Abstract: A hydraulic cylinder comprising a hydraulically operated power lifting ram for lifting heavy loads further includes a guide cylinder concentric about and enclosing the ram, the guide cylinder being secured to the lift platform for further support of the load and reciprocating in unison with the ram under application of hydraulic pressure. The guide cylinder is equipped with a safety locking means which prevents the hydraulic cylinder and its load from lowering in the event of a sudden loss in hydraulic pressure. The safety locking means is in contact with the guide cylinder substantially during the full stroke of the hydraulic operated ram, providing a unique method of locking the cylinder in any position within tolerances normally associated with gear driven devices.