420 



THE INDIA RUBBER WORLD 



[Ai-RiL 1, 1920. 



the tire serial number, month and year of manufacture, and 

 the name of the manufacturer. 



(b) The tires shall also have marked, by stamping deeply 

 into the steel tire channel, the tire serial number and a .symbol 

 representing the name of the manufacturer. The above data 

 shall be stamped under the overhanging edge of the steel chan- 

 nel. In case of artillery tires they shall be marked according 

 to blue print submitted. 



(c) Painting: Paint metal bases with rust-resisting paint. 



(d) Wrapping; No wrapping required. 



(f) Marking: Shipping instructions to be shown on printed 

 label pasted to inside of tire band and covered with a protec- 

 tive coating of silicate of soda over the label. 



MATERIAL. 



See General Specilications. 



(a) Rubber Compound: The rubber compound shall con- 

 tain not less than 65 per cent, by volume, of best quality new 

 rubber. If reclaimed rubber or mineral rubber is used, it must be 

 in addition to the 65 per cent of new rubber required, and the 

 manufacturer must declare the amount and kind of reclaimed 

 rubber or rubber substitutes used in his formula. The use of 

 "refined" or ground vulcanized rubber in the compound will 

 not be permitted. Compound shall be free from saponifiable 

 oils or anything made therefrom. 



(a) The total sulphur shall not be more than 8 per cent of 

 the weight of the new rubber used, except as follows : 



If the manufacturer desires lo use sulphur-bearing fillers, 

 thereby causing the total sulphur to be over 8 per cent of the 

 weight of the new rubber, he may do so, but shall submit for 

 analysis a sample of the finished unvulcanized stock. Such stock 

 shall not show a sulphur content in the acetone extract of over 

 8 per cent of the weight of new rubber used. 



TESTS. 



See Genera! Specifications. 



Rubber Compound: {a) Phvskal — 



Specific Gravity. 1.40 or Over. Below 1.40. 



Tensile strength 1.800 2,000 



Ultimate elongation inches 1-4^ 1-4^ 



Per cent set 2 minutes after breaking 40 40 



Above based on the average of not less than five samples. 



(b) Aging. Prepare five flat samples of rubber to be tested; 

 place in an oven for two hours at a temperature of 228 degrees 

 F. After removing from the oven, allow to stand for 24 hours 

 and determine elongation. The reduction in elongation at the 

 breaking point shall be not over 35 per cent. 



(c) Adhesion. The adhesion test shall be made as follows: 

 Place tire horizontally on platen of tire-applying press, the 



tire being supported above the lower platen of the press on a 

 steel band having the same diameter as the base of the tire 

 to be tested. Place on the upper side of the tread a band yi- 

 inch thick with inside diameter I'A inches larger than outside 

 diameter of flange of base band. The corners of the band to 

 be rounded with ^-inch radius. For the tire to pass successfully 

 the hard rubber must not break loose from the base. 



In making ring-adhesion tests of solid rubber tires the ap- 

 plied pressure on a 36-inch tire should be 17 tons and on a 

 40-inch tire 19 tons. The pressure used on tires of other dia- 

 meters should be in proportion to these pressures. 



Standardization of minimum sectional areas, hard base pressed- 

 on solid rubber truck tires. The following standard of minimum 

 areas is adopted for the various widths of solid rubber tires : 

 Inches. Square Inches. 



i'A 6.75 



4 7.75 



5 10.75 



6 13.75 



7 16.75 



8 19.75 

 10 25.75 

 12 31.75 

 14 38.75 . 



The areas hereinabove given refer to the sectional areas, in- 

 cluding both the hard and soft rubber of finished tires, on stand- 

 ard base bands. 



(rf) Rebound. The rebound shall not be less than 50 as 

 measured on a Whitney rebound instrument. The tire under 

 test shall be held at 70 degrees F. for a period of 24 hours 

 before testing and the instrument shall be mounted rigidly in 

 a vertical position. The tire shall be hung on a solid anvil below 

 the instrument. 



