This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X255S, 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 SI125X255S
The AirTAC SI125 Standard Cylinder SI125X255S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 255mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X255S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke255 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X255S
- 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 SI125X255S
The AirTAC SI125X255S is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 255 mm stroke. It delivers 6136 N push force at 0.5 MPa through a G1/2 port. The direct replacement is the SAI125X255S, matching the interface, stroke, force and mounting.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure and long life. It also adds SAIL lock and BSAI clamp-lock variants the SI lacked. The -S magnet works with legacy CS1-B/DS1-B sensors.
Airtac SI125 Standard Cylinder SI125X255S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X255S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X255S |
| Bore size | Ø125 mm |
| Stroke | 255 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 SAI125X255S 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 SAI125X255S 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 SI125X255S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×255 | 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 SI125X255S Is Used
Heavy Press Clamping
Secures large metal workpieces in machining fixtures, utilising the 6136 N push force at 0.5 MPa to hold components rigidly against cutting loads.
Pallet Lift Gates
Actuates heavy-duty loading dock gates, where the 255 mm stroke provides the precise travel needed to clear palletised goods safely.
Automated Assembly Rams
Drives large pressing and insertion operations in automated lines, benefiting from the adjustable 40 mm air cushions to decelerate heavy masses.
Replacing the Airtac SI125 Standard Cylinder SI125X255S with the SAI125X255S
To replace the SI125X255S, order the SAI125X255S. Verify the ISO 15552 mounting interface, 255 mm stroke, G1/2 port, and M27x2 rod thread. The -S magnet enables CS1-B/DS1-B sensors. For sizing, neighbouring bores are 100 mm (3927 N push @0.5 MPa) and 160 mm (10053 N). Note that a plain cylinder drifts without live air; for load holding use the SAIL or BSAI lock variants. Since the 255 mm stroke is under 300 mm, side-load risks are lower, but always guide the load to prevent rod bending.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X255S
- ✓ 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 SI125X255S FAQ
Yes, the SI125X255S is discontinued. The direct replacement is the AirTAC SAI125X255S. It is dimensionally interchangeable per ISO 15552, retaining the same 125 mm bore, 255 mm stroke, G1/2 port, and mounting interface.
It features a G1/2 air port and M27x2 rod thread. Force output is 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 SAI125X255S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X255S replacement — usually within 7-8 hours.