The AirTAC Airtac SCJ250 Standard Cylinder SCJ250X125-20S 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, 125mm nominal stroke, PT1" ports and adjustable end cushioning.
The SCJ250X125-20S is a heavy-duty double-acting single-rod pneumatic cylinder from the AirTAC SCJ adjustable-stroke family. With a 250 mm bore and a 50 mm rod, it delivers a substantial 24544 N of push force at just 0.5 MPa, making it ideal for large-scale pressing, clamping, and material handling applications where force demand is high. This model features a 20 mm rear-cap adjusting screw, allowing operators to fine-tune the stroke end position in the field without dismounting the cylinder.
A built-in magnet (denoted by the -S suffix) is integrated into the piston, enabling direct mounting of CMSG/DMSG/EMSG reed or solid-state sensors along the tie-rod barrel for precise end-of-stroke position feedback. The cylinder body length A(SCJ) is 409 mm, and it uses a PT1 inch port with an M42x2 rod thread. As an ISO 6430 class tie-rod cylinder, it is designed for robust industrial use with a 40 mm air cushion to decelerate the piston smoothly.
| Model | Airtac SCJ250 Standard Cylinder SCJ250X125-20S |
|---|---|
| Series | SCJ adjustable-stroke tie-rod cylinder (ISO 6430 class) |
| Bore size | Ø250 mm |
| Nominal stroke | 125 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. |
| ×125 | 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.
Provides up to 44178 N of force at 0.9 MPa for secure workpiece holding in large CNC machining fixtures, with the 20 mm adjustment enabling fine pressure control on different part thicknesses.
The adjustable stroke end allows operators to dial in the exact stopping position for heavy pallets on a conveyor line, accommodating different pallet sizes without changing the actuator.
During press setup, the 20 mm stroke adjustment screw is used to precisely set the final pressing depth, compensating for tool wear or material spring-back over long production runs.
Select this SCJ250 model when your application requires the highest force output in the SCJ range, with 24544 N push at 0.5 MPa. If your force requirement is lower, stepping down to the 200 mm bore reduces push force to 15708 N, saving space and air consumption. For applications needing a fixed, non-adjustable stroke, the standard SC250 cylinder provides the same force in a slightly more compact body. This model is a direct replacement for any AirTAC SCJ250X125-20S cylinder with PT ports, a basic mount, and a magnet. For this 125 mm stroke, side-loading is typically not a primary concern, but always ensure the load is guided externally if any radial force is present to prevent premature rod bearing wear.
Adjustable-stroke checklist
At the standard 0.5 MPa operating pressure, the push force is 24544 N and the pull force is 23562 N. The maximum push force at the 0.9 MPa operating limit is 44178 N. The pull force is lower because the 50 mm piston rod reduces the effective piston area on the return stroke.
The rear-cap adjusting screw limits the piston's forward stroke end by up to 20 mm. It is a mechanical stop for stroke tuning, not a locking device. The cylinder will not hold its position if air pressure is lost; an external rod lock or pilot-operated check valve is required for load holding without live pressure.
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