This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X550S, 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 SI125 Standard Cylinder SI125X550S
The AirTAC SI125 Standard Cylinder SI125X550S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 550mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X550S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke550 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X550S
- 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 SI125 Standard Cylinder SI125X550S
The AirTAC SI125X550S is a discontinued double-acting ISO 15552 profile cylinder with a 125mm bore and 550mm stroke. Delivering 6136N push force at 0.5MPa via a G1/2 port, it is replaced by the SAI125X550S. This direct upgrade shares the exact ISO 15552 mounting interface, bore, stroke, force and port.
The SAI features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure. The SAI family also adds SAIL and BSAI lock variants the SI lacked.
Airtac SI125 Standard Cylinder SI125X550S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X550S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X550S |
| Bore size | Ø125 mm |
| Stroke | 550 mm |
| Acting type | Double acting |
| Port size | G1/2 |
| Rod thread | M27×2.0 |
| 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 – 500 mm/s |
| Cushion | Adjustable, 40 mm |
| Max standard stroke | Up to 1500 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI125X550S carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø125mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 6136 N | 5734 N |
| 0.7 MPa | 8590 N | — |
| Max (@1.0 MPa) | 1251 kgf | |
The SAI125X550S produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI125 Standard Cylinder SI125X550S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | 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 SI125 Standard Cylinder SI125X550S Is Used
Heavy Press Operations
Ideal for high-tonnage pressing and forming tasks requiring the full 6136N thrust at 0.5MPa over a 550mm travel distance.
Large Material Routing
Shifts heavy pallets or structural components along production lines, utilizing the extended stroke and robust 32mm rod.
Automated Storage Retrieval
Drives multi-tier shuttle arms in automated warehousing, where the 313kg vertical lift capacity handles dense loads.
Replacing the Airtac SI125 Standard Cylinder SI125X550S with the SAI125X550S
To replace the SI125X550S, order the SAI125X550S. Verify the ISO 15552 mounting accessory (LB, FA, CA, TC), the G1/2 port, and the -S magnet for CS1-B/DS1-B switches. The 125mm bore yields 6136N push at 0.5MPa; if less force is needed, an 80mm bore gives 2513N, while a 160mm bore offers 10053N. Note: a plain cylinder drifts without live air—the cushion only decelerates. For load holding, use an external rod lock or pilot check valve, or specify an SAIL/BSAI lock variant. For the 550mm stroke, use external guides to prevent rod bending from side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X550S
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI125 Standard Cylinder SI125X550S FAQ
Yes, the SI125X550S is discontinued. The direct replacement is the SAI125X550S. It is dimensionally interchangeable per ISO 15552, retaining the same 125mm bore, 550mm stroke, G1/2 port, and mounting interface.
The 125mm bore features a G1/2 air port. It generates 6136N push and 5734N pull at 0.5MPa, 8590N push at 0.7MPa, 11045N push at 0.9MPa, and a theoretical max of 1251kgf at 1.0MPa. Speed is 30-500mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X550S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X550S replacement — usually within 7-8 hours.