272 THE TESTING OF CHAINS. 



the proof stress insisted upon by the Admiralty is that the 

 chain shall be subjected to a stress of 7 '65 tons per square 

 inch of the total cross section of the link. If the chain is 

 made from 1 in. iron, the area of cross section of the link 

 is 1'57 sq. in., which gives a total proof load of 7*65 by 

 1*57, or 12 tons. When the proof load has been put upon 

 the chain every link is carefully examined in order to find 

 out if any of the joints have shown a tendency to open, or 

 whether the metal has exhibited any flaws or signs of 

 weakness. Tests of this kind are carried out in special 

 machines. One of these, made by Messrs. J. Buckton and 

 Co.. is precisely similar in principle to the horizontal 

 compound lever machine by the same makers, Fig. 34, 

 p. 85. In the case of the chain tester the frame G is 

 replaced by a cast-iron trough 88 ft. long and 2 ft. wide. 

 One end of the chain to be tested is attached to the cross- 

 head, which is linked to the short end of the lever by the 



FIG. 136. Buckton's 250-Ton Chain Tester. 



links K. The attachment is made by means of a pin 

 slipped through the last link of the chain. The other end 

 is fastened to the crosshead H, fixed at some point in the 

 trough, according to the length of chain to be tested. The 

 capacity of this machine, which is in use at the Horwich 

 Locomotive Works, is 100 tons, and the greatest length of 

 chain which can be tested is 82ft., and the shortest 4 ft.* 

 A machine of larger capacity, supplied by Messrs. 

 Buckton to the British Admiralty, is shown on Fig. 136. 

 This machine is capable of testing a cable up to a length of 

 90 ft., and to a load of 250 tons. The gearing to the right 

 is for testing shafts in torsion up to 3 in. diameter, and 

 at a load of 300,000 inch pounds. 



Another machine of smaller capacity, and portable, 

 is shown on Fig. 137. One end of the chain is fixed 

 to a movable crosspiece between the two girders shown, 

 and the other to the right-hand crosshead which is 

 linked to the hydraulic ram. The water under 

 pressure is supplied by a hand-pump, and the load upon 

 the specimen is indicated by a pressure gauge. The 



* Engineering, October 9th, 1891. 



