12 



BULLETIN 867, U. S. DEPARTMENT OF AGRICULTURE. 



the height of the racks. By adjusting the slides at the bottom, 

 controlled by levers, the discharge may be made continuous or 

 intermittent. Usually the latter practice is followed. 



The heating is effected by rising columns of hot air. This air is 

 drawn in by a fan at the bottom and side of the bean-holding equip- 

 ment and passed over hot closed steam pipes. To prevent the beans 

 from drjing out, and also to increase the heating effect of the hot air, 



Fig. 3.— Bean racks, showing steel uprights 

 and shelves, saddles, and slide levers. 

 Every surface on which beans are sup- 

 ported is inclined so the beans and dust 

 will flow out when the slides are open, 

 leaving the racks clean. These racks are 

 of smooth galvanized steel and are fitted 

 no closely, without bolts. 





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Fig. 4.— Section of bean rack showing it (at the 

 left) discharging at intervals and (at the right) 

 right) in continuous flow. By throwing the 

 small levers at the bottom of the racks the 

 method of discharge is instantly changed from 

 one to the other. The upper large lever oper- 

 ates the slides for discharge at intervals, but 

 is not used when the beans arc flowing con- 

 tinuously. 



a jet of live si cam is sometimes introduced into the hot-air stream as 

 it emerges from the nests of steam pipes. It is found that an air 

 temperature of about 180° F. will raise that of the beans when deliv- 

 ered to the machines to about 110° F. 



Although the above is a method of procedure now followed in com- 

 mercial practice, it might be well to consider the following facts with 

 regard to improved operation. It is generally conceded in expeller 

 practice that better oil yields are obtained when appreciable quan- 



