Airtac SAILB Rear Lock Cylinder SAILB125X450
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X450 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 450mm 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
- Stroke450 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X450
The AirTAC SAILB125X450 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 when the piston reaches the retracted stroke end, securely holding a 5734N pull load at 0.5 MPa without requiring continuous live air pressure. A standard carbon steel rod and PT tapered port threads are specified for this configuration.
Because the lock occupies the back end, the variable air cushion on the locker side is shorter at 24 mm compared to the 40 mm cushion on the free end. The lock releases automatically via air supply to the release port, or manually via the lever. For position sensing, adding a magnet allows the use of AirTAC CMSE reed or DMSE solid-state sensors.
Airtac SAILB Rear Lock Cylinder SAILB125X450 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X450 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 450 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 SAILB125X450 Is Used
Vertical Lift Hold
Holds heavy vertical loads in the retracted position during power loss, preventing gravity-driven drops.
Clamp and Hold
Secures heavy workpieces at the retracted stroke end without consuming continuous pneumatic energy.
Safety Gate Locking
Keeps safety gates and heavy barriers locked in the closed position until release air is supplied.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X450 the Right Lock Cylinder?
Choose this 125 mm bore when a 100 mm bore (3681N pull at 0.5 MPa) lacks the force to lift your load, or step down if 80 mm (2268N pull) suffices. Select the SAILB back-lock variant to hold the rod in the retracted position; choose SAILF if your application requires holding at the extended stroke end. If your process requires clamping at an arbitrary mid-stroke point rather than a stroke-end hold, use the BSAI clamp-lock cylinder instead.
The mechanical lock provides a static hold after the cylinder stops; it is 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—use an independent-exhaust solenoid valve. For human safety applications, add an independent safety measure. At a 450 mm stroke, use appropriate mounting guides to prevent excessive side-load wear on the rod.
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 SAILB125X450 FAQ
At 0.5 MPa, the push force is 6136N and the pull force is 5734N. At 0.7 MPa, the push force is 8590N. The maximum operating pressure is 1.0 MPa, yielding a push force of 1251 kgf.
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 cylinder stops and is not a mid-stroke clamp or dynamic brake. It unlocks automatically via air supply or manually via the release lever.
Related AirTAC Lock & Standard Cylinders
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