The anatomy of a linear guide carriage

2024-04-18

In a linear guide with four ball tracks arranged in an O-configuration, the load capacity is generally the same in all four directions. That means it doesn’t matter if you’re pushing, pulling, or applying a lateral force—the guide handles it equally well.

Why? Because internally, the setup is symmetrical, with the ball tracks spaced 90 degrees apart. So, for example, if you're pushing down on the carriage, it's the bottom two ball tracks that carry the load. If you're pulling upwards, it's the top two that kick in.

This basic construction applies to both ball and roller guides. The reason roller guides can handle more load than ball guides is because the contact area between the rolling elements and the raceways is larger. However, rollers are stiffer and flex less, which means they also demand more from the system they’re installed in.

If you lose a ball from a ball-type guide, it will still function (though with reduced capacity). But if you’re missing a roller in a roller guide, things can go south fast—the rollers can misalign and jam the entire carriage.

Some ball carriages from certain brands can be disassembled and reinstalled onto the rail without the balls falling out. That’s much trickier with rollers, simply because their shape makes them harder to secure in place.

As a general rule of thumb:

• Ball-type linear guides are common in handling systems and lighter production equipment.
• Roller guides are preferred for heavy-duty machinery like metal-cutting equipment.
But as always—it depends on your application.

Here’s a video on the topic with Carry Lindholm from Bosch Rexroth: