Alfalfa in Kansas. 



293 



Disk Harrows. 



These machines are indispensible in this section of the country. While 

 made in various sizes, the 16-inch disk seems to be the best. From 8 to 

 24 disks are used, the following being very common: 14 by 16 and 

 16 by 16. 



Bearings are either of oil-soaked wood or chilled iron, and are very 

 important. The oiling device must be of good construction and should 

 be handy. 



The full blade is better than the cutaway or spading for a single disk. 

 If double, the cutaway is commonly preferred. The notched parts of the 

 disk do not cut into soil, but the unnotched portions will go deeper than 

 the full blade. With a double disk the ground, is really gone over twice. 



Attachments can be purchased to place around the seat of a double 

 disk. These ought to be used more, for a jar could easily throw the 

 operator between the front and rear gangs. 



Tongue trucks or fore carriages make a harrow more convenient. 

 They can then be used without a tongue, tongue set in the center, or set 

 over for three horses. However, many harrows are sold without the fore 

 carriage. 



OPERATION AND CARE. By setting over the tongue when using a 

 three-horse team side draft will not be a troublesome factor. 



Better work can be obtained by lapping, although this requires more 

 time. The gangs must be set at different angles if one gang is passing 

 over soft ground and the other gang is in undisked land. 



As the work done by a disk blade depends upon their penetration, 

 the governing factors are as follows: the line of draft, angle at which 

 the gangs are set, curvature and sharpness of the disk blades, and 

 weight of the harrow. 



Transport trucks are of considerable value whenever the conditions 

 are such that the harrow must be hauled some distance across meadows 

 or over rocky roads. They make it easier to draw the harrow by hand 

 in the shed. (See "Disk Harrow," in index.) 



Fio. 229. The smoothing or spike-tooth harrow. 



