The AirTAC Airtac SCJ250 Standard Cylinder SCJ250X400-20 is a genuine double-acting SINGLE-ROD air cylinder with a rear-cap ADJUSTING SCREW: the stroke end is field-adjustable within a 20 mm range without swapping the cylinder. Ø250mm bore, 400mm nominal stroke, PT1" ports and adjustable end cushioning.
The SCJ250X400-20 is a double-acting, single-rod pneumatic cylinder with a field-adjustable stroke, built around a robust 250 mm bore tie-rod body. Its rear-cap adjusting screw provides up to 20 mm of stroke-end reduction, letting commissioning engineers fine-tune the piston's end position without replacing the cylinder or adding external hard stops. With a 50 mm diameter piston rod and a 1-inch PT port, this model delivers a substantial 24544 N of push force at 0.5 MPa, rising to 44178 N at the maximum operating pressure of 0.9 MPa.
This SCJ unit is an ISO 6430 class cylinder, designed for heavy-duty industrial applications where the stroke length needs precise on-machine adjustment. The 400 mm nominal stroke is well within the bore's 1500 mm maximum standard stroke. It features an adjustable air cushion for controlled deceleration and operates on filtered air from 0.15 to 1.0 MPa. The standard configuration includes a TPU seal for a temperature range of -20 to +70 °C and PT threads.
| Model | Airtac SCJ250 Standard Cylinder SCJ250X400-20 |
|---|---|
| Series | SCJ adjustable-stroke tie-rod cylinder (ISO 6430 class) |
| Bore size | Ø250 mm |
| Nominal stroke | 400 mm |
| Stroke adjustment | Up to 20 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. |
| -20 | 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 final pressing depth in a large hydraulic-style pneumatic press. The 20 mm adjustment screw allows operators to compensate for tooling wear or material thickness variations without disassembling the press, maintaining consistent product quality.
Control a diverter gate on a conveyor for oversized pallets or bulk materials. The adjustable stroke lets you set the exact gate opening angle during commissioning to match different product widths, preventing jams and ensuring smooth flow.
Position a heavy guide roller in a steel processing line. The SCJ250's adjustable stroke end is critical for aligning the roller's contact point with the strip centerline, a setup that can be quickly recalibrated for different coil widths.
Select the SCJ250X400-20 when your application demands high force and the ability to dial in the stroke end position during setup or changeovers. If you need a higher force output, stepping up to a larger bore is not possible as this is the largest standard size, but you can increase operating pressure up to 1.0 MPa. For a lower force class, the SCJ200 bore provides 15708 N of push force at 0.5 MPa. If your application does not require stroke adjustability, a fixed-stroke SC250X400 cylinder is a direct alternative. For a direct replacement, match the 250 mm bore, 400 mm nominal stroke, 20 mm adjustable range, PT port thread, and basic mounting. For a stroke of 400 mm, ensure the rod is adequately supported against side loads; an external guide rail or a self-guided cylinder is recommended to prevent rod bending and premature seal wear.
Adjustable-stroke checklist
At 0.7 MPa operating pressure, the theoretical push force is 34361 N, and the pull force on the return stroke is 23562 N. The pull force is lower because the 50 mm piston rod reduces the effective area on the cap-end side of the piston.
Yes, the SCJ250X400-20 is a direct dimensional replacement for an SC250X400, provided the extra body length for the rear adjusting screw is accommodated. You must also match the port thread (PT), mounting style, and magnet option. The key benefit is gaining the 20 mm field-adjustable stroke range, which the fixed SC model does not offer.
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