A sprag clutch assembly for an aircraft drive wheel drive system capable of moving an aircraft autonomously on the ground in both forward and reverse directions is provided. The clutch is mounted within an aircraft drive wheel to be operatively engaged to control drive means braking torque when the aircraft is driven in a forward or reverse direction. The clutch assembly includes a plurality of pivoted sprag elements activatable to transmit torque and configured so that ratcheting occurs only when the aircraft drive wheel is driven in a forward direction and a braking torque is applied when the aircraft drive wheel is driven in reverse when the relative speed of the drive system is slower than the drive wheel speed, thereby permitting the drive system drive motor to function as a brake when the clutch assembly is engaged and the aircraft is reversing.