March I, 1920] 



THE INDIA RUBBER WORLD 



351 



Go\ ernment Standard Specifications for Rubber Tires, Tire Repairs 



and Accessories. 



General Specifications. 



THESE SPECIFICATIONS cover bicycle, motorcycle and automo- 

 bile ribbed or non-skid pneumatic casings, solid tires, pneu- 

 matic inner tubes and accessories used by the War Depart- 

 ment. The following are details and tests as are common to the 

 products. For specific information applying directly to particular 

 articles, see detailed specifications which shall take precedence 

 whenever there is any conflict. 



All casings shall be of the manufacturer's standard non-skid, 

 clincher type, designed for the S. A. E. clincher rim of the 

 sizes as specified in the detailed specifications. 



CONSTRUCTION. 



To be manufactured from the best designated material ; free 

 irom all imperfections and of dimensions as given in the de- 

 tailed specifications or proposal submitted to manufacturer. 



(a) Au. F.^BRic must be thoroughly dried in accordance with 

 standard manufacturing practice before it is rubberized. .\ny 

 change in the weight or construction must meet with the ap- 

 proval of the War Department and authority be given the manu- 

 facturer in writing. 



(b) pL.Ars: Each casing shall have a flap in accordance 

 ■with standard manufacturing practice unless otherwise specified. 



( (■ ) Lining: The inside of each casing shall be properly 

 lined in accordance with standard manufacturing practice. 



MARKING. WRAPPING AND PACKING, 



(Does not apply to solid tires.) 



(c) Marking: Casings shall be plainly marked with raised 

 rubber letters. "U. S. A.," manufacturer's name, serial number, 

 ■date, size, and the equivalent metric system as recommended by 

 the Society of Automotive Engineers. 



(b) Wrapping: All casings shall be spirally wrapped ac- 

 cording to standard practice and properly labeled on the outside 

 and marked "U. S. A.," size, type, name of manufacture, and 

 the month and year of manufacture stamped thereon in a con- 

 spicuous place. 



(c) Packing: Packing shall conform to requirements as 

 •outlined in the original proposal. 



MATERIAL, 



(a) Fabric: The cotton fabric or cord layers shall be well, 

 «vcnly. and firmly woven from good cotton, as free from un- 

 sightly defects, dirt, knots, lumps, and irregularities of twist as 

 is consistent with the best manufacturing practice and conform 

 - detailed specifications. 



(/'I Rt;BBER Compounds: They shall conform to the detailed 

 -l»-cirication and be free from ingredients known to the rubber 

 ii;idc as "oil substitutes," and contain no reclaimed rubber un- 

 les> specifically permitted. 



When new rubber is specified, it shall be the best quality new 

 wild f.r plantation rubber. 



TESTS. 



All tests on material as a whole and on individual parts shall 

 be performed according to methods adopted by the National 

 Bureau ol Standards as outlined in their Circular No. 38, "Test- 

 ine of Rubber Goods." in effect at date of opening of proposal. 



Hydrostatic and tensile tests shall be in pounds per square 

 inch. Hydrostatic tests are to be made at the discretion of the 

 inspector. 



(a) Fabric: The usual methods of inspection used by tire 

 companies in commercial practice to discover defects in each 

 roll of fabric shall be employed. 



The tensile strength shall be obtained by cutting strips from 

 fabric 6 inches long, 1'4 inches wide and unraveled from each 

 side to a width of one inch. Jaws of testing machine shall 

 not be more than 1 inch wide and 3 inches apart, separating at 

 the rate of 12 inches per minute. Results obtained by taking the 

 average of three tests each on both warp and filling shall be 

 accepted as the tensile strength of the fabric. The tests shall 

 he made ^vhen practicable after conditioning the fabric in an at- 



mosphere having a relative humidity of 65 per cent and at a 

 temperature of 70 degrees F. for two hours. When not practicable 

 to test as above, the fabric may be tested under existing humidity 

 conditions and results corrected to a 6 per cent moisture basis by 

 multiplying by the following factor: 



100 



100 plus 7 (per cent moisture — 6) 



XoiE. — The factor will be less than unity when the per cent 

 moisture is greater than 6, and vice versa. 



Moisture shall be determined by weighing six samples together 

 before testing, and tensile strength immediately obtained in rapid 

 succession. The broken samples (entire) after rupture shall be 

 placed in a ventilated drying oven at 105 degrees to 110 degrees 

 C (321 degrees to 230 degrees F.) until weight is constant. 

 Moisture present shall be calculated on the basis of the bone dry 

 sample. 



All fabric weights are given in ounces per square yard, and 

 sliall be calculated on 6 per cent moisture basis. Tolerance 3 

 per cent, plus or minus. 



(61 Cord Fabric: Tensile strength of cords shall be made 

 ion 10 individual cords taken from each cord and the results must 

 be up to the standard specification of the individual manufac- 



(c) Friction or Adhesion: The friction between plies of 

 fabric or rubber compound shall be determined on a sample 1 

 inch in width, measured circumferentially, and be cut from the 

 casing and tested by using a standard friction or dead weight 

 machine. 



On a section of the casing the plies are started and pulled down 

 2 inches at one bead; which bead is clamped in the jaws of the 

 friction testing apparatus. Test shall be made on any or all plies 

 of the fabric. The adhesion between breaker and tread, breaker 

 and cushion, cushion and carcass, side wall and carcass shall be 

 determined. The rate of separation shall be not more than 1 

 inch per minute when the weight outlined in the detailed specifi- 

 cation is used. 



(rf) Rt^BER Compolnd: Test pieces shall be cut longitudi- 

 nally and shall be J^-inch wide over a gage length of 2 inches, 

 the ends being gradually enlarged to width approximately 1 

 inch. Results shall be based upon the average of four tests made 

 at a temperature between 65 degrees and 90 degrees F., unless 

 otherwise specified. 



The tensile strength shall be determined with a machine, the 

 jaw separating at the rate of 20 inches per minute. The per- 

 manent set shall be determined by sample stretched 2 inches to 

 10 inches for 10 minutes followed by a rest of 10 minutes, unless 

 otherwise specified. 



(i-l Road Test: Casings will not be given consideration un- 

 less the maker submitting the bid furnishes an affidavit stating 

 that he has maintained and will continue to maintain machines 

 used exclusively for test work, as called for in detailed specifica- 

 tions. 



The speeds, loads, tire sizes, inflations and road conditions 

 must be such that the casings are properly tested. The Gov- 

 erimient may appoint an inspector to see that the above condi- 

 tions are complied with. 



A bidder must supply an affidavit before delivering casings to 

 the Government, stating that the casings to be delivered are the 

 .same cross-section and practically duplicate, in construction and 

 material as casings which he has previously tested in accordance 

 with the above, and a sufficient number of casings satisfactory 

 to the Government, shall have averaged on the rear wheels the 

 number of miles as called for in detailed specifications. 



INSPECTION. 



The Government reserves the right to make any inspection 

 test or analysis necessary to insure the product meeting all re- 

 nuiremcnts of specification which shall be conducted in accord- 

 ance with methods outlined and approved by the War Depart- 

 ment, and which shall be furnished to successful bidders. 



PNEUMATIC AUTO CASING (FABRIC CONSTRUCTION). 



NO. GS 1010 30 by 3", inches. 



NO. GS 1011 31 by 4 inches. 



