Airtac SAILB Rear Lock Cylinder SAILB125X80S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X80S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 80mm 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
- Stroke80 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X80S
The AirTAC SAILB125X80-S is a double-acting ISO 15552 profile cylinder equipped with a spring-applied, air-released mechanical lock housed in the back cover. Because the lock engages when the piston reaches the retracted stroke end, it secures the rod-in position and safely holds the load without requiring continuous live air pressure. In this 125 mm bore class, the cylinder generates a substantial 6136 N push force and 5734 N pull force at 0.5 MPa, making it well-suited for heavy vertical lifting tasks.
This model includes a magnet (-S) for position sensing and is fully compatible with AirTAC CMSE reed and DMSE electronic solid-state switches. A key design detail is that the variable air cushion at the locker end is shorter (24 mm) than the standard free-end cushion (40 mm). The lock itself is a static holding device that engages only after the rod has stopped; it is not a mid-stroke clamp or a dynamic brake for a moving rod.
Airtac SAILB Rear Lock Cylinder SAILB125X80S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X80S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 80 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 SAILB125X80S Is Used
Vertical Lift Safety
Holds heavy lifted loads securely in the retracted position during a sudden air pressure loss or power failure, preventing uncontrolled drops.
Machine Guard Hold
Locks a retracted machine guard or heavy door in the closed position without consuming continuous compressed air, improving energy efficiency.
Heavy Clamping
Maintains maximum clamping force at the end of the stroke while the press is idle, ensuring the workpiece remains secured without live pressure.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X80S the Right Lock Cylinder?
Select this 125 mm bore cylinder when an application requires robust holding power at the retracted position, as the back lock specifically secures the rod-in state. If your load demands clamping at an arbitrary intermediate position, you must choose the BSAI clamp-lock cylinder instead. For lighter vertical loads, stepping down to a 100 mm bore reduces the 0.5 MPa push force to 3927 N, whereas staying at 125 mm provides 6136 N of thrust.
When integrating this lock cylinder, avoid using fast-exhaust valves, as back-pressure on the locker side can inadvertently release the lock; always use an independent-exhaust solenoid valve. If human safety depends on the load remaining retracted, add an independent mechanical safety measure as well. For exact replacement matching, verify the 125 mm bore, 80 mm stroke, back locker position, PT tapered port threads, carbon steel rod, and -S magnet option.
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 SAILB125X80S FAQ
At 0.5 MPa, this 125 mm bore cylinder provides a push force of 6136 N and a pull force of 5734 N. 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 retracted stroke end. It engages statically after the cylinder stops and is released automatically via air supply or manually via a lever; it does not clamp at mid-stroke.
Related AirTAC Lock & Standard Cylinders
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