Power Team’s RA556L and RA1006L (100T) lock-nut, hydraulic jacking cylinders are nearly 50% lighter than steel versions and are uniquely designed to include a spring retract feature.  The engineered plunger thread and mating lock feature provides mechanical load holding quality to the lifting process.  By incorporating incremental pauses and adjusting the lock nut against the cylinder body before proceeding will provide an extra level of safety to your jacking project.