Airtac SAILB Rear Lock Cylinder SAILB125X50
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X50 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 50mm 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
- Stroke50 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X50
The AirTAC SAILB125X50 is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. This safety mechanism engages automatically when the piston reaches the retracted stroke end, securing loads securely without requiring continuous live air pressure. Built with a carbon steel rod and PT threaded ports, it provides a robust 6136N push force at 0.5MPa.
Because the lock physically clamps the rod only at the back-end terminal position, it functions as a static holding device rather than a dynamic brake for moving rods. The variable air cushion at the locker end is specifically machined shorter (24mm versus 40mm at the free end) to accommodate the locking hardware. For position sensing, adding a -S magnet allows integration with AirTAC CMSE reed and DMSE electronic sensors.
Airtac SAILB Rear Lock Cylinder SAILB125X50 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X50 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 50 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 SAILB125X50 Is Used
Vertical Lift Holding
Secures heavy elevated platforms in the retracted position instantly if air pressure drops, preventing uncontrolled descent.
Clamp and Hold
Maintains high-force clamping on large workpieces at the end of the stroke without consuming continuous pneumatic energy.
Safety Gate Lock
Keeps heavy industrial safety gates firmly locked in the closed position until the air-release signal is actively supplied.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X50 the Right Lock Cylinder?
Choose this 125mm bore when an 80mm cylinder's 2513N push at 0.5MPa is insufficient to handle heavy vertical loads, but a 160mm bore would be excessive. Select the SAILB configuration specifically when the machinery requires the load to be safely held in the retracted (rod-in) position during a power loss. If your application demands clamping at an arbitrary mid-stroke point rather than the stroke end, the BSAI clamp-lock cylinder is the correct alternative.
When integrating this cylinder, strictly avoid using fast-exhaust valves; back-pressure on the locker side can inadvertently release the spring-applied lock. Always use an independent-exhaust solenoid valve for the release air. If human safety depends on the load remaining retracted, implement an independent mechanical safety measure alongside the lock. To replace this unit, verify the 50mm stroke, back locker position, 1/2-inch PT port, and required mounting accessories.
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 SAILB125X50 FAQ
At a 0.5MPa operating pressure, this 125mm bore cylinder generates a push force of 6136N and a pull force of 5734N. 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.
Related AirTAC Lock & Standard Cylinders
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