This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI125X420, 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 SI125X420
The AirTAC SI125 Standard Cylinder SI125X420 is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø125mm bore and 420mm stroke, G1/2 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI125X420, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ125 mm
- Stroke420 mm
- Port sizeG1/2
- Acting typeDouble acting
- Rod threadM27×2.0
- StatusDiscontinued → SAI125X420
- 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 SI125X420
The AirTAC SI125X420 is a discontinued double-acting ISO 15552 profile cylinder delivering a push force of 6136 N at 0.5 MPa. AirTAC replaced this legacy unit with the SAI125X420, a direct replacement retaining the exact 125 mm bore, 420 mm stroke, G1/2 port, and mounting interface.
The SAI upgrade features a revised piston seal with two Y-shaped one-way elements for low start-up pressure and extended life. Note this specific SKU lacks a magnet (-S) and cannot accept position sensors.
Airtac SI125 Standard Cylinder SI125X420 Technical Specifications
| Model | Airtac SI125 Standard Cylinder SI125X420 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI125X420 |
| Bore size | Ø125 mm |
| Stroke | 420 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 SAI125X420 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 SAI125X420 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 SI125X420
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 125 | Bore size in mm. |
| ×420 | 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 SI125X420 Is Used
Heavy Stamping Press
Drives large platens and heavy tooling in metal forming, relying on the 6136 N thrust to actuate high-tonnage mechanical linkages.
Pallet Lift Gate
Raises and lowers loaded pallets in distribution hubs, where the 313 kg vertical lift capacity handles substantial packaging weights over the 420 mm travel.
Mold Clamping Fixture
Secures large injection mold halves or heavy industrial castings, utilizing the adjustable 40 mm air cushions to decelerate the massive moving mass.
Replacing the Airtac SI125 Standard Cylinder SI125X420 with the SAI125X420
To replace the SI125X420, order the SAI125X420. Verify the ISO 15552 mounting accessory (LB, FA, CA, TC) and the G1/2 port thread (PT, G, or NPT). Because this 420 mm stroke exceeds 300 mm, use an external guide to prevent rod bending and side-load damage. For sizing, the neighboring 100 mm bore yields 3927 N push at 0.5 MPa, while the 160 mm bore yields 10053 N. A plain cylinder drifts on air loss; for load holding, specify the SAIL lock or BSAI clamp-lock variant, or use an external pilot check valve. This non-magnet SKU cannot support sensing.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI125X420
- ✓ 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 SI125X420 FAQ
Yes, the SI125X420 is discontinued. The direct replacement is the AirTAC SAI125X420. It is dimensionally interchangeable per ISO 15552, matching the 125 mm bore, 420 mm stroke, G1/2 port, and mounting interface, so it drops directly into existing fixtures.
This double-acting cylinder uses a G1/2 air port. At 0.5 MPa it provides 6136 N push and 5734 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 SAI125X420
Send us the quantity and destination. We confirm price, stock and lead time on the SAI125X420 replacement — usually within 7-8 hours.