Abstract: An anvil adjustment assembly of a vertical shaft impactor includes an anvil ring configured to be disposed within a housing of the vertical shaft impactor. The anvil ring includes a tab which is coupled to an elongate jack bolt having a first end and a second end. A jack bolt housing partially surrounds the bolt and is coupled to the housing. A first locking collar and a second locking collar are coupled to the jack bolt. The first locking nut is coupled to the jack bolt on one side of the tab, and the second locking nut is coupled to the jack bolt on the opposite side of the tab. The jack bolt moves along a longitudinal axis within the jack bolt housing between a first position and a second position, and the movement of the jack bolt along the longitudinal axis induces longitudinal movement of the anvil ring.