December 1, 1918.] 



THE INDIA RUBBER WORLD 



133 



rings was enclosed in a bridge on either side of the axle, but 

 these were found cumbersome and heavy and presented too much 

 parasite head resistance. Then came one of lighter rubber-cord 

 construction that gives very good results ; however, it is evident 

 that the shock absorber is still in its infancy and opportunities 

 for improvement are abundant. The life of the rubber cord, 

 which is composed of many small strands of rubber covered by 

 a braided cotton cover, is governed by the life of the cotton. 

 When the covering breaks, the efficiency of the cord is at an end. 

 The greatest reason why the rubber cord is used is because of 

 the peculiar hysteresis curve that it gives. It has, moreover, 

 great ability for absorbing shock in landing and taxing across a 

 field. The old type of rubber ring has very little hysteresis 

 except when the stock is of such a nature that it cannot come 

 back, and consequently takes permanent set. Obviously, a unit 

 of rubber that elongates when a load is applied, and returns 

 promptly to its original length when the load is released, affords 

 little shock-absorbing ability, because its action is equal in both 

 directions. A new type of shock absorber recently developed is 

 made of rubber with all the advantages of the cord, but with 

 none of its disadvantages. In order to prolong the life of the 

 rubber cord or rubber shock absorber in some of the lighter 

 fighting planes, a protecting collar of rubber has been made to 

 be inserted in such a way that the pinching action of the 

 metal portion of the spool and bed is eliminated, so that the 

 cord is free from punishment and its efficiency is impaired only 

 by its own action. 



RUBBER WASHERS, STRIPS AND COLLARS. 



Because of the continuous vibration of airplanes, petrol tanks 

 and all delicate parts are guarded to some extent with rubber, 

 either in washer or strip form. Special designs of oil strips 

 have been made for use in the head cowl of the rotary motors. 

 These prevent the oil from spraying the face of the pilot and 

 not only add greatly to his comfort, but to his safety as well. 

 Then, too, there are rubber radiator collars, used when the shaft 

 of the motor with the propeller fastened on the end protrudes 

 through the radiator. This rubber protects the delicate portion 

 of the housing so that it will not be cut through by the harsher 

 member under constant vibration. 



TANK COVERS. MATTING AND TUBING. 



Interesting tests have also been made on a gasoline tank cover 

 so constructed that the inner stock of the cover kept under pres- 

 sure, and when penetrated by bullets the holes are immediately 

 closed, thereby retaining the fuel and permitting the aviator to 

 reach his own line with safety. Rubber matting is being used, 

 principally the pyramid type, in place of aluminum. These 

 molded pieces of matting are used on the pedal bar, for foot 

 control in the foot-holes and on the floors of the large bombers. 



Tubing as well as hose is essential. Light tubing is used for 

 conveying gasoline and oil under low pressure, and acid tubing 

 is also required. There are also numerous pieces of rubber 

 tubing that are compounded to endure long periods of oxidation. 

 These are placed in the pipe lines at critical points where metal 

 tubing cannot be used to advantage. 



OXYGEN HELMET. 



The pilots at some of the aviation fields have recently become 

 interested in rubber clothing providing warmth for themselves 

 while in flight. A most important equipment of an army aviator 

 is the oxygen mask for high altitudes. Without this helmet the 

 cruising radius of a pilot would be confined to what his own 

 physique would stand, but with the helmet, the cruising radius 

 is only limited by the capacity of the machine which he flies. 

 The apparatus consists of a helmet, similar to the present gas 

 helmet used by the Army, with the exception that pure oxygen is 

 breathed instead of air passing through purifying substances. 



Formerly aircraft engineers were skeptical about the mechani- 

 cal efficiency of rubber, but during the past year such develop- 

 ments have taken place that they are beginning to recognize the 



advantages of the use of rubber and are awaiting with mterest 

 the introduction of other rubber parts and the refinement of 

 those now in use. 



UNITED STATES ARMY SPECIFICATIONS FOR 

 RUBBER BLANKETS. 



MATERIALS. 



"T^HE body of the blanket to be of gray sheeting, best quality, 

 •*■ at least 36 inches wide, weighing not less than three and 

 ninety one hundredths (3-90/100) ounces to the linear yard, 35 

 inches wide ; counting not fewer than 56 threads and not more 

 than 66 threads to the inch in both warp and filUng. and having 

 a tensile strength of not less than 56 pounds to the inch in the 

 width in both warp and filling. 



Blankets to be thoroughly and uniformly coated with a high- 

 grade black rubber compound containing not less than 75 per 

 cent (by volume) best grade fine Para or plantation Hevea rub- 

 ber, the sulphur content not to exceed 5 per cent by weight of 

 the total rubber content. The surface rubber to be calendered 

 and not spread upon sheeting. Each blanket to be vulcaniEcd 

 after being manufactured. 



SIZE AND DESCRIPTION. 



To be 83 Va inches long and 71 Va inches wiae, all four edges 

 to be turned in with a 1^-inch hem, securely cemented, making 

 the complete blanket 80 inches by (58 inches. Where edges of 

 material are joined to form proper width, the joined edges must 

 be turned under and securely cemented as in tne standard, the 

 tensile strength of the joint to be at least 40 pounds per inch 

 of width. Blanket to have one No. 3 brass grommet in each 

 corner, four on each end, and five on each side, one inch from 

 edge of blanket, placed equal distances apart, about 13 inches, 

 as shown in standard sample. Completed blanket to weigh not 

 more than 6 pounds 4 ouijces and not less than 5 pounds 12 

 ounces. 



MAEKING. 



Each blanket to be stamped or stenciled on under surface with 

 the following, fast-color black ink being used : near center : 

 "Med. Dept. LI. S. A." (one-inch black letters) : in one corner: 

 (name and location of contractor and date of contract). 



FOLDING AND PACKING. 



Five blankets will be folded to form a bundle about IS by 36 

 inches. Seven of these bundles (35 blankets) will be packed 

 in boxes strongly made of %-inch (finished) material, strapped 

 for e.xport shipment (specifications for export packing boxes 

 furnished on request). Each box to be marked on its end with 

 the contents, name of contractor and date of the contract. 



WORKMANSHIP AND FINISH. 



Workmanship and finish of blankets to be first-class in every 

 respect, equal to and like standard sample at Field Medical 

 Supply Depot, United States Army, 21 M srreet. Northeast, 

 Washington, D. C. 



WASTE RECLAMATION COUNCIL MEETING. 



A meeting of the Waste Reclamation Council was held Thurs- 

 day, November 21, at Washington, D. C, when the importance 

 of waste materials during the war and in the after-w^ar pro- 

 gram was discussed. 



Among the speakers were former President William II. Taft 

 and Hugh Frayne, chairman of the Labor Division of the War 

 Industries Board. Louis Birkenstein, Chief of Salvage of the 

 Department of Reclamation and Conservation of the War De- 

 partment, who represented the National Association of Waste 

 Material Dealers, pledged the association's cooperation in carry- 

 ing out the Government's plan for collecting and marketing 

 waste materials. 



"Rubber Machinery," by Henry C. Pearson, is filled with valu- 

 able information for rubber manufacturers. Price, $6. 



