Airtac SAILB Rear Lock Cylinder SAILB63X125
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB63X125 is a genuine double-acting ISO 15552 profile cylinder with a Ø63mm 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.
- BoreØ63 mm
- Stroke125 mm
- Port sizeG3/8
- Lock positionBack cover
- Rod threadM16×1.5
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB63X125
The AirTAC SAILB63X125 is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. This built-in lock engages automatically when the piston reaches the retracted stroke end, securely holding the rod in place without requiring continuous live air pressure. In the 63mm bore class, it delivers a push force of 1559N and a pull force of 1402N at 0.5 MPa, utilizing a 3/8 PT port and a 20mm carbon steel rod.
Because the lock mechanism occupies space in the end cover, the variable air cushion at the locker end is shorter at 21mm compared to the 30mm cushion on the free end. The lock is a static holding device that engages only after the cylinder has stopped at the stroke terminal, meaning it is not designed to brake a moving rod. For position sensing, this non-magnet version can be upgraded with a magnet (-S) to accept AirTAC CMSE reed or DMSE electronic solid-state sensors in the dual-side barrel grooves.
Airtac SAILB Rear Lock Cylinder SAILB63X125 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB63X125 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø63 mm |
| Stroke | 125 mm |
| Acting type | Double acting, with lock |
| Port size | G3/8 |
| Rod thread | M16×1.5 |
| 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 (30 mm free end / 21 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 (Ø63mm)
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 1559 N | 1402 N |
| 0.7 MPa | 2182 N | — |
| Max (@1.0 MPa) | 318 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 SAILB63X125 Is Used
Vertical Lift Safety
Prevents gravity-loaded vertical platforms from crashing down when air supply is cut, holding the load securely at the retracted stroke end.
Clamp and Hold
Maintains a secure holding force on workpieces in machining or assembly fixtures without consuming continuous compressed air.
Emergency Stop Holding
Engages automatically upon loss of pressure to freeze heavy safety gates or machine guards in the closed position.
Is the Airtac SAILB Rear Lock Cylinder SAILB63X125 the Right Lock Cylinder?
Choose this 63mm bore lock cylinder when your application requires maintaining a retracted position during power loss or emergency stops, offering a push force of 1559N at 0.5 MPa. If your force requirements are lower, the 50mm bore provides 982N of push force; if you need more holding power, stepping up to the 80mm bore yields 2513N. Select the SAILB back-lock configuration specifically when the load must be secured in the rod-in position, whereas the SAILF front-lock variant holds the extended rod-out position.
If your machinery needs to freeze the load at an arbitrary mid-stroke point rather than at the stroke end, the SAILB63X125 is the wrong choice; you must use the BSAI clamp-lock cylinder instead. When integrating this model, strictly 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 any application where human safety depends on the load remaining suspended, add an independent mechanical safety measure. Replacement parts must match the 63mm bore, 125mm stroke, back lock position, 3/8 PT port threads, and your required mounting style.
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 SAILB63X125 FAQ
At a standard 0.5 MPa operating pressure, the 63mm bore generates a push force of 1559N and a pull force of 1402N. The maximum push force reaches 2805N at 0.9 MPa.
The lock is spring-applied and air-released, located in the back cover to hold the rod only at the retracted stroke end. It engages statically after the piston stops and is never to be used as a dynamic brake. Unlocking is done automatically by supplying release air or manually via the release lever.
Related AirTAC Lock & Standard Cylinders
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