain parts, such as the engine, himself.

The author limits his consideration of rear axles to that of the bevel-gear type and takes up the subject under the heads of load-carrying member, gearing, driving-shaft, brakes and materials. Several different forms of cast and pressed axle housings are briefly described. Mention is then made of the axle gearing and data given showing the end thrust for straight-tooth bevel pinions. The methods of supporting pinions and of attaching bevel gears to the differential are discussed. Forms of differentials are considered, several different conventional types being illustrated. The subject of driving shafts is briefly reviewed, as is also that of brakes and brake materials. The author concludes his paper by figures showing the tensile strength, elastic limit and elongation of the metals used in the various parts of the rear axle and also explains some oil-retaining and dust-protecting features of design.

In this paper the author gives the results of an investigation of coarse crystallization. This investigation was carried out with commercial materials such as cold-drawn wire, hot and cold-rolled sheet, strip steel, cold-drawn tube and cold-pressings. The results of other investigations are briefly outlined. Coarse crystallization, or grain-growth, it is stated, is due to the action of a limited amount of strain, exceeding the elastic limit, followed by annealing within certain temperature ranges. The experimental work which led to this conclusion is explained in detail in the paper. The effect of forging, cold-drawing, cold-rolling and cold-pressing was determined with commercial materials. Some study was made of the effect of carbon on grain-growth and of the effect of coarse crystallization on the physical properties. In the discussion of commercial materials special reference is made to those used in motor car construction.

The author outlines the factors leading to the present high cost of automobile fuel, states that the introduction of new distillation processes will not solve the problem, but that the development of kerosene-utilizing appliances will produce results satisfactory to everybody. It is stated why kerosene cannot be used on the present gasoline cars. The adaptation of the gasoline automobile engine to the use of heavier fuels than will vaporize without the use of heat is entirely a problem of heating and heaters. The author reviews at length the principles embodied in and the construction of the heated vaporizers or vaporizing heaters now used in stationary and traction kerosene engines and in alcohol engines, giving illustrations of a number of such devices. After thus developing what in his opinion are desirable and good principles, the author describes a form of vaporizer embodying such principles, which he states has had successful trials (both block and road) in automobile service.

Perplex and difficult of solution are many of the new administrative problems which appear in the marketing of commercial cars. This is particularly true on account of the transition taking place in the industry, from the manufacture of pleasure cars to the production and application of the commercial type to economic service, and administrations are suddenly confronted with realization of the necessity for entirely different methods of operation, if not a completely different fabric of organization. The characteristics of the commercial line are in radical contrast with the pleasure car business, the inception and purpose of the one being so different from the other as to render obsolete many of the formulated practices heretofore in vogue, conspicuous among which is a too complete reliance upon the individualistic function performed by the salesman.