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GEOLOGY AND MINING INDUSTRY OF LEADVILLE. 



The table below gives the principal types used, their numbers, nominal horse- 

 power required, and capacity. 



Blake crushers. The crush'ers manufactured by the Blake Crusher Company 

 belong to two styles: (1) The older style or eccentric pattern and (2) the Challenge 

 Rock-Breaker, or Sectional Cushioned Crusher. Of the eccentric pattern, a horizontal 

 and vertical section will be found in Plate XLI, Figures 1 and 2; the drawing given 

 is a copy of that furnished by the company for a No. 2. The circle D is a section of 

 the fly-wheel shaft, which should make from 225 to 250 revolutions per minute. The 

 dotted circle E is a section of the eccentric. Fis a pitman or connecting-rod, which 

 connects the eccentric with the toggles G 6, whose bearings form an elbow or toggle- 

 joint. H is the fixed jaw ; this rests against the end of the frame A. P P are chilled 

 iron plates, between which the rock is crushed. When worn at the lower end they 

 can be inverted and thus present a new wearing surface. The cheeks 1 1 fit in 

 recesses on each side and hold the chilled plates P P in place. By changing the posi- 

 tion of the cheeks from right to left when worn, both will have a new surface. J is the 

 movable jaw. It is supported by the round bar of iron /L, which passes freely through 

 it and forms the pivot upon which it revolves. L is a spring of india-rubber, which is 

 compressed by the forward movement of the jaw and assists its return. M M are bolt- 

 holes. B is the fly-wheel. C is the driving-pulley. Q Q Q Q are oiling tubes; R It R R, 

 steel bearings; 0, the toggle-block; N, the wedge; 1", the wedge-nut; S, set-screws lor 

 tightening toggle-block ; T, bush and key. The frame A A and supports % Z are made 

 of cast iron. This crusher is being gradually .superseded by the Challenge Rock- 

 Breaker, manufactured by the same firm, which has many points of superiority over 

 the preceding, and is not quite so delicate in construction or so apt to get out of order. 



The Challenge or sectional cushioned crusher is represented in perspective and 

 vertical section in Plate XLI, Figures 3 and 4, which are copied from the company's 

 drawing of a No. 5 crusher. Its crushing capacity per hour is 9 tons when the jaws 

 are set 1 inches apart and when its speed is 275 revolutions per minute. Flint, haid 

 ores that break with a snap, dolomite, hematite, and old slags go through the crusher 

 at that rate in the same conditions, but with sand or soft ore the capacity is sensibly 

 diminished. The 9 horse-power indicated as being necessary to drive this crusher is 

 purely nominal, and represents, so to speak, an average; in practice the driving engine 

 should have greater power, in order to overcome irregular or unexpected resistance. 



The Challenge crusher consists of a three-sided frame- work F, of cast iron, with a 

 broad flanged base, holding the movable jaw in suspension, which forms the front part 

 of the machine, between the upright convergent jaws of which the stone is crushed. 



