This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40X390S, 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 SI40X390S
The AirTAC Airtac SI40 Standard Cylinder SI40X390S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 390mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40X390S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke390 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40X390S
- 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 SI40X390S
The AirTAC SI40X390S is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore and 390mm stroke. Delivering 628N push force at 0.5MPa via a G1/4 port, it is replaced by the SAI40X390S. This direct successor matches the exact mounting interface, bore, stroke, output force, and port size.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure and long life. The SAI family also adds SAIL, SAIF, and BSAI lock variants the SI lacked. Your -S magnet works with legacy CS1-B/DS1-B sensors.
Airtac SI40 Standard Cylinder SI40X390S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40X390S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40X390S |
| Bore size | Ø40 mm |
| Stroke | 390 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 SAI40X390S 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 SAI40X390S 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 SI40X390S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | Bore size in mm. |
| ×390 | 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 SI40X390S Is Used
Package Diversion
Pushes medium-weight cartons across transfer belts using the 628N push force at 0.5MPa over a 390mm reach.
Pallet Handling
Positions empty pallets or totes at loading stations where the 32kg vertical lift capacity is sufficient.
Component Ejection
Ejects machined parts from a fixture using the full 390mm stroke, relying on the adjustable air cushions.
Replacing the Airtac SI40 Standard Cylinder SI40X390S with the SAI40X390S
To replace the SI40X390S, order the SAI40X390S. Confirm the ISO 15552 mounting interface, 40mm bore, 390mm stroke, G1/4 port (PT/G/NPT thread), and mounting accessory. The -S magnet enables CS1-B/DS1-B switches. For sizing, a 50mm bore gives 982N push at 0.5MPa, while dropping to 32mm yields 402N. A plain cylinder drifts on air loss since cushions only decelerate; for load holding use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant. At 390mm, prevent rod bending by using an external guide to minimize side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40X390S
- ✓ 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 SI40X390S FAQ
Yes, the SI40X390S is discontinued. The direct replacement is the SAI40X390S. It is dimensionally interchangeable per ISO 15552, retaining the same 40mm bore, 390mm stroke, force, G1/4 port, and mounting interface.
The bore is 40mm with a G1/4 air port. Force output is 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 SAI40X390S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40X390S replacement — usually within 7-8 hours.