448 



THE INDIA RUBBER WORLD 



[May 1, 1917. 



The influence of inflation pressure is clearly shown in curve A, 

 which represents the rolling resistance of the rear wheels under 

 normal load with fabric tires. With reduction of inflation pres- 

 sure from 80 to 30 pounds the rolling resistance increases from 

 30 to 45 pounds. 



When the load on the wheel was reduced, the rolling resistance 

 decreased from 30 to 25 pounds under high inflation pressure. 

 Reduction of pressure caused an increase of resistance in this 

 case, but not quite as pronounced as in the first curve. Curve B 

 shows the rear wheel resistance under light load. 



Curve C shows the resistance of the front wheels under load 

 equal to that on the rear, and displays the same characteristics 

 as curve B. The uniformly greater resistance of curve B is due 

 to the transmission system connected with the rear wheels. 



An approximate calculation of the increase of power caused 

 by under inflation can be made from the above experiments. 

 From the diagram the total rolling resistance at 80 pounds pres- 

 sure, front and rear wheels combined, is 51.9 pounds, while the 

 corresponding value at 30 pounds inflation is 72.5 pounds. Add- 

 ing to these values the wind resistance calculated for 25 miles 

 per hour (30 pounds), the total car resistance for the two cases 

 is found to be 81.9 and 102.5 pounds. The conclusion is that an 

 increase of power amounting to 25 per cent may be caused by 

 very much under-inflated tires. 



CORD VERSUS FABRIC TIRES. 



Only a limited number of tests of cord tires have been made 

 under conditions permitting accurate comparison with fabric tires. 



One such comparison is shown on the diagram, curve D, 

 where a cord lire, 32 by 4, was tested under exactly the same 

 conditions on the front wheels for the whole range of pressures. 



The characteristics of this cord tire are, greatly reduced re- 

 sistance loss and ability to run at low inflation without much 

 increase of resistance. 



While these experiments point to the value of cord tires for 

 reducing tire losses, more numerous and exhaustive tests are 

 required covering a wider scope. 



S. A. E. HAS A KEW MEANING. 



On April 19 the Society of Automobile Engineers became the 

 Society of Automotive Engineers, as a result of the amalgamation 

 of the membership of the American Society of Aeronautic 

 Engineers, the Society of Tractor Engineers and engineers ot 

 company members of the National Association of Engine and 

 Boat Manufacturers. "Automotive" is, in a sense, a new word 

 made necessary to describe comprehensively the various forms 

 of self-propelled mechanical apparatus, such as aircraft, water- 

 craft, passenger and freight motor cars and tractors of various 

 types. This word, which is sound etymologically, has been under- 

 stood and accepted by the public with surprising rapidity in view 

 of its novelty. Both the words "automotive" and "engineer" are 

 very emblematical of modern progress and of the most advanced 

 types of transportation in peace or war. 



A Washington office of the society will be opened in the 

 Munsey Building in connection with the Council of National 

 Defense as soon as arrangements can be made. This action was 

 brought about by the closer co-operation of the society with the 

 various Government departments, which work is increasing 

 every day. 



The society has been active in classifying its membership as to 

 capability for Government service industrially or with the troops. 

 Over two thousand of the members have filled out blanks indi- 

 cating their experience in designing and producing engines and 

 other parts for airplanes, motor trucks, watercraft of various 

 types, tractors and munitions. Three or more grades of men 

 have been classified according to the following callings : Chief 

 engineers, assistant engineers, draftsmen, electrical engineers, 

 superintendents, metallurgists, inspectors, apparatus testers. 



laboratory engineers, truckmasters, purchasing agents, service 

 men, tool designers, executives, chemists and fuel and lubricant 

 engineers. Trained in the highest speed industry the world has 

 ever known, to get results without precedent as to equipment, 

 material or time available and to assume large responsibilities, 

 the members of the S. A. E. are well qualified to solve any auto- 

 motive problems on which the Government may desire assist- 

 ance. They are quite ready and willing to do anything that will 

 assist the United States, serving in any capacity in which their 

 country may see fit to use them at any time. 



Because of war conditions, the summer meeting of the society, 

 scheduled to be held the last week in June at Ottawa Beach, Lake 

 Michigan, has been called oflf by the Council of the society, it 

 having been found that each day finds the engineers more and 

 more engrossed in war activities, and correspondingly fewer of 

 the members with spare time for such a meeting. Instead of 

 four days at Ottawa Beach it has been decided to hold a one- 

 day meeting in Washington, D. C, on June 25. Washington was 

 selected because many Government departments are closely as- 

 sociated with the work of the society. 



The United States War Department, as a result of collaboration 

 with the Society of Automotive Engineers, has revised its speci- 

 fications for military motors, on a more practical basis, and less 

 severe in several unimportant details. For the lj4-ton trucks 

 the specifications call for 36 by 4 inch demountable tires. 



TIEE PRICES ADVANCED. 



The expected advance in tire prices has arrived. For the 

 second time since January 1, the manufacturers have felt the 

 necessity of marking up their price schedules, on account of 

 the extra cost of materials and labor. In January, tire prices 

 were increased, about 10 per cent on casings and 5 per cent on 

 tubes. The difficulty of securing raw cotton of proper quality 

 and consequent high cost of tire fabrics, is given as the principal 

 cause of present increase. Crude rubber prices have been high, 

 but not enough to greatly increase manufacturing cost. 



The various companies have acted independently in this ad- 

 vance, but in nearly every case the increase is around, or exactly 

 10 per cent, and this rate applies to both tubes and casings and 

 to all kinds, including Ford sizes, pneumatic, motorcycle and 

 solid or truck tires. The variations from this 10 per cent include 

 Firestone tires, some of which have advanced 1234 per cent, and 

 Goodrich Q. D. ajid Silvertown tires, 15 per cent. Meahanical 

 goods have also advanced 10 per cent. 



AMERICAN TIRES IN BRAZIL. 



.■\merican tire manufacturers lead in the exports to Sao Paulo, 

 according to the commerce reports. Before the war, France 

 supplied most of the tires used in this market, while United 

 States exports were less than 5 per cent. In 1915 Italy led, but 

 had to cede her place to .America in 1916. 



The imports of pneumatic tires for the three years preceding 

 1916 and the first nine months of 1916 were: 



Jan. 1 to 

 Sept. 30, 

 Country of origin. 1913. 1914. 1915. 1916. 



Belgium $62,157 



France $1S8.330 167,363 $38,957 $46,156 



Germany 34,649 23,330 



Great Britain 777 21,510 2.702 111 



Ttalv '46.188 8,559 186.899 166.007 



United States 11,240 .9,015 165,536 221,257 



.MI others 376 2,416 



Totals $281,560 $294,350 $394,094 $433,531 



It is understood that by a recent agreement between the rep- 

 resentatives of certain American manufacturers and European 

 factory agents, tire prices in Sao Paulo, as in Rio de Janeiro, 

 will be maintained on a fixed non-competitive basis. There is 

 a small local production of solid tires, but as the work is done 

 chiefly by hand the industry cannot yet compete with the imported 

 article. 



