This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125BX400S, 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 SI125BX400S
The AirTAC SI125 Standard Cylinder SI125BX400S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 400mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125BX400S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke400 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125BX400S
- 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 SI125BX400S
The AirTAC SI125BX400S is a discontinued double-acting ISO 15552 profile cylinder featuring a 125 mm bore, 400 mm stroke, and a SUS304 stainless steel piston rod. Generating 6136 N push force at 0.5 MPa, it is replaced by the SAI125BX400S. This direct upgrade shares the exact ISO 15552 mounting interface, G1/2 port, and M27x2 rod thread, fitting existing fixtures seamlessly.
The SAI features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and long life. It retains the CS1-B/DS1-B legacy sensor groove, while the SAI family adds SAIL lock and BSAI clamp-lock variants absent in the SI line.
Airtac SI125 Standard Cylinder SI125BX400S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125BX400S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125BX400S |
| Bore size | Ø125 mm |
| Stroke | 400 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 SAI125BX400S 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 SAI125BX400S 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 SI125BX400S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×400 | 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 SI125BX400S Is Used
Heavy Press Clamping
Secures large metal castings during machining operations, utilizing the 6136 N push force and 400 mm travel to accommodate bulky workpieces.
Pallet Diverting
Actuates heavy-duty routing gates on conveyor lines, where the robust 125 mm bore and SUS304 rod withstand harsh industrial environments.
Long-Stroke Ejection
Pushes finished parts completely out of molding machinery, relying on the 400 mm extension and adjustable 40 mm cushions to stop smoothly.
Replacing the Airtac SI125 Standard Cylinder SI125BX400S with the SAI125BX400S
To replace the SI125BX400S, order the SAI125BX400S, confirming the ISO 15552 interface, 400 mm stroke, G1/2 port, and the -S magnet for current AirTAC switches. Sizing both ways: the neighboring 100 mm bore yields 3927 N push at 0.5 MPa, while the 160 mm bore yields 10053 N. Note that a plain cylinder drifts without live air; the cushion only decelerates. For load holding, use an external rod lock or the SAIL/BSAI variants. At 400 mm stroke, prevent rod bending by using external guides to manage side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125BX400S
- ✓ 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 SI125BX400S FAQ
Yes, the SI125BX400S is discontinued. The direct replacement is the SAI125BX400S. It is dimensionally interchangeable per ISO 15552, retaining the same 125 mm bore, 400 mm stroke, G1/2 port, and mounting accessories.
At 0.5 MPa it provides 6136 N push and 5734 N pull. At 0.7 MPa push is 8590 N, and at 0.9 MPa it is 11045 N. The theoretical max force is 1251 kgf at 1.0 MPa. Operating speed for this 125 mm bore is 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125BX400S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125BX400S replacement — usually within 7-8 hours.