June 1, 1919.] 



THE INDIA RUBBER WORLD 



Tires combining extreme lightness with toughness and resili- 

 ency had thus been the early desideratum, but, with heavier 

 and more powerful machines, maximum cushioning ability to 

 resist the lateral thrusts that occur when an airplane side-swipes 

 the earth in landing, became fully as important as light weight, 

 so that large cross-section was essential. As early as 1909 

 Palmer cords had been made up to 7-inch cross-section, and in 

 1915 a new Goodyear airplane cord tire was brought out in 

 America to meet this need. It was a 26 by 4 clincher with a car- 

 cass consisting of four to six-cord fabric layers. Since that 

 time developments have been rapid, owing to the impetus of 

 war, and various companies have been producing airplane tires 

 of ever larger diameter and cross-section as the needs of the 

 Government have advanced. 



It is a far cry from the frail airplane wheels and small tires 

 of 1910 to these giant wheels and Palmer cords with their canvas 

 shields to prevent wind resistance to the turning of tlie wheel 

 as a result of cross drafts through the spokes, but as the develop- 

 ment of aviation has been phenomenal and revolutionary, so also 

 has been the achievement in tire building. Indeed, the latter 

 has been a big factor in making the former possible. But for 

 cord-tire construction, the airplane might not be what it is to-day. 

 and it is a matter worthy of more than passing mention that the 

 Palmer tire, the pioneer in its class, still heads the list of 

 progress. 



of wheels; (5) limitations imposed on the size of brakes, due to 

 the small size of wheels. 



The larger sections used in these tires, together with the space 

 taken up by the demountable rim, leave a very small wheel 

 diameter, and this imposes severe limitations on the size of brake 



PNEUMATIC TIRES ON TRUCKS.' 



FOR vehicles up to 1,500 pounds capacity, inclusive, pneumatic 

 tires should be used except under very rare conditions. Ve- 

 hicles of 2,000 to 3,000 pounds capacity are being rapidly changed 

 to pneumatic equipment in the large majority of cases, due to 

 the development of the cord tire. A considerable percentage of 

 2 to 2^-ton vehicles will probably be placed on pneumatic equip- 

 ment when the subject has been more clearly demonstrated and 

 design changes which may be found necessary have been made. 



A limiting factor to the preceding statements is to be found 

 in the character of roads on which pneumatic equipment is 

 operated, and the freedom of the roads from litter of scrap- 

 metal, glass, etc. 



The modern cord tire is excellent for operation on almost 

 every kind of road. The structural strength of these tires ren- 

 ders them less susceptible to injury from stone bruises, etc., 

 when operated on rough roads, if the proper inflation pressures 

 are used, than the fabric type. The types of tread which have 

 been developed are of great assistance in snow and mud and on 

 wet surfaces. In consequence, with these advantages, it is safe 

 to say that the pneumatic tire will compare favorably with the 

 solid tire under almost every condition of road. 



ADVANTAGES OF PNEUMATIC TIKES. 



The claims of advantage may be listed as follows: (1) reduc- 

 tion in mechanical repairs; (2) increase in permissible speed; 

 (3) decrease in gasoline consumption; (4) decrease in oil con- 

 sumption; (S) less fatig-ue for men; (6) lessened depreciation 

 of roads ; (7) greater tractive ability. 



OBJECTIONS TO PNEUMATIC TIRES. 



The objections to pneumatic tires are not so numerous, but 

 need careful consideration lest the prospective buyer be carried 

 away with the idea that their use offers a solution for all trou- 

 bles, and involves no special problems needing attention. The 

 objections are: (1) high initial cost compared with solid tires; 

 (2) the need of carrying emergency equipment; (3) the diffi- 

 culty attendant on making road changes due to weight and high 

 inflation pressures required; (4) reduction of the high-gear 

 ability and limitation of the total ability due to larger diameter 



'Abstract from a paper by B. B. Bachman, published in "The Journal of 

 the Society of Automotive Engineers," April, 1919, pages 298-302. 



12-Inch Cord Truck Tire on Rear of Trailer. 



equipment and decreases the ability of the brakes at the same 

 time. This is very important because the greater speeds put 

 considerably heavier duty on the braking systems. 



The heavy duty pneumatic tire, particularly in the larger sizes, 

 has come into prominence in the last few years when engineers 

 were so completely occupied as to leave little time for the thor- 

 ough investigation of the subject to determine what effect their 

 use would have on future design. That there will be need of a 

 considerable change in design with respect to some particulars 

 seems very evident. 



The increase in speed carries with it a demand for more ef- 

 ficient brake equipment. Inasmuoh as air pressure will be needed 

 to inflate the tires, calling for an efficient air compressor, it 

 may be found feasible to add the other elements necessary to 

 provide for the use of air brakes. 



PRACTICAL TEST. 



A leading American tire manufacturing company is manufac- 

 turing a cord construction pneumatic tire of the straight-side 

 type which has proved a successful commercial proposition. 



A fleet of five-ton trucks last year made a successful trip from 

 Boston to San Francisco on 40 by 8-inch front and 44 by 10- 

 inch rear pneumatic tires. This trip was made in 257 hours and 

 10 minutes running time at an average of slightly over 14 miles 

 per hour, a full load being carried all the way. The trucks at 

 the end of the trip were in excellent condition and the whole 

 performance was rendered possible by reason of freedom from 

 vibration troubles resulting from the cushioning qualities of the 

 big pneumatic tires. 



GENERAL ELECTRIC CO. ELECTS DIRECTORS. 



The General Electric Co., Schenectady, New York, at its 

 meeting held May 13, 1919, elected the following directors : 

 Gordon Abbott. Oliver Ames, George F. Baker, Jr., Anson W. 

 Burchard, C. A. Coffin, George P. Gardner, Henry L. Higgin- 

 son, Robert Treat Paine, 2d, Marsden J. Perry, Seward Prosser, 

 E. W. Rice, Jr., Charles Steele, Philip Stockton, and B. E. 

 Sunny. 



