Rodless Cylinders

How to choose a rodless cylinder

The first decision is how the piston drives the carriage. Magnetic coupling keeps the cylinder tube completely sealed; a mechanical joint gives a rigid connection that handles more load. The comparison below uses SMC's published figures as a general guide. Always confirm allowable load and moment for your bore size in the SMC series catalog.

Choosing a guide type

Once you know the coupling type, the guide determines how much load, moment, and accuracy the carriage can handle. Moving from left to right in each row below generally increases load capacity and precision.

An unguided cylinder (CY3B or MY1B) is the right choice when the load rides on its own external guide. Use an integrated guide when the carriage itself must carry the load or resist moment.

Options that affect your part number

Stroke adjusting units. MY1B cylinders can be ordered with adjustment bolts and low load or high load shock absorbers at one or both ends to fine-tune end position and absorb kinetic energy. The adjuster code appears after the stroke in the part number (for example, the L in MY1B20-100L).

Auto switches. Both CY and MY series accept SMC auto switches for end-of-stroke and position sensing. On CY3R, choose the version with a switch rail if you plan to add switches.

Clean room versions. SMC offers magnetically coupled clean room series, including 12-CY3B and CYP, for applications where particle generation matters.

Piping. Several series offer standard or centralized piping, which lets you route both air lines to one end of the cylinder.

Rodless cylinder FAQ

What is the difference between a magnetically coupled and a mechanically jointed rodless cylinder?

A magnetically coupled rodless cylinder moves its carriage with magnets through a fully sealed tube, so it has no external leakage but is limited by its magnetic holding force. A mechanically jointed rodless cylinder connects the piston to the carriage through a sealed slot, which supports higher loads and moments and cannot decouple. In SMC's lineup, CY series cylinders are magnetically coupled and MY series cylinders are mechanically jointed.

When should I use a rodless cylinder instead of a rod-type cylinder?

Use a rodless cylinder when you need a long stroke in limited space, since a rod cylinder needs room for the rod to extend and a rodless cylinder does not. Rodless cylinders also carry the load directly on the carriage, and guided versions resist moment without an external guide. Rod cylinders remain simpler and lower cost for short strokes and push or pull applications.

What happens if a magnetically coupled cylinder is overloaded?

If the load, impact, or speed exceeds the magnetic holding force, the external carriage can separate from the internal piston. The carriage can usually be re-coupled by moving it back over the piston position, but repeated decoupling means the application needs a larger bore or a mechanically jointed cylinder. Check SMC's allowable load and holding force data for your bore size before selecting.

Which SMC rodless cylinder handles the heaviest loads?

Within SMC's rodless lineup, mechanically jointed cylinders with linear guides, MY1H and the high rigidity MY1HT, are designed for the highest loads and moments. MY1B is also available up to a 100 mm bore for applications where the load is carried on an external guide. Final selection depends on load mass, moment, speed, and mounting orientation.

Can rodless cylinders be mounted vertically?

Yes, many SMC rodless cylinders can be mounted horizontally, inclined, or vertically, but allowable load is usually lower in vertical mounting. For magnetically coupled cylinders, the load must stay well within the magnetic holding force so the carriage does not decouple. Confirm vertical load limits in the SMC catalog for the specific series and bore.