352 



THE INDIA RUBBER WORLD 



(Makch 1, 1920. 



GEI^ERAL. 



(a) This specification covers requirements for pneumatic auto 

 casings of fabric construction, size 30 by 3^ inches, which shall 

 be designed to carry a load of 570 pounds when inflated to 55 

 pounds per square inch and size 31 by 4 inches a load of 815 

 pounds when inflated to 65 pounds per square inch; both de- 

 signed for the S. A. K. clincher rim size 30 by 3;/2 inches. 



(fr) See General Specifications for tires which are a part 

 hereof. 



CONSTRUCTION. 



See General Specifications. 



(n) Splices on the first ply of fabric shall be gum stripped. 



(b) Carcass of casing for 30 by 3}^-inch shall consist of not 

 less than four nor more than five separate plies of tire fabric 

 and 31 by 4-inch not less than five nor more than six separate 

 plies, with friction coat on two sides and skim coat on one 

 side. The gage of one ply frictioned on two sides and skim 

 coated on one shall be at least 0.04S-inch. Each ply shall have 

 not more than two splices, which must be at least 7 inches apart, 

 and the splices in the casing shall be at least 3 inches apart; all 

 measurements on the circumference of the casing. 



(f) Beads shall be constructed with a core filler as in standard 

 commercial practice. 



(d) One chafing strip of square-woven fabric weighing not 

 less than 8 ounces per square yard shall be used on each side of 

 the casing; and shall extend upward on the side of the casing 

 at least 3s-inch from the channel of the bead. 



(e) There shall be a cushion of rubber compound applied 

 over the fabric w^hich shall be wider than the breaker. The min- 

 imum gage shall be 0.04S-inch for 30 by 354-inch and O.OSO-inch 

 for 31 by 4-inch. 



(/■) Over the cushion there shall be at least one breaker strip. 

 of open weave fabric made from long-staple cotton weighing not 

 less than 8 ounces per square yard, as in standard commercial 

 practice, coated on both sides with a rubber compound which 

 shall insure a perfect union between the cushion and tread after 

 the cure. Breaker strip for 30 by 3^-inch, minimum width 2% 

 inches, for 31 by 4-inch, minimum width 2^ inches. 



(g) Rubber dimensions: 



Sizes 30x31^5 31x4 



Thickness Inches. M inimum. 



Tread of casing in center... A H 



Si'dl Ka\\ "!'"^° . ".°.".'^ . '. . ^°' .'.°. . °" .' 0.05 0.05 



(h) No flaps shall be supplied. 



MARKING, WRAPPING AND PACKING. 



See General Specifications. 



MATERIAL 



See General Specifications. 



(a) Fabric must be square woven (23 by 23) from Egyptian 

 long-staple cotton or its physical equivalent, as approved by the 

 Government, weighing 17]4 ounces per square yard. 



(h) Rubber compound: 



New Rubber, Reclaimed 

 Per Cent Rubber. Per 

 Volume. Cent Weight. 



Minimum. Ma.ximum. 



Tread 65 



Side wall 65 15 



Friction and cushion 75 



TESTS. 



(o) Cross-sectional diameter of each tire inflated according 



to the recommended weight and load schedule of the S. A. E. 



shall he for 30 by iyz-inch less than 3-7/16 inches ; and for 



31 by 4-inch, 4 inches. 



(b) Shall withstand water pressure of 300 pounds per square 

 inch without injury. 



(c) Fabric: Tensile- strength, warp or filling, 165 pounds min- 

 imum. 



(d) Friction: 



Strength of union between plies of fabric minimum 16 



Strength of union between breaker and tread minimum 28 



Strength of union between breaker and cushion minimum 28 



Strength of union between cushion and carcass minimum 16 



Strength of union between side wall and carcass minimum 10 



(c) Rubber Compound: 



Tread. Side Wall. 



Minimum. Minimum. 



Tensile strength 2.200 1.500' 



Ultimate elongation inches 2-II 2-11 



Set: 



Stretch inches 2-10 2-10 



Set per cent 25 25 



(f) Road Te.st : Manufacturer shall maintain at least two 

 cars used exclusively for test work. They shall average at least 

 1,000 miles per car per week; and a sufficient number of casings 

 (not less than six) shall have averaged on the rear wheeb at 

 least 4,000 miles. 



INSPECTION. 



See General Specifications. 



PNEUMATIC AUTO CASINGS (CORD CONSTRUCTION). 



NO. GS 1020 • 33 by 4 inches 



NO. GS 1021 35 by 6 inches 



NO. GS 1022 36 by e inches 



NO. GS 1023 88 by 7 inches 



NO. GS 1024 *0 by 8 inches 



GENERAL. 



(a) This specification covers requirements for pneumatic auto- 

 mobile casings of cord construction which conform to the fol- 

 lowing: 



Designed to Inflation Per 



Carry Load — Square Inch. 

 Size. Pounds. Pounds. 



33 by 4 inches 815 65 



35 by 5 inches 1,500 75 



36 by 6 inches 2,000 90 



38 by 7 inches 2,700 100 



40 by 8 inches 3,650 110 



Designed for S. A. E. straight side rim as follows: 



Casing Size. Rim Size. 



33 by 4 inches 32 by 3' S inches and 33 



by 4 inches. 



35 by 5 inches 34 by 4J^ inches. 



36 by 6 inches 36 by 6 inches. 



38 by 7 inches 38 by 7 inches. 



40 by 8 inches 40 by 8 inches. 



(b) See General Specifications for tires, which are a part 

 hereof. 



CONSTRUCTION. 



See General Specifications. 



(a) Casings shall consist of number of separate plies of cord, 

 applied in such manner that an equal number of plies shall run 

 in each diagonal direction across the casing as follows : 



Number of Plies. 



Size. Minimum. Maximum. 



33 by 4 inches 4 8 



35 by 5 inches 4 10 



33 by 6 inches 4 12 



38 bv 7 inches 4 14 



40 by 8 inches 4 16 



(6) Two chafing strips weighing not less than 8 ounces per 

 square yard shall be used in each side of casing. Each chafing 

 strip shall extend upward on side of casing from the heel of the 

 bead as follows : 



Extension 

 Upward. 



33 by 4 inches '. 1 



35 by 5 inches ; 1% 



36 by 6 inches I'A 



38 by 7 inches lH 



40 by 8 inches 2 



(f) One chafing strip shall extend at least 3/16-inch above the 

 other for sizes 33 by 4 inches and 35 by 5 inches ; and }4-inch 

 for 36 by 6 inches, 38 by 7 inches, and 40 by 8 inches. 



(d) There shall be a cushion of rubber compound applied over 

 the cords, which shall 'be wider than the breaker and gage as 

 in Table I. 



(e) Over the cushion there shall be at least one breaker strip 

 of open-weave fabric made from long-staple Egyptian cotton 

 or its physical equivalent as approved by the Government ; weight 

 as in Table I, such as in standard commercial practice, coated 

 on both sides with a rubber compound to insure a perfect union 

 between the cushion and tread after cure. 



Table I. 



■ight Thick- 



Thi( 



Thick- 



33 bv 4 



35 b'y 5 



36 by 6 

 38 by 7 



Cushion. 

 . . 0.05 

 . . .0625 



Per of Cas- Tread Exclu- of 

 Square ing in sive of Non- Side 

 Yard. Center, skid Design. Wall 



Ounces. Inch. 



Inch. 



D.0625 

 .0625 

 .0625 

 .0625 

 .062S 



MARKING. WRAPPING AND PACKING. 



See General Specifications. 



