This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125BX275S, 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 SI125BX275S
The AirTAC SI125 Standard Cylinder SI125BX275S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 275mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125BX275S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke275 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125BX275S
- 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 SI125BX275S
The AirTAC SI125BX275S is a discontinued double-acting ISO 15552 profile cylinder featuring a SUS304 stainless steel piston rod and a built-in magnet. Delivering 6136 N push force at 0.5 MPa through a G1/2 port, its direct replacement is the SAI125BX275S. This current-production SAI model maintains the same 125 mm bore, 275 mm stroke, and mounting interface, dropping directly into existing fixtures.
The SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and extended life. Note that plain cylinders drift without live air; for load holding, explore the SAIL or BSAI lock variants the SI line lacked.
Airtac SI125 Standard Cylinder SI125BX275S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125BX275S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125BX275S |
| Bore size | Ø125 mm |
| Stroke | 275 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 SAI125BX275S 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 SAI125BX275S 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 SI125BX275S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×275 | 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 SI125BX275S Is Used
Heavy-Duty Pressing
Drives 6136 N of thrust at 0.5 MPa for seating large bearings and heavy industrial assemblies requiring a robust 125 mm bore.
Pallet Handling
Shifts heavy loaded pallets on conveyors where the SUS304 stainless rod resists moisture and harsh factory environments.
Automated Forming
Provides reliable 275 mm stroke actuation for large metal or composite forming stations, easily swapping to the SAI125BX275S.
Replacing the Airtac SI125 Standard Cylinder SI125BX275S with the SAI125BX275S
To replace the discontinued SI125BX275S, order the SAI125BX275S. Verify your ISO 15552 mounting interface (LB, FA, TC, etc.), the G1/2 air port, and the M27x2 rod thread. The -S magnet supports legacy CS1-B/DS1-B sensors, while the SAI uses current AirTAC switches. The -B rod specifies SUS304 stainless steel for corrosion resistance. For load sizing, the 6136 N push at 0.5 MPa safely handles 3682 N; if you need more force, the 160 mm bore offers 10053 N. Remember, air cushions only decelerate; they do not hold loads. Use an external rod lock or pilot check valve for secure holding. At 275 mm stroke, ensure guide alignment to prevent rod bending.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125BX275S
- ✓ 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 SI125BX275S FAQ
Yes, the SI125BX275S is discontinued. The direct replacement is the SAI125BX275S. It is dimensionally interchangeable per ISO 15552, retaining the same 125 mm bore, 275 mm stroke, 6136 N force, G1/2 port, and mounting fixtures.
The 125 mm bore generates 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. It uses a G1/2 port and M27x2 rod thread.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125BX275S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125BX275S replacement — usually within 7-8 hours.