BUCKTON TESTING MACHINE. 55 



to manipulate. The lever is a straight horizontal one resting 

 upon a horizontal knife edge; the upper end of the specimen 

 to be tested is attached to the short arm of the lever ; a 

 heavy poise or ba'ance weight rests upon the long arm, 

 and causes the short end to exert a pull upon the specimen. 

 The weight is a heavy one, and of invariable magnitude, 

 and the variations in the load upon the specimen depend 

 upon the relative positions of the poise weights. 



The lever being straight, and the force exerted by the 

 balance weight being vertically downwards, the pull upon 

 the specimen is vertically upwards, and consequently the 

 specimen must be held in a vertical position. It may be 

 mentioned that most of the large machines of the 

 Buckton or Wicksteed type, which are in use at the 

 present time in this country, are either of a 50-ton or 

 100-ton capacity. 



*26. The so-ton Machine. On Fig. 21 is shown a side ele- 

 vation of a Buckton 50-ton testing machine, and a careful 

 inspection of this figure ought to make clear to the reader 

 its general principle and arrangement, and the way in 

 which it is manipulated. Most of the Buckton-Wicksteed 

 vertical machines in use in testing laboratories in this 

 country and abroad are designed and built upon the same 

 lines, although many of them have their own peculiarities 

 in detail ; these will be referred to later. 



The distinctive features of the Buckton-Wicksteed type 

 of machine have already been briefly referred to and 

 described. The tension specimen which is to be tested is 

 held at its lower extremities by wedge clips resting in a 

 shackle, which is linked to the piston rod of an hydraulic 

 cylinder ; this is bolted to the lower part of the main 

 standard of the machine. 



The upper end of the specimen is fixed in a similar 

 way to a shackle hanging from a suspending link, which is 

 itself hung from the knife edge D. This knife edge is fixed 

 into the beam or steelyard A ; so that any pull that is put 

 upon the specimen is directly transmitted to this knife 

 edge in the beam. The beam itself consists of two plates 

 or sides joined by cross pieces at the ends and at inter- 

 mediate points, and is, for the most part open between the 

 plates. In some machines this beam is constructed of 

 steel side plates and cas'-iron cross pieces ; in some others, 

 the whole is made in one casting. 



The steelyard has fixed into it a knife edge B, the edge 



1 Proc. Inst. Mecb. Eng., 1882 and 188(5. 



