DRAFT OF OTHER IMPLEMENTS 219 



made twelve trial runs, all showed the heaviest draft on a 

 3j-ton crop of timothy. Two showed a lighter draft on a 2|-ton 

 crop of alfalfa than on a field of wild hay, which was very 

 thick at the bottom. The other three, running at higher speed, 

 handled the dense stand of fine grass better than alfalfa. 



Six-foot binders range in draft from 300 to 500 Ibs., requir- 

 ing three or more horses to pull them at a speed high enough to 

 do good work. Professor Davidson quotes tests showing 314 Ibs. 

 as the average of two 6-foot machines, or 5j Ibs. to the foot. 

 To some extent the same statement as to economy in cutting 

 a wide swath might be made as with mowers. However, the 

 binder must elevate and bind the extra grain at some additional 

 expenditure of power; 12-foot headers require from 600 to 800 

 Ibs., or from 50 to 70 Ibs. per foot cut. A header binder of the 

 same size will require from 100 to 200 Ibs. extra to operate the 

 binding attachment. More horses are more commonly used 

 on binders than on mowers in proportion to draft. Since there 

 are more opportunities for sluggish movement of the straw to 

 clog the working parts, a high speed must be maintained. The 

 average farm horse is able to maintain a pull of 150 Ibs. only 

 by reducing the net speed to two miles per hour or less. To 

 maintain two and one half miles per hour, at which speed the 

 machines work to best advantage, more power is required. 



There are probably more data available as to the draft of 

 wagons than any other piece of farm equipment. The height 

 and width of wheels, the position of the load, the angle of 

 traces, speed of travel, lubrication, character of road surface, 

 grade, and many other factors enter into the question of draft 

 of vehicles. The higher the wheel, the less the draft, in pro- 

 portion to the draft of the total weight of load and vehicle. 

 Road surfaces are never entirely level and wheels are con- 

 tinually encountering obstacles. The higher the wheel, the 

 less the percentage of grade which each obstacle opposes. Con- 

 sequently, less momentary force is required to lift the load over 

 the obstacle. This process is constantly repeated; hence, 



