This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X550STC, 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 SI125X550STC
The AirTAC SI125 Standard Cylinder SI125X550STC 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 SAI125X550STC, 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 → SAI125X550STC
- 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 SI125X550STC
The AirTAC SI125X550STC is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 550 mm stroke. Generating 6136 N push force at 0.5 MPa, it uses a G1/2 port and TC trunnion mount. AirTAC replaced this EOL unit with the SAI125X550STC, a direct sharing the same interface, force, and stroke.
The SAI upgrade features two Y-shaped one-way piston seals for low start-up pressure and long life. The SAI family also adds SAIL and BSAI lock variants the SI lacked. Your -S magnet works with legacy CS1-B/DS1-B sensors.
Airtac SI125 Standard Cylinder SI125X550STC Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X550STC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X550STC |
| 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 SAI125X550STC 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 SAI125X550STC 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 SI125X550STC
| 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 SI125X550STC Is Used
Heavy Stamping Press
Drives large platens and dies requiring 6136 N thrust at 0.5 MPa, absorbing end-of-stroke impact via 40 mm adjustable cushions.
Pallet Lift Station
Raises loaded pallets vertically; the 550 mm stroke moves heavy goods between conveyor elevations when paired with external guides.
Large Clamp Actuator
Secures bulky workpieces in machining cells, using the TC trunnion to pivot and accommodate angular alignment during clamping.
Replacing the Airtac SI125 Standard Cylinder SI125X550STC with the SAI125X550STC
To replace the SI125X550STC, order the SAI125X550STC. It drops right into existing fixtures via the ISO 15552 mounting interface, preserving the 125 mm bore, 550 mm stroke, G1/2 port, and TC trunnion mount. Confirm your thread option (PT/G/NPT) and keep the -S magnet for current AirTAC switch compatibility. If you need more force, the neighboring 160 mm bore offers 10053 N push at 0.5 MPa; if less is needed, the 100 mm bore provides 3927 N. Note: a 550 mm stroke invites rod bending under side loads—use external guides to prevent premature seal wear. A plain cylinder drifts without air; for load holding, use an external pilot check valve or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X550STC
- ✓ 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 SI125X550STC FAQ
Yes, the SI125X550STC is discontinued. The direct replacement is the SAI125X550STC. It is dimensionally interchangeable per ISO 15552, retaining the same 125 mm bore, 550 mm stroke, G1/2 port, and TC mounting interface.
The 125 mm bore uses a G1/2 port. At 0.5 MPa it provides 6136 N push and 5734 pull force. At 0.7 MPa push is 8590 N, and at 0.9 MPa it is 11045 N. The theoretical maximum force is 1251 kgf at 1.0 MPa. Operating speed is 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X550STC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X550STC replacement — usually within 7-8 hours.