Airtac SAILB Rear Lock Cylinder SAILB125X125S
The AirTAC Airtac SAILB Rear Lock Cylinder SAILB125X125S 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 SAILB125X125S
The AirTAC SAILB125X125-S is a double-acting ISO 15552 profile cylinder equipped with a spring-applied, air-released mechanical lock 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 heavy loads remain safely parked without relying on live pressure. In the 125mm bore class, it generates 6136N of push force and 5734N of pull force at 0.5 MPa, making it suitable for heavy-duty handling.
This model includes a magnet (-S) for position sensing with AirTAC CMSE reed or DMSE electronic solid-state switches. The carbon steel rod provides robust side-load resistance, while the variable air cushion at the locker end is specifically shortened to 24mm to accommodate the locking mechanism. The lock releases automatically via air supply or manually via a lever, but note that the cushion only decelerates the piston near stroke end and never acts as the holding device.
Airtac SAILB Rear Lock Cylinder SAILB125X125S Technical Specifications
| Model | Airtac SAILB Rear Lock Cylinder SAILB125X125S |
|---|---|
| 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 SAILB125X125S Is Used
Vertical Load Holding
Secures elevated heavy loads in the retracted position during a power loss, preventing sudden drops on lifting fixtures.
End-of-Stroke Clamping
Holds the rod firmly at the retracted terminal without consuming compressed air, ideal for maintaining grip on heavy jigs.
Safety Gate Hold
Keeps heavy safety gates or machine guards locked in the closed position until the release air is actively supplied.
Is the Airtac SAILB Rear Lock Cylinder SAILB125X125S the Right Lock Cylinder?
Choose this 125mm bore when a 100mm bore (providing 3927N push at 0.5 MPa) is insufficient, or step down if an 80mm bore (2513N push) meets your requirement. Select the SAILB configuration when the load must be held in the retracted (rod-in) position; choose SAILF instead if the extended end requires holding. If your application demands clamping at an arbitrary mid-stroke point rather than a stroke-end static hold, the BSAI clamp-lock cylinder is the correct choice.
For safe operation, do not use a fast-exhaust valve with this lock cylinder; use an independent-exhaust solenoid valve, as back-pressure on the locker side can inadvertently release the lock. The lock holds statically after the rod stops and is not a dynamic brake. If human safety depends on the load staying retracted, add an independent safety measure. To replace this unit, match the 125mm bore, 125mm stroke, back locker position, PT tapered 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 SAILB125X125S FAQ
At 0.5 MPa operating pressure, this 125mm bore cylinder provides 6136N of push force and 5734N of pull force. 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 when air is cut. It unlocks automatically via air supply or manually via a lever, but it does not clamp at mid-stroke.
Related AirTAC Lock & Standard Cylinders
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