Airtac SAILB Rear Lock Cylinder SAILB125X225S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X225S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 225mm 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.
- BoreØ125 mm
- Stroke225 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X225S
The AirTAC SAILB125X225-S is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. Because the lock engages when the piston reaches the retracted stroke end, it secures the rod-in position and holds the load without requiring live air pressure. In the 125mm bore class, this pneumatic actuator generates 6136N of thrust and 5734N of pull force at 0.5 MPa, making it well-suited for heavy vertical lifting tasks. The standard carbon steel rod provides durable service in industrial environments.
This model includes a built-in magnet (-S) for position sensing via AirTAC CMSE reed switches or DMSE solid-state electronic sensors. A notable design feature is the variable air cushion: the cushion at the locker end measures 24mm, which is physically shorter than the 40mm cushion on the free end. This lock is strictly a static holding device that engages after the cylinder stops; it is not a dynamic brake for a moving rod.
Airtac SAILB Rear Lock Cylinder SAILB125X225S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X225S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 225 mm |
| Acting type | Double acting, with lock |
| Port size | G1/2 |
| Rod thread | M27×2 |
| 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 – 500 mm/s |
| Cushion | Adjustable (40 mm free end / 24 mm lock end) |
| Max stroke | Up to 1500 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 (Ø125mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 6136 N | 5734 N |
| 0.7 MPa | 8590 N | — |
| Max (@1.0 MPa) | 1251 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 SAILB125X225S Is Used
Vertical Lift Holding
Secures heavy elevated loads in the retracted position automatically when air pressure drops, preventing sudden falls on lifting machinery.
Safety Gate Lock
Holds safety gates and access barriers closed at the stroke end without relying on continuous live air pressure, ensuring secure perimeters.
Clamp and Hold Station
Maintains a firm clamping force on manufactured parts at the end of the stroke during machining or assembly processes.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X225S the Right Lock Cylinder?
Select this 125mm bore actuator when a standard 100mm bore cylinder lacks sufficient force, as stepping up to 125mm increases push thrust at 0.5 MPa from 3927N to 6136N. Choose the SAILB configuration specifically when the load must be held securely at the retracted stroke end upon power loss. If your application instead requires clamping at an arbitrary mid-stroke point, the BSAI clamp-lock cylinder is the correct alternative, as the SAIL lock only engages at the stroke terminal.
For safe operation, avoid using fast-exhaust valves with this lock cylinder; an independent-exhaust solenoid valve is required because back-pressure on the locker side can inadvertently release the lock. If human safety depends on the load staying up, add an independent safety measure alongside the lock. When replacing this unit, match the 225mm stroke, back locker position, PT tapered port threads, and the -S magnet. The 225mm stroke is below the 1500mm maximum standard stroke, but always use proper guide rails to manage side loads on longer strokes.
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 SAILB125X225S FAQ
At 0.5 MPa, this 125mm bore cylinder provides 6136N of push thrust and 5734N of pull force. At 0.7 MPa, the push force increases to 8590N.
The spring-applied lock engages automatically when the piston reaches the retracted stroke end in the back cover, holding the load without live pressure. To unlock, supply air to the release port for automatic release or use the manual release lever. It is a static hold only and does not clamp mid-stroke.
Related AirTAC Lock & Standard Cylinders
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