Il6 FARM MACHINERY 



it to clog when the ground is wet, and the other is its 

 weak point, the bearing. With the shoe drill, the wear is 

 upon the shoe itself, but with the disk there is a spindle, 

 and being so close to the surface of the soil, it is in a bad 

 place to keep free from dirt and to lubricate. The bear- 

 ings in use consist almost universally of chilled iron. 

 Wood has proved itself to be especially well adapted for 



. ^S^- 



FIG. 86 A STANDARD SINGLE-DISK DRILL WITH COVERING CHAINS 



a place of this kind, but does not seem to be used. At 

 any rate, in the purchase of a drill a close inspection 

 should be made of the bearings to see that they are so 

 designed as to give a large wearing surface, to be as 

 nearly as possible dust proof, and to be provided with the 

 proper kind of oil cups or other device for oiling. 



154. Distance between furrow openers. Drills are 

 usually made 5, 6, or 7 inches between furrow openers. 

 Perhaps 6 inches is the width generally used. They are 



