The present invention is an anti fall device for use with scissor type mechanically actuated lifting devices. The anti fall device comprises a a slave safety hydraulic cylinder capable of supporting a lifting device upon failure of a drive assembly thereby arresting descent of the lifting device when the lifting device is normally stationary or moving upwardly and a drive assembly of the lifting device fails and the lifting device begins to descend uncontrollably. The hydraulic cylinder includes a one way check valve for preventing reverse hydraulic fluid flow upon uncontrolled descent of the lifting device thereby arresting movement of the hydraulic cylinder and arresting descent of the lifting device. The invention also includes an hydraulic velocity fuse in fluid communication with the hydraulic cylinder. The velocity fuse is triggered at a preselected fluid flow rate for controllably lowering the lifting device.
