Actuators · Air bellows

Air Bellows

Air bellows are single-acting pneumatic actuators that look more like a flexible rubber-and-fabric tire than a cylinder — and that's the point. They have almost no friction, no alignment problems, no lubrication need, and provide very high force in a very short stroke. Ideal for vibration isolation under heavy machinery (replacing rubber pads), air springs in suspension systems, short-stroke high-force lifting (presses, clamping). The Norgren family covers three product lines: M/31000 (Ø 6-16 inch / 152-406 mm) and M/32000 (Ø 21-26 inch / 533-660 mm) non-serviceable; PM/31000 (Ø 2¾-12 inch / 78-330 mm) serviceable — the rubber bellow can be replaced. High-temperature (TM/31000, TM/32000, TPM/31000 — IR material, -20…+70 °C) and extreme-temperature (EM/31000, EPM/31000 — ECO material, +50…+115 °C) variants on request. Operating pressure: 5.5 bar dynamic (recommended) / 8 bar max; force table at 6 bar.

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Almost frictionless operationNo piston rod, no piston seal, no rod bushing — the bellow is just a flexible membrane. Friction approaches zero at start of motion, which is critical for vibration isolation and very low force triggering. Cylinders typically need ~0.5-1 bar to start moving; bellows respond to fraction of that.

No alignment, no maintenanceThe flexible bellow tolerates angular and axial misalignment (within rated limits) — no precision mounting required. No lubrication, no maintenance — the only failure mode is bellow rupture from over-pressure or chemical attack. Decades of life in clean industrial use.

Short stroke, high forceAir bellows are designed for short strokes (M/31000: 55-430 mm; PM/31000: 20-320 mm — depending on diameter and number of convolutions) at very high force. A Ø 26 inch M/32000 at the 6-bar force-table reference generates over 200 kN (~20 tons); smaller sizes from a few to tens of kN. Ideal for clamping, short-press operations, lifting jigs, and machinery vibration isolation where the pad needs to also actuate.

Available series

Air bellows

M/31000

Air bellows, single acting

Datasheet (PDF) →

PM/31000

Serviceable air bellows, single acting

Datasheet (PDF) →

Frequently asked questions

Air bellow if you need: almost zero friction at start of motion (vibration isolation, very low actuation pressure), misalignment tolerance (no precision mounting), or very large diameter (over 200 mm — most cylinders top out at Ø 200). Short-stroke cylinder if you need: double-acting (return force without spring or weight), defined stroke endpoints with cushioning, or rod-based mounting for guidance. Air bellows are single-acting — return is by external force (gravity, spring, opposing bellow).

Force is (effective area) × (pressure). PDF force table at 6 bar (Norgren reference): Ø 6 inch ≈ 10 kN; Ø 12 inch ≈ 45 kN; Ø 26 inch (660 mm) ≈ 205 kN (~20 tons). Operating range: 5.5 bar dynamic (recommended, 79 psi) — 8 bar max (116 psi). Note that effective area changes with stroke — published curves on the datasheet show force vs. height for each diameter and number of convolutions. Always size from the datasheet curve at the operating height, not from the nominal diameter alone.

Yes — this is one of the classic applications. A pressurised bellow under heavy machinery acts as a tunable air spring: higher pressure = stiffer spring, lower = softer. Pneumatic isolation is much better than rubber pads for low-frequency disturbance because of its low natural frequency (1.6-3.6 Hz at 4 bar) — effective isolation starts from excitation frequencies several times higher (the datasheet example shows 99% isolation at 20 Hz). The serviceable PM/31000 is preferred here — bellows degrade under continuous vibration loading and need eventual replacement.