Airtac SAILB Rear Lock Cylinder SAILB50X125S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB50X125S is a genuine double-acting ISO 15552 profile cylinder with a Ø50mm bore, 125mm 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.
- BoreØ50 mm
- Stroke125 mm
- Port sizeG1/4
- Lock positionBack cover
- Rod threadM16×1.5
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB50X125S
The AirTAC SAILB50X125-S is a double-acting ISO 15552 profile cylinder featuring a built-in mechanical lock in the back cover. Because the lock is spring-applied and air-released, cutting the release air drives a lock pin into the carbon steel rod, securely holding the load at the retracted stroke end without relying on live pressure. Delivering 982N of push force and 825N of pull force at 0.5MPa, it provides robust load handling for vertical or gravity-resistant applications.
This model includes a piston magnet for position sensing with CMSE reed and DMSE electronic switches. The variable air cushion at the locker end is 20mm, intentionally shorter than the 30mm cushion at the free end to accommodate the locking mechanism. For safe operation, avoid fast-exhaust valves and use an independent-exhaust solenoid valve, as back-pressure on the locker side can unintentionally release the lock.
Airtac SAILB Rear Lock Cylinder SAILB50X125S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB50X125S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø50 mm |
| Stroke | 125 mm |
| Acting type | Double acting, with lock |
| Port size | G1/4 |
| Rod thread | M16×1.5 |
| 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 – 800 mm/s |
| Cushion | Adjustable (30 mm free end / 20 mm lock end) |
| Max stroke | Up to 1200 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 (Ø50mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 982 N | 825 N |
| 0.7 MPa | 1374 N | — |
| Max (@1.0 MPa) | 200 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 SAILB50X125S Is Used
Vertical Power-Off Safety
Secures elevated loads in the retracted position instantly if air pressure drops, preventing gravity-driven crashes.
End-of-Stroke Clamping
Holds workpieces firmly at the fully retracted terminal without wasting continuous compressed air energy.
Gate and Pallet Stopping
Locks heavy conveyor diverters or pallet stops in the closed position, releasing only when the release port is pressurized.
Is the Airtac SAILB Rear Lock Cylinder SAILB50X125S the Right Lock Cylinder?
Choose this 50mm bore when 40mm (628N push at 0.5MPa) lacks the force to hold your load, but 63mm (1559N) would be physical overkill. Select the SAILB configuration when the load must be secured in the retracted position, whereas SAILF holds the extended rod-out position. If your application requires clamping at an arbitrary mid-stroke point rather than a static hold at the stroke end, the BSAI clamp-lock cylinder is the correct choice. Always add an independent safety measure if human safety depends on the load staying up.
To replace this unit, match the 50mm bore, 125mm stroke, back locker position, PT 1/4 port threads, and the -S magnet option. It supports the full ISO 15552 mounting set including Basic, FA, FB, CA, CB, CR, LB, TC, FTC, TCM1, and 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 SAILB50X125S FAQ
At 0.5MPa, it provides 982N of push force and 825N of pull force. At 0.7MPa, the push force increases to 1374N.
The lock is spring-applied and air-released, engaging only at the retracted stroke end after the cylinder stops. It is unlocked automatically by supplying air to the release port or manually via the release lever.
Related AirTAC Lock & Standard Cylinders
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