Airtac SEJ Adjustable Cylinder SEJ125X60-20S
The AirTAC Airtac SEJ Adjustable Cylinder SEJ125X60-20S is a genuine double-acting ISO 15552 double-rod cylinder with a mechanically ADJUSTABLE stroke: a back-rod stop screw lets you fine-tune the retract end over a 20mm window, so this Ø125mm unit covers an effective stroke of 40–60mm without changing cylinders. Force is equal in both directions.
- BoreØ125 mm
- Nominal stroke60 mm
- Adjust window20 mm
- Effective stroke40–60 mm
- Port sizePT1/2
- CushionAdjustable, 40 mm
About the Airtac SEJ Adjustable Cylinder SEJ125X60-20S
The AirTAC SEJ125X60-20S is a double-acting, double-rod ISO 15552 profile cylinder featuring a 20mm adjustable stroke window. A rod exits both ends, yielding identical annulus areas so output force is perfectly balanced at 5734 N each way at 0.5 MPa. You can mechanically dial the retract end from 40 to 60 mm via a stop screw on the back rod, letting you fine-tune the end position directly on the machine without changing hardware.
This 125 mm bore unit runs at 30-500 mm/s and includes a magnet (-S) for CMSE reed or DMSE electronic sensors. It carries an extruded aluminum barrel with no external tie rods, a PT1/2 port, and a 32 mm rod with an M27x2 thread. Adjustable air cushions at both ends decelerate the heavy load near stroke end, while the extended overall length accommodates the rear adjustment mechanism.
Airtac SEJ Adjustable Cylinder SEJ125X60-20S Technical Specifications
| Model | Airtac SEJ Adjustable Cylinder SEJ125X60-20S |
|---|---|
| Series | SEJ ISO 15552 adjustable-stroke cylinder |
| Bore size | Ø125 mm |
| Nominal stroke | 60 mm |
| Adjustment window | 20 mm (40–60 mm) |
| Configuration | Double rod, double acting |
| Port size | PT1/2 |
| Rod thread | M27×2 |
|---|---|
| Operating pressure | 0.15 – 1.0 MPa |
| Proof pressure | 1.5 MPa |
| Temperature | -20 to +70 °C (0–150 °C with FKM seals) |
| Speed range | 30 – 500 mm/s |
| Cushion | Adjustable, 40 mm |
Specifications follow the official AirTAC SEJ datasheet and ISO 15552 / VDMA 24562 dimensions. The adjustment screw shortens the retract end only; do not exceed the 20mm window. Port options: PT (standard) / G (BSPP).
Theoretical Output Force (Ø125mm)
| Pressure | Force (both directions) |
|---|---|
| 0.5 MPa | 5734 N |
| 0.7 MPa | 8027 N |
| Max (@1.0 MPa) | 1169 kgf |
A rod exits both ends, so extend and retract force are identical. Actual usable force is lower than theoretical; size with a safety margin.
Model Code: Airtac SEJ Adjustable Cylinder SEJ125X60-20S
| SEJ | ISO 15552 double-rod double-acting cylinder with adjustable stroke. |
|---|---|
| 125 | Bore size in mm. |
| ×60 | Nominal stroke length in mm. |
| -20 | Adjustment stroke window in mm (options: 10/20/30/40/50/75/100). |
| -S | Optional built-in magnet for CMSE / DMSE sensor sensing. |
Rod material: carbon steel (blank) / SUS420J2 (A) / SUS304 (B). Seals: TPU (blank) / FKM high-temp (H) / NBR (N). Thread: PT (blank) / G. Mounting (SEJ): Basic, LB, FA, TC, FTC, TCM1, TCM2. Related: SED (double rod, fixed stroke), SE (single rod).
Where the Airtac SEJ Adjustable Cylinder SEJ125X60-20S Is Used
Press Tonnage Calibration
Dial in the exact 40-60 mm contact stroke on a heavy press to calibrate tonnage, utilizing the 5734 N both-way force to securely seat stamping dies.
Variable-Stop Material Feeds
Adjust the mechanical stop screw on the fly to change material feed lengths, using the equal push and pull forces to advance heavy steel coils without skewing.
Heavy Weldment Changeover
Switch a robotic weld cell between different chassis heights by turning the back-rod stop screw, leveraging the 125 mm bore power to clamp thick fabricated frames.
Is the Airtac SEJ Adjustable Cylinder SEJ125X60-20S the Right Cylinder?
Verify the 20 mm adjustment window covers your required positioning range, giving an effective 40-60 mm stroke. If you need less force, stepping down to the 100 mm bore drops the both-way output to 3681 N at 0.5 MPa. If you require more power, this 125 mm bore is the largest standard SEJ size, providing 8028 N at 0.7 MPa. For fixed-position applications that never need commissioning adjustments, a standard SED double-rod cylinder provides the same equal-force output without the stop screw.
Remember that a plain SEJ does not hold position on air loss; the air cushion and stop screw only set the mechanical end and decelerate the load, so add an external rod lock for fail-safe holding. When replacing an ISO 15552 cylinder, match the 125 mm bore, 60 mm nominal stroke, PT1/2 port, and mounting choice (Basic, FA, LB, TC, FTC, TCM1, or TCM2). The -S magnet ensures compatibility with your existing CMSE or DMSE sensors.
Quick checklist
- ✓ Need on-machine stroke fine-tuning?
- ✓ Adjustment window (20mm) covers your range
- ✓ Equal force both directions OK
- ✓ Port/thread type (PT/G)
- ✓ Magnet (-S) for CMSE/DMSE sensors?
Installation & Maintenance Notes
- check Use clean air filtered to 40µm or finer.
- check Keep within 0.15 – 1.0 MPa operating pressure.
- check Set the stop screw within the 20mm window; lock it after adjusting.
- check Adjust end cushion screws for smooth stops.
- check Use correct mounting accessory (LB/FA/TC/FTC/TCM1/TCM2).
- check Installation by qualified personnel per AirTAC docs.
Airtac SEJ Adjustable Cylinder SEJ125X60-20S FAQ
The -20 designation means the retract stroke is mechanically adjustable over a 20 mm window via a stop screw on the back rod. For this 60 mm nominal stroke model, the effective retract stroke can be dialed from 40 mm up to 60 mm. You lock the screw after setting your exact end position.
Because it is a double-rod cylinder, the force is identical in both directions. It outputs 5734 N at 0.5 MPa, 8028 N at 0.7 MPa, and reaches a maximum of 1169 kgf at 1.0 MPa.
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