Abstract: The accompanying specification discloses a mine cage safety device comprising at least one friction wheel adapted to roll freely over the shaft wall or mine cage guide timber when the cage is lifted upwards and downwards in the mine shaft. When the cage accelerates past a critical level as in a free fall the friction wheel actuates a hydraulic trigger means that in turn sets off an explosive charge which instantaneously drives braking means against the timber guides to thereby arrest the free fall of the mine cage.