Non-choking Jaw Plates

When the non-choking concave demonstrated its capabilities in the gyratory crusher, it was only natural that the principle should be applied to the jaw crusher. But, inasmuch as the Blake-type jaw is used very largely for primary breaking, where maximum receiving opening is, more often than not, a controlling factor, the application of non-choking plates to standard machines of this type has one unfavorable aspect, as will be evident from an examination of Fig.3, "Standard Blake jaw crusher – non-choking swing jaw plate." This diagram shows the same machine as the last one considered, except that the swing jaw is fitted with a curved jaw plate.

These non-choking jaw plates have been developed in two styles, reversible and non-reversible. The advantage of the reversible design has been outlined in connection with its application to the gyratory reduction crusher. For both types of jaw plate, the effective receiving opening is reduced, as compared to the standard, straight-plate setup. For the non-reversible plate, this reduction is determined by the actual increase in depth of the plate, resulting from the introduction of the curve. For the reversible plate, it is established by the point where the tangent to the curved surface coincides with the maximum angle of nip for the material being crushed. Similar restrictions were outlined in our discussion of non-choking concaves in gyratory crushers.

Regarding the reversible plate, it should be noted that, while that portion of the chamber above the point of nip does no crushing, it does constitute an "active" receiving hopper and, as such, is of definite value in minimizing bridging across the receiving opening. For applications which do not require the full rated receiving opening of the crusher, non-choking jaw plates offer a substantial improvement in performance, an improvement comparable to that resulting from the substitution of non-choking concaves in the gyratory crusher. While this is readily apparent from a comparison of the two diagrams we have presented, more concrete evidence is contained in the table of capacity ratings, which gives ratings for both types of jaw plates, for sizes up to, and including, the 60- x 48-in. machine.