Airtac SAILB Rear Lock Cylinder SAILB125X800
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X800 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 800mm 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
- Stroke800 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X800
The AirTAC SAILB125X800 is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock built into the back cover. This lock engages automatically to hold the rod securely at the retracted stroke end, maintaining the load without requiring continuous live air pressure. With a robust 125mm bore, it generates 6136N of pull force at 0.5MPa, making it highly capable for heavy lifting tasks.
The locker end features a variable air cushion of 24mm, which is intentionally shorter than the 40mm cushion on the free end to accommodate the locking mechanism. It operates at speeds from 30-500mm/s and uses a carbon steel rod with a PT tapered port thread. For position sensing, adding the -S magnet option enables compatibility with AirTAC CMSE reed and DMSE solid-state sensors.
Airtac SAILB Rear Lock Cylinder SAILB125X800 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X800 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 800 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 SAILB125X800 Is Used
Vertical Lift Holding
Secures heavy lifted loads in the retracted position during a power loss, preventing sudden drops.
Pallet Stop Gate
Holds a heavy pallet stop gate in the retracted end position without consuming continuous air pressure.
Safety Barrier
Locks a heavy safety barrier in the withdrawn position, requiring an active air signal to unlock.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X800 the Right Lock Cylinder?
Choose this 125mm bore when the 80mm bore (2268N pull at 0.5MPa) lacks the force to hold your load, but the 160mm bore (9425N pull) is oversized. Select the SAILB back-lock configuration when the load must be secured in the retracted position; for holding at the extended rod-out position, the SAILF front-lock version is required. If your application requires clamping at an arbitrary mid-stroke point rather than a stroke-end hold, the BSAI clamp-lock cylinder is the correct choice.
Because the lock is a static holding device that engages after the cylinder stops, it will not brake a moving rod. Valve selection is critical: never use a fast-exhaust valve, as back-pressure on the locker side can unintentionally release the lock; always use an independent-exhaust solenoid valve. At an 800mm stroke, the extended rod is highly susceptible to side-load bending; ensure external guide rails are used to prevent cylinder damage. If human safety depends on the load remaining up, add an independent safety measure. Replacement requires matching the 125mm bore, 800mm stroke, back locker position, PT port, and standard mounting options.
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 SAILB125X800 FAQ
At 0.5MPa, the 125mm bore provides 6136N of pull force and 8590N of push force. At 0.7MPa, the push force is 8590N and pull is 5734N. The maximum operating pressure is 1.0MPa.
The lock is spring-applied and air-released, located in the back cover to hold the rod at the retracted stroke end. It engages statically after the piston stops and does not brake a moving rod. Unlocking requires supplying air to the release port or using the manual override lever.
Related AirTAC Lock & Standard Cylinders
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