This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40BX55S, 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 SI40 Standard Cylinder SI40BX55S
The AirTAC Airtac SI40 Standard Cylinder SI40BX55S is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 55mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40BX55S, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke55 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40BX55S
- 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 SI40 Standard Cylinder SI40BX55S
The AirTAC SI40BX55S is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore, 55mm stroke, G1/4 port and a SUS304 stainless steel rod. Delivering 628 N push force at 0.5 MPa, it is directly replaced by the SAI40BX55S. This direct upgrade shares identical ISO 15552 mounting-interface dimensions, bore, stroke and output force, dropping straight into existing fixtures.
The SAI successor features an upgraded piston seal with two Y-shaped one-way elements for low start-up pressure and long life. The built-in magnet supports legacy CS1-B/DS1-B sensors, while the SAI family introduces SAIL, SAIF and BSAI lock variants the SI lacked.
Airtac SI40 Standard Cylinder SI40BX55S Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40BX55S |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40BX55S |
| Bore size | Ø40 mm |
| Stroke | 55 mm |
| Acting type | Double acting |
| Port size | G1/4 |
| Rod thread | M12×1.25 |
| 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, 27 mm |
| Max standard stroke | Up to 1200 mm |
Specifications follow the official AirTAC SI datasheet (now discontinued). The SAI40BX55S carries the same ISO 15552 ratings. Confirm against the product label before installation. Thread options: PT / G / NPT.
Theoretical Output Force (Ø40mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 628 N | 528 N |
| 0.7 MPa | 880 N | — |
| Max (@1.0 MPa) | 128 kgf | |
The SAI40BX55S produces the same force from the same bore. Actual usable force is lower than theoretical; size with a margin.
Model Code: Airtac SI40 Standard Cylinder SI40BX55S
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | 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 SI40 Standard Cylinder SI40BX55S Is Used
Stainless Rod Clamping
Ideal for compact clamping stations where the SUS304 rod resists washdowns while providing 628 N of push force at 0.5 MPa.
Short-Stroke Diversion
The 55mm stroke handles precise package diverting on conveyors, fitting neatly into tight ISO 15552 fixture spacing.
Replacing the Airtac SI40 Standard Cylinder SI40BX55S with the SAI40BX55S
To replace the SI40BX55S, order the SAI40BX55S: it matches the 40mm bore, 55mm stroke, G1/4 port, M12x1.25 rod thread and ISO 15552 mounting interface. Retain your existing mounting accessories and confirm the -S magnet for current AirTAC switches. If you need more force, the neighbouring 50mm bore yields 982 N push at 0.5 MPa; if less is acceptable, the 32mm bore provides 402 N. Note that a plain cylinder drifts on air loss—the cushion only decelerates—so use an external rod lock or pilot check valve for held loads. The SUS304 rod offers corrosion resistance, and a Viton H seal raises operating temperature to 150 C.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40BX55S
- ✓ Same bore / stroke / force
- ✓ Port/thread type (PT/G/NPT)
- ✓ Magnet (-S) for sensors?
- ✓ Mounting reused (FA/FB/CA/CB/CR/LB/TC)
Airtac SI40 Standard Cylinder SI40BX55S FAQ
Yes, the SI40BX55S is discontinued. The direct replacement is the SAI40BX55S. It is dimensionally interchangeable per ISO 15552, retaining the same 40mm bore, 55mm stroke, G1/4 port and mounting interface, but adds an upgraded piston seal.
The 40mm bore features a G1/4 air port and M12x1.25 rod thread. It delivers 628 N push and 528 N pull at 0.5 MPa, 879 N push at 0.7 MPa, 1130 N push at 0.9 MPa, and a theoretical max of 128 kgf at 1.0 MPa.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40BX55S
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40BX55S replacement — usually within 7-8 hours.