This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X400SFTC, 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 SI125X400SFTC
The AirTAC SI125 Standard Cylinder SI125X400SFTC 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 SAI125X400SFTC, 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 → SAI125X400SFTC
- 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 SI125X400SFTC
The AirTAC SI125X400SFTC is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 400 mm stroke. It delivers 6136 N push force at 0.5 MPa through a G1/2 port. The direct replacement is the SAI125X400SFTC, matching the bore, stroke, force, port and FTC trunnion mount exactly.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure and long life. The SAI family adds SAIL and BSAI lock variants the SI lacked. This -S SKU uses CS1-B/DS1-B sensors.
Airtac SI125 Standard Cylinder SI125X400SFTC Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X400SFTC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X400SFTC |
| 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 SAI125X400SFTC 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 SAI125X400SFTC 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 SI125X400SFTC
| 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 SI125X400SFTC Is Used
Heavy Press Operations
Applies 6136 N of thrust at 0.5 MPa for forming, stamping, and heavy-duty press tasks in automated manufacturing lines.
Pallet Diversion
Uses the 400 mm stroke and FTC trunnion mount to push heavy pallets smoothly onto secondary conveyor branches at high speed.
Replacing the Airtac SI125 Standard Cylinder SI125X400SFTC with the SAI125X400SFTC
To replace the SI125X400SFTC, order the SAI125X400SFTC. Confirm the ISO 15552 interface, 125 mm bore, 400 mm stroke, G1/2 port (PT/G/NPT), FTC trunnion mount, and the -S magnet. Sizing both ways: the 100 mm bore gives 3927 N push at 0.5 MPa, while the 160 mm bore yields 10053 N. At 0.7 MPa this 125 mm bore outputs 8590 N. A plain cylinder drifts on air loss; the cushion only decelerates. For load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant. With a 400 mm stroke, use an external guide to prevent rod bending and side-load wear.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X400SFTC
- ✓ 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 SI125X400SFTC FAQ
Yes, the SI125X400SFTC is discontinued. The direct replacement is the SAI125X400SFTC. It is dimensionally interchangeable per ISO 15552, keeping the same 125 mm bore, 400 mm stroke, G1/2 port, and FTC mounting interface.
The G1/2 port bore delivers 6136 N push and 5734 N pull at 0.5 MPa, 8590 N push at 0.7 MPa, 11045 N at 0.9 MPa, and a theoretical max of 1251 kgf at 1.0 MPa. Operating speed is 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X400SFTC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X400SFTC replacement — usually within 7-8 hours.