Airtac SCJ40 Standard Cylinder SCJ40X25-20STC
The AirTAC Airtac SCJ40 Standard Cylinder SCJ40X25-20STC 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. Ø40mm bore, 25mm nominal stroke, PT1/4 ports and adjustable end cushioning.
- BoreØ40 mm
- Nominal stroke25 mm
- Stroke adjust-20 mm
- Port sizePT1/4
- Rod threadM12×1.25
- CushionAdjustable, 21 mm
About the Airtac SCJ40 Standard Cylinder SCJ40X25-20STC
The SCJ40X25-20STC is a double-acting, single-rod pneumatic cylinder with a field-adjustable stroke end, letting you fine-tune the final position by up to 20 mm without swapping the unit. Its 40 mm bore delivers 628 N of push force at 0.5 MPa, making it a compact workhorse for light clamping, stopping, and ejection tasks where the end-stop needs dialling in during commissioning.
This model includes a built-in magnet (S) for barrel-mounted sensors and a centre trunnion pivot (TC) with the TCM1 bracket, so the cylinder can swing as the rod extends. The 16 mm diameter rod and PT1/4 ports keep flow rates high, while the 21 mm air cushion quietly decelerates the piston. The body length A(SCJ) is 185 mm, slightly longer than a fixed-stroke SC of the same bore to house the rear adjusting screw.
Airtac SCJ40 Standard Cylinder SCJ40X25-20STC Technical Specifications
| Model | Airtac SCJ40 Standard Cylinder SCJ40X25-20STC |
|---|---|
| Series | SCJ adjustable-stroke tie-rod cylinder |
| Bore size | Ø40 mm |
| Nominal stroke | 25 mm |
| Stroke adjustment | Up to 20 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.
Theoretical Output Force (Ø40mm)
| 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.
Model Code: Airtac SCJ40 Standard Cylinder SCJ40X25-20STC
| SCJ | Adjustable-stroke tie-rod cylinder series. |
|---|---|
| 40 | Bore size in mm. |
| ×25 | 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.
Where the Airtac SCJ40 Standard Cylinder SCJ40X25-20STC Is Used
Commissioning & Fine-Tuning
The 20 mm rear adjustment screw lets technicians dial in the exact stroke end on a new machine without fabricating shims or hard stops, speeding up factory acceptance tests.
Product Stopper Gates
Ideal for a mini conveyor gate where the stopping position must be tweaked for different box heights. The centre trunnion mount allows the body to pivot, reducing rod side-load.
Small-Part Ejector
The adjustable stroke lets you set a precise, repeatable push-off distance for ejecting plastic components from a mould, with the magnet confirming full retraction via a CMSG sensor.
Is the Airtac SCJ40 Standard Cylinder SCJ40X25-20STC the Right Cylinder?
Choose the SCJ40 bore when 628 N of push at 0.5 MPa covers your load; if you need more force, step up to the 50 mm bore (982 N push). If your application never requires stroke adjustment, a simpler fixed-stroke SC40 will reduce cost and overall length. This SCJ40X25-20STC is a direct replacement for any AirTAC SCJ40 with a 25 mm nominal stroke, 20 mm adjust range, PT ports, centre trunnion mounting, and a magnet.
Adjustable-stroke checklist
- ✓ Need to fine-tune stroke on the line?
- ✓ Nominal stroke + adjust range (-20)
- ✓ Required force at your working pressure
- ✓ Port/thread type (PT/NPT/G)
- ✓ Magnet (-S) for sensors?
Installation & Maintenance Notes
- check Use clean air filtered to 40µm or finer.
- check Keep within 0.15 – 1.0 MPa operating pressure.
- check Set the rear adjusting screw, then lock it before running.
- check Adjust end cushion screws for smooth stops.
- check Use SCJ mounting accessory (FA / LB / TC / TCM1).
- check Installation by qualified personnel per AirTAC docs.
Airtac SCJ40 Standard Cylinder SCJ40X25-20STC FAQ
At the standard 0.5 MPa operating pressure, the push force is 628 N and the pull force is 528 N. The pull force is lower because the 16 mm piston rod reduces the effective piston area on the return stroke.
Yes, if you need the 20 mm stroke-end adjustability. The SCJ40 has the same mounting footprint and port size (PT1/4) as the SC40, but the body is slightly longer (185 mm) to accommodate the rear screw. Ensure your machine has clearance for the extra length.
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