108 



THE INDIA RUBBER WORLD 



[December 1, 1911. 



Cutting Press for Standard 

 Test Bodies. 



Tests of compression at various temperatures. 



Tests of plasticity. 



Tests of flexion. 



Tests of wear and tear and determination of the coefficient of 

 friction. 



Tests of punching fabrics or soft materials. 



Tests of cables, cords and metallic wires. 



(All the coefficients of importance in the separate tests can be 

 shown by diagrams, which are automatically traced.) 



In order to per- 

 mit at all times the 

 adjustment of the 

 machine, there is a 

 special patented ar- 

 rangement. The 

 action of the ma- 

 chine is produced 

 by a spring. The 

 inventor has de- 

 cided to avoid the 

 use of balance 

 levers, which are 

 very bulky and are 

 no more accurate 

 than the special 

 steel spring which 

 he has adopted. He claims that a good quality of spring not 

 subjected to the maximum charge (which totally compresses it) 

 forms a very convenient and accurate testing device. 



ELASTO-DUROMETER. 



The same concern supplies another apparatus on the Pierre 

 Breui! system, called the "Elasto-Durometer," intended (as the 

 name implies) to measure elasticity and toughness. Both these 

 tests are effected by the same machine, through the use of 

 special parts. These machines furnish numerous and detailed 

 results of constant description ; being moreover in general use. 



SCHOPPEr's RUBBER TESTER. 



The firm of Louis Schopper, Leipzig, makes a specialty of 

 the construction of testing machinery for the rubber and allied 

 trades. In contrast with the P. B. machine, Schopper's Patent 

 Rubber Tester is of a dynamometer type, worked by a lever; 

 being one of the most carefully made and most accurate of its 

 kind. With the view of obtaining a maximum of regularity and 

 uniformity, it is operated by water power. 



At the same time it is to be noticed that the Patent Rubber 

 Tester is not meant for carrying out the numerous tests which 

 are possible with 

 the P. B. machines. 

 With reference to 

 the preparation of 

 standard test bodies, 

 it has been demon- 

 strated with the 

 Schopper machines 

 that the form of the 

 sample tested exer- 

 cises considerable 

 influence upon the 

 result of the test; 

 whence the neces- 

 sity of adopting a standard form. Numerous tests have estab- 

 lished the fact that the preferable form is that of a ring. 



Together with the Schopper machine there are consequently 

 furnished all the accessories needed for the preparation of test 

 samples; that is to say: 



Vulcanizing plates and matrices. 



Cutting press (as shown by illustration). 



These are the Schopper appliances used by the Royal Testing 



Apparatus for Cutting Test-strips. 



Institute of Gross Lichterfelde for the official tests referred to 

 in the October, 1911, issue of The India Rubber World. 



CLAYTON, BEADLE & STEVENS SYSTEM. 



Like the machines previously referred to, that of Clayton is a 

 dynamometer, giving the resistance, the elongation at the point of 

 rupture, the elongation under a given burden and the hysteresis 

 of gums and compounds — whether vulcanized or not. 



The principal difference in contrast with the Schopper and the 

 P. B. machines, consists in the fact that the Clayton Dynamom- 

 eter has not a spring like the dynamometer P. B., and has not a 

 lever like the Schopper Rubber Tester. 



The Clayton dynamometer has an arrangement similar to that 

 of the Riehle cement testing machine. A stream of water reaches 

 a balanced receptacle at the rate of one kilo (2.2 lbs.) a minute. 

 The weight of the water reaching the point gradually, exercises 

 traction upon the sample being tested. At the moment of rup- 

 ture, the stream of water 

 is automatically stopped 

 and the breaking load is 

 found by weighing the 

 amount of water in the 

 receptacle. The stream 

 can, moreover, be stopped 

 at any time, in order to 

 read off the extension 

 under a given load. The 

 quantity of water in the 

 receptacle can also be 

 gradually diminished. As 

 may be understood, this 

 dynamometer is remark- 

 ably easy to handle, while 

 it is capable of giving re- 

 sults equally accurate and 

 varied. 



THE SCHWARTZ RUBBER 

 TESTING MACHINE. 



In the machine of Pro- 

 fessor Schwartz, as illus- 

 trated, a standard test 

 body is loaded at a given 

 rate (as in the machines 

 previously referred to) ; 

 but, without reaching the 

 breaking load. Then the 

 load is gradually dimin- 

 ished at the same rate. 

 Both loading and unload- 

 ing are graphically rec- 

 orded, and by the curves 

 on the chart is shown the 

 hysteresis of the gum or 

 compound in question. 

 The following physical quantities can thus be determined: — 



1. The rate of extension with load. 2. The work done in ex- 

 tension. 3. The work done by the rubber in retracting. 4. The 

 work expended in the rubber itself. 5. The sub-permanent set 

 remaining after a given extension. 



OTHER DYNAMOMETERS. 



Other dynamometers are those of C. O. Weber and C. L. 

 Delaloe, while in the textile industry there are numerous models 

 varying in strength and accuracy. 



One of them is a Schopper dynamometer specially intended for 

 cloth, belting and other materials, and in a general way similar 

 to the Schopper Rubber Tester. In connection with this model, 

 there is used the Schopper apparatus for cutting test-strips, as 

 shown by illustration. These machines, while not having been 

 intended for rubber tests are capable of furnishing excellent 

 results. 



A. SCHWAkl.- ivLIUlKK TkSTI.NG 



Hysteresis Machine. 



i 



