September i, 1905.') 



THE INDIA RUBBER WORLD 



405 



AIR BRAKE HOSE TESTING APPARATUS. 



IN view of the expense of the air brake equipment for an ex- 

 tensive railway system and the importance of the quality 

 of the rubber hose involved, the management of the Nor- 

 folk and Western railway some time ago secured the de- 

 signing by its motive power department of a series of devices 

 for thoroughly testing air brake hose, as the result of which the 

 etTiciency of the material may now be thoroughly determined 

 before it is placed in service. There are presented herewith 

 two illustrations. Figure i showing the device for the bursting 

 test of hose to the right and the appa- 

 ratus for the buckling test to the left. 

 Another view of the buckling test ma- 

 chine is shown by Figure 2. 



The latter machine is designed to re- 

 produce as far as possible the vibration 

 or buckling to which air brake hose is 

 subjected on the road. It is operated 

 by a pulley driven by a belt from a 

 countershaft above. On the shaft of 

 this pulley is a crank for giving motion 

 to a vibrating arm. 



The hose is coupled at one end to a 

 stationary nipple and the other end to 

 a blank nipple, fitted into a vibratory 

 arm. The number of vibrations are 

 taken by a stroke counter and a con- 

 stant air pressure is maintained in the 

 hose by using a reducing valve, and a 

 small diaphragm is introduced in the 

 supply pipe leading from the reducing 

 valve to the hose. This diaphragm 

 contains a very minute hole — about 

 one one-hundredth of an inch in diam- 

 eter — which reduces the supply to a 

 very small volume. Connecting to this 

 pipe is also a gage which indicates the 

 pressure, making it possible to see at 

 all times that the machine is working 

 in proper condition, and at the same 

 time this gage is equipped with a 

 proper arrangement for completing an 

 electric circuit. When the hand drops 

 to a given point at which time the cir- 

 cuit is completed, the machine shuts 

 off automatically. The leak in the hose 

 is made uniform in all hose tested by 

 this diaphragm above mentioned, which 

 has the effect of causing the pressure 

 hand on the gage to drop to the point 

 where the circuit is completed and the 

 machine cut off when the leak in the 

 hose exceeds the leak in the diaphragm. 

 In order to save time in placing and 

 removing the hose, unions are so ar- 

 ranged that the hose may be held se- 

 curely by a lever clamp. A constant 

 pressure of air is maintained in the 

 hose by using a standard Westinghoues 

 signal line reducing valve, and it is 

 found that the best results are ob- 



HOSE TESTING APPARATUS— FIQ. 1 



HOSE TESTIN3 APPARATUS— FIQ. 



tained by the use of fifteen pounds pressure. 



In order to announce a break and consequent leak in the 

 hose, a whistle is attached to the end of the vibrating arm, as 

 shown in the illustrations, and connected to the upper end of 

 the hose. Air is maintained in the hose and kept from leak- 

 ing through to the whistle by a plain bevel seat valve, which is 

 held closed by pressure of the air. On the opposite side is a 

 spring to unseat the valve, which is set at 12 pounds. When a 

 leak occurs in the hose and the pressure is reduced below 12 

 pounds, the valve unseats, permitting 

 air to pass to the whistle, announcing 

 the leak. An ordinary cyclometer is 

 arranged on the frame supporting the 

 machine and is operated by the crank 

 engaging the lugs thereon, so that the 

 number of vibrations are counted auto- 

 matically. The hose is usually given 

 about 120 vibrations per minute, and 

 while no specifications have been pre- 

 pared in this direction, the hose should 

 stand about 75.000 vibrations, or buck- 

 lings, before failing. 



The apparatus for the bursting lest 

 consists of a frame for supporting the 

 hose and pipe connections and a differ- 

 ential piston for supplying the neces- 

 sary pressure. The position of the 

 hose is shown in Figure i and the man- 

 ner in which it is clamped is also indi- 

 cated. In making the test water is ad- 

 Miitted from below to fill the hose and 

 small cylinder. The valve is then 

 I losed and air admitted to the top of 

 the upper and larger cylinder, forcing 

 the piston down and supplying a pres- 

 sure to the hose. The diameter of the 

 smaller piston in this instance is 2?/ 

 inches, and the larger, or air cylinder, 

 is 8 inches in diameter. The Master 

 Car Builders' Association requires that 

 a test hose must stand for 10 minutes a 

 pressure of 500 pounds before bursting. 

 Besides the appliances here describ- 

 ed the Norfolk and Virginia road has 

 simple tests for friction and stretching, 

 as required by the Master Car Build- 

 ers' Association. Unfortunately there 

 are no testing machines at present that 

 duplicate the weird things that care- 

 less train men do to hose to its fre- 

 quent detriment. Nor are the effects 

 of extremes in heat and cold measured 

 and recorded. But doubtless they 

 will be sometime. 



In presenting the description The 

 India Rubber World has had the as- 

 sistance of Mr. W. W. Lemen, the com- 

 pany's engineer of tests, and the illustra- 

 tions appear through the courtesy of the 

 Railway Master Mechanic of Chicago. 



