This model is discontinued
AirTAC has phased out the SI series. You can still order this code here: we ship the direct replacement SAI40BX550, 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 SI40BX550
The AirTAC Airtac SI40 Standard Cylinder SI40BX550 is a double-acting ISO 15552 (orig. ISO 6431) profile-barrel cylinder with a Ø40mm bore and 550mm stroke, G1/4 air ports and adjustable end cushioning. This model is discontinued — the direct replacement is the SAI40BX550, which matches its ISO interface, bore, stroke, force and mounting.
- BoreØ40 mm
- Stroke550 mm
- Port sizeG1/4
- Acting typeDouble acting
- Rod threadM12×1.25
- StatusDiscontinued → SAI40BX550
- 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 SI40BX550
The AirTAC SI40BX550 is a discontinued double-acting ISO 15552 profile cylinder with a 40mm bore, 550mm stroke, and a SUS304 stainless steel rod. Delivering 628 N push force at 0.5 MPa, it is replaced by the SAI40BX550 direct upgrade. This successor maintains the exact G1/4 port, M12x1.25 thread, and mounting interface.
The SAI upgrade features a two Y-shaped one-way piston seal for low start-up pressure. Note this SKU lacks a magnet, so it cannot take a sensor. The SAI family also adds SAIL and BSAI lock variants.
Airtac SI40 Standard Cylinder SI40BX550 Technical Specifications
| Model | Airtac SI40 Standard Cylinder SI40BX550 |
|---|---|
| Series | SI ISO 15552 profile cylinder (discontinued) |
| Replacement | SAI40BX550 |
| Bore size | Ø40 mm |
| Stroke | 550 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 SAI40BX550 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 SAI40BX550 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 SI40BX550
| SI | ISO 15552 profile-barrel cylinder (discontinued). |
|---|---|
| 40 | Bore size in mm. |
| ×550 | 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 SI40BX550 Is Used
Long-Stroke Diversion
Pushes packages across a 550 mm transfer lane with 628 N at 0.5 MPa, guided externally to prevent rod bending.
Stainless Lowering Arm
Uses the SUS304 rod for washdown resistance while lowering light fixtures, safely managing a 32 kg vertical lift.
Pallet Stopper Gate
Acts as a 40mm bore stopper on a conveyor line; note a pilot check valve is required to hold the load if air drops.
Replacing the Airtac SI40 Standard Cylinder SI40BX550 with the SAI40BX550
To replace the SI40BX550, order the SAI40BX550. Verify your ISO 15552 mounting fixtures, the G1/4 port, and the M12x1.25 rod thread. This SKU has no magnet (-S), so it cannot accept CS1-B/DS1-B switches; order a magnet-equipped SAI if sensing is needed. Sizing options: a 32mm bore yields 402 N push at 0.5 MPa, while a 50mm bore yields 982 N. Because stroke is 550mm, use external guides to prevent rod bending and side loads. For load holding on air loss, add a pilot check valve or use the SAIL/BSAI lock variants, as cushions only decelerate.
Replacement checklist
- ✓ Same ISO 15552 interface → SAI40BX550
- ✓ 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 SI40BX550 FAQ
Yes, the SI40BX550 is discontinued. The direct replacement is the SAI40BX550. It is dimensionally interchangeable per ISO 15552, keeping the same 40mm bore, 550mm stroke, force, G1/4 port, and mounting interface.
The G1/4 port bore delivers 628 N push and 528 N pull at 0.5 MPa, 879 N push at 0.7 MPa, 1130 N at 0.9 MPa, and a 128 kgf max at 1.0 MPa. It operates at 30-800 mm/s with 27mm adjustable cushions.
Related AirTAC SAI Cylinders
Request a Quote for the SAI40BX550
Send us the quantity and destination. We confirm price, stock and lead time on the SAI40BX550 replacement — usually within 7-8 hours.