An axial cam with a plurality of followers mounted within its diameter drives the followers in both axial directions. The followers operatively actuate valves such as those of an internal combustion engine. The cam can be driven about its exterior perimeter, providing an axially compact embodiment. The phasing of select followers can be established by modifying the azimuth positions of those followers with the cam in operation. By providing the cam with a symmetric actuating profile its followers can be linked to alternately actuate same-function valves in different engine cylinders.