Airtac SAILB Rear Lock Cylinder SAILB125X400
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X400 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 400mm 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
- Stroke400 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X400
The AirTAC SAILB125X400 is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. It securely holds the load at the retracted stroke end, providing a reliable 6136N pull force at 0.5MPa. This design ensures machinery remains safely positioned during a pressure loss without requiring continuous live air.
To unlock, supply air to the release port for automatic operation or use the manual release lever. The carbon steel rod and PT tapered ports ensure robust performance. Note that the locker-end air cushion is 24mm, intentionally shorter than the 40mm cushion on the free end to accommodate the locking mechanism.
Airtac SAILB Rear Lock Cylinder SAILB125X400 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X400 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 400 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 SAILB125X400 Is Used
Vertical Lift Safety
Holds heavy vertical loads securely in the retracted position during power loss, preventing sudden drops on lifting platforms.
Clamp and Hold
Maintains clamping force at the end of the stroke without consuming continuous air, ideal for sustained workholding tasks.
Gate and Door Control
Secures heavy industrial gates in the closed position, relying on the mechanical lock to resist external forces.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X400 the Right Lock Cylinder?
Choose this 125mm bore when a 100mm bore (providing 3681N pull at 0.5MPa) lacks the necessary holding capacity, or step down if an 80mm bore (2268N pull) is sufficient. Select the SAILB configuration when the load must be secured in the retracted position; choose SAILF for extended holding. If your application requires clamping at an arbitrary mid-stroke point, use the BSAI clamp-lock cylinder instead.
The lock engages only after the piston stops at the stroke terminal, acting as a static hold rather than a dynamic brake. Avoid using fast-exhaust valves, as back-pressure on the locker side can inadvertently release the lock; utilize an independent-exhaust solenoid valve. With a 400mm stroke, ensure adequate side-load guidance to prevent rod bending. Add an independent safety measure if human safety depends on the suspended load.
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 SAILB125X400 FAQ
At 0.5MPa, the push force is 6136N and the pull force is 5734N. At 0.7MPa, the push force increases to 8590N.
The lock is spring-applied and air-released. It engages statically when the piston reaches the retracted stroke end. It unlocks automatically via air supply to the release port or manually via a lever.
Related AirTAC Lock & Standard Cylinders
Request a Quote for Airtac SAILB Rear Lock Cylinder SAILB125X400
Send us the quantity and destination. We confirm price, stock and lead time — usually within 7-8 hours.