Airtac MKJ Adjustable Cylinder MKJ20X40-20S

The MKJ20X40-20S is an AirTAC multi-mount cylinder, a compact square-body actuator that fixes from 6 directions (front, back, left, right, top and bottom) so it can be bolted wherever the machine layout needs it, and mounted side by side with neighbours to save space. This is the adjustable-stroke variant: double acting, 20 mm bore and 40 mm stroke, with an additional 20 mm of adjustable stroke on top of the base stroke. At 0.5 MPa the bore delivers a theoretical push thrust of about 157.1 N, enough for clamping, positioning and stopping duties on light fixtures. Cushioning is a bumper, which absorbs end-of-stroke impact without the plumbing of an air cushion.

This is a genuine AirTAC part. The MK family is the no-rotating series: a fixed rod and plate stop the piston rod from turning, which matters when the load must stay square to the mount. The trailing S in this code means the cylinder is supplied with a magnet, so magnetic-switch sensing is available as the SKU shows; the non-S version carries no magnet. Dimensions and sizing are per stroke, so contact us and we will confirm them from the datasheet on request.

Start with the bore: 20 mm gives about 157.1 N theoretical push thrust at 0.5 MPa (the pull side is lower), so size it against the force your clamp or stopper needs. Choose MK rather than MD when the rod must not rotate, since MK adds a no-rotating plate, brass bushing and fixed rod; MD is the standard series where some rotation is acceptable. The MKJ adjustable-stroke design adds a 10, 20 or 30 mm adjustable range on top of the base stroke, so you can fine-tune the effective stroke at setup. This unit is double acting with the magnet (trailing S) and a PT thread; drop the S if you do not need switch sensing, and a G thread is available. Keep the stroke inside the bore's table (up to 60 mm for bore 20) and remember the compact cover: an over-long stroke is a common mis-selection. Side-load allowances are not quoted here, so route them to us.