WORKING THE SOIL 153 



are made in various sizes and weights of frame. For 

 heavy land, where it is necessary to weight the disk 

 down, an extra heavy frame is necessary. It would 

 probably be advisable to get the extra strong frame for 

 any kind of land, because even in light sand there are 

 times when a disk may be used to advantage to kill 

 quackgrass or to chew up sod before plowing. In such 

 cases it is customary to load on a couple of sacks of 

 sand in addition to the weight of the driver. When a 

 disk is carrying 300 or 400 pounds besides its own 

 weight the racking strains which pull from different 

 directions have a tendency to warp or twist a light 

 frame out of shape. To keep a disk cultivator in good 

 working order it is necessary to go over it thoroughly 

 before doing heavy work. Bolts must be kept tight, all 

 braces examined occasionally, and the heavy nuts at 

 the ends of the disk shafts watched. They sometimes 

 loosen and give trouble. The greatest difficulty in run- 

 ning a disk harrow or cultivator is to keep the boxings 

 in good trim. Wooden boxes are provided with the 

 implement. It is a good plan to insist on having a full 

 set of eight extra boxes. These wooden boxes may be 

 made on the farm, but it sometimes is difficult to get 

 the right kind of wood. They should be made of hard 

 maple, bored according to size of shaft, and boiled in 

 a good quality of linseed oil. Iron boxings have never 

 been satisfactory on a disk implement. Wooden ones 

 make enough trouble, but wood has proved better than 

 iron. On most disk cultivators there are oil channels 

 leading to the boxings. These channels are large 

 enough to carry heavy oil. The lighter grades of cylin- 

 der oil work the best. It is difficult to cork these oil 

 channels tight enough ^p keep the sand out. Oil and 

 sand do not work wen together in a bearing. The 



