150 



THE INDIA RUBBER WORLD 



[February i, 1904. 



at the end of the first year, the same test at the end of two years, 

 and a test of one half second at the end of 2% years. The 

 more expensive hose gave an original stretching test of 4}^ 

 inches, with a set of /j inch, and at the end of 16 months a 

 stretching test of 3V4 inches with a set of }s inch. The cheap 

 hose, when new, gave a stretching test of z}i inches, and a set 

 of T V of an inch, and at the end of 18 months it gave a test of 

 2J^ inchesand a set of ^ inch. 



These tests seem to justify the conclusion that a medium or 

 even low priced hose with a good bursting test is the most 

 economical in service, although care should be taken not to go 

 to extremes in the matter of cheapness. 



The Chicago, Burlington and Ouincy specifications No. 15-A 

 for air brake hose are based on the results of the above describ- 

 ed test. Compared with those issued by many other roads it 

 will be noted that the stretching test prescribed for the inner 

 tube is very moderate, and that no friction test is called for, 

 while the bursting test required is also moderate and designed 

 to secure the proper quality of duck and care in making the 

 hose. The life of various standard makes of air hose determined 

 by tests on other roads varies from 12 to 38 months and aver- 

 ages 24 months. 



THE SPECIFICATION CONDENSED. 



These specifications prescribe that air brake hose shall be 4 ply and 

 the inner tube not less than / 2 inch thick ; each length to be 22 inches 

 (% inch variation allowed), and capped with rubber, vulcanized at each 

 end ; wrapping to be frictioned on both sides, with a distinct layer of 

 rubber between each two plies. Inside diameter not to be less than 1^4 

 inches nor more than i/ s inches. Standard lengths of hose to be 

 labeled to permit of future identification [See The India Rubber 

 World, January 1, 1903 — page 115J. Bursting Test. — A section of 3 

 inches to be cut from the test hose and the remaining 19 inches mounted 

 on standard nipples, where it must stand a hydraulic pressure of 150 

 pounds per square inch, without expanding more than f'j inch in di- 

 ameter, and subsequently a hydraulic pressure of 500 pounds per square 

 inch for 10 minutes, without bursting. Stretching Test. — A section of 

 inner tube 1 inch wide is stretched 300 per cent, and immediately re- 

 leased ; marks 2 inches apart are then placed on it, and the rubber 

 stretched until the marks are 8 inches apart, held for 10 minutes, then 

 released for 10 minutes, and the elongation noted. The rubber must 

 stretch 300 per cent, for 10 minutes without breaking, and must not 

 take a permanent elongation of more than % inch. 



The opinion seems to prevail among railway authorities that 

 a fair statement of the service obtainable from air brake hose, 

 would be that, irrespective of quality, one third to one half of 

 it gives satisfactory service, while the balance falls short of 

 this, largely by reason of preventable causes, due principally to 

 carelessness in the repair shops and on the road. 



Among these preventable causes of injury and ultimate fail- 

 ure, perhaps that of most common occurrence is careless work- 

 manship in inserting couplings and nipples, resulting in dam- 

 age to the inner tube by cutting and to the duck plies by over- 

 straining. In mounting air brake hose the ordinary procedure 

 consists in holding the casting in a vise, cementing the nipple 

 end with a rubber solution to aid in crowding the hose over it by 

 aquick thrust of the same assisted by 

 the weight of the workman's body. 

 There can be no objection to this 

 method of doing the work, provided 

 the nipple is smooth and not so large 

 as to overstrain the duck. Herein 

 is found the importance of specify- 

 ing enlarged ends which, by con- 

 forming approximately to the taper 

 of the nipple, is relieved of strain 

 and much of the consequent liability 



to injury. A very practical invention bearing on this point is 

 the combination of the enlarged end with a thickening of the 

 inner tube at the end of the taper, thus forming a reinforce- 

 ment or cushion of rubber to receive the wear caused by bend- 

 ing about the end 

 of the nipple. 

 Figure 1 illus- 

 trates this ar- 

 rangement which 

 has been patent- 

 fig 1- ed by The B. F. 



Goodrich Co. (Akron, Ohio). Its practical value has been 

 demonstrated in service, the " Akron " brand air brake hose 

 giving from 36 to 40 months actual service. 



A simple mechanical means for coupling air brake hose is 

 illustrated in the diagrams of Figure 2 which show the appar- 

 atus in use by the Chicago, Milwaukee and St. Pa,ul railway. 

 The upper portion of the figure shows the machine in place. 

 A crosshead, connected to a hand lever, carries half an air 

 brake hose coupling to serve as a holder for the part to be in- 

 serted in the hose, 

 which is held for that 

 purpose in a vise ar- 

 rangement shown 

 clearly in the lower 

 half of the figure. 

 The vise is held se- 

 curely shut on the 

 hose by means of a 

 link arrangement 

 locked down by a cam 

 lever which throws 

 up over the handle 

 portion shutting on 

 the hose. With this 

 arrangement a man 

 can couple about 140 

 pieces of hose per 

 day, without the 

 great effort necessary 

 when done by hand. 

 Figures 3, 4, 5 and 

 6 illustrate typical in- 



juries to air brake yW///////////7?/\ 

 hose. The first of 



these (Fig. 3) shows fig. 2. 



a break caused by injury to the inner tube by the insertion 

 of the nipple. That caused by separating cars without un- 

 coupling the air hose is shown in Figure 4. In this instance 

 the friction uniting the plies was evidently low grade, permit- 

 ting the bias duck to pull out in the form of a curl like a shav- 

 ing. A better quality friction would have held the plies so 

 firmly united that the hose would have broken abruptly. Fig- 

 ure 5 shows the effect of chafing. In this case the rubber 



fiq. 3. 



