416 



THE INDIA RUBBER WORLD 



[May 1, 1913. 



Railroad Air Brake Hose. 



By J. S. Shcafe, Engineer of 

 A PAPKR I'RF.PARED FOR THE THIRD INTERNA 



THE requirements of air brake hose are prescribed by the 

 Master Car Builders' Association so that hose applied to all 

 railroad eiiuipnient shall be uniform and up to a certain 

 standard. But air brake hose, as now being manufactured, docs 

 not comply with the M. C. B. requirements in other than the phy- 

 sical tests. 



For instance, M. C. B. specifications prohibit the use of rubber 

 substitutes. Pure rubber certainly cannot be used at the price 

 paid. Neither can a fair grade of rubber. In calling for a 

 "hand made tube composed of three calenders of rubber," the 

 requirement is not met as hand made tubes and those consisting 

 ■of three calenders of rubber are only made on special order and 

 at an advance in price. The great bulk of air hose tubes today 

 are single calender and machine made, or "squirted." 



In calling for swelled ends more difficulty is met witli in the 

 manufacture and a less perfect hose results. The inside and 

 outside diameters should be the same throughout the entire 

 length of the hose. 



Air brake hose today is poorer than formerly and both the 

 railroads and manufacturers may be blamed; the former for 

 continually hammering down the price asked for an honest 

 article, and the latter for consenting to attempt the manufacture 

 of an article at a price below that which they know can be fairly 

 met. The quality of air hose of necessity must be improved and 

 both the manufacturer and consumer must work together, mak- 

 ing concessions where necessary, for the ultimate mutual good. 

 Air hose today is sold as low as 30 cents and as high as 50 

 cents per foot, a difference of 66 per cent. How much can be 

 expected of air hose costing the minimum? 



This is a splendid illustration of false economy as the extra 

 number of poor hose lengths necessarily purchased overbalances 

 the increased cost of better hose ; this too, when only the rela- 

 tive service is considered. In addition, and directly attributable 

 to cost, should be considered the labor of collecting, shipping, 

 dismounting and fitting u]), each of which would not be neces- 

 sary so frequently to be done with better hose. 



The M. C. B. Association, allow a cap from 1/16 inch to % 

 inch in thickness. A cap of 1/16 inch is better than one of % 

 incli thickness. Even less than 1/16 inch would be preferable. 

 If the cap is made only thick enough to protect the exposed 

 end of the fabric during the process of vulcanization the clamp 

 used will not overlap the fabric, thus increasing the possibility 

 of hose pulling of? of nipple. 



Some claim has been made that air hose is quite generally 

 porous. The percentage of porous hose, i. e., those pieces which 

 have leaked and which, on examination, have no evident defect, 

 may be fairly placed at not over 5 per cent. This appears to be 

 a reasonable maximum. 



The cause of the largest number of failures appears to be the 

 result of outside injury. Such failures are entirely apart from 

 any inherent weakness of the hose. The "Railway Age Gazette" 

 of April 19, 1912, places the number of such failures at from 65 

 to 70 per cent. There is good evidence at hand in hose shops to 

 corroborate this statement. 



The use of power machines for inserting nipples and couplings 

 into air hose should be discouraged. The inner tube will be cut 

 if there is any roughness to the shank of the nipple or coupling, 

 or if they are out of line in entering. Mounting can be almost 

 as rapidly done by hand and with the certainty that no damage 

 to the inner tube results. 



One of the M. C. B. requirements is that the friction between 

 layers of duck shall be such that a 20-pound weight attached to 

 the free end shall, in ten minutes, unwind less than 8 inches, the 



Tests, Illinois Central Railroad. 



TIONAI. Rinsiir.R CONFERENCE, BUT NOT READ. 



section being 1 inch in width. Just how far a "high friction" 

 hose is advantageous is a question. Tests made by a large rail- 

 road, wherein a machine was used for kinking the hose while 

 under pressure, resulted in a better showing for hose made with 

 little friction than that made to meet the M. C. B. requirement. 

 While this may not prove anything it at least opens up a very 

 interesting point in the subject of air hose. In the same tests, 

 hose with poor friction, gave better results in the bruise test. 

 This bruise test was made by fastening the hose, under air 

 pressure, to an anvil, and causing a 20-pound weight to fall upon 

 it at the nipple end. 



There can be no doubt of the deterioration of the average air 

 hose within six months of manufacture. The making of hose 

 to wear well is quite the important part of the manufacturer's 

 problem. No matter how good the hose is at the start if it be- 

 comes useless after a few months, the loss to the consumer is 

 immense. 



Some rubber manufacturers say that a good stretch test of the 

 tube and cover, combined with a tensile strength requirement, 

 will do more than any other one thing to increase the life of the 

 hose. Tensile strength proposed by these manufacturers varies 

 from 650 to 1,200 lbs. per square inch. As hose in service does 

 not stretch the 200 or 300 per cent., is the stretch test practical? 

 A rubber band will stretch many hundred per cent, and yet its 

 deterioration is rapid. 



It would appear that the rubber manufacturers could make a 

 more lasting hose by compounding a tube and cover with just 

 as much or as little flexibility as would be necessary for long 

 life. The minimum amount of flexibility would have to be suffi- 

 cient to allow bending, without kinking, in coupling up. 



It would also appear that the amount of damage caused by 

 pulling hose apart, without uncoupling, is exaggerated. It is 

 probably the universal practice in yards for switchmen and train- 

 men to thus neglect uncoupling. If an observation will be made 

 in a yard, it will be found, on examining hose so treated, that 

 failure is evident in none of them, provided the coupling has not 

 been jammed and that a wedge has not been made use of to take 

 up leakage in the gasket. As proof of this we have the strength 

 of our air hose, versus the resiliency of the gaskets ; the former 

 is much greater. 



In considering defective hose, and from which follows a leaky 

 train line blamed on the hose, leaky angle cocks, nipples and 

 couplings must not be lost sight of. They contribute their fair 

 share of the extra burden on the air pump. A more careful in- 

 spection of air ho.se by car inspectors may save damage, as a hose 

 ready to fail may be sometimes removed in time to avoid failures. 



Some attention has been given to the question of making air 

 hose with one or more ply woven. This appears likely to be the 

 best hose of the future. 



If the manufacturers will produce a hose with an inner tube 

 hard enough to protect itself from the nipple, and a cover hard 

 enough to protect itself from the clamp, both of ability to with- 

 stand the action of time and weather for approximately 36 

 months, and will demand a price commensurate with the in- 

 gredients entering into the manufacture, the whole situation will 

 be greatly improved. 



WANT AMEHICAN LAMPBLACK. 



.\n .\merican consul states that a firm in his district desires 

 to hear from American manufacturers of lampblack, with the 

 object of representing them in Europe. The consular report is 

 No. 10,771. 



