THE EXTRACTION OF THE JUICE BY MILLS 215 



in the same horizontal line, as in Fig. 124. Connection from the end of the 

 main spur wheel shaft to the shafts of the top rollers is made by a distance 

 piece and coupling boxes, as sho\\Ti in Fig. 125. To allow pla\'for the top 

 roller, the coupling boxes only very loosely envelop the shafts and distance 

 pieces. The top roller shaft carries a pinion, engaging with pinions on the 

 shafts of the lower rollers. It is not generally customaW at present to carT\- 

 pinions on the end of the miU shafts remote from the engine. As a modi- 

 fication the mill roll gearing may be carried on the reduction gear bedplate, 

 connection to each roller being made by separate distance pieces and coupling 

 boxes. 



The train of gearing described above is almost vmiversal. ^'ario^lS 

 patents include internal-geared spur wheels ; Robinson, 851 of 1853, 2065 

 of 1S09 ; Caird and Robertson, 3066 of 1867 : be\-el gear, Wilson, 2754 of 



^im 



nna ^ 



Fig. 121 



1S61 : wonn and wheel drive, Halpin and AUiott, 2039 of 1873 ; Webb, 

 3747 of 1869 : pitch chains, Rousselot, 5050 of 1876 : helical teeth, Watson, 

 1324 of 1877. 



The Motive Power of Milling Plants. — Putting on one side the exceptional 

 cases where water power is available, and neglecting those districts where 

 cattle power is still used, steam power may be regarded as the only prime 

 mover to be considered. The earher British patents all show a vertical 

 engine as the type employed. The beam engine is shown for the first time 

 in Robinson's patent (2065 of 1859), and this type was installed b}- Scotch 

 firms as standard tUl about 1890, after which date horizontal engines are 

 found. American practice introduced the Corhss engine, and the use of 

 this type remains standard practice with U.S. firms. British firms, though 

 building this t\-pe, seem to incUne rather to the piston valve engine. 



The introduction of the steam turbine as a prime mover dates from 1913, 

 when the " Amistad " factory- in Cuba w^as " electrified." Since then no 

 inconsiderable proportion of new installations have adopted this method. 