(e) Road Test. Manufacturer shall maintain at least one 

 truck, used exclusively for test work, which shall average at 

 least 500 truck miles per week, and a sufficient number of tires, 

 at least four, have averaged on rear wheels, at least 7,000 miles. 



Test on tire of S-inch cross-section size, or larger, will be 

 considered as representative of all solid tire cross-section sizes. 



INSPECTION. 



See General Specifications. 



One tire in each lot of 500 (the tire to be selected at random 

 by the inspector) shall be tested, and if the tire fulfills all the 

 requirements of the specifications, the lot of tires represented 

 by it will be accepted, including the tire on which tests have 

 been made. Failure to conform to the specifications in any 

 particular, the lot of tires represented by it, including the tire 

 on which tests have been made, will be rejected. If, however, 

 the maker of the tires demands a further lest, three more tires 

 from the lot rejected will be selected by the inspector, and if all 

 tires are found satisfactory, the lot of tires represented by the 

 tires subjected to test will be accepted, the manufacturer to bear 

 the cost of the tires upon which tests have been conducted. If 

 any tire fails in the latter tests, the whole lot will be rejected. 

 CLINCHER BICYCLE TIRES. 



No. GS 1000 28 by I'/z inches. 



No, GS 1001 28 by 1% inches. 



GENERAL. 



(a) This specification covers the requirements for bicycle 

 pneumatic castings of fabric construction of the sizes 28 by V/i 

 inches and 28 by 1^ inches. They shall be of the manufacturers 

 standard, nonskid, double clincher type and satisfactorily fit, 

 the standard 28 by Ij/a inch single clinch all steel bicycle rim. 



(b) See General Specifications for Tires' which are a part 

 hereof. 



CONSTRUCTION. 



See General Specifications. 



(a) Carcass of the casing shall consist of two plies of fabric 

 frictioned both sides. 



(b) The tread of the casing shall not be less than 0.120-inch 

 thick and the side wall not less than 0.032-inch thick when 

 measured on the cured casing. 



MARKING, WRAPPING AND PACKING. 



See General Specifications. 



MATERIAL. 



(o) Fabric shall be square-woven (26 by 26). 

 (b) Rubber Compounds : 



New 

 Rubber, Per 

 Cent. Volume. 



Tread minimum 55 



Side wall do 55 



Friction do 65 



TESTS. 



(a) Measurements: The cross-section of diameter of each 

 tire inflated to 40 pounds shall not be less than 1-29/64 inches 

 in 28 by 1^ inches and 1-37/64 inches in 28 by 1;^ inches. 



(b) Fabric shall have a tensile strength for each warp and 

 filling of not less than 110 pounds per inch or its physical equiva- 

 lent or cords as approved. 



(f ) Friction : Friction between piles of fabric shall average 

 not less than 10 pounds and between tread and plies or between 

 side wall and plies shall average not less than 9 pounds. 



((/) Rubber Compound: 



Tread, Side Wall. 



Minimum. Minimum 



Tensile strength 1 ,600 1 ,200 



Ultimate elongation 2-10 2-10 



Set: 



Stretch inches 2-10 2-10 



Set per cent 25 25 



INSPECTION. 



See General Specifications. 



^The General Specifications referred to in these specifications were pub- 

 lished on page 351, in The India Rubber World. March 1. 1920. 

 PNEUMATIC MOTORCYCLE CASINGS. 



Minimum. 



No. GS 1005 28 by 3 inches. 



No. GS 1006 29 by 3>/2 inches. 



GENERAL, 



(a) This specification covers requirements for pneumatic 

 motorcycle casings of fabric construction. Size 28 by 3 inches 

 shall be designed to carry a load of 325 pounds when inflated to 

 40 pounds per square inch ; size 29 by Syi inches, a load of 400 

 pounds when inflated to 45 pounds per square inch ; both de- 

 signed for S.A.E. clincher motorcycle C.C. rim 28 by 3 inches. 



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

 hereof. 



CONSTRtrCTION. 



See General Specifications. 



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



(b) Carcass of casing shall consist of four separate plies of 

 tire fabric, with friction coat on two sides and skim coat on one 

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



