206 AGRICULTURAL ENGINEERING 



soil to the best advantage, — more so than a smaller disk, — 

 and is not of as heavy draft as a larger disk. A disk blade 

 26 or 28 inches in diameter can be used for a longer period, 

 because much more metal is provided for wear. 



The disk plow does not have a tongue and does not make 

 as good corners as the modern high-class sulky plows. If the 

 disk is of proper shape and size, the plow pulverizes and mixes 

 the soil thoroughly, which features are essential in good plow- 

 ing. This plow will cover standing weeds to good advantage, 

 but loose trash is troublesome. It cannot be used at all in 

 tough sod. 



It is a mistake to try to cut too wide a furrow with a disk 

 plow. A furrow with a width greater than 8 inches results 

 in more or less "cutting" or "covering." 



The vital parts of a disk plow are the disk and its bearing. 

 The former should be constructed of the best of material, 

 for which the faith of the manufacturer must be taken, and 

 the bearing should have plenty of material to resist wear 

 and reliable means of excluding dirt and providing lubrica- 

 tion. 



Deep -Tilling Machine. This is a new machine which 

 has come upon the market within the last two years, and, as 



far as providing 

 a means of plow- 

 ing the soil to a 

 greater depth 

 than hitherto is 

 concerned, it is 

 a success. The 

 machine is a disk 

 gang plow with 

 the second or 

 rear disk set to 



Fig. 116. A deep-tilling machine. 



