13. The principle as applied to delivery systems.— That the tendency with large companies is toward a standardization of their delivery and office equipment no less than of their production machinery, is shown by the following advertisement: Another big order for — trucks was placed yesterday— an order for ten from the Long Island Express Company. This concern already has ten — trucks, purchased on Jan uary 31, 1911. The reorder makes twenty of them, all told, $72,000 in — trucks.
Rather significant is this order. When a big company invests as much money as this in one manufacture of truck, its own answer to the motor-truck question is clear.
But consider for a moment what other express companies have in the way of — trucks : American Express Com pany, 27 ; Westcott Express Company, 11 ; Adams Express Company, 4.
These three express companies have an investment in — trucks of $161,000. Four companies, all told, total $233, 600 in trucks, an investment that is greater than the capital of many motor-truck manufacturers.
14. Interchangeable ,parts.—More important than the number of designs is the matter of standard or in terchangeable parts, both of the same machine and of the machines of an entire line. Mr. C. U. Car penter, in his "Profit-Making Management," sum marizes as follows: The great advantage of standardized products is, of course, apparent. It means cheapening production thru duplication of parts and ease of handling; increase of output per square foot of floor area thru quicker production, and the consequent reduction in indirect expense per piece ; the possibility of building for stock in slack times and so keeping up the factory output ; quicker deliveries and more orders, better satisfied customers, and a more rapid turning over of working capital.
The differences in legs, screws, pins and other un important parts of machines are largely the result of the individual designer's whim, and should be obvi ated. The Engineering Standards Committee of the Institution of Civil Engineers discovered in their in vestigations that a large part of the differences in British rolled sections had been deliberately intro duced by the manufacturers, so that duplicates and repair parts would have to be ordered from the origi nal maker; and that, instead of having the desired result, this action, because of the need of special tools and dies and the expense of changing rolls, had so in= creased production costs that the American and Ger man plants were gaining the trade by underselling.
VVhere small parts are standardized, the need of con tinually redesigning them is eliminated and conse quently the designer can concentrate his skill on the essential elements of the problem.
15. Importance emphasized by Whitmore, 1841.— The importance of interchangeable parts was first emphasized by Joseph Whitmore in his paper, "A Uniform System of Screw Thread," read before the British Institution of Civil Engineers in 1841. Such a system was first generally adopted by American watch manufacturers. During the middle of the last century some of these manufacturers made a lasting impression on foreign engineers by dismantling two watches, mixing the parts with similar unused stock parts and then reassembling the watches as the for eigners handed them the parts, selected at random. Similar astonishment has been occasioned in more re cent times by certain of our automobile makers, who performed the same severe test; they dismantled a car after a long run, mixed the parts with similar stock parts and after reassembling them made another long run.
16. Use of "limiting dimensions."—To insure the fitting together without any filing of parts which have been made by different workmen, the system of "limiting dimensions" has been developed. This sys tem provides that important dimensions shall be marked in an appropriate manner as to the maximkim variation allowable if the part is to match with its neighbors. The workman thus knows where special accuracy is required, and is supplied with limiting gauges for testing his work.