The AirTAC Airtac SCJ250 Standard Cylinder SCJ250X125-40 is a genuine double-acting SINGLE-ROD air cylinder with a rear-cap ADJUSTING SCREW: the stroke end is field-adjustable within a 40 mm range without swapping the cylinder. Ø250mm bore, 125mm nominal stroke, PT1" ports and adjustable end cushioning.
The SCJ250X125-40 is a heavy-duty double-acting, single-rod pneumatic cylinder engineered for applications demanding substantial force with precise, field-adjustable stroke-end positioning. With a 250 mm bore, it delivers a formidable 24544 N of push force at 0.5 MPa, scaling up to 44178 N at the maximum operating pressure of 0.9 MPa. The rear-cap adjusting screw provides a 40 mm range to fine-tune the stroke end, making it ideal for commissioning large-scale machinery or accommodating tooling wear without cylinder replacement.
This ISO 6430 class tie-rod cylinder features a robust 50 mm diameter piston rod with an M42x2 thread and a PT 1 inch port. The integrated variable air cushion, with a 40 mm cushion length, decelerates high-inertia loads smoothly at the end of travel. The body length A for this SCJ model is 409 mm, providing a compact yet powerful solution for demanding industrial environments.
| Model | Airtac SCJ250 Standard Cylinder SCJ250X125-40 |
|---|---|
| Series | SCJ adjustable-stroke tie-rod cylinder (ISO 6430 class) |
| Bore size | Ø250 mm |
| Nominal stroke | 125 mm |
| Stroke adjustment | Up to 40 mm (rear adjusting screw) |
| Acting type | Double acting (single rod) |
| Port size | PT1" |
| Rod thread | M42×2 |
| Fluid | Air (filtered by 40µm element) |
|---|---|
| Operating pressure | 0.15 – 1.0 MPa |
| Proof pressure | 1.5 MPa |
| Temperature | -20 to +70 °C |
| Speed range | 30 – 500 mm/s |
| Cushion | Adjustable, 40 mm |
| Max stroke | Up to 1500 mm |
Specifications follow the official AirTAC SCJ (adjustable-stroke) datasheet. The rear adjusting screw sets the stroke end position; force is the same as the equivalent single-rod SC bore. Confirm against the product label before installation. Thread options: PT (standard) / G.
| Pressure | Push force | Pull force |
|---|---|---|
| 0.5 MPa | 24544 N | 23562 N |
| 0.7 MPa | 34361 N | — |
| Max (@1.0 MPa) | 5006 kgf | |
SCJ is single-rod, so force matches the equivalent SC bore: push uses the full bore area, pull subtracts the rod area. Actual usable force is lower than theoretical due to friction and back-pressure; size with a safety margin.
| SCJ | Adjustable-stroke tie-rod cylinder series. |
|---|---|
| 250 | Bore size in mm. |
| ×125 | Nominal (maximum) stroke length in mm. |
| -40 | Adjustable-stroke range in mm (options 10/20/30/40/50/75/100). |
| -S | Optional built-in magnet for sensor position sensing. |
Related types: SC (single rod, fixed stroke), SCD (double rod), SCT (multi-position). SCJ mounting: Basic, FA, LB, TC, TCM1. Seals: TPU standard / H = Viton / N = NBR. Thread: blank = PT, G = G thread.
Adjust the stroke end by up to 40 mm to set precise daylight openings or bottom-dead-center positions on large forming presses, compensating for different die heights or material springback during setup.
Fine-tune the opening of a discharge gate on a large silo or hopper, controlling material flow rate by adjusting the cylinder's stroke end to set a specific gate angle without changing the actuator.
Dial in the exact end position for a pivoting arm or lift mechanism during initial machine commissioning, allowing engineers to quickly correct for minor fabrication tolerances in the surrounding structure.
Select the SCJ250 when your application requires the immense force of a 250 mm bore but also needs the flexibility to adjust the stroke end by up to 40 mm on the machine. If your force calculation falls between bore sizes, stepping down to a 200 mm bore provides 15708 N of push force at 0.5 MPa, while this 250 mm bore offers a significant power increase. For applications where the stroke is fixed and never needs adjustment, the standard SC250 fixed-stroke cylinder is a more economical choice.
This model is a direct replacement for an existing AirTAC SCJ250X125-40 cylinder with a PT port, basic mounting, and no magnet. For strokes of 300 mm or longer, always evaluate the side-load on the 50 mm rod; an external guide rail or a switch to a guided cylinder is required to prevent rod bending and premature seal failure.
Adjustable-stroke checklist
The push force is calculated using the full 250 mm bore area. At 0.5 MPa, it's 24544 N; at 0.7 MPa, it's 34361 N; and at the max operating pressure of0.9 MPa, it reaches 44178 N. The pull force is lower due to the 50 mm rod area, providing 23562 N at0.5 MPa.
The rear adjusting screw mechanically limits how far the piston can extend, allowing you to shorten the nominal 125 mm stroke by up to 40 mm. It is a stroke-end position limiter, not a locking device. The piston will drift if air pressure is lost. To hold a load without pressure, you must add an external rod brake or a pilot-operated check valve.
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