This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X550S, 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 SI40X550S
The AirTAC Airtac SI40 Standard Cylinder SI40X550S 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 SAI40X550S, 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 → SAI40X550S
- 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 SI40X550S
The AirTAC SI40X550S is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 550mm stroke. Delivering 628N push force at 0.5MPa via a G1/4 port, it is replaced by the SAI40X550S. This direct upgrade shares the exact ISO 15552 mounting interface, bore, stroke, force and accessories, fitting existing fixtures perfectly.
The SAI upgrade features a new piston seal with two Y-shaped one-way elements for low start-up pressure and long life. The SI -S suffix indicates a piston magnet for legacy CS1-B/DS1-B sensors, while the SAI family also adds SAIL, SAIF and BSAI lock variants.
Airtac SI40 Standard Cylinder SI40X550S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X550S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X550S |
| 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 SAI40X550S 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 SAI40X550S 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 SI40X550S
| 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 SI40X550S Is Used
Package Diversion
Pushes medium-weight cartons on packaging lines using the 628N push force at 0.5MPa over a 550mm reach.
Pallet Push-Off
Acts as a sweep arm to index goods off pallets, requiring the 550mm extension and G1/4 air supply.
Replacing the Airtac SI40 Standard Cylinder SI40X550S with the SAI40X550S
To replace the SI40X550S, order the SAI40X550S. Verify the ISO 15552 mounting interface, 40mm bore, 550mm stroke, G1/4 port (PT/G/NPT thread options) and your mounting accessory. The -S suffix means a piston magnet is present for CS1-B/DS1-B switches. If sizing alternatives, neighbouring bores are 32mm (402N push @0.5MPa) or 50mm (982N push @0.5MPa). Because this is a 550mm stroke, use external guides to prevent rod bending and side-load damage. A plain cylinder drifts on air loss; for load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X550S
- ✓ 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 SI40X550S FAQ
Yes, the SI40X550S is discontinued. The direct replacement is the SAI40X550S. It is a true ISO 15552 profile cylinder sharing the same 40mm bore, 550mm stroke, 628N force, G1/4 port and mounting interface, so it drops directly into existing fixtures.
The 40mm bore delivers 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. Operating speed is 30-800mm/s. It features a 16mm rod, M12x1.25 thread, and 27mm adjustable air cushions at both ends.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40X550S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X550S replacement — usually within 7-8 hours.