The AirTAC Airtac SCJ40 Standard Cylinder SCJ40X125-50 is a genuine double-acting SINGLE-ROD air cylinder with a rear-cap ADJUSTING SCREW: the stroke end is field-adjustable within a 50 mm range without swapping the cylinder. Ø40mm bore, 125mm nominal stroke, PT1/4 ports and adjustable end cushioning.
The SCJ40X125-50 is a double-acting, single-rod pneumatic cylinder with a rear-cap adjusting screw that provides 50 mm of field-adjustable stroke reduction. Operating at 0.5 MPa, it delivers 628 N of push force and 528 N of pull force, making it a practical choice for applications where the end-stop position must be dialled in during commissioning or changed between product runs.
With a 16 mm diameter piston rod and a 21 mm air cushion at each end, this cylinder decelerates the load smoothly without external shock absorbers. The body length (A dimension) is 185 mm for the SCJ series, and the PT1/4 port supplies ample flow for speeds up to 800 mm/s. The 125 mm nominal stroke is well within the 1200 mm maximum standard stroke for the 40 mm bore.
| Model | Airtac SCJ40 Standard Cylinder SCJ40X125-50 |
|---|---|
| Series | SCJ adjustable-stroke tie-rod cylinder |
| Bore size | Ø40 mm |
| Nominal stroke | 125 mm |
| Stroke adjustment | Up to 50 mm (rear adjusting screw) |
| Acting type | Double acting (single rod) |
| Port size | PT1/4 |
| Rod thread | M12×1.25 |
| 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 – 800 mm/s |
| Cushion | Adjustable, 21 mm |
| Max stroke | Up to 1200 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 | 628 N | 528 N |
| 0.7 MPa | 880 N | — |
| Max (@1.0 MPa) | 128 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. |
|---|---|
| 40 | Bore size in mm. |
| ×125 | Nominal (maximum) stroke length in mm. |
| -50 | 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.
The 50 mm adjustment range allows technicians to fine-tune the actuator's end-stop on a new assembly line without swapping cylinders or machining custom stops, speeding up machine qualification.
On a packaging line, the stroke can be quickly shortened to accommodate a different box size. The rear screw adjusts the retract position, ensuring the pusher plate contacts each variant correctly.
In a clamping or pressing fixture, the adjustable stroke can be extended slightly over time to compensate for jaw or pad wear, maintaining consistent clamping force without reprogramming a servo.
Step up to the SCJ50 bore for a push force increase to 982 N at 0.5 MPa if the 628 N output of this SCJ40X125-50 is marginal. For applications that do not require stroke-end adjustment, the fixed-stroke SC40X125 is a simpler, lower-cost alternative. This SCJ model is a direct dimensional replacement for another AirTAC SCJ40X125-50 with PT ports and basic mounting.
At a 125 mm stroke, rod deflection under side load is generally not a concern for a 16 mm rod in typical pneumatic applications, but ensure the load is guided and aligned axially to maximize seal life. If the application involves a pivoting movement, consider the TC centre trunnion mounting option.
Adjustable-stroke checklist
At the standard 0.5 MPa operating pressure, it generates 628 N of push force and 528 N of pull force. The maximum push force at 0.9 MPa is 1130 N. The force is identical to a fixed-stroke SC40 cylinder.
Only if you need the adjustable stroke feature. The SCJ body is slightly longer to house the adjusting screw. For a direct fixed-stroke replacement, use the SC40X125. The SCJ40X125-50 replaces another AirTAC SCJ of the same bore, stroke, and 50 mm adjustment range.
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