Airtac SAILB Rear Lock Cylinder SAILB125X25S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X25S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 25mm 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
- Stroke25 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X25S
The AirTAC SAILB125X25-S is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. This lock engages automatically when the piston reaches the retracted stroke end, securely holding loads without requiring continuous live air pressure. Equipped with a magnet, it supports position sensing via CMSE reed and DMSE electronic switches.
Delivering 6136 N push and 5734 N pull force at 0.5 MPa, this bore 125 unit is built for heavy-duty tasks. The carbon steel piston rod provides robust side-load resistance. To accommodate the locking mechanism, the locker-end air cushion is 24 mm, intentionally shorter than the 40 mm cushion on the free end.
Airtac SAILB Rear Lock Cylinder SAILB125X25S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X25S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 25 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 SAILB125X25S Is Used
Vertical Lift Safety
Holds a lifted platform securely in the retracted position instantly if air pressure drops, preventing sudden descent.
Heavy Clamp Hold
Maintains tremendous clamping force on a workpiece at stroke end without consuming continuous compressed air.
Gate Guard Locking
Keeps a heavy safety gate firmly closed and retracted during machine operation until the release air is activated.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X25S the Right Lock Cylinder?
Choose this SAILB model when you need to secure a retracted load safely upon power loss, such as pulling a heavy carriage back. If your application requires holding the load at the extended rod-out position, select the SAILF variant instead. For applications needing the rod clamped at an arbitrary mid-stroke point, the BSAI clamp-lock cylinder is the correct choice rather than this stroke-end lock.
Remember that this lock is a static holding device, not a dynamic brake for a moving rod. Avoid using fast-exhaust valves; back-pressure on the locker side can inadvertently release the lock, so an independent-exhaust solenoid valve is required. If human safety relies on the load staying elevated, always add an independent mechanical safety measure. Replacement specifications: 125 mm bore, 25 mm stroke, PT tapered port threads, back locker, and -S magnet.
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 SAILB125X25S FAQ
At 0.5 MPa operating pressure, this bore 125 cylinder provides 6136 N of push force and 5734 N of pull force. At 0.7 MPa, the push force increases to 8590 N.
The lock is spring-applied and air-released, located in the back cover to hold the rod only at the fully retracted stroke end. It engages statically after the cylinder stops and is released automatically by supplying air to the release port or manually via a lever.
Related AirTAC Lock & Standard Cylinders
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