Abstract: The improved blowout preventer ram tail rod locking device of the present invention includes a housing, a body movable in the housing, having a threaded rod and coacting with the outer end of the ram tail rod to lock it in the ram closed position, a nut rotatably mounted within said housing, having ractchet teeth and engaging the threads onthe threaded rod, a braking piston slidably mounted within said housing and having ratchet teeth engaging withthe ratchet teeth of the nut, the ratchet teeth on said nut and piston allowing freedom of rotation of the nut during movement of the body into engagement with the ram tail road and preventing rotation of the nut in the opposite direction, and menas for exerting pressure on said braking piston to disengage the racthet teeth during retracting movement of the wedge.