What are rodless cylinders and how do they work?
Rodless actuators, commonly referred to as rodless cylinders, are linear pneumatic actuators designed to provide smooth, guided and precise linear motion without a protruding piston rod. Instead of a conventional rod, a guided carriage travels along the actuator body driven by compressed air through an internal piston mechanism. This configuration allows longer travel distances in compact installations, reducing space and simplifying machine layout.
The pneumatic operation combines a sealed piston with integrated linear guides that maintain precision and withstand lateral loads. Depending on the series, motion is transferred from the piston to the external carriage via magnetic or mechanical coupling, enabling direct attachment of workpieces or tooling.
What types of rodless cylinders does SMC offer?
SMC provides two main types of rodless pneumatic actuators, each designed for specific operating principles and application requirements:
Mechanically jointed rodless cylinder
Mechanically coupled cylinders use a physical connection between the internal piston and the external carriage through a slotted cylinder body. This design provides direct force transmission and is suited for applications requiring high load capacity and robust performance.
Magnetically coupled rodless cylinder
Magnetically coupled cylinders operate with a fully sealed cylinder tube. Motion is transmitted to the external slider via strong magnetic force — with no mechanical contact between the internal piston and the outer carriage. This creates a clean, low-maintenance rodless pneumatic cylinder ideal for sensitive production environments.
Benefits of SMC’s rodless actuators
SMC rodless cylinders are designed to support reliable motion control in automated systems. Key benefits include:
- Compactness: Designed to deliver long stroke lengths within a minimal footprint, enabling installation in space-constrained or low-profile machine layouts
- High precision: Integrated guide mechanisms ensure precise carriage movement and reliable handling of lateral and overhung loads without external guidance systems
- Flexible configuration: Choice of bore size, stroke, cushion type, stroke adjustment unit, auto switch type and piping direction allows precise matching to the application — standard and made-to-order specifications available.
Typical applications for rodless actuators
Rodless air cylinders, originally developed for areas where space is restricted, can be used in a wide range of applications, for example: for transferring, moving or positioning components or work pieces, in long stroke applications, assembly automation, packaging and electronics, among others.
How to select the right rodless cylinder
Selecting the right rodless air cylinder depends on several key application parameters. Engineers should first define load mass, stroke length, operating speed, mounting orientation and required positioning accuracy. Particular attention should be paid to allowable moment loads and guide load factors, which are determined by the load position and centre of gravity relative to the carriage. In SMC selection procedures, the sum of load-related factors (mass, static moment and dynamic moment) should remain within allowable limits to ensure reliable operation and service life.
Operating pressure, ambient conditions and required cushioning or shock absorption should also be considered during model selection. SMC provides https://www.smc.eu/en-gb/products/engineering-tools/cylinder_configurator/cylinder_configurator_online and detailed catalogue data to help calculate load ratios, piston speed and moment capacity to confirm the most suitable rodless actuator for an application.
Frequently asked questions about rodless cylinders
What is the advantage of a rodless cylinder compared to a standard cylinder?
Rodless pneumatic cylinders allow the stroke to be contained within the overall actuator length, making them ideal for long-stroke applications in limited installation space. They also enable direct load mounting on a carriage, often eliminating the need for external guide systems.
What is the difference between a mechanically jointed and a magnetically coupled rodless cylinder?
Mechanically coupled rodless cylinders (such as the SMC MY3 series) use a physical connection between the internal piston and the external slide table through a slotted body, offering high load capacity and direct force transmission. Magnetically coupled rodless cylinders (CY3B, CY3R) use magnetic force through a fully sealed cylinder tube with no mechanical contact between internal and external components, providing a cleaner, lower-maintenance solution.
Both types are widely used depending on load requirements and environmental conditions.
Can rodless cylinders be used in vertical or inclined orientations?
Yes. SMC rodless cylinders support horizontal, inclined and vertical mounting. For vertical operation, both allowable load mass (Wv) and maximum operating pressure (Pv) must be observed. For magnetically coupled series, intermediate stops in vertical orientation must use an external stopper rather than an air pressure circuit.
What bore sizes are available?
SMC rodless cylinders are available in bore sizes Ø6 to Ø63 mm. The mechanically jointed MY3 series covers Ø16 to Ø63 mm; the magnetically coupled CY3B and CY3R series extend coverage down to Ø6 mm for lighter-duty applications.
What stroke lengths are available for SMC rodless cylinders?
Stroke length depends on the series and bore size. For example, mechanically coupled MY3 rodless cylinders are available with strokes up to 3000 mm, while some guided series such as MY2 variants can reach up to 5000 mm in long-stroke configurations.
Rodless cylinders are therefore well suited for long-travel positioning and transfer applications.
Are auto switches available for position detection?
Yes. Many SMC rodless cylinder series support auto switches mounted along the cylinder body for position detection, often with flexible mounting positions.
