Airtac SAILB Rear Lock Cylinder SAILB40X250S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB40X250S 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 SAILB40X250S
The AirTAC SAILB40X250-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 automatically drives a lock pin into the carbon steel rod, securely holding the load at the retracted stroke end without requiring live pressure. In the 40mm bore class, it generates 628N of push force and 528N of pull force at 0.5 MPa, making it well-suited for lighter-duty holding tasks.
This model includes a magnetic piston (-S) for precise position sensing with AirTAC CMSE reed switches or DMSE solid-state electronic sensors. To accommodate the locking hardware, the variable air cushion at the locker end is shortened to 20mm, compared to 27mm on the free end. The unit operates efficiently between 30-800 mm/s and features PT tapered port threads.
Airtac SAILB Rear Lock Cylinder SAILB40X250S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB40X250S |
|---|---|
| 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 SAILB40X250S Is Used
Vertical Lift Safety
Holds retracted vertical loads securely in place during a power loss or pressure drop, preventing sudden drops on small lifting jigs.
Pallet Stopper Hold
Locks a pneumatic stopper arm in the rod-in position to reliably halt and hold lightweight pallets on a packaging line.
Clamp-and-Hold Fixture
Maintains a retracted clamping state without consuming continuous air, saving energy while keeping the workpiece area clear.
Is the Airtac SAILB Rear Lock Cylinder SAILB40X250S the Right Lock Cylinder?
Select this 40mm bore cylinder when your application requires safety holding at the rod-in position; if you need to hold the load at the extended rod-out position, choose the SAILF variant instead. If your process requires clamping at an arbitrary mid-stroke point rather than the stroke end, the BSAI clamp-lock cylinder is the correct choice. For higher force needs, stepping up to the 50mm bore yields 982N push at 0.5 MPa.
Remember that this lock is a static holding device that engages after the piston stops, not a dynamic brake for a moving rod. Avoid using fast-exhaust valves, as back-pressure on the locker side can unintentionally release the lock; use an independent-exhaust solenoid valve instead. For safety-critical suspended loads, always add an independent mechanical safety measure. At a 250mm stroke, ensure adequate side-load support by using external guide rails to prevent rod binding. Replacement matches require: 40mm bore, 250mm stroke, back locker, PT ports, and a magnetic piston.
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 SAILB40X250S FAQ
At 0.5 MPa, this 40mm bore cylinder provides 628N of push force and 528N of pull force. At 0.7 MPa, the push force increases to 879N.
The lock is spring-applied and air-released. It engages only at the retracted stroke end after the rod stops. To unlock, you supply air to the release port or use the manual release lever. It is a static hold, not a mid-stroke clamp.
Related AirTAC Lock & Standard Cylinders
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