Airtac SAILB Rear Lock Cylinder SAILB125X175S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X175S 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 SAILB125X175S
The AirTAC SAILB125X175-S is a double-acting ISO 15552 profile cylinder featuring a spring-applied, air-released mechanical lock housed in the back cover. This safety mechanism engages automatically to hold the rod securely at the retracted stroke end whenever the release air is cut, dropping the load safely without relying on live pressure. It delivers a robust 6136N push force at 0.5MPa and includes a magnetic piston for position sensing.
Unlike a standard SAI unit, this model integrates load-holding safety directly into the actuator. The variable air cushion at the locker end is specifically shortened to 24mm compared to the 40mm cushion on the free end, accommodating the lock hardware. For position feedback, the integrated magnet works seamlessly with AirTAC CMSE reed and DMSE electronic solid-state switches.
Airtac SAILB Rear Lock Cylinder SAILB125X175S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X175S |
|---|---|
| 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 SAILB125X175S Is Used
Vertical Lift Safety
Secures elevated platens in the retracted position during a power loss, preventing gravity-driven drops in heavy lifting rigs.
Machine Guard Hold
Maintains a locked retracted state for heavy safety doors and machine guards, keeping the hazard zone clear without consuming air.
Clamp and Hold
Locks large workpieces firmly at the end of the retraction cycle, ensuring zero drift during heavy machining operations.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X175S the Right Lock Cylinder?
Choose this 125mm bore when an 80mm cylinder (providing 2513N push at 0.5MPa) lacks the thrust for heavy vertical loads, but a 160mm bore is physically oversized. Select the SAILB configuration when the load must be secured in the retracted position; choose SAILF if the extended end requires holding. If your application demands clamping at an arbitrary mid-stroke point rather than a terminal position, the BSAI clamp-lock cylinder is the correct alternative.
This lock is a static holding device that engages after the cylinder stops, not a dynamic brake for a moving rod. Pneumatic routing is critical: never use a fast-exhaust valve with this cylinder, as back-pressure on the locker side can inadvertently release the lock—always use an independent-exhaust solenoid valve. For any human-safety lifting application, add an independent mechanical safety measure. Replacement specifications: 125mm bore, 175mm stroke, back locker, PT tapered ports, carbon steel rod, and a magnetic piston (-S).
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 SAILB125X175S FAQ
At 0.5MPa, it 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, located in the back cover to hold the rod only at the retracted stroke end. It engages statically after the piston stops and is released automatically via air supply or manually via a lever.
Related AirTAC Lock & Standard Cylinders
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