This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI50X400STC, 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 SI50 Standard Cylinder SI50X400STC
The AirTAC Airtac SI50 Standard Cylinder SI50X400STC is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø50mm bore and 400mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI50X400STC, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ50 mm
- Stroke400 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM16×1.5
- StatusDiscontinued → SAI50X400STC
- 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 SI50 Standard Cylinder SI50X400STC
The AirTAC SI50X400STC is a discontinued double-acting ISO 15552 profile cylinder with a 50mm bore and 400mm stroke. It delivers 982N push and 825N pull at 0.5MPa via a G1/4 port. AirTAC replaced this legacy unit with the SAI50X400STC, a direct sharing the exact ISO 15552 mounting interface, TC trunnion mount, and output force.
The SAI upgrade introduces a two-piece Y-shaped piston seal for lower start-up pressure and longer life. The SAI family also adds SAIL, SAIF, and BSAI lock variants absent in the SI line.
Airtac SI50 Standard Cylinder SI50X400STC Technical Specifications
| Model | Airtac SI50 Standard Cylinder SI50X400STC |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI50X400STC |
| Bore size | Ø50 mm |
| Stroke | 400 mm |
| Acting type | Double acting |
| Port size | G1/4 |
| Rod thread | M16×1.5 |
| 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 – 800 mm/s |
| Cushion | Adjustable, 30 mm |
| Max standard stroke | Up to 1200 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI50X400STC carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø50mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 982 N | 825 N |
| 0.7 MPa | 1374 N | — |
| Max (@1.0 MPa) | 200 kgf | |
The SAI50X400STC produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI50 Standard Cylinder SI50X400STC
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 50 | Bore size in mm. |
| ×400 | 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 SI50 Standard Cylinder SI50X400STC Is Used
Material Diversion
Drives 400mm stroke diverters on packaging lines, utilizing the 982N push force at 0.5MPa to shift moderate loads smoothly between belt lanes.
Component Ejection
Ejects machined parts from CNC fixtures over a 400mm reach, relying on adjustable 30mm end cushions to decelerate the 20mm rod safely.
Replacing the Airtac SI50 Standard Cylinder SI50X400STC with the SAI50X400STC
To replace the SI50X400STC, order the SAI50X400STC. Verify the ISO 15552 TC trunnion interface, 50mm bore, 400mm stroke, and G1/4 port (PT/G/NPT thread options). The -S suffix means it has a piston magnet for CS1-B/DS1-B sensors; the SAI replacement uses current AirTAC switches. If sizing up or down, neighbouring bores are 40mm (628N push @0.5MPa) and 63mm (1559N push @0.5MPa). At 400mm stroke, use an external guide to prevent rod bending and side-load wear. A plain cylinder drifts without air; for load holding, use an external rod lock, pilot check valve, or the SAIL/BSAI lock variant.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI50X400STC
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI50 Standard Cylinder SI50X400STC FAQ
Yes, the SI50X400STC is discontinued. The direct replacement is the SAI50X400STC. It shares the identical ISO 15552 mounting interface, 50mm bore, 400mm stroke, G1/4 port, and TC mount, fitting existing fixtures perfectly while upgrading the piston seal.
The 50mm bore features a G1/4 air port and a 20mm rod. It delivers 982N push and 825N pull at 0.5MPa, 1374N push at 0.7MPa, 1767N push at 0.9MPa, and a theoretical max of 200kgf at 1.0MPa. Operating speed is 30-800 mm/s.
Related AirTAC SAI Cylinders
Request a Quote for the SAI50X400STC
Send us the quantity and destination. We confirm price, stock and lead time on the SAI50X400STC replacement — usually within 7-8 hours.