This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125AX550, 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 SI125AX550
The AirTAC SI125 Standard Cylinder SI125AX550 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 SAI125AX550, 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 → SAI125AX550
- 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 SI125AX550
The AirTAC SI125AX550 is a discontinued double-acting ISO 15552 profile cylinder featuring a 125 mm bore and 550 mm stroke. It delivers 6136 N push force at 0.5 MPa, uses a G1/2 port, and includes an M27x2 rod thread with a 40 mm adjustable air cushion. The direct replacement is the SAI125AX550, which maintains the exact same ISO 15552 mounting interface, bore, stroke, output force, and porting for seamless fixture integration.
This SAI upgrade introduces a two Y-shaped one-way piston seal for low start-up pressure and long life. The original SI line lacked the SAIL air-released lock, SAIF built-in valve, and BSAI clamp-lock variants now available. This specific SKU uses a SUS420J2 stainless steel rod (option A) and lacks a magnet, so it cannot accept CS1-B or DS1-B sensors.
Airtac SI125 Standard Cylinder SI125AX550 Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125AX550 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125AX550 |
| 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 SAI125AX550 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 SAI125AX550 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 SI125AX550
| 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 SI125AX550 Is Used
Heavy Press Staging
Ideal for positioning heavy stamping blanks into presses, using the 6136 N push force at 0.5 MPa to shift substantial mass reliably.
Pallet Lift Gates
Drives large automated pallet gates where the 550 mm stroke and SUS420J2 stainless rod provide the reach and corrosion resistance needed.
Bulk Material Diverters
Actuates heavy-duty diverter arms on aggregate or bulk handling lines, with external guides recommended to manage the 550 mm stroke side loads.
Replacing the Airtac SI125 Standard Cylinder SI125AX550 with the SAI125AX550
To replace the SI125AX550, order the SAI125AX550 and confirm the ISO 15552 mounting interface, 550 mm stroke, G1/2 port (PT/G/NPT thread), and your mounting accessory. This SKU has no magnet (-S), so it cannot support position sensing; if sensing is needed, specify a magnet on the SAI order. Because this is a 550 mm stroke, use external guides to prevent rod bending and side loads. Sizing both ways: if you need less force, the 100 mm bore offers 3927 N push @0.5 MPa; if you need more, the 160 mm bore provides 10053 N. Note that a plain cylinder does not hold load on air loss—the cushion only decelerates. For load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variants.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125AX550
- ✓ 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 SI125AX550 FAQ
Yes, the SI125AX550 is discontinued. The direct replacement is the SAI125AX550. It is dimensionally interchangeable per ISO 15552, matching the 125 mm bore, 550 mm stroke, 6136 N force, G1/2 port, and mounting interface.
The G1/2 port bore delivers 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 max of 1251 kgf at 1.0 MPa. The speed range is 30-500 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125AX550
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125AX550 replacement — usually within 7-8 hours.