Airtac SAILB Rear Lock Cylinder SAILB125X400S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X400S is a genuine double-acting ISO 15552 profile cylinder with a Ø125mm bore, 400mm 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
- Stroke400 mm
- Port sizeG1/2
- Lock positionBack cover
- Rod threadM27×2
- UnlockAir + manual
About the Airtac SAILB Rear Lock Cylinder SAILB125X400S
The AirTAC SAILB125X400-S is a double-acting ISO 15552 profile cylinder featuring a built-in mechanical lock in the back cover. A spring-applied, air-released mechanism engages a lock pin when the piston reaches the retracted stroke end, securely holding the load without requiring live air pressure. In the 125mm bore class, it generates 6136N of push force and 5734N of pull force at 0.5 MPa, making it well-suited for heavy vertical load management.
This model includes a magnetic piston for position detection, compatible with AirTAC CMSE reed switches and DMSE electronic sensors. A key design detail is the variable air cushion: the locker end features a 24mm cushion stroke, which is shorter than the 40mm cushion at the free end. The lock provides a static hold after the cylinder stops, rather than acting as a dynamic brake for a moving rod.
Airtac SAILB Rear Lock Cylinder SAILB125X400S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X400S |
|---|---|
| Series | SAIL ISO 15552 cylinder with lock |
| Bore size | Ø125 mm |
| Stroke | 400 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 SAILB125X400S Is Used
Vertical Lift Safety
Secures elevated loads at the top retracted stroke end instantly upon air pressure loss, preventing sudden drops on heavy lifting platforms.
Clamp and Hold
Maintains a rigid, unyielding clamp on heavy workpieces at the stroke end without continuously consuming compressed air.
Overhead Gate Control
Holds massive industrial doors securely in the closed retracted position, relying on the mechanical lock rather than constant fluid pressure.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X400S the Right Lock Cylinder?
Choose this 125mm bore if your application requires the 6136N thrust at 0.5 MPa; stepping down to an 80mm bore yields 2513N, while moving up to a 160mm bore provides 10053N. Select the SAILB configuration when the load must be secured at the retracted rod-in position, and choose SAILF if it needs holding at the extended rod-out position. If your design requires locking at an arbitrary mid-stroke point rather than the stroke end, the BSAI clamp-lock cylinder is the correct choice.
For safe operation, avoid using a fast-exhaust valve, as back-pressure on the locker side can unintentionally release the lock; an independent-exhaust solenoid valve is required. Because this unit features a 400mm stroke, ensure external guide rails are used to prevent excessive side-load wear on the rod seals. Replacement matches require a 125mm bore, 400mm stroke, back locker position, PT port threads, and the -S magnet option.
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 SAILB125X400S FAQ
At 0.5 MPa operating pressure, the 125mm bore generates 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, engaging automatically to hold the rod only at the retracted stroke end. To unlock it, you supply air to the release port for automatic unlocking or use the manual release lever.
Related AirTAC Lock & Standard Cylinders
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