Airtac SAILB Rear Lock Cylinder SAILB125X175
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X175 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 175mm 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
- Stroke175 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X175
The AirTAC SAILB125X175 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 load without requiring live air pressure. Fitted with a carbon steel rod and PT tapered ports, it provides a robust 6136N push force at 0.5MPa, making it well-suited for heavy vertical lifting tasks.
Unlike a standard SAI cylinder, this model provides true fail-safe load holding at the stroke terminal. The variable air cushion at the locker end is 24mm, intentionally shorter than the 40mm cushion at the free end to accommodate the locking mechanism. For position detection, you can add a magnet (-S) to use AirTAC CMSE reed or DMSE electronic solid-state sensors in the dual-side barrel grooves.
Airtac SAILB Rear Lock Cylinder SAILB125X175 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X175 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 175 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 SAILB125X175 Is Used
Vertical Lift Safety
Holds heavy lifted platforms securely at the retracted stroke end during a sudden air pressure loss or emergency stop.
Clamp and Hold
Maintains a positive mechanical lock on a clamped workpiece at the rod-in position without consuming continuous air.
Gate Safety Lock
Prevents heavy safety gates from dropping unexpectedly by engaging the spring-applied lock at the closed terminal.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X175 the Right Lock Cylinder?
Select this 125mm bore when a 100mm bore (offering 3927N push at 0.5MPa) is insufficient for your load, but a 160mm bore (10053N) is oversized. Choose the SAILB configuration specifically when the load must be safely held in the retracted (rod-in) position. If your application requires clamping at an arbitrary mid-stroke point rather than the stroke end, select the BSAI clamp-lock cylinder instead.
Remember that this lock is a static holding device, 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; always use an independent-exhaust solenoid valve. For safety-critical suspended loads, add an independent mechanical safety measure. Replacement matches require the exact 175mm stroke, back locker position, PT 1/2 port, and standard mounting options like FA, FB, or TC.
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 SAILB125X175 FAQ
At 0.5MPa operating pressure, the 125mm bore provides 6136N of push force and 5734N of pull force. At 0.7MPa, the push force increases to 8590N.
The lock is spring-applied and air-released, engaging statically only when the piston reaches the retracted stroke end. It is unlocked automatically by supplying air to the release port or manually via a lever, but it cannot hold the rod at an arbitrary mid-stroke position.
Related AirTAC Lock & Standard Cylinders
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