This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X500STC, 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 SI125X500STC
The AirTAC SI125 Standard Cylinder SI125X500STC is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 500mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X500STC, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke500 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X500STC
- 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 SI125X500STC
The AirTAC SI125X500STC is a discontinued double-acting ISO 15552 profile cylinder featuring an extruded aluminum barrel, a 125 mm bore, and a 500 mm stroke. Built for heavy-duty motion, it delivers 6136 N of push force at 0.5 MPa and uses a G1/2 air port with an M27x2 rod thread. Because this legacy unit is end-of-life, AirTAC specifies the SAI125X500STC as the direct replacement, matching the exact ISO 15552 mounting interface, TC trunnion accessory, output force, and travel length.
The SAI upgrade retains all bore and port ratings but introduces an upgraded piston seal with two Y-shaped one-way elements for lower start-up pressure and longer service life. For position sensing, this SI unit includes a piston magnet (-S) compatible with legacy CS1-B/DS1-B switches, whereas the SAI family uses current AirTAC sensors. If high-temperature operation up to 150 C is required, both legacy and replacement types offer a Viton H seal option.
Airtac SI125 Standard Cylinder SI125X500STC Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X500STC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X500STC |
| Bore size | Ø125 mm |
| Stroke | 500 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 SAI125X500STC 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 SAI125X500STC 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 SI125X500STC
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×500 | 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 SI125X500STC Is Used
Heavy Machinery Forming
Drives large press dies and forming platens where 6136 N of push force at 0.5 MPa is required for shaping thick materials.
Bulk Material Diversion
Actuates heavy-duty diverter gates on high-capacity conveyor lines, utilizing the TC trunnion mount to handle structural pivoting.
Replacing the Airtac SI125 Standard Cylinder SI125X500STC with the SAI125X500STC
To replace the discontinued SI125X500STC, order the SAI125X500STC. Confirm the ISO 15552 TC trunnion mounting interface, the 125 mm bore, the 500 mm stroke, the G1/2 port, and the -S magnet for legacy CS1-B/DS1-B sensors. When sizing, check neighboring bores: a 100 mm bore yields 3927 N push at 0.5 MPa, while a 160 mm bore yields 10053 N. This 125 mm bore provides 6136 N push and 5734 N pull at 0.5 MPa, reaching 8590 N at 0.7 MPa. A standard double-acting cylinder does not hold load on air loss—the air cushion only decelerates near stroke end—so use an external rod lock, a pilot check valve, or the SAIL/BSAI lock variants for secure holding. Because the 500 mm stroke is long, use an external guide to prevent rod bending and side-load damage. Operating speed is 30-500 mm/s.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X500STC
- ✓ 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 SI125X500STC FAQ
Yes, the AirTAC SI125X500STC is discontinued. The direct replacement is the SAI125X500STC. It features the same ISO 15552 TC mounting interface, 125 mm bore, 500 mm stroke, G1/2 port, and output force, fitting directly into existing fixtures.
This double-acting cylinder uses a G1/2 air port and an M27x2 rod thread. At 0.5 MPa it provides 6136 N push and 5734 N pull force. At 0.7 MPa push is 8590 N, and at 0.9 MPa it is 11045 N. The theoretical maximum force is 1251 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI125X500STC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X500STC replacement — usually within 7-8 hours.