Abstract: A rotary actuator (10) rotates a drive shaft (40), which in turn rotates a stem (76) between an actuator housing (32) and a central body (48). Drive pins (50, 52) extend between the central body of a rotary sleeve (42), and move within helical guide slots (80, 82) to linearly raise and lower the central body (48), which is connected to the linear controller (18).