Airtac SAILB Rear Lock Cylinder SAILB125X125
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X125 is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 125mm 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
- Stroke125 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X125
The AirTAC SAILB125X125 is a double-acting ISO 15552 profile cylinder featuring a built-in mechanical lock in the back cover. A spring-applied, air-released lock engages when the piston reaches the retracted stroke end, securely holding the rod in place without requiring live air pressure. Delivering 6136N of push force at 0.5MPa, this 125mm bore unit uses a PT tapered port thread and a carbon steel rod for robust side-load resistance.
Unlike a standard SAI cylinder, this SAILB variant provides true static load holding at the stroke terminal, but it is not a mid-stroke clamp. The variable air cushion at the locker end is notably shorter at 24mm compared to the 40mm cushion on the free end, a specific design accommodation for the lock housing. To unlock, supply air to the release port or use the manual override lever.
Airtac SAILB Rear Lock Cylinder SAILB125X125 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X125 |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 125 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 SAILB125X125 Is Used
Vertical Power-Off Holding
Prevents heavy elevated platens from dropping when air supply is cut, using the back-cover lock to hold the rod in the retracted position.
Safety Gate Interlock
Secures safety barriers in the retracted state during power loss, maintaining a fail-safe hold until air is actively supplied to release the lock.
Press Clamping at Stroke End
Holds a clamped workpiece securely at the retracted stroke terminal without continuous pneumatic pressure, saving energy during machining.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X125 the Right Lock Cylinder?
Select this 125mm bore model when an application requires 6136N of push force at 0.5MPa, or step down to the 80mm bore offering 2513N if the load is lighter. Choose the SAILB configuration specifically because the load must be held in the retracted position; if your safety requirement is to hold the rod extended, the SAILF variant is the correct match. For applications needing the rod clamped at an arbitrary mid-stroke position rather than the stroke end, the BSAI clamp-lock cylinder is required instead.
Remember that this is a static holding lock that engages after the cylinder stops, not a dynamic brake for a moving rod. Valve selection is critical: never use a fast-exhaust valve with this cylinder, as back-pressure on the locker side can unintentionally release the lock; always use an independent-exhaust solenoid valve. If human safety depends on the load remaining elevated, add an independent safety measure. Replacement matches: 125mm bore, 125mm stroke, back locker, PT ports, standard mounting, no 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 SAILB125X125 FAQ
At 0.5MPa, this 125mm bore cylinder 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, engaging only when the piston reaches the retracted stroke end in the back cover. It provides a static hold, not a mid-stroke clamp, and can be released automatically via air or manually via a lever.
Related AirTAC Lock & Standard Cylinders
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