GREENWOOD MACHINE. 77 



with a glass casing, which can be opened and partly 

 removed when a test is to be made. 



HORIZONTAL COMPOUND-LEVER TESTING MACHINE. 

 BY MESSRS. GREENWOOD AND BATLEY. LEEDS. 



39. The testing machine which has just been described 

 Ihas a combined leverage of 15,000 to 1 ; that of Messrs. 

 Greenwood and Batley, which we are now about to discuss, 

 ihas one of about 100 to 1. These are both compound 

 lever machines, but while Mr. Adamson employs four 

 levers, the present machine has only two one straight 

 and one at right angles. The Greenwood machines are 

 nearly all alike in principle. There are differences in 

 detail and arrangement, according to the kind of work 

 they are intended to be used for. 



On Fig. 30 is shown a general view of a 50-ton machine, 

 which is in use at several engineering colleges, govern- 

 ment arsenals, and private works. 



The machine is a horizontal one, and is arranged to test 

 up to a maximum load of 50 tons in tension, compression, 

 cross-breaking, and torsion. 



The arrangement of the levers in these machines is 

 best shown on the diagrammatic view on Fig. 19 (6). 

 There are two levers : one a bell-crank lever, whose short 

 vertical arm is attached to the specimen, and whose long 

 horizontal arm is acted upon by the second or straight 

 lever; this second lever carries the movable and variable 

 jockey weight, whose magnitude and position determines 

 the load on the specimen. 



Keverting to the general view in Fig. 30, it will be seen 

 that the machine consists, in the first place, of a cast-iron 

 : bed, supported on four standards. At the left-hand end of 

 the bed is a frame, carrying the weighing levers ; at the 

 _ right-hand end is a casting consisting for the most part of 

 the straining cylinder. These two castings, one at each 

 .end, besides being fixed to the bed of the machine, are 

 further stayed by cast-iron struts fitted between their 

 1 upper parts. 



The straining ram at the right-hand end of the bed 



works out of its cylinder in a direction from left to right. 



This ram carries on its end a crosshead, which has attached 



( four screws running from end to end of the machine. 



A system of spur wheels is arranged on the ram crosshead, 



: the wheels being rotated by the hand wheel shown. There 



