Why Do Thrust Bearings Fail?

Bearings of any type are not ever-lasting components. Over time, they experience wear, corrosion, and other forms of degradation depending on the applications in which they are installed. However, it is not common for them to fail without reason. Consisting of a donut-shaped piece of material, bearings are intended to restrict or limit the motion of a machine’s moving parts while simultaneously reducing friction between such parts.

Thrust bearings, in particular, are a type of rotary bearing that is designed to resist thrust and support axial forces caused by helical gears in vehicle gearboxes. They fail on rare occasions, but when they do, this results in catastrophic consequences for engines. Beyond significant repair costs, their failure poses a serious safety threat to all personnel in the general area.
In an engine block, thrust bearings are positioned into grooves formed in the block’s webbing. Their main function is to limit the crankshaft’s forward and backward movement by restricting the crankshaft within a certain area of motion. By controlling these movements, tolerances within the entire rotating assembly can be preserved. This is especially important at high revolutions to maintain the engine’s service life. To better understand why thrust bearings fail, we will outline three of the most common causes below.
Contaminants and Surface Finish
Dirt and contaminants can damage every type of bearing, making it the leading cause of failure. To prevent the build up of grime, an effective maintenance schedule should be put in place and cleaning should be carried out with clean clothes and refined oil. Additionally, polishing the thrust surface frequently is also paramount, and this can be achieved with a polishing machine. If any grinding marks are present on the crankshaft face, they can act like wiper blades to remove the thrust bearing’s surface oil film.
Without proper cleaning and maintenance, thrust bearings can become misaligned and grind against its surface which may generate sparking. This produces “hot spots” on the surface which can damage the overall operation of the bearing. It is worth noting that the thrust surface should always be set at 90 degrees to the crankshaft center-line, creating a thrust face that is square to the axis of the main bearing journal.
Overloading is typically caused by operator error or a distorted crankcase. In either case, overloading causes unnecessary wear and tear, as well as thrust bearing failure. To avoid overloading, the operator must not idle excessively or attempt to “hot rod.” If the problem sources from the crankcase, any additional loads should be removed and the bearing can be repaired using a 90 degree oil routine.
Simplified Purchasing is an online distributor of bearings, fasteners, and other related components that are vital to the proper functionality of engines and other machines. With over 2 billion new, used, obsolete, and hard-to-find options, customers can meet operational requirements with ease. Backed by rapid lead times and unbeatable cost savings on thousands of parts. As our supply chain network stretches across the United States, we can offer expedited shipping services on select in-stock items for both domestic and international customers.
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