Airtac SAILB Rear Lock Cylinder SAILB40X125
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB40X125 is a genuine double-acting ISO 15552 profile cylinder with a Ø40mm bore, 125mm 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
- Stroke125 mm
- Port sizeG1/4
- Lock positionBack cover
- Rod threadM12×1.25
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB40X125
The AirTAC SAILB40X125 is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock built into the back cover. It safely holds the load at the retracted stroke end, meaning the rod stays secured without live air pressure. Delivering 879N of push force at 0.7MPa, this carbon steel rod unit is ideal for lighter-duty safety holds.
The lock engages automatically once the piston reaches the back terminal, acting as a static holding device rather than a dynamic brake. To unlock, you simply supply air to the release port or use the manual override. Note that the variable air cushion at this locker end is 20mm, intentionally shorter than the 27mm cushion on the free end to accommodate the locking mechanism.
Airtac SAILB Rear Lock Cylinder SAILB40X125 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB40X125 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø40 mm |
| Stroke | 125 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 SAILB40X125 Is Used
Vertical Lift Hold
Secures a raised load in the retracted position instantly if air pressure drops, preventing sudden crashes in light-duty lifting rigs.
Power Failure Safety
Maintains the piston safely at the back stroke end during power loss, keeping guarding doors and safety flaps closed.
End-of-Stroke Clamp
Holds a workpiece firmly at the retracted terminal without consuming continuous air, ideal for energy-efficient machining fixtures.
Is the Airtac SAILB Rear Lock Cylinder SAILB40X125 the Right Lock Cylinder?
Choose this 40mm bore when your application requires 879N of push force at 0.7MPa; stepping up to the 50mm bore increases that to 1374N, while dropping to a smaller bore would not provide enough holding capacity for vertical lifts. Select the SAILB configuration when the load must remain retracted on power loss, and choose SAILF if it needs to hold extended. If your process requires clamping at an arbitrary mid-stroke position, the BSAI clamp-lock cylinder is the correct alternative.
For safe operation, never use a fast-exhaust valve with this lock cylinder; use an independent-exhaust solenoid valve to prevent back-pressure on the locker side from accidentally releasing the lock. Always add an independent mechanical safety measure if human safety depends on the load staying up. This model uses a PT 1/4 port, and replacements must match the 40mm bore, 125mm stroke, back locker position, and mounting type.
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 SAILB40X125 FAQ
At 0.7MPa operating pressure, this 40mm bore cylinder provides 879N of push force and 738N of pull force. It can deliver up to 1130N push at 0.9MPa.
The lock is spring-applied and air-released, engaging only when the piston reaches the retracted stroke end in the back cover. It provides a static hold, not a dynamic brake, and is released by supplying air to the release port or using the manual override.
Related AirTAC Lock & Standard Cylinders
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