This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X303S, 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 SI125X303S
The AirTAC SI125 Standard Cylinder SI125X303S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 303mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X303S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke303 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X303S
- 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 SI125X303S
The AirTAC SI125X303S is a discontinued double-acting ISO 15552 profile cylinder featuring a 125 mm bore and 303 mm stroke. It delivers a robust 6136 N push force at 0.5 MPa. AirTAC replaced this legacy unit with the SAI125X303S, a direct upgrade retaining the exact ISO 15552 mounting interface, G1/2 port, and output force.
The SAI replacement features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. This -S model includes a piston magnet for legacy CS1-B/DS1-B sensors, while the SAI family also introduces SAIL and BSAI lock variants absent in the original SI line.
Airtac SI125 Standard Cylinder SI125X303S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X303S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X303S |
| Bore size | Ø125 mm |
| Stroke | 303 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 SAI125X303S 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 SAI125X303S 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 SI125X303S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×303 | 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 SI125X303S Is Used
Heavy-Duty Pressing
Applies the 6136 N push force at 0.5 MPa for seating large bearings and assembling heavy drivetrain components.
Pallet Handling
Drives robust 303 mm stroke lifts and transfers for loaded pallets, utilizing the stable ISO 15552 profile barrel.
Automated Forming
Powers large-stroke metal bending or stamping stations where high kinetic energy requires the 40 mm adjustable cushion.
Replacing the Airtac SI125 Standard Cylinder SI125X303S with the SAI125X303S
To replace the SI125X303S, order the SAI125X303S. Verify your ISO 15552 mounting fixtures, the G1/2 air port, and the M27x2 rod thread. The -S suffix confirms your piston magnet is present for CS1-B/DS1-B switches; the SAI replacement uses current AirTAC sensors. If downsizing, a 100 mm bore yields 3927 N at 0.5 MPa, while a 160 mm bore provides 10053 N. Because the 303 mm stroke exceeds 300 mm, use external guides to prevent rod bending and side-load damage. Note that a plain cylinder drifts on air loss—the cushion only decelerates. For load holding, specify an external pilot check valve or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X303S
- ✓ 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 SI125X303S FAQ
Yes, the SI125X303S is discontinued. The direct replacement is the SAI125X303S. It shares the identical ISO 15552 mounting interface, 125 mm bore, 303 mm stroke, output force, and G1/2 port, fitting directly into your existing fixtures.
At 0.5 MPa, the push force is 6136 N and the pull force is 5734 N. At 0.7 MPa it pushes 8590 N, and 11045 N at 0.9 MPa. The theoretical maximum 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 SAI125X303S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X303S replacement — usually within 7-8 hours.