Airtac SAILB Rear Lock Cylinder SAILB40X25
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB40X25 is a genuine double-acting ISO 15552 profile cylinder with a Ø40mm bore, 25mm 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
- Stroke25 mm
- Port sizeG1/4
- Lock positionBack cover
- Rod threadM12×1.25
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB40X25
The AirTAC SAILB40X25 is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock in the back cover. This built-in lock engages when the piston reaches the retracted stroke end, securely holding the rod and load without requiring continuous live air pressure. With a 40mm bore, it delivers 879N of push force at 0.7 MPa and uses a standard carbon steel rod with PT threaded ports.
Because the lock occupies the back end, the variable air cushion on that side is shorter (20mm) compared to the free end (27mm). The lock releases automatically by supplying air to the release port, or manually via the override lever. For position sensing, adding a magnet allows the use of AirTAC CMSE reed or DMSE solid-state sensors in the dual-side barrel grooves.
Airtac SAILB Rear Lock Cylinder SAILB40X25 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB40X25 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø40 mm |
| Stroke | 25 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 SAILB40X25 Is Used
Vertical Power-Off Hold
Prevents a raised vertical load from dropping when air pressure is lost, utilizing the back-cover lock to secure the rod in its retracted position.
Clamp-and-Hold Fixture
Maintains clamping force on a workpiece at the end of the stroke without consuming continuous compressed air.
Safety Gate Locking
Keeps a safety barrier or gate securely closed in the retracted state until the release air is actively supplied.
Is the Airtac SAILB Rear Lock Cylinder SAILB40X25 the Right Lock Cylinder?
Choose this 40mm bore lock cylinder when you need to hold a load securely at the retracted position during a power loss; if your application requires holding at the extended end instead, select the SAILF40X25. If the mechanism must lock at an arbitrary mid-stroke point rather than a stroke end, the AirTAC BSAI clamp-lock cylinder is the correct choice. For this 25mm stroke, side-load concerns are minimal, but always match your replacement on bore, stroke, locker position (B), PT porting, and mounting.
Remember that this is a static holding lock that engages after the cylinder 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; an independent-exhaust solenoid valve is required. If human safety depends on the load staying up, 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 SAILB40X25 FAQ
The 40mm bore provides 628N of push force at 0.5 MPa and 879N at 0.7 MPa. The pull force is 528N at 0.5 MPa due to the single-rod design.
The lock is spring-applied and air-released. It engages statically when the rod reaches the retracted stroke end, holding the load without live pressure. It unlocks automatically via air supply or manually via a lever, but it does not clamp at mid-stroke.
Related AirTAC Lock & Standard Cylinders
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