Airtac SAILB Rear Lock Cylinder SAILB125X900S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X900S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 900mm stroke and a built-in spring-applied, air-released mechanical lock in the back cover — it holds the load at the retracted (rod-in) stroke end even when air is lost.
- BoreØ125 mm
- Stroke900 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X900S
The AirTAC SAILB125X900-S is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. Because the lock engages at the retracted stroke end, it securely holds the rod-in position without requiring continuous live air pressure. Equipped with a magnetic piston (-S), it supports position sensing using AirTAC CMSE reed or DMSE electronic solid-state switches.
Delivering 6136N of pull force at 0.5MPa and utilizing a 1/2 PT port, this bore size operates at a controlled speed range of 30-500mm/s. The variable air cushion at the locker end is specifically designed at 24mm, which is shorter than the 40mm cushion on the free end, ensuring precise deceleration before the static lock engages.
Airtac SAILB Rear Lock Cylinder SAILB125X900S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X900S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 900 mm |
| Acting type | Double acting, with lock |
| Port size | G1/2 |
| Rod thread | M27×2 |
| Lock type | Spring-applied, air-released (back cover) |
|---|---|
| Unlock | Automatic (air) & manual |
| Operating pressure | 0.15 – 1.0 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 500 mm/s |
| Cushion | Adjustable (40 mm free end / 24 mm lock end) |
| Max stroke | Up to 1500 mm |
Specifications follow the official AirTAC SAIL datasheet (ISO 15552). Confirm against the product label before installation. Port options: PT / G.
How the Lock Holds
The lock is spring-applied and air-released: a spring drives a lock pin into the rod when the release air is removed, so the load is held at the retracted (rod-in) stroke end without live pressure. Supply air to the release port to unlock automatically, or use the manual release lever.
The lock engages only when the piston reaches the stroke terminal on the back-cover side — it is a static end-of-stroke hold, not a mid-stroke clamp and not a moving-rod brake. For locking at any position along the stroke, choose a BSAI clamp-lock instead.
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 | |
Cylinder thrust is separate from the lock's holding capability. Actual usable force is lower than theoretical due to friction and back-pressure — size with a margin.
Where the Airtac SAILB Rear Lock Cylinder SAILB125X900S Is Used
Vertical Lift Safety
Holds heavy vertical loads in the retracted position automatically during a power loss, preventing sudden drops until air is restored.
Machine Guard Hold
Locks a retracted safety guard or heavy door firmly in place without consuming continuous compressed air during machine operation.
Clamp and Hold
Secures a workpiece at the end of the retraction cycle, maintaining positive holding force without relying on system pressure.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X900S the Right Lock Cylinder?
Choose this 125mm bore when a 100mm bore (providing 3681N pull at 0.5MPa) lacks the power to lift your load, but a 160mm bore (9425N pull) would be excessive. Select the SAILB configuration when the load must be safely held in the retracted position; if your application requires holding at the extended rod-out position, the SAILF variant is required instead. For applications demanding clamping at an arbitrary mid-stroke point rather than a stroke-end hold, the BSAI clamp-lock cylinder is the correct choice.
This cylinder features a 900mm stroke, which requires external guide rails to prevent rod side-loading and premature seal wear. The mechanical lock is a static holding device that engages after the piston stops, not a dynamic brake for moving rods. Avoid using fast-exhaust valves, as back-pressure on the locker side can unintentionally release the lock; always use an independent-exhaust solenoid valve. If human safety depends on the load staying retracted, implement an independent mechanical safety measure. Replacement specifications: 125mm bore, 900mm stroke, back locker, PT threads, magnetic piston (-S), and standard ISO 15552 mountings (Basic, FA, FB, CA, CB, CR, LB, TC, FTC, TCM1, TCM2).
Quick checklist
- ✓ Hold needed at the retracted (rod-in) end?
- ✓ Or lock anywhere → use BSAI
- ✓ Independent-exhaust valve fitted
- ✓ Port/thread type (PT/G)
- ✓ Extra safety measure for people
Airtac SAILB Rear Lock Cylinder SAILB125X900S FAQ
At 0.5MPa operating pressure, this 125mm bore cylinder provides 6136N of push force and 5734N of pull force. At 0.7MPa, the push force increases to 8590N.
The lock is spring-applied and air-released, located in the back cover to hold the rod only at the retracted stroke end. It engages statically after the cylinder stops and is released automatically via air pressure or manually via a lever; it does not clamp mid-stroke.
Related AirTAC Lock & Standard Cylinders
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