This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X550LB, 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 SI125X550LB
The AirTAC SI125 Standard Cylinder SI125X550LB 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 SAI125X550LB, 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 → SAI125X550LB
- 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 SI125X550LB
The AirTAC SI125X550LB is a discontinued double-acting ISO 15552 profile cylinder with a 125 mm bore and 550 mm stroke. It delivers 6136 N push and 5734 N pull at 0.5 MPa, utilizing a G1/2 port and an LB foot mounting interface. AirTAC replaced this EOL unit with the SAI125X550LB, a direct replacement retaining the exact ISO 15552 mounting dimensions, bore, stroke, force, and port size.
The SAI upgrade features a modernized piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. For this non-magnet SKU, position sensing via CS1-B or DS1-B switches is not possible. The SAI family also introduces SAIL and BSAI lock variants absent from the SI line.
Airtac SI125 Standard Cylinder SI125X550LB Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X550LB |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X550LB |
| 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 SAI125X550LB 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 SAI125X550LB 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 SI125X550LB
| 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 SI125X550LB Is Used
Heavy Pressing
Applies 6136 N of thrust at 0.5 MPa for seating heavy industrial components and actuating large forming presses.
Pallet Diversion
Drives robust 550 mm stroke diverter arms to reroute heavy pallets along high-capacity material handling lines.
Replacing the Airtac SI125 Standard Cylinder SI125X550LB with the SAI125X550LB
To replace the SI125X550LB, order the SAI125X550LB. Confirm the ISO 15552 LB foot mount, 550 mm stroke, and G1/2 port. This non-magnet SKU cannot accept sensors. If sizing up or down, neighboring bores are 100 mm and 160 mm; at 0.5 MPa, the 100 mm yields 3927 N push, while the 160 mm yields 10053 N. Because this is a plain double-acting cylinder, it will not hold a load without live air—the cushion only decelerates. For load holding on air loss, use an external rod lock or pilot check valve, or specify an SAIL or BSAI lock variant. At 550 mm stroke, prevent rod bending by guiding the load externally to avoid side loads.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X550LB
- ✓ 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 SI125X550LB FAQ
Yes, the SI125X550LB is discontinued. The direct replacement is the SAI125X550LB. It shares the identical ISO 15552 LB mounting interface, 125 mm bore, 550 mm stroke, output force, and G1/2 port, fitting existing fixtures perfectly.
The 125 mm bore provides 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 a 40 mm adjustable cushion.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X550LB
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X550LB replacement — usually within 7-8 hours.