Abstract: An apparatus for injecting fluid into the crushing region of a rotary crusher, which may be either a gyratory crusher or a cone crusher, is disclosed. The injection of fluid can be through conventional nozzles, ports, or through other shapes of apertures. The injection of fluid can be on a continuous basis, on a time-modulated basis, or on a spatially modulated basis. The invention is not limited to use with a particular type of material to be crushed, nor is it limited to use with a particular type of injected fluid. Performance is improved in three areas: (a) a substantial throughput increase is achieved, (b) the output produce is more uniform and therefore of higher value than a non-uniform product would be, and (c) greater size reduction is achieved on a single pass. The invention can increase the capacity of an existing crushing installation, or enable use of a smaller crusher than would normally be required.