FARM MACHINERY 281 



18x22 inches to 44x66 inches, and 32x54 inches to 36x58 

 inches. The 36x58-inch separator requires from 25 to 40 

 actual horsepower to operate it successfully; and such a 

 machine will thresh from 500 to 1000 bushels of wheat in 

 a day, or about twice as much oats. 



Selection of a Threshing Machine. The choice of a 

 threshing machine will depend largely upon the amount of 

 grain to be threshed and also upon the method followed in 

 threshing. In the United States, it is customary for the 

 threshing to be done by experts who make a business of that 

 kind of work. There are some localities where the individual 

 farmer owns a threshing outfit, in which case the smaller 

 sizes are used. Special machines are provided for special 

 conditions. The threshing of beans and peas requires a 

 special machine, as well as the threshing of clover. 



QUESTIONS 



1. Describe the four distinct operations performed by the modern 

 threshing machine. 



2. Name the parts that perform each operation. 



3. Describe the construction of the cylinder. 



4. Describe the concave and its adjustment. 



5. What is the' main purpose of the grate? 



6. Where is the straw rack, and what work does it perform? 



7. What is the purpose of the grain pan? 



8. What function is performed by the shoe? 



9. Describe the construction and work of the self-feeder. 



10. What is the work of the weigher? 



11. How is the size of threshing machines designated? 



12. What are some of the important considerations involved in the 

 selection of a threshing machine? 



