Cylinders & actuators

How to Measure a Pneumatic Cylinder for Replacement

A cartoner may use several similar-looking cylinders to push cartons, stop product or move a guide. Start with the machine station and the full cylinder model. Those details help a supplier tell two cylinders apart when the bodies look alike.

Where to measure

Reference drawings. Verify dimensions on your part or the manufacturer’s drawing.

Retracted and extended lengths

Measure from the same rear mounting center to the rod-end mounting center. Subtract retracted length from extended length to find stroke.

Cylinder bore and rod diameter

Bore is the inside diameter of the barrel. Use the model code or manufacturer drawing to confirm it. Rod diameter is measured across the smooth rod.

Cartons passing through a packaging machine with a pneumatic cylinder

Record the cylinder and its job

Capture the manufacturer, model and suffix from the label. Add the machine make and model, where the cylinder sits, and whether it pushes, clamps or stops a carton. If the label is unreadable, check the machine parts list or a previous purchase record.

Measure stroke and mounting dimensions

Stroke is the difference between fully extended and fully retracted lengths measured from the same reference points. Use the manufacturer drawing or a loose, depressurized cylinder. Take the bore from the model code or drawing because it refers to the internal diameter. Measure the rod end, mounting hole centers and retracted length, then record port thread, port orientation and any switches or cushioning.

List what the replacement needs to include

Specify whether the order is for the cylinder alone or also includes the clevis, mounting brackets, switches and fittings. If the original model has been superseded, ask for a dimensional drawing so your maintenance team can verify fit before ordering.

Manufacturer reference: SMC ISO cylinder catalog