14 CIRCULAR 443, U. S. DEPARTMENT OF AGRICULTURE 



Recent investigations made on a portable dehydrator (fig. 4, p. 4) 

 at the Agricultural Research Center, Beltsville. Md., consisted 

 of determining the performance characteristics of this type of dehy- 

 drator and the drying requirements of forage crops. Also the relative 

 efficiency of preservation of the nutrients and the feeding value when 

 fed to dairy cows were compared with other methods of harvesting. 



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Figure 7. — Portable forage deliydraror rested at the Agricultural Research Center, 



Beltsville, Md. 



Figure 7 shows the machine during test. The machine is mounted on 

 wheels. When it is to be transported, the collector standing on the 

 ground and the feed conveyor are disconnected and moved separately. 

 The machine consists of a 3-foot combustion chamber which extends 

 part way inside the 5-foot cylinder. The 5-foot cylinder or drum is 

 closed at the back end except where the high-moisture forage enters. 

 The outer drum is 7 feet in diameter and 14 feet long. It has an open- 

 ing near one end from which the forage is lifted by suction and passed 

 on to the coolers. Flanges or nights are attached to the inside of the 

 drum for lifting and spreading the chopped forage through the drying 

 chamber as the drum revolves. Heat is supplied by an oil burner 

 located at the opposite end of the drum from where the forage enters. 

 Controls regulate the rate of fuel burning to maintain a uniform outlet 

 air temperature. A 20-horsepower gasoline engine is used for supply- 

 ing power to the machine. 



The time required for the forage to pass through the dehydrator 

 is relatively short, only a few minutes. As the forage loses moisture 

 its movement through the drier is speeded up. For this reason, over- 



