The AirTAC Airtac SCJ250 Standard Cylinder SCJ250X125-75S 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, 125mm nominal stroke, PT1" ports and adjustable end cushioning.
The SCJ250X125-75S is a double-acting, single-rod pneumatic cylinder from AirTAC's adjustable-stroke SCJ series, designed for heavy-duty applications requiring fine-tuning of the piston's end position. With a 250 mm bore and a 50 mm diameter rod, it delivers a substantial 24544 N of push force at 0.5 MPa, making it suitable for pressing, clamping, and lifting large assemblies. The rear-cap adjusting screw provides a generous 75 mm of stroke-end reduction, allowing operators to dial in the precise stopping point without dismounting the cylinder or adding external hard stops.
This model features a built-in magnet (suffix -S), enabling direct mounting of CMSG/DMSG/EMSG reed or solid-state sensors along the tie-rod barrel for reliable end-of-stroke or mid-stroke position feedback. Operating on filtered air from 0.15 to 1.0 MPa, the cylinder includes an adjustable air cushion (40 mm length) to decelerate the massive piston smoothly, protecting the end caps from impact. The body length A(SCJ) is 409 mm, and the standard PT 1 inch port ensures high flow for rapid cycling of this ISO 6430 class cylinder.
| Model | Airtac SCJ250 Standard Cylinder SCJ250X125-75S |
|---|---|
| Series | SCJ adjustable-stroke tie-rod cylinder (ISO 6430 class) |
| Bore size | Ø250 mm |
| Nominal stroke | 125 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. |
| ×125 | 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 final pressing depth on a 250-bore platen press during setup. The 75 mm adjustment screw lets commissioning engineers quickly find the optimal stroke end for consistent part forming without reprogramming the machine controller.
Adjust the retract stop of a log-cutting saw carriage to match different timber diameters. The on-the-fly adjustability reduces changeover time between batches, while the built-in magnet provides a clean signal for the next feed cycle.
Compensate for the gradual wear of friction pads on a large structural welding fixture. Over time, the 75 mm adjustment range allows operators to extend the clamp's stroke end, maintaining full clamping force without replacing the pads immediately.
Select the SCJ250X125-75S when your application demands a very high force output combined with a field-adjustable stroke end. If 24544 N of push force at 0.5 MPa exceeds your requirement, consider stepping down to the 200 mm bore SCJ series, which provides 15708 N of push force. For applications needing a fixed, non-adjustable stroke, the standard SC series offers a simpler, more rigid solution. A critical consideration for this 125 mm stroke is side-loading; the 50 mm rod is robust, but any significant lateral force can cause premature rod bearing and seal wear. Always use an external guide rail or a guided cylinder to absorb side loads and ensure the rod moves in a pure linear path. This SCJ cylinder is a direct replacement for another AirTAC SCJ250 with a 125 mm nominal stroke, 75 mm adjustment range, PT port, and magnet, using the same basic mounting footprint.
Adjustable-stroke checklist
At 0.7 MPa operating pressure, the theoretical push force is 34361 N, and the pull force is 23562 N. The pull force is lower due to the area of the 50 mm piston rod. These forces are identical to the fixed-stroke SC250 cylinder.
No, the rear adjusting screw is designed only to shorten the full-extend stroke end by up to 75 mm. It creates a new, single fixed end position. For applications needing multiple intermediate stops, consider an SCT multi-position cylinder or a servo-pneumatic positioning system.
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