Airtac SAILB Rear Lock Cylinder SAILB125X500
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X500 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 SAILB125X500
The AirTAC SAILB125X500 is a double-acting ISO 15552 profile cylinder featuring a built-in mechanical lock in the back cover. It delivers 6136N of push force and 5734N of pull force at 0.5MPa, making it suited for heavy-load automation. The lock is spring-applied and air-released, meaning it safely holds the rod at the retracted stroke end without requiring live air pressure.
This model uses a 1/2 PT port and a 32mm carbon steel rod. The variable air cushion at the locker end is 24mm, which is intentionally shorter than the 40mm cushion on the free end to accommodate the locking hardware. To unlock, supply air to the release port for automatic operation or use the manual release lever.
Airtac SAILB Rear Lock Cylinder SAILB125X500 Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X500 |
|---|---|
| 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 SAILB125X500 Is Used
Vertical Lift Safety
Secures elevated loads in the retracted position automatically upon air pressure loss, preventing sudden drops on heavy lifting rigs.
Pallet Stopper
Holds a stopped pallet firmly at the retracted stroke end without consuming continuous air, ensuring stable processing.
Power Failure Hold
Maintains the rod in the safe retracted position during an emergency shutdown or power outage until release air is restored.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X500 the Right Lock Cylinder?
Choose this 125mm bore when 80mm (2513N push at 0.5MPa) is insufficient, but a 160mm bore is oversized. Pick the SAILB configuration when the load must be secured in the retracted position; select SAILF if you need to hold the extended end. If your application requires clamping at an arbitrary mid-stroke point, use the BSAI clamp-lock cylinder instead.
This lock is a static holding device that engages after the cylinder stops, not a dynamic brake. Avoid fast-exhaust valves, as back-pressure on the locker side can accidentally release the lock; use an independent-exhaust solenoid valve. At 500mm stroke, use external guides to manage side loads. For safety-critical vertical holds, add an independent mechanical measure. Replacement requires matching bore, stroke, back locker position, PT ports, and mounting.
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 SAILB125X500 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 spring-applied lock engages when the piston reaches the retracted stroke end, holding the load without live air. It is a static hold, not a dynamic brake. Unlock it by supplying release air or using the manual lever.
Related AirTAC Lock & Standard Cylinders
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