180 POWER AND THE PLOW 



The levers are like those of the solid moldboard gang in 

 appearance and function. On some gangs the angle of the 

 disk to the line of draft is open to adjustment. It is claimed 

 that if the disk be set so the beveled face on the rear of the 

 cutting edge is level at the bottom of the furrow and per- 

 pendicular at the surface of the ground the disks will run practi- 

 cally without side draft. In addition to setting the disks closer 

 together, a less abrupt angle can be used to secure better pene- 

 tration. For trashy ground the disk may be set to have a 

 coulter-like effect, thus cutting and burying the vegetation 

 more satisfactorily. A running-board and seat may be pro- 

 vided. The latter is usually located at the rear, as the weight 

 of the driver aids in holding the plows in line. Weight boxes 

 and extra weights are often provided at the rear of each gang. 



Castings serve to hold the disks to the frame. The disk 

 may have a shaft through the centre, with a bearing at either 

 end, or an axle attached to the rear, or convex, surface only. 

 In either case the bearing is long, well lubricated, and often 

 chilled, as the disk must be kept permanently in perfect align- 

 ment. Ball bearings to receive the end thrust are a valuable 

 feature. Scrapers are necessary to clean the disks, and they 

 aid in turning the soil. They are often given a moldboard 

 curvature to accomplish the latter, and one maker states that 

 the successful turning of the soil depends more on the size 

 and adjustment of the scraper than on any other part of the 

 disk plow. 



The hitch to the engine is by the same means as used on 

 the solid moldboard gangs. However, it must be put close to 

 the right side of the gang in order to overcome the latter's 

 tendency to crowd to the left and jump out of the furrow. 



The centre of resistance, especially on outfits of one or two 

 small gangs, is therefore to the right of the centre of the 

 engine, one disk-plow manufacturer stating that three fourths 

 of the load is on the right drive- wheel. Greater difficulty 

 in steering and unequal strain on the engine are the results. 



