Dynamic bearing systems are engineered shafts that allow relative rotation between two components. One of the parts is permanently fixed while the other rotates on it. The design of bearing systems ranges from simplistic models to complicated types that have multiple moving sections. They also feature special components to help them transmit motion. This post helps to demystify the two common types of bearing systems:

Journal bearing (also referred to as shaft or Bushing)

This is perhaps the simplest form of bearing systems. It also goes by names such as plain bearing, bushing bearing, or journal bearing. The bearing system is constructed with a running clearance fit made from a shaft (journal) and a bushing. The design is aimed at ensuring that the interface facilitates rotational motion of the journal on the bearing hole. It is important to ensure that a lubricating compound is required to make the movement of the shaft and the bearing smooth.

Today, journal bearings are constructed by leveraging materials technologies like oil impregnated bushings to help create a joint with low sliding resistance friction. See the image.

Journal bearings are relatively simple to design. Their application requires an elaborate lubricating mechanism for optimal operation. However, if your system is only moving light loads, there are some purely “dry” journal bearings that do not need lubrication.

For optimal production, it is prudent that the journal bearings are positioned at a point where they are easily accessible for easy repairs. If you fail to effectively lubricate the system, there is a high likelihood of system failure.

Rolling Bearing (Ball bearings)

The common definition of a bearing is a mechanical component that features a rolling component for lowering friction between a reference point and a shaft. The reference point is in many cases a stationary hole. The common type of bearing is the roller/ ball type. These bearings are designed with an inner raceway that is fitted firmly to an inner shaft.

The rolling elements of the bearings could be conical rollers or balls that roll on the opposite side of the inner lining of the raceway. Therefore, it is not difficult to figure out how the system works.

To operate effectively, the rolling elements require proper lubrication and sealing between the outer and inner raceways of the bearing. This helps to prevent contamination from the immediate environment. See the demonstration:

Demonstration of a ball bearing

The rolling elements of a ball bearing are designed from hardened materials such as steel alloys. They could even be coated with additional coatings such as chrome to increase wear and corrosion resistance. If corrosion is a major problem, stainless steel ball bearings can also be used.  If a bearing will be subjected to huge thrust loads, it is advisable to go for the needle or cylindrical bearing system. See the image of a needle bearing below:

For cheap applications where the bearing can be easily lubricated and maintained, it is advisable to consider journal bearing. However, if the bearings will be hidden and not easily accessible, the technicians could recommend the rolling contact bearings.

If you want your system to realize high productivity, it is prudent to ensure that only the right bearings are used. Make sure to explore all the contingencies with technicians to make production easy, smooth and cheap.