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Welcome to this installment of MC² on Linear Bearings & Linear Splines!

Recall that these linear-motion supports take the form of guide rails, slides, and ways … and include profile rails, linear bearings, guide wheels, slides, and plain-bearing systems that bear load while employing either sliding or rolling to allow translational motion. Typical designs pair rail or shaft with mating carriages or runner blocks.

You’ll find some resources on linear guides and slides to help design engineers choose from the vast array of these linear systems … and satisfy requirements for loading, stroke, speed, accuracy, and design life.

Also check out our library on preloading considerations and market-specific topics … including machine-tool applications and semiconductor manufacturing (where rolling linear guides abound); advanced medical applications (where square rails are common); and simpler machine axes (where forgiving slide designs maintain build ruggedness).

Lisa Eitel

Senior Editor, Design World

Linear Systems MC Classroom is Sponsored by:


Specify • Trends • Measure • Performance

Specifying and sizing linear rails for motion systems

Why use integrated position measuring with linear guides?

What are the differences between plain and rolling linear guides?

Trends: Consumer health-monitoring devices

The best approach to specifying and sizing linear rails is to define the most critical parameters of the application first.

Linear guides provide accurate, high-capacity travel for a wide variety of machine types and processes.

While their general function is the same, their design and performance differ significantly.

Growth of consumer health-monitoring devices is prompting new uses of linear-motion designs.

Linear Motion Video

Learn how to apply the most important equations for sizing, selecting, and comparing linear bearings.

Round shaft or profiled rail? How to choose

Choosing the wrong linear motion system can be a costly mistake, resulting in design or structural changes, poor machine performance, or oversized components with higher costs.

Design World’s MC² video on linear guide and slide systems

Welcome to this installment of Design World’s MC² (motion control classroom) on linear guide and slide systems. Linear-motion systems work in all kinds of applications, from industrial drawers to Cartesian robots

Common applications for linear rails

Linear rails are the backbone of many industrial applications, providing low-friction guidance and high stiffness for loads that can range from just a few grams to thousands of kilograms.

Their range of sizes, accuracy classes, and preloads make linear rails suitable for virtually any performance requirement.


Technical Focus • Tips • Linear Bushings • Geometry

Technical summary: What is linear motion design engineering?

Tips for selecting and applying telescoping linear bearings

How raceway geometry affects profiled rail guide performance

How do self-aligning linear bushings work?

Technologies including linear motors, linear actuators, and linear rolling guides.

Profiled rail bearings are ideal for applications that require long stroke lengths in a fixed footprint.

The two most common raceway geometries are referred to as circular arc and Gothic arch

Linear bushings ride on a hardened, round shaft to provide linear guidance with low friction.

Feature Resource:

Demystifying the 2:1 Ratio andthe Stick-Slip Phenomenon

A Technical Whitepaper Explaining the Theory Behind the Binding Ratio and How it Relates to Stick-Slip.

By the end of the 1980s, PBC Linear had invented and begun commercially producing the first plain bearings which were size-interchangeable with linear ball bearings. This prompted PBC Linear to define the 2:1 Ratio rule, which was first introduced to the marketplace in the 1990s. Since then, the rule has been adapted by most linear plain bearing manufacturers as one of the guiding principles regarding plain bearing use.

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