Evolution of Large/Heavy-Duty Pneumatic Cylinders in China

    Historically known as “heavy-duty cylinders” in China, these feature bores from 32–320 mm and strokes up to 3000 mm. Barrels are made from seamless steel tubes; end caps from steel plate or cast iron. Large-diameter piston rods are chrome-plated and polished, used in metallurgy and heavy machinery.

    During China’s pneumatic industry founding era (1967–1980), national focus on heavy industry drove demand. In 1975, a nationwide collaborative design effort produced the first-generation QGA (non-cushioned), QGB (adjustable cushion), and JB (fixed cushion, for metallurgy) series—bore 32–400 mm.

    First-Gen Design: Single-rod, double-acting. Barrels: seamless steel. Rods: 45# steel. End caps/pistons: HT250 gray iron. Tie rods: cold-drawn 35# steel. Seals: Yx-type hydraulic leather rings (no dedicated pneumatic seals existed), resulting in high starting pressure (0.2–0.35 MPa). No wear rings; front cap supported rod via bronze bushing.

    Despite age, these remain in service in harsh environments. Post-1983, companies like Jinan Huaneng upgraded them with precision-drawn aluminum barrels.

    Transition to Second Generation (1983 onward):
    (1) ISO-standardized mounting dimensions.
    (2) Domestic development of precision-drawn aluminum tubes (≤100 mm bore by 1985; ≥250 mm by 2010).
    (3) National pneumatic seal standards established (~1990), enabling oil-free operation.
    (4) Domestic production of magnetic rings and proximity switches (~1985).
    (5) Zinc/aluminum die-cast end caps adopted (~1989).