204 AGRICULTURAL ENGINEERING 



from the land, and the front furrow wheel regulated to keep 

 the large land wheel traveling directly to the front. 



Draft of Plows.. The draft or pull required to move a 

 plow at work varies widely with the soil conditions and the 

 adjustment of the plow. The draft will vary from 4 to 10 

 pounds to each square inch of cross section of the furrow slice, 

 the method of comparision commonly used. In stubble 

 ground the draft should not exceed 43^ pounds per square 

 inch of the furrow. Thus a 16-inch plow running six inches 

 deep will have a furrow with a cross-section of 96 square 

 inches. If the draft be 43^ pounds per square inch the total 

 draft will be 432 pounds, an easy load for three 1300- to 

 1400-pound horses. 



A sulky plow with a driver of medium weight will run with 

 as light draft, when in proper adjustment, as a walking plow. 

 This is due to the reduction of sole and landside friction. A 

 plow out of adjustment will often pull half again as heavy as 

 it should. 



In making a selection of a sulky plow, care should be taken 

 to see that all parts subject to wear can be easily renewed. 

 The greater part of a sulky plow is not subject to wear and 

 will last indefinitely if not broken. The modern plow 

 must have wheel boxes which will not only exclude all dirt 

 but also provide a magazine for a liberal supply of grease. 

 Many sulky plows are now constructed with too light a frame. 

 Choice should be made of the heavy, rigid plow, even if the 

 cost is slightly higher and the draft slightly greater. 



The Disk Plow. There are two conditions under which 

 the disk plow will do good work. The hard, dry soils of some 

 of the Western states are more easily subdued by means of 

 the disk plow than any other. These soils at certain times 

 of the year are turned up in lumps by the common plow, but 

 the disk plow cuts its way through the lumps and breaks 



