The major maintenance procedure of removing and replacing the hydraulic ram or cylinder in a hydraulic elevator due to corrosion, wear, or oil leakage.
Full Definition
Hydraulic cylinder replacement is one of the most significant maintenance interventions on a hydraulic elevator. Reasons include external cylinder corrosion (especially on single-bottom cylinders buried in the ground), oil leakage past piston seals, internal scoring, or age-related metal fatigue. The procedure requires decommissioning the elevator, draining the hydraulic fluid, excavating the pit in the case of in-ground cylinders, extracting the old cylinder, installing the new cylinder with correct alignment, refilling and bleeding the hydraulic circuit, and conducting full commissioning tests. EN 81-2 and successor standards specify inspection and replacement criteria. Some cylinders have secondary containment (double-wall construction) to prevent oil escaping to ground; these are mandatory in environmentally sensitive areas.
