SHOP TESTS. 281 



147. Drop Test. This is a test to which steel rails and 

 steel tyres are subjected. When applied to steel rails it 

 consists in supporting the 24ft. length of the rail on bear- 

 ings 3ft. apart and situated at equal distances from both 

 ends. A cast-iron weight of half a ton is raised to a height 

 of 15ft. above the rail, and allowed to fall on its middle. 

 The effect of this blow is to produce a certain amount of 

 permanent set in the form of deflection, and this is not 

 supposed to exceed a certain amount for the first blow, 

 such as 2^in. 



A similar test is applied to steel tires for rolling stock. 

 The tire is allowed to rest between supports and a weight 

 of one ton allowed to fall upon it. The drop is repeated 

 from increasing heights until a specified deflection is 

 produced. This may be two inches for every foot of its 

 internal diameter. 



148. Smithy Tests. Many useful tests are made 

 upon wrought iron and steel by the smith. 



For wrought iron a common test is that shown on 

 Fig. 144. Here the bar or strip is nicked and then bent, 

 the fibrous or non-fibrous nature of the specimen being 



PIG. 145. RAMSHOBN TEST FOB IRON. 



exhibited at the fracture. For good wrought iron the 

 fracture should show a silky fibre. Another is the 

 Ramshorn test (Fig. 145). Here the strip is split at the 

 end and turned over, and also a hole is punched and 

 drifted. This is done when the rnetal is hot. 



Another test is to twist a strip through a certain 

 number of turns without fracture. These are only a few 

 of the many miscellaneous tests that are applied to bars, 

 plates, and samples of sectional iron and steel, but they 

 will serve to indicate in what direction these are carried out. 



