Telescopic hydraulic cylinders are multi-stage hydraulic cylinders with multiple piston rods nested in a telescopic structure. They feature a special design that is extremely compact when retracted while achieving strokes 3-6 times the retracted length when extended. They are ideal for applications requiring long strokes in limited installation space, including dump truck bed lifting, construction machinery outriggers, machine tool long-distance feed mechanisms, press machine deep drawing, and injection molding machine large mold opening/closing. Single-acting types are mainstream with return by self-weight or external force, though double-acting types are also manufactured. Unlike conventional single-stage cylinders, they feature specialized design with multi-stage telescopic mechanisms for high space efficiency.