The AirTAC Airtac SCJ250 Standard Cylinder SCJ250X400-75 is a genuine double-acting SINGLE-ROD air cylinder with a rear-cap ADJUSTING SCREW: the stroke end is field-adjustable within a 75 mm range without swapping the cylinder. Ø250mm bore, 400mm nominal stroke, PT1" ports and adjustable end cushioning.
The SCJ250X400-75 is a double-acting, single-rod pneumatic cylinder from the AirTAC SCJ adjustable-stroke family, designed for heavy-duty applications where the stroke end position must be fine-tuned on the machine. Its rear-cap adjusting screw provides a 75 mm range to shorten the nominal 400 mm stroke, allowing commissioning engineers to dial in the exact end-stop without swapping the cylinder or adding external hard stops. With a 50 mm diameter piston rod and a 1-inch PT port, this big-bore actuator delivers substantial force for pressing, clamping, and material handling tasks.
Operating on filtered air from 0.15 to 1.0 MPa, this ISO 6430 class cylinder generates a powerful 24544 N of push force at just 0.5 MPa, rising to 44178 N at the maximum operating pressure of 0.9 MPa. The pull force is slightly lower at 23562 N at 0.5 MPa due to the single-rod design. The body length A(SCJ) is 409 mm, and it features a 40 mm adjustable air cushion to decelerate the piston smoothly at the end of its travel. The standard operating speed for this bore class is 30-500 mm/s, and the temperature range is -20 to +70 °C with the default TPU seals.
| Model | Airtac SCJ250 Standard Cylinder SCJ250X400-75 |
|---|---|
| Series | SCJ adjustable-stroke tie-rod cylinder (ISO 6430 class) |
| Bore size | Ø250 mm |
| Nominal stroke | 400 mm |
| Stroke adjustment | Up to 75 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. |
| ×400 | Nominal (maximum) stroke length in mm. |
| -75 | 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.
Fine-tune the pressing depth on a large hydraulic-style pneumatic press during initial setup. The 75 mm adjustment range allows operators to compensate for tooling tolerances and material spring-back without disassembling the machine.
Actuate a heavy-duty log stop on a conveyor line. The adjustable stroke end lets operators quickly change the stop position for different log diameters, with the 24544 N push force easily holding the timber in place at 0.5 MPa.
Clamp large sand molds in an automated foundry line. The stroke can be precisely dialed in to accommodate mold wear over thousands of cycles, maintaining consistent clamping force without over-compressing the mold halves.
This 250 mm bore model is the largest in the SCJ range, suitable for applications requiring extreme force. If your load calculation falls closer to the 15708 N push force of the SCJ200 bore at 0.5 MPa, stepping down to a 200 mm bore will reduce air consumption and physical size without sacrificing performance. For applications needing a fixed, non-adjustable stroke, the standard SC250 series offers a simpler, more compact solution. When replacing an existing unit, ensure a direct match: an AirTAC SCJ adjustable-stroke cylinder with a 250 mm bore, 400 mm nominal stroke, and a 75 mm adjustment range, using PT port threads.
Given the substantial 400 mm stroke, careful attention must be paid to side-loading and rod buckling. The 50 mm rod provides significant rigidity, but for applications with a non-axial load, an external guide rail or a switch to a guided cylinder is strongly recommended to prevent premature seal wear and rod damage. This cylinder accepts the SCJ mounting subset: basic foot (LB), front flange (FA), or centre trunnion (TC with TCM1 bracket).
Adjustable-stroke checklist
At the standard operating pressure of 0.5 MPa, this cylinder provides 24544 N of push force and 23562 N of pull force. The push force is higher because pressure acts on the full bore area, while on the return stroke, the 50 mm rod reduces the effective piston area. At the maximum 0.9 MPa operating pressure, the push force reaches 44178 N.
The rear cap has an integrated adjusting screw that limits the piston's retraction, effectively shortening the stroke end by up to 75 mm from the nominal 400 mm. It is not a speed or force controller. You can replace a fixed-stroke SC cylinder with this SCJ model if you need field adjustability, but you must match the 250 mm bore, PT port thread, and ensure the SCJ's longer body length (409 mm) fits your mounting space.
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