Abstract: A bowl support ring for a gyratory rock crusher has an annular inwardly directed threaded surface extending in an upright direction. A bowl having an outwardly directed threaded surface is engageable with the threaded surface on the bowl support ring for supporting the bowl on the support ring and for rotatably adjusting it to different vertical planes. A locking ring threadedly engaged with the bowl above the support ring is connected to downwardly extending hydraulic cylinders secured to the main frame of the crusher. These cylinders are arranged to apply a hold-down force on the locking ring which in turn provides a hold-down force acting through the threads of the locking ring and bowl to maintain the bowl in a stationary vertical position and also to frictionally lock the threads of the locking ring and bowl together to maintain the bowl in a non-rotatable position. A plurality of retainer pins with adjustable thrust portions maintain the locking ring in proper spaced relation from the support ring.