Abstract: A rotary ring-type log debarker has barking tools operated by double-acting air cylinders with air pressure supplied through solenoid valves from a pressure chamber in the rotor. During normal debarker operation the rotor pressure chamber is isolated from an external source of air pressure. Air is supplied to the rotor pressure chamber intermittently only when necessary to maintain or increase air pressure in the chamber through a pilot air-operated ring-type air seal between the rotor and its stator. The seal is loaded only during the addition of air to the rotor pressure chamber to minimize wear on the sealing surfaces. Positive, instantaneous opening and closing of the tools and changes in air pressure in the rotor pressure chamber are effected from a remote operator's console while the rotor is either rotating or stationary.