'24 



142. Full sized material for eye-bars shall bend cold 180 

 to a curve, whose inner radius is equal to the thickness of 

 the material, without fracture on the outside of the bend. 



143. Pins ever 7 inches in diameter shall be forged. 

 Blooms for pins shall have at least three times the sectional 

 area of the finished pins. ( 138.) 



LOW steei. *I44- Low Steel shall have an ultimate strength, on same 

 sized samples, of 55,000 to 65,000 pounds per square inch, 

 an elastic limit not less than one-half the ultimate strength, 

 and a minimum elongation of 23 per cent, in 8 inches. 



145. Before or after heating to a light yellow heat and 

 quenching in cold water, this steel must stand bending 180 

 degrees, to a curve whose inner radius is equal to the 

 thickness of the sample, without sign of fracture. 



146. For both kinds of steel, inch or less in thickness, 

 rivet holes punched as in ordinary practice ( 55, 56, 57), 



Drifting, must stand drifting to a diameter one-third greater than 

 that of the original holes, without cracking either in the 

 periphery of the holes or on the external edges of the 

 piece, whether they be sheared or rolled. 



Rivet steei. 147. Rivet Steel shall have an ultimate strength of 48,000 

 to 58,000 pounds per square inch, an elastic limit not less 

 than one-half the ultimate strength and an elongation of 26 

 per cent. 



148. The steel for rivets must, under the above bending 

 test (145), stand closing solidly together without sign ot 

 fracture. When nicked and bent around a bar of its own 

 diameter it shall break gradually and give a fine, uniform, 

 silky fracture. 



variation in 149. A variation of cross-section or weight in the finished 

 members of 2^ per cent, from the specified size may be 

 cause for rejection. 



STEEL CASTINGS. 



steei Castings. 150. Steel castings will be used for drawbridge wheels, 

 track segments and gearing. (Art. i.) 



* Use permitted, but not recommended. 



