648 



THE INDIA RUBBER WORLD 



of the core will accommodaic are built up in this way, when 

 the flaps are dusted with soapstone and turned back against 

 the body of the patch and the cloth wrapping applied. 



VULCANIZING. 



The assembled, cloth-wrapped patches arc now ready for vul- 

 canizing or curing, as it is commonly called. This is done in a 

 horizontal, open steam vulcanizer. The cores, with their as- 

 sembled and cloth-wrapped patches, are hung on stationary metal 

 rims within the vulcanizer and about 38 pounds of steam pres- 

 sure applied for 38 minutes. 



After the cloth wrapping is unwound the patches are stripped 

 from the core and dusted with soapstone, when they arc ready to 

 be marked and packed. 



ZWEBELU'S HINTS TO REPAIRMEN. 

 THE NON-SKID IMPRESSION PAD. 



The impression pad is used for retaining the non-skid pattern 

 on tires or for reproducing it on tread sections, etc. When the 

 non-skid pattern is being replaced, soapstone can be used to 

 fill with and good work obtained. However, there is no pressure 

 obtained by the use of soapstone, and for this reason the im- 

 pression pad is found to be the best. 



(1.) Pads are made to fit the molds, and are usually tlie length 

 of the mold. 



(2.) When applying the pad on the tire, place it beyond the 

 point of injury, and where the non-skid design is in first-class 

 condition. The pad can be tied on so it will adhere and not slip. 



(3.) When making an impression pad, make it right. Take a 

 ply of reclaimed fabric of the proper length and width. Buff 

 and cement the fabric and place on this two layers of 1/16-inch 

 tread gum, or more, if the non-skid is deep, and then cure. The 

 result is a strong non-chipable pad that will last for seventy-five 

 cures or more without losing the impression. 



(4.) Impression pads are inexpensive and better when re- 

 claimed fabric is used. Scrap, waste or dirty gum is used be- 

 tween the fabric and the last ply of gum coming in contact with 

 the tire. 



PNEUMATIC TRUCK TIRES WITHSTAND SEVERE TESTS. 



W. V. Logan of the United States Tire Co., in a paper read 

 before the metropolitan section of the Society of .Automotive En- 

 gineers in New York, May 12, 1920, on the development of the 

 pneumatic truck tire, told of some interesting experiments that 

 have been made. The story of the working out of the idea of 

 applying pneumatic tires to heavy trucks since it was first formed 

 in 1909, with the enumeration of the advantages to be gained. 



fF.M. 



formed the main portion of the address. .-M the close, Mr. Logan 

 showed in moving pictures exactly what takes place in a solid or 

 a pneumatic truck tire when subjected to excessive shocks and 

 strains. The tests were made at the truck tire factory of the 

 United States Rubber Co. 



••MI the trucks, except the S-ton truck in the gutter jump, were 

 loaded beyond their rated capacity; the speed was between 17 

 and 20 miles an hour. The platform from which they jumped 

 was IK- feet high. The deflectioii of the tires as they struck the 

 ground was 50 per cent of their cross-section diameter. 



The jumping truck weighted 10,800 pounds loaded, and the 

 tires used were six-inch in front and eight-inch in rear. The 

 same truck took gutter and curbstone tests as well as the jump 

 tests. In eight jumps there was not a blow-out nor tire trouble 

 of any kind, and after the tests the four tires were taken off and 

 dissected but not a break nor a scratch was found on the inside 

 of the casings. Moreover, after eight or nine jumps had been 

 made, all on the same identical spot, absolutely no harm was 

 done to the concrete road. It was found that the impact of the 

 pneumatic tired truck on the surface was two-thirds less than the 

 impact of a solid tired truck. 



DEVELOPMENT OF THE SIX-WHEEL TRUCK. 



P. W. Litchfield, vice-president and factory manager of 

 The Goodyear Tire & Rubber Co., expressed his views on 

 tires and their future at the dinner given by the company to 

 the Cleveland and Detroit sections of the Society of Automotive 

 Engineers at Akron, Ohio, in May last. After an interesting 

 review of the history of transportation, in which he showed 

 how .trcct-car. must ijivc wav I,, n„:„„- l„s,. and prophesied 



the disappearance of railroads, he turned to the question of truck 

 tires. He believes that the pneumatic-tired truck and the long- 

 distance truck can handle in the future the passenger and freight 

 business, now managed entirely by the railroads. Larger loads 

 and longer distances make possible an enormous increase in the 

 volume of the tnotor truck business, but the use of the truck 

 is very limited if solid tires are used, as greater speed and carry- 

 nig capacity are obtained with pneumatic tires. Larger units 

 must be employed; 3-ton and 5-ton trucks have been used and 

 the tires for 3-ton sizes are being rapidly changed to pneumatic 

 equipment. Largely as an experiment the .\kron-to-Boston ex- 

 liress was started, and it proved an excellent tire-testing experi- 

 ment. It was learned that while it is not difficult to make 12, 

 possibly 15 and perhaps 20-inch tires, it is questionable whether 

 they are the tires for this service. When considering 10 and 

 12-ton trucks it was found that the truck body and center of 

 gravity were too high. The remedy was to use multiple wheels, 

 that is, more than four, say six; four wheels have proved ineffi- 

 cient on European railroad cars as compared with American 

 freight cars, and that holds good for motor trucks also. The 

 truck should be on tandem wheels and not on twin tires on the 

 same wheel and the riding quality and carrying conditions will 

 be better. By putting the extra wheels under the rear end of 

 the truck body the damage to tires is avoided, w^hich follows 

 with large single tires, because tires are distorted with a big 

 body overhang, and more traction is obtained with a four- 

 wheel drive. 



