Airtac SAILB Rear Lock Cylinder SAILB40X250
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB40X250 is a genuine double-acting ISO 15552 profile cylinder with a Ø40mm bore, 250mm 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.
- BoreØ40 mm
- Stroke250 mm
- Port sizeG1/4
- Lock positionBack cover
- Rod threadM12×1.25
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB40X250
The AirTAC SAILB40X250 is a double-acting profile cylinder dimensionally interchangeable per ISO 15552, 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 the load without requiring live air pressure. It delivers a push force of 879N at 0.7 MPa and utilizes a 1/4 PT tapered port with a 16mm carbon steel rod.
Because the locker side requires space for the locking mechanism, the variable air cushion at the back end is shortened to 20mm, compared to the 27mm cushion on the free end. To unlock, you can supply air to the release port for automatic operation or use the manual release lever. For position feedback, adding a -S magnet enables CMSE reed and DMSE solid-state sensors in the dual-side barrel grooves.
Airtac SAILB Rear Lock Cylinder SAILB40X250 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB40X250 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø40 mm |
| Stroke | 250 mm |
| Acting type | Double acting, with lock |
| Port size | G1/4 |
| Rod thread | M12×1.25 |
| 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 (27 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 (Ø40mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 628 N | 528 N |
| 0.7 MPa | 880 N | — |
| Max (@1.0 MPa) | 128 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 SAILB40X250 Is Used
Vertical Lift Safety
Holds a raised load securely at the retracted stroke end during a power loss, preventing sudden drops in lifting rigs.
Clamp and Hold
Maintains clamping force on a workpiece at the rod-in position without continuously consuming compressed air.
Gate Stop Mechanism
Locks a conveyor diverter gate in the closed position securely, requiring an air signal to release and open.
Is the Airtac SAILB Rear Lock Cylinder SAILB40X250 the Right Lock Cylinder?
Choose this 40mm bore when you need 879N of push force at 0.7 MPa; step down if your application requires less holding capacity, or step up to a 50mm bore for 1374N if the load demands greater thrust. Select this SAILB configuration when the mechanism must be secured at the rod-in retracted position, whereas a SAILF variant holds the extended rod-out end. If your process requires clamping at an arbitrary mid-stroke point rather than the stroke terminal, select the BSAI clamp-lock cylinder instead.
The lock is a static holding device that engages after the cylinder stops, not a dynamic brake for a moving rod. Valve selection is critical: do not use a fast-exhaust valve, and use an independent-exhaust solenoid valve, as back-pressure on the locker side can unintentionally release the lock. For any safety-critical vertical lift, add an independent mechanical safety measure. At 250mm stroke, use appropriate guide rails to prevent side-load damage to the rod. Replacement matches: 40mm bore, 250mm stroke, back locker, PT port, standard mounting, no 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 SAILB40X250 FAQ
At 0.7 MPa, the push force is 879N and the pull force is 528N. The maximum operating pressure is 1.0 MPa, yielding a maximum push force of 1130N.
The lock is spring-applied and air-released, engaging only when the piston reaches the retracted stroke end in the back cover. It is a static hold, not a mid-stroke clamp or dynamic brake. To unlock, supply air to the release port or use the manual release lever.
Related AirTAC Lock & Standard Cylinders
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