The Model D86 Valve Overtorque Protector ™ is permanently mounted on the valve operating nut. No special tools or valve modifications are required. It’s easily mounted on direct buried valves without excavation. Operating torque is applied to the 2-inch AWWA nut on the Model D86 then transmitted through the D86 to the valve. The Model D86 will transmit sufficient torque to free up and operate the valve. If excessive torque is applied, the drive will disengage and prevent valve damage. The drive will automatically re-engage at the original setting with further rotation in either direction.