A gyratory crusher is described having an upright shaft supporting a generally conical crushing head within a surrounding stationary concave carried by a crusher frame and defining an annular crushing chamber between the concave and the head. A capacity regulator is provided having a cap, and a generally cylindrical member with a vertical central axis. The cylindrical member depends from the cap to provide a lower end coaxial with the cap. an annular shield is connected to the lower end of the depending member to project radially outward therefrom with an outer diameter substantially equal to the outer diameter of the top of the crushing chamber. A regulator support means is carried by the crusher, that projects within the depending member and defines a regulator support surface for carrying the regulator with the annular shield coaxially over the crushing chamber. A vertically jacking mechanism is interposed between the cap of the regulator and the support surface within the depending member of the regulator, operative to raise and lower the annular shield relative to the concave and regulate the crushers capacity to receive and pass stone into the crushing chamber.