CHAPTER XXXV. 

 STANDARD TYPES OF CRUSHING AND PULVERIZING MACHINERY 



IT has seemed advisable to devote a chapter to the description of 

 various standard types of crushing and pulverizing machinery. In 

 selecting the particular machines to be described in this chapter, the 

 writer has attempted to include those, and only those, which are known 

 to him as being in satisfactory operation at one or more American cement- 

 plants. It is possible that in endeavoring to exclude worthless types 

 some meritorious machines may have been unintentionally neglected; 

 but it is safe to say that over 95 per cent of the cement made in this 

 country is crushed and pulverized by machines described in the follow- 

 ing pages. 



In describing the various types of crushers and pulverizers, the 

 drawings of the mills and the data relative to their construction and 

 mechanical operation have been taken mostly from trade catalogues 

 or from descriptions prepared by the manufacturers. The data on 

 output, fineness and power lequired were, however, in almost all cases 

 obtained from managers of cement-mills, and are believed to be entirely 

 reliable. 



Classification of Grinding Machinery. 



So many types and varieties of crushing and pulverizing machinery 

 are now on the market that it is difficult, from a single description, to 

 form much of an idea of the relation of any given one of these machines 

 to any of the others. To aid in this, the machines described in the 

 following pages have been grouped under eight classes, according to 

 their general methods of action. This grouping is as follows: 

 Class 1. JAW CRUSHERS; material crushed between two jaws which approach 



and recede BLAKE CRUSHER. 



Class 2. CONE GRINDERS ; material crushed by the revolution of a toothed cone 



or spindle within a toothed cup GATES CRUSHER, CRACKERS. 



Class 3. ROLLS; material crushed between two or more plain, fluted, or toothed 



cylinders revolving in opposite directions ROLLS. 



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