Airtac BSAI Locking Clamp Cylinder BSAI125X250S
The AirTAC Airtac BSAI Locking Clamp Cylinder BSAI125X250S is a genuine double-acting ISO 15552 cylinder with a Ø125mm bore, 250mm stroke and a spring-applied, air-released clamp-lock that holds the rod at ANY position along its travel — with a static holding force of 8600 N.
- BoreØ125 mm
- Stroke250 mm
- Cylinder portG1/2
- TypeSingle rod (BSAI)
- Enclasp portG1/8
- Rod threadM27×2
About the Airtac BSAI Locking Clamp Cylinder BSAI125X250S
The AirTAC BSAI125X250-S is a double-acting ISO 15552 profile cylinder equipped with a built-in clamp-lock mechanism. It features a 125 mm bore, a 250 mm stroke, and a carbon steel single rod. A spring-applied, air-released gripper clamps the rod to hold the load at ANY position along the travel, delivering a static holding force of 8600 N. Because it includes a magnet (-S), it supports CMSE reed and DMSE electronic sensors for position feedback. The cylinder generates a practical maximum thrust of 8590 N at 0.7 MPa, but the 8600 N holding force is a separate mechanical specification; you must size the clamp capacity against the static load weight, not the pneumatic thrust.
This model uses a third G1/8 enclasp port (separate from the 1/2 cylinder ports) to release the lock at 0.15-0.7 MPa. Remember that the variable air cushions only decelerate the piston near the stroke ends; the mechanical clamp is the sole device holding the payload. The clamp locks only after the rod has stopped, meaning it cannot brake a moving actuator. Furthermore, it must be unlocked with balanced air pressures on both sides of the piston, or the rod may jump abruptly upon release.
Airtac BSAI Locking Clamp Cylinder BSAI125X250S Technical Specifications
| Model | Airtac BSAI Locking Clamp Cylinder BSAI125X250S |
|---|---|
| Series | BSAI ISO 15552 clamp-lock cylinder |
| Bore size | Ø125 mm |
| Stroke | 250 mm |
| Type | Single rod (BSAI), double acting |
| Cylinder port | G1/2 |
| Rod thread | M27×2 |
| Lock type | Spring-applied, air-released clamp (any position) |
|---|---|
| Static holding force | 8600 N |
| Enclasp / unlock port | G1/8 |
| Operating pressure | 0.15 – 0.7 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 500 mm/s |
| Max stroke | Up to 1000 mm |
Specifications follow the official AirTAC BSAI datasheet (ISO 15552). Operating pressure is 0.15–0.7 MPa (lower than a plain SAI). Port options: PT / G.
How the Clamp-Lock Holds
static holding force (Ø125 mm)
A spring-applied gripper clamps the rod and holds the load at any position in the stroke — not just at the stroke end (that is a SAIL) — and it is bidirectional: it holds whether the rod was extending or retracting.
Theoretical Output Force (Ø125mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 6136 N | 5734 N |
| 0.7 MPa (max) | 8590 N | — |
Push/pull as tabulated. Rated to the 0.7 MPa operating maximum for this series. The clamp holding force (8600 N) is separate from cylinder thrust. Size with a margin.
Where the Airtac BSAI Locking Clamp Cylinder BSAI125X250S Is Used
Machining Position Hold
Secures heavy workpieces at an exact intermediate point inside the stroke for multi-axis machining or inspection operations without maintaining live air pressure.
Vertical Axis Drop Prevention
Locks a 125 mm bore vertical load instantly upon air loss, utilizing the 8600 N static holding force to prevent gravity-driven falls anywhere in the travel.
Heavy Payload Safety Arrest
Acts as an emergency holding brake for large suspended tools, engaging only after the cylinder has fully stopped to lock the carbon steel rod firmly in place.
Is the Airtac BSAI Locking Clamp Cylinder BSAI125X250S the Right Clamp-Lock?
Choose this 125 mm bore when an application demands extreme holding capacity, stepping up from a 100 mm bore that provides 5500 N holding force and 5497 N thrust at 0.7 MPa. Select the BSAI clamp-lock over a SAIL model when you need to arrest and hold a load at any intermediate stroke position, rather than just at the stroke end. If no intermediate holding is required, a plain SAI cylinder without the clamp head suffices. For safety-critical loads, note that this clamp is not a dynamic brake, and human safety requires an additional independent measure.
As a replacement match, ensure you specify the single-rod configuration, 125 mm bore, 250 mm stroke, and PT tapered ports. The large M27x2 rod thread provides excellent structural rigidity and side-load resistance, though external guidance is always recommended for optimal longevity. The correct mounting set for this single-rod variant includes Basic, FA, FB, CA, CB, CR, LB, TC, TCM1, and TCM2. The -S magnet works seamlessly with AirTAC CMSE and DMSE switches.
Quick checklist
- ✓ Hold needed at any position?
- ✓ Or stroke-end only → use SAIL
- ✓ Holding force ≥ your load
- ✓ Balanced-pressure unlock circuit
- ✓ Extra safety measure for people
Airtac BSAI Locking Clamp Cylinder BSAI125X250S FAQ
The BSAI125X250-S provides a static holding force of 8600 N. The spring-applied gripper clamps the rod to hold the load at any position along the 250 mm stroke, but it only locks after the cylinder has stopped moving and cannot brake a moving rod.
The clamp must be released by applying air to the G1/8 enclasp port, but only after the air pressures on both sides of the piston are balanced. If the pressures are not balanced when unlocked, the rod can move abruptly, creating a hazard.
Related AirTAC Lock & Standard Cylinders
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