Airtac SAILB Rear Lock Cylinder SAILB125X800S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X800S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 800mm 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
- Stroke800 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X800S
The AirTAC SAILB125X800-S is a double-acting ISO 15552 profile cylinder featuring a built-in mechanical lock in the back cover. Because the lock is spring-applied and air-released, cutting the release air drives a lock pin into the carbon steel rod, securely holding the load at the retracted stroke end without requiring live pressure. In the 125mm bore class, it generates a robust 6136N pull force at 0.5MPa, making it well-suited for heavy vertical lifting tasks.
This model includes a magnetic piston (-S) for position detection and is fully compatible with AirTAC CMSE reed and DMSE electronic solid-state sensors. To accommodate the locking hardware, the variable air cushion at the locker end is slightly shorter, measuring 24mm compared to the 40mm cushion at the free end. The lock engages automatically as a static holding device once the piston stops at the terminal position, rather than acting as a dynamic mid-stroke brake.
Airtac SAILB Rear Lock Cylinder SAILB125X800S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X800S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 800 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 SAILB125X800S Is Used
Vertical Lift Safety
Secures heavy elevated loads at the retracted stroke end instantly upon air pressure loss, preventing sudden drops in heavy lifting machinery.
Pallet Stopper
Holds a stopped pallet firmly in place at the end of stroke without consuming continuous compressed air, saving energy in conveyor lines.
Machine Guard Hold
Maintains a safety guard in the locked retracted position during maintenance until deliberate release air is supplied to unlock the mechanism.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X800S the Right Lock Cylinder?
Select this 125mm bore cylinder when an application requires substantial load-holding capability at the retracted rod-in position; if less force is needed, the 100mm bore offers 3681N pull at 0.5MPa. For holding a load at the extended rod-out position instead, the SAILF variant is required. If your application demands clamping at an arbitrary mid-stroke point rather than the stroke terminal, the AirTAC BSAI clamp-lock cylinder is the correct choice.
The lock provides a static hold only after the cylinder stops, so it will not brake a moving rod. Valve selection is critical: never use a fast-exhaust valve with this cylinder, and always use an independent-exhaust solenoid valve, as back-pressure on the locker side can unintentionally release the lock. For safety-critical loads that must remain suspended, add an independent mechanical safety measure. This 800mm stroke unit operates at 30-500mm/s and uses PT tapered 1/2-inch ports; for a stroke of this length, ensure external side-load guides are used to prevent rod binding.
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 SAILB125X800S FAQ
The 125mm bore generates a push force of 6136N and a pull force of 5734N at 0.5MPa. At 0.7MPa, the push force increases to 8590N.
The lock is spring-applied and engages only at the retracted stroke end after the cylinder stops. Supplying air to the release port unlocks it automatically, or you can use the manual release lever. It is a static hold, not a mid-stroke brake.
Related AirTAC Lock & Standard Cylinders
Request a Quote for Airtac SAILB Rear Lock Cylinder SAILB125X800S
Send us the quantity and destination. We confirm price, stock and lead time — usually within 7-8 hours.