Airtac SAILB Rear Lock Cylinder SAILB125X50S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X50S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 50mm 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
- Stroke50 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X50S
The AirTAC SAILB125X50-S is a double-acting ISO 15552 profile cylinder equipped with a mechanical lock in the back cover. It secures the rod automatically at the retracted stroke end, delivering 6136N of pull force at 0.5MPa. The lock is spring-applied and air-released, meaning a loss of release pressure causes a lock pin to engage the rod, holding the load securely without consuming live air. Unlocking requires supplying air to the release port or using the manual override lever.
This model includes a magnetic piston for position detection with CMSE reed and DMSE electronic sensors. A distinct mechanical detail is the variable air cushion: the locker end features a 24mm cushion stroke, shorter than the 40mm stroke at the free end, to accommodate the locking hardware. The standard carbon steel rod provides robust side-load resistance, and the fluid ports use PT tapered threads.
Airtac SAILB Rear Lock Cylinder SAILB125X50S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X50S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 50 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 SAILB125X50S Is Used
Vertical Lift Safety
Holds elevated platforms securely in the retracted position during a power loss, preventing sudden drops.
Clamp and Hold
Maintains constant clamping force on heavy workpieces at the stroke end without requiring continuous air pressure.
Gate and Door Control
Secures heavy industrial gates in the closed position mechanically, ensuring they remain shut until actively released.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X50S the Right Lock Cylinder?
Choose this 125mm bore when a 100mm bore (providing 3681N pull at 0.5MPa) is insufficient to hold your load, but a larger 160mm bore (9425N pull) is unnecessary. Select the SAILB configuration when the safety requirement is to hold the load in the retracted position; choose SAILF if the extended position must be secured. If your application requires clamping at an arbitrary mid-stroke point rather than the stroke end, select the BSAI clamp-lock cylinder instead.
Because the lock engages statically after the piston stops, it cannot act as a dynamic brake for a moving rod. Valve selection is critical: never use a fast-exhaust valve, and always use an independent-exhaust solenoid valve, as back-pressure on the locker side can unintentionally release the lock. For overhead lifting where human safety is a factor, add an independent mechanical safety device. To replace this unit, match the 125mm bore, 50mm stroke, back locker position, PT ports, and the -S magnet option.
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 SAILB125X50S FAQ
At 0.5MPa, this 125mm bore cylinder provides 6136N of pull force and 8590N of push force. At the maximum operating pressure of 1.0MPa, it delivers a push force of 1251kgf.
The lock is spring-applied and air-released, engaging only when the piston reaches the retracted stroke end. It holds statically after stopping and is not a mid-stroke clamp or dynamic brake. Unlocking is achieved automatically by supplying release air or manually via the lever.
Related AirTAC Lock & Standard Cylinders
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