15 CIRCULAR 443, U. S. DEPARTMENT OF AGRICULTURE 



unless it is placed in a comparatively thin layer the chopped hay 

 forms a mattress practically impervious to the passage of the drying 

 gases. However, crushing of the forage by running it through a 

 crushing device patterned after a clothes wringer and cracking the 

 stems, especially the nodes, is found to be of appreciable assistance in 

 drying the forage. 



The ordinary silage cutter can be adapted for chopping the forage 

 by slowing down the feed table so that the forage is cut into lengths less 

 than three-eighths of an inch long. A combination silage cutter and 

 hammer mill has been found suitable for processing the undried mate- 

 rial. No screens are used in the hammer mill and it is set to receive 

 the chopped forage directly from the silage cutter. The impact of the 

 hammers on the chopped green forage has been found sufficient to 

 crack open the stemmy sections and further aid the evaporation of 

 water in the drier. 



Examination of table 3 shows that the power requirements for the 

 experimental apron-conveyor drier ranged from 22 to 28 kilowatt- 

 hours per 1,000 poimds of water evaporated. The power requirements 

 are distributed approximately as follows: 



Percent 



Moving apron and auxiliary conveyors 11 



Moving drying gases 83 



Oil-burner operation 6 



For an experimental rotary drier the power requirements ranged 

 from 11 to 19 kilowatt-hours per 1,000 pounds, distributed roughly as 

 follows: 



Percent 



Chopping forage 25 to 35 



Moving drying gases 45 to 60 



Oil-burner operation 4 to 8 



Rotating drum and conveying forage 10 to 15 



With these figures in mind it will be found that a drum drier capable 

 of evaporating 3,000 pounds of water per hour will need motive power 

 equivalent to 35 or 40 horsepower to run it. This would be divided 

 as follows: 



Horsepower 



Chopper 15 



Fan and drum 20 



Burner 14 



Conveying equipment 3 



A danger in motor installation is to overmotorize. Induction-type 

 electric motors rimning underloaded heat up badly as well as deliver 

 power at low efficiencies, thus increasing the power consumption. 

 TVhere electric power is not available, power distribution to the vari- 

 ous places about the drier may be accomplished by means of a long 

 countershaft. The motive power in this case may be in the form of a 

 tractor or a stationary gas, oil, or Diesel engine. 



OPERATION OF DRIERS AND COST OF DRYING 



By care in the planning of a forage-drier installation, economies 

 can be effected in all of the important items that go to make up the 

 cost of operation. The cycle of operations comprises unloading the 

 trucks or wagons, feeding the wet forage into a chopper or directly 

 into the drier, and disposing of the dried material at the point where 

 it is discharged from the drier system. Ordinarily the material is 



