|
The theoretical maximum size of cube that the knobs will grip, when the rolls are set at minimum spacing, is 24 in.; but the rolls will reduce any stone that can be introduced into the 7-ft square hopper. Large blocks will span across the tops of the two rolls; immediately the slugger teeth on the one roll so equipped go to work on these block s and quickly shatter them into pieces that can be gripped between the sets of regular teeth; from this point on, the action is a mixture of sledging and pressure crushing. The same selective segregation which we described in connection with the single-roll machine occur in the double-roll crusher; the smaller pieces are cleared quickly, leaving the rolls free to work on the larger blocks.
The entire performance on individual skip-loads of stone takes place in a very short period of time. Ten-ton loads of mixed-size medium limestone will clear the crusher in from 10 to 15 sec.;
large single blocks, weighing from 6 to 8 tons, are crushed in from 5 to 20 seconds, depending upon the toughness of the individual piece, and upon the way it happens to land in the crushing chamber. These performances were clocked on machines turning out a 6-in. product. |
