This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X55S, 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 SI125X55S
The AirTAC SI125 Standard Cylinder SI125X55S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 55mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X55S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke55 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X55S
- 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 SI125X55S
The AirTAC SI125X55S is a discontinued double-acting ISO 15552 profile cylinder with a 125mm bore and 55mm stroke. It delivers 6136N push force at 0.5MPa via a G1/2 port. AirTAC replaced this legacy unit with the SAI125X55S, a direct sharing the exact ISO 15552 mounting interface, bore, stroke, output force, and porting to fit existing fixtures directly.
The SAI upgrade introduces a refined piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. This -S model includes a piston magnet for legacy CS1-B/DS1-B sensors, while the SAI family also adds lock variants (SAIL, BSAI) absent in the original SI line.
Airtac SI125 Standard Cylinder SI125X55S Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X55S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X55S |
| Bore size | Ø125 mm |
| Stroke | 55 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 SAI125X55S 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 SAI125X55S 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 SI125X55S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×55 | 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 SI125X55S Is Used
Heavy Press Operations
Drives high-tonnage pressing and forming tasks where the 6136N push force at 0.5MPa is required for deforming or seating heavy industrial components.
Large Mold Clamping
Provides reliable clamping force for large injection molds or heavy fabrication fixtures, utilizing the 32mm rod and M27x2 thread for rigid load engagement.
Replacing the Airtac SI125 Standard Cylinder SI125X55S with the SAI125X55S
To replace the SI125X55S, order the SAI125X55S and verify the ISO 15552 mounting interface, 125mm bore, 55mm stroke, G1/2 port (PT/G/NPT thread options), and your specific mounting accessory. Because the -S suffix denotes a magnet, confirm your sensor setup; the legacy SI used CS1-B/DS1-B switches, whereas the SAI replacement uses current AirTAC switches. If sizing upward or downward, note the 125mm bore yields 6136N push at 0.5MPa, while the neighbouring 100mm bore yields 3927N. A plain cylinder drifts on air loss since the cushion only decelerates; for load holding, specify the SAIL or BSAI lock variant, or use an external pilot check valve. Rod material options include carbon steel, SUS420J2 (A), or SUS304 (B).
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X55S
- ✓ 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 SI125X55S FAQ
Yes, the SI125X55S is discontinued. The direct replacement is the AirTAC SAI125X55S. It shares the identical ISO 15552 mounting interface, 125mm bore, 55mm stroke, output force, and G1/2 port, fitting existing fixtures perfectly without modifications.
The 125mm bore features a G1/2 port and delivers 6136N push and 5734N pull at 0.5MPa. At 0.7MPa the push force is 8590N, and the theoretical maximum force is 1251kgf at 1.0MPa. It operates at speeds of 30-500mm/s with a 40mm adjustable air cushion at each end.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X55S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X55S replacement — usually within 7-8 hours.