This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40AX550S, with the same bore, stroke, output force, port and mounting, so it fits the same application. The SAI replacement keeps the same ISO 15552 mounting interface, bore, stroke, output force and accessories, so it drops straight into existing fixtures. It is the current-production version of this cylinder with an upgraded piston seal.
Airtac SI40 Standard Cylinder SI40AX550S
The AirTAC Airtac SI40 Standard Cylinder SI40AX550S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 550mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40AX550S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke550 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40AX550S
- No minimum order. A single piece can be ordered.
- Ready in 3–5 business days. That is the time we take to process the order and hand it to the carrier. Transit time after that depends on the destination.
About the Airtac SI40 Standard Cylinder SI40AX550S
The AirTAC SI40AX550S is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 550mm stroke. It delivers 628N push force at 0.5MPa via a G1/4 port. The direct replacement is the SAI40AX550S, matching the interface, force, and mounting. The SAI upgrades the piston seal to two Y-shaped one-way elements for lower start-up pressure and longer life. This unit features the -A SUS420J2 stainless piston rod for corrosion resistance, and the -S magnet for legacy CS1-B/DS1-B sensors.
The SAI family also introduces SAIL, SAIF, and BSAI lock variants absent in the SI line. Note that a plain cylinder drifts without live air; the cushion only decelerates. For a 550mm stroke, use external guides to prevent rod bending.
Airtac SI40 Standard Cylinder SI40AX550S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40AX550S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40AX550S |
| Bore size | Ø40 mm |
| Stroke | 550 mm |
| Acting type | Double acting |
| Port size | G1/4 |
| Rod thread | M12×1.25 |
| Fluid | Air (filtered by 40µm element) |
|---|---|
| Operating pressure | 0.15 – 1.0 MPa |
| Proof pressure | 1.5 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 800 mm/s |
| Cushion | Adjustable, 27 mm |
| Max standard stroke | Up to 1200 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI40AX550S carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø40mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 628 N | 528 N |
| 0.7 MPa | 880 N | — |
| Max (@1.0 MPa) | 128 kgf | |
The SAI40AX550S produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI40 Standard Cylinder SI40AX550S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | Bore size in mm. |
| ×550 | Stroke length in mm. |
| -S | Optional built-in magnet for sensor position sensing. |
Legacy SI-family variants: SID (double rod), SIJ (adjustable stroke) — each maps to its SAI equivalent (SID→SAID, SIJ→SAIJ). Rod material: carbon steel (blank) / SUS420J2 (A) / SUS304 (B).
Where the Airtac SI40 Standard Cylinder SI40AX550S Is Used
Long-Stroke Diversion
Pushes packages across transfer lines using the 550mm stroke, relying on the SUS420J2 stainless rod to resist moisture in washdown areas.
Pallet Handling
Actuates stoppers and gates in pallet flow systems where the G1/4 port and 628N thrust provide consistent actuation force.
Replacing the Airtac SI40 Standard Cylinder SI40AX550S with the SAI40AX550S
To replace the SI40AX550S, order the SAI40AX550S. Confirm the ISO 15552 mounting interface, 40mm bore, 550mm stroke, G1/4 port (PT/G/NPT thread options), and mounting accessory. The -S magnet enables position sensing, and the -A rod specifies SUS420J2 stainless steel. When sizing, neighbouring bores offer different forces: the 32mm bore yields 402N push at 0.5MPa, while the 50mm bore yields 982N. For load holding, a plain cylinder does not lock on air loss; the cushion only decelerates. Use an external rod lock, a pilot check valve, or the SAIL/BSAI lock variant. Because 550mm exceeds 300mm, add external guides to prevent rod bending under side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40AX550S
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI40 Standard Cylinder SI40AX550S FAQ
Yes, the SI40AX550S is discontinued. The direct replacement is the SAI40AX550S. It is dimensionally interchangeable per ISO 15552, matching the 40mm bore, 550mm stroke, 628N force, G1/4 port, and mounting fixtures.
The G1/4 port supplies a 16mm rod. Force ratings are 628N push and 528N pull at 0.5MPa, 879N push at 0.7MPa, 1130N push at 0.9MPa, and a theoretical max of 128kgf at 1.0MPa. Speed is 30-800mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40AX550S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40AX550S replacement — usually within 7-8 hours.