Airtac SAILB Rear Lock Cylinder SAILB125X80
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X80 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 80mm 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
- Stroke80 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X80
The AirTAC SAILB125X80 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 the release air is cut, ensuring power-loss safety without consuming live pressure. It delivers a robust 6136N push force and 5734N pull force at 0.5 MPa.
Unlike a plain SAI cylinder, this model provides true static load holding at stroke termination. The variable air cushion at the locker end is shorter at 24mm compared to the free end at 40mm, effectively decelerating the piston before the lock engages. The carbon steel rod utilizes an M27x2 thread, and positioning is tracked via external sensors rather than an internal magnet.
Airtac SAILB Rear Lock Cylinder SAILB125X80 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X80 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 80 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 SAILB125X80 Is Used
Vertical Load Holding
Secures heavy lifted platforms in the retracted position automatically upon air pressure loss, preventing sudden drops.
Power-Out Safety Gate
Keeps heavy safety gates firmly closed at the retracted stroke end during facility power or air supply failures.
Heavy Clamp Retraction
Holds a large clamping arm retracted under zero pressure to allow safe workpiece loading and unloading.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X80 the Right Lock Cylinder?
Choose this 125mm bore when an 80mm bore (providing 2513N push at 0.5 MPa) lacks the thrust for heavy vertical loads, but before stepping up to a 160mm bore. 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, the BSAI clamp-lock cylinder is the correct alternative.
The lock is a static holding device that engages only after the rod stops, not a dynamic brake for moving loads. Avoid fast-exhaust valves, as back-pressure on the locker side can inadvertently release the lock; use an independent-exhaust solenoid valve instead. For human-safety critical suspended loads, always add an independent mechanical safety measure. Replacement specifications: 125mm bore, 80mm stroke, back locker, PT tapered ports, and no internal magnet.
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 SAILB125X80 FAQ
At 0.5 MPa operating pressure, the 125mm bore provides a push force of 6136N and a pull force of 5734N. At 0.7 MPa, the push force increases to 8590N.
The lock is spring-applied and air-released, holding the rod statically at the retracted stroke end only. It engages after the piston stops and is not a mid-stroke clamp or 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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