This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X420S, 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 SI125X420S
The AirTAC SI125 Standard Cylinder SI125X420S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 420mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X420S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke420 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X420S
- 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 SI125X420S
The AirTAC SI125X420S is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 420 mm stroke. It delivers 6136 N push force at 0.5 MPa. The direct replacement is the SAI125X420S, which maintains the exact same ISO 15552 mounting interface, bore, stroke, output force, and G1/2 port size to fit existing fixtures seamlessly.
The SAI upgrade features a modernized piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. The SAI family also introduces lock and clamp variants (SAIL, BSAI) absent in the legacy SI line. This -S model includes a piston magnet for CS1-B/DS1-B sensors.
Airtac SI125 Standard Cylinder SI125X420S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X420S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X420S |
| Bore size | Ø125 mm |
| Stroke | 420 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 SAI125X420S 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 SAI125X420S 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 SI125X420S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×420 | 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 SI125X420S Is Used
Heavy Press Clamping
Secures large metal castings during machining operations, utilizing the 6136 N push force at 0.5 MPa to hold components rigidly against cutting forces.
Pallet Transfer Gates
Actuates heavy-duty diverter gates in conveyor systems, where the 420 mm stroke provides the full travel needed to redirect loaded pallets.
Replacing the Airtac SI125 Standard Cylinder SI125X420S with the SAI125X420S
To replace the SI125X420S, order the SAI125X420S and verify the ISO 15552 mounting interface, 420 mm stroke, G1/2 port (PT/G/NPT thread), and mounting accessory. Because the stroke is 420 mm, use external guides to prevent rod bending and side-load damage. Sizing both ways: a 100 mm bore yields 3927 N push at 0.5 MPa, while a 160 mm bore yields 10053 N. A plain cylinder drifts without live air; for load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant. The SAI family also offers the SAIF self-valve for smaller bores (32-100).
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X420S
- ✓ 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 SI125X420S FAQ
Yes, the SI125X420S is discontinued. The direct replacement is the SAI125X420S. It is dimensionally interchangeable per ISO 15552, retaining the same 125 mm bore, 420 mm stroke, output force, G1/2 port, and mounting interface.
The G1/2 port is fixed by the 125 mm bore. Force ratings are: 6136 N push and 5734 N pull at 0.5 MPa, 8590 N push at 0.7 MPa, 11045 N push at 0.9 MPa, and a theoretical maximum of 1251 kgf at 1.0 MPa. Operating speed is 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X420S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X420S replacement — usually within 7-8 hours.