Abstract: A fail-safe system for a power-driven rotary lawn mower having a conventional, propeller-like blade utilizes a bearing assembly mounted upon the drive shaft and connected to the blade by cables. Upon accidental disconnection of the blade from the shaft during operation of the machine, the cables will catch the blade and prevent its ejection, and will thrust the bearing assembly against a retaining collar rigidly mounted upon the shaft outwardly thereof. The bearing will permit free-wheeling action of the blade while retarding rotation relative to the shaft, thereby safely retaining it until the operator has an opportunity to stop the machine.