Airtac SAILB Rear Lock Cylinder SAILB40X300
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB40X300 is a genuine double-acting ISO 15552 profile cylinder with a Ø40mm bore, 300mm 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
- Stroke300 mm
- Port sizeG1/4
- Lock positionBack cover
- Rod threadM12×1.25
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB40X300
The AirTAC SAILB40X300 is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. This mechanism securely holds the rod at the retracted stroke end, providing a reliable static hold without requiring live air pressure. Delivering 628N of push thrust at 0.5 MPa, it utilizes a carbon steel rod and PT tapered port threads.
Unlike a standard SAI cylinder, this model integrates load-holding safety directly into the actuator. The lock engages only after the piston fully stops at the back terminal, meaning it cannot clamp a moving rod or hold an arbitrary mid-stroke position. Furthermore, the variable air cushion at the locker end is notably shorter at 20mm compared to the 27mm cushion on the free end, ensuring compact deceleration without interfering with the lock mechanism.
Airtac SAILB Rear Lock Cylinder SAILB40X300 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB40X300 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø40 mm |
| Stroke | 300 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 SAILB40X300 Is Used
Vertical Retract Safety
Secures a lifted vertical load in the fully retracted position, preventing sudden drops if compressed air supply is lost during operation.
Clamp-and-Hold at End
Holds a clamped workpiece securely at the rod-in stroke terminal without consuming continuous pneumatic energy.
Gate Safety Locking
Keeps safety gates or heavy guards locked shut in the retracted end position until the air-release port is actively pressurized.
Is the Airtac SAILB Rear Lock Cylinder SAILB40X300 the Right Lock Cylinder?
Choose this 40mm bore when an application requires safely holding a retracted load up to 628N at 0.5 MPa; if your setup demands greater thrust, stepping up to the 50mm bore yields 982N. Select the SAILB configuration when the load must be secured in the rod-in position, whereas SAILF secures the extended position. If your process requires clamping at any intermediate point rather than the stroke end, you must use a BSAI clamp-lock cylinder instead. To replace this unit, match the 40mm bore, 300mm stroke, back locker position, PT port threads, and standard carbon steel rod.
Because the stroke is 300mm, ensure external guide rails are used to prevent excessive side-loading on the rod. For the lock to function safely, never use a fast-exhaust valve, as back-pressure on the locker side can unintentionally release the lock; always utilize an independent-exhaust solenoid valve. If human safety depends on the load staying retracted, add an independent mechanical safety measure as well.
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 SAILB40X300 FAQ
At 0.5 MPa operating pressure, the 40mm bore provides 628N of push thrust and 528N of pull thrust. At 0.7 MPa, the push force increases to 879N.
The lock is spring-applied and air-released, engaging automatically to hold the rod only at the fully retracted stroke end. It unlocks by supplying air to the release port or by using the manual release lever, but it cannot hold the rod at a mid-stroke position.
Related AirTAC Lock & Standard Cylinders
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