Linear bearing: what is it and what is it used for

linear bearing

Not everything is electronic components, many projects also need knowledge about mechanical parts, such as robotics and other mechatronics applications. Therefore, it is also interesting to know about linear bearing. A key piece to make many applications possible and that has some peculiarities compared to other types of bearings, working well in precision systems or in transport systems where robustness is sought.

In this guide you will know all the details of this type of part, as well as its possible applications, advantages and disadvantages, the types that exist, and even where to buy these cheap parts.

What is linear bearing?

linear bearing

Un bearing or bearing It is a basic element of mechanics that helps reduce friction between the shaft and the parts connected to it. It can be found in a multitude of devices, from electrical appliances, to fans, through vehicles, etc.

Instead, if we refer to a linear bearing, is a specific type of bearing that is used for translational movements (instead of rotary). It is made up of a cage and rolling segments made of steel and balls made of the same material.

Linear Bearing Types

There are different types of linear bearings, each with its advantages over the others:

  • with balls: this type of linear bearing has low friction thanks to metal balls inside, and is the most common. The contact of the ball with the shaft is very small, which reduces friction, although they exert great pressure on the shaft, so it is recommended that they be used on hardened shafts. They are also quite durable, high load bearing, easily lubricated, low noise, inexpensive, and perform well. In turn they can be:
    • Open: Feature a small opening and are used in applications where multiple shaft supports and full shaft support are needed to prevent flexing.
    • Closed: they are closed, forming the complete circumference, thus completely embracing the axis.
    • Linear guides: They are a subtype of linear ball bearing, but they run on a profiled rail, so the bearings are in the shape of an arc, with an opening.
  • Of rollers: they use metal rollers instead of spheres. However, they have a higher load carrying capacity than the equivalent size ball bearing. The downside is that they are less tolerant of lateral forces. The variants are:
    • roller chain: they are very versatile, and roll on their outside diameter along a track. They are called chain because they are joined by outer rings or pins. Some models incorporate an additional axial roller to better withstand lateral loads.
    • roller guide: similar to ball guides, but with a higher load capacity due to the fact that the balls are replaced by rollers. Also, they are quite compact and precise, so they can be used in medical applications.
    • Crossed Roller Linear Belt: this other subtype offers a very high precision, and a great load capacity. However, they are highly vulnerable to contamination by design, which is why they are often used in clean room or clean room applications.
  • Plain Linear Bearings: They have evolved rapidly in the last 20 years, along with the development of low-friction plastics and new ceramics, since they are made with these materials. They can be subdivided into:
    • Plastic: They have a very low coefficient of friction and no rolling elements, so you don't have to worry about contamination, dirt or dust getting in.
    • Ceramics: similar to the plastic ones, but they are quieter and smoother, there are even some that do not need lubrication.

Bearing Applications

There are many applications for this mechanical part. You will find some examples in industrial sectors, mechanics in general, or transportation:

  • For vehicle axles.
  • In moving parts of robots.
  • Conveyor belts.
  • Fans.
  • Moving heads of printers and 3D printers.
  • Home appliances.
  • Machines of all kinds.
  • Camera tripods.
  • Gym equipment.
  • Elevators
  • Bank security camera doors.
  • In the world of medicine.
  • etc.

Common Linear Bearing Problems

types of bearings

Linear bearings share some typical problems with the rest of the bearings, in addition to others due to their architecture. Knowing these problems can prevent many setbacks during operation, as well as prevent some of them with proper maintenance. The list of frequent problems is:

  • Problems in the track itself or the displacement rail along which the bearing runs, which tend to deteriorate with use.
  • They can also become misaligned due to poor assembly or shock, which can force the bearing and accelerate deterioration or prevent its correct operation.
  • Dirt is often an accelerator of corrosion and bearing wear. Keeping them clean is essential.
  • Proper lubrication should also be monitored. Insufficient lubrication causes friction, corrosion and increased wear. Excessive lubrication can also be counterproductive. And of course you should always use proper lubricants.
  • Improper handling of the bearing or using the wrong tools can also cause breakage or problems.
  • Repeated use and fatigue are also causes of failure, but in the face of this, linear bearings can only be replaced when they reach their end of life or use more robust bearings (if they exist).
  • Overloading the bearings also often causes many problems. Always follow the manufacturer's recommendations.

How to choose the right bearing?

It is also essential choose the right linear bearing for your project. This avoids many breakdowns or inconveniences mentioned above. To do this, you must take into account the following factors:

  • Loading capacity: is the factor that will indicate the amount of weight or forces that the bearing can support, or the time that it will last intact under those forces.
  • Lifespan: Many manufacturers usually detail the life of their bearings based on the turns or hours that they could last. For example, 15000 hours.
  • operating speeds: it is also important to verify this other value, even more so if it is a bearing from which you want to extract a high speed, since the speed is conditioned by, among other things, the temperature at which the bearing will work. A bearing for a cold device is not the same as another destined for the interior of an engine that reaches high temperatures, etc.
  • Acceleration: it changes from one model to another, and can also be essential for the choice depending on what you want it for.
  • Size: size matters to fit your project.
  • Operating temperature: indicates the range of temperatures in which the bearing can work optically. Keep in mind that at high temperatures the material could change its hardness or evaporate the lubricant, causing the supported load to decrease, and at very low temperatures it could freeze, affecting mobility.
  • Price: it is important to know well how much you can invest in this type of pieces. Generally, as they are small in size, they are usually very cheap. But there may be some special or large size bearings that can be priced well above.

Basic bearing maintenance

Keeping the bearings in perfect condition so that they work optimally and extend their useful life is as simple as performing a good basic maintenance:

  1. Open the bearing cap in a clean environment. You can read the manufacturer's instructions so as not to damage the bearing during the process.
  2. Clean the bearing with a cleaning agent.
  3. Once the dirt and rust that the bearing may have has been removed, the next thing is to apply the lubricating oil or grease. You should only put a small amount.
  4. Then put the bearing cap back on.
  5. Rotate the bearing several times so that the lubricant is evenly distributed.

where to buy cheap linear bearings

For purchase this type of linear bearing, is not easy. You should go to specialized mechanical stores, or in some hardware stores. It is also possible to buy them on Amazon, like these that we recommend here:

To lubricate the bearings, avoid using vegetable oils, or other types of inappropriate grease, as they can do more harm than good to the bearings. exist special lubrication products on the table:


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