Airtac SAILB Rear Lock Cylinder SAILB125X500S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X500S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 500mm 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
- Stroke500 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X500S
The AirTAC SAILB125X500-S is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. This lock engages automatically to hold the rod securely at the retracted stroke end whenever release air is cut, ensuring heavy loads remain safely positioned without consuming live pressure. In the 125mm bore class, it generates 6136N of push force and 5734N of pull force at 0.5 MPa, making it well suited for substantial lifting and holding tasks.
Because this variant includes the -S magnet option, it directly supports AirTAC CMSE reed and DMSE electronic solid-state sensors for precise end-position confirmation. The locker end utilizes a shorter 24mm air cushion compared to the 40mm cushion on the free end, effectively managing deceleration within the constrained lock geometry. Fluid must be filtered to 40 um, and the standard carbon steel rod handles high axial stresses across the 500mm travel.
Airtac SAILB Rear Lock Cylinder SAILB125X500S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X500S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 500 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 SAILB125X500S Is Used
Vertical Lift Safety
Holds heavy vertical loads safely in the retracted position during a power loss event, preventing sudden drops without requiring continuous air pressure.
Machine Guard Hold
Secures a retracted machine guard or heavy gate in the closed position, relying on the mechanical lock to maintain a safe perimeter.
Clamp and Dwell
Maintains a robust 6136N clamping force at the rod-in stroke end for dwell operations, saving energy by eliminating the need for constant pneumatic pressure.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X500S the Right Lock Cylinder?
Select this 125mm bore when a 100mm bore (providing 3927N push at 0.5 MPa) is insufficient, but a 160mm bore (10053N push) would be excessive. Choose the SAILB configuration when the load must be held at the rod-in retracted position; if your application requires holding at the extended position, the SAILF variant is required instead. For applications needing the rod clamped at an arbitrary mid-stroke point rather than a stroke end, the BSAI clamp-lock cylinder is the correct choice.
The lock is a static holding device that engages after the cylinder stops, not a dynamic brake for a moving rod. Never use a fast-exhaust valve with this cylinder; instead, use an independent-exhaust solenoid valve, as back-pressure on the locker side can inadvertently release the lock. If human safety depends on the load staying up, add an independent safety measure. At 500mm of stroke, use proper guiding to prevent excessive side loads on the carbon steel rod. Replacement parts must match the 1/2 PT port, the chosen mounting style (such as LB or TC), and the -S magnet specification.
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 SAILB125X500S FAQ
At 0.5 MPa operating pressure, the 125mm bore provides 6136N of push force and 5734N of pull force. At 0.7 MPa, the push force increases to 8590N.
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 unlocked by supplying air to the release port or using the manual release lever.
Related AirTAC Lock & Standard Cylinders
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