Thrust Bearing Guide
Introduction to Bearings
Bearings are the mechanical parts that are used to hold a driving shaft in place and provide support to it when the shaft is rotating. The presence of bearings dampens the vibration that is generated when the shaft rotates. They protect the neighboring components of the shaft by means of separating the shaft from the components. In addition to protecting other components in the machinery, the bearing also helps to reduce the friction and smooth the rotation of the driving shaft.
There are several types of bearings and they are classified based on their functions and where they are applied. The most common bearing types include the ball bearings, roller bearings, thrust bearings, linear bearings, and slide bearings, etc. In this article, the main focus will be on the thrust bearings and the ball bearings. The function as well as the applications of thrust bearings will be covered in the following paragraphs. Before cutting to the main point, we will go through the general construction of a bearing first.
Anatomy of Bearings
Generally speaking, a bearing is a ring-like devise that is comprised of the outer ring, the inner ring and the rollers. The rollers, or called the balls, are contained in between the inner ring and outer ring of the bearing. Based on the way the tiny rollers are positioned in between the rings, the bearings can be divided into two major subtypes: the ball bearings and the roller bearings. The way the balls are disposed in different types of bearings gives distinguishable mechanical characteristics between the counterparts.
Thrust bearings are a subtype of ball bearings. The ball bearings are the bearing type that contains balls in the construction of it. The balls refer to the rolling elements inside a bearing. They ball bearings are design to provide radial and axial support to the rotating shaft and minimize the friction between the shaft and other stationary components. The contact surface of ball bearings is a single point. The contact surface refers to the contact area of the rail of the rings and the balls.
Just like other types of bearing, the primary goal of the thrust bearings is to provide support to the shaft and reduce the friction when the shaft rotates. However, the thrust bearings are designed to provide support to the axial loads in particular. The axial loads are the loads that are transmitted linearly along the axis of the driving shaft. The thrust bearings can be found on power hand drills where pressure is applied on the drill axially to drill through materials. A thrust bearing can also be seen on a merry-go-round to support the entire rotating weight.
Types of Thrust Ball Bearings
The disposition of the rolling elements inside a bearing affects its mechanical characteristics. The configuration of the rolling elements also has influence on how the bearings work and what they can do best. Depending on the types of rollers the thrust bearings use, there are tapered thrust bearings, cylindrical thrust bearings, needle roller thrust bearings and more.
Tapered Thrust Bearings
The axial loads that a thrust bearing can handle have to do with the angle between the bearing axis and the line of contact. The line of contact is determined by how tapered the rollers are. The angle greater than forty five degrees is considered capable of providing the axial support. When the angle is greater than ninety degrees, the thrust bearing can only provide axial support to the mechanism. The thrust bearings that only provide axial support are also called the pure thrust bearings.
Cylindrical Thrust Bearings
This type of thrust bearings utilizes the cylindrical rollers. The rollers are disposed around the bearing in a perpendicular radial fashion. The rollers are crowned in order to reduce the stress between the rollers and the outer wall of the bearing. The cylindrical thrust bearings do not need much axial space to provide the axial support. They are also the type that has better axial support over radial load support.
Needle Thrust Bearings
Needle thrust bearings have the minimal height among all the types of thrust bearings and they have more rollers than other types do as well. They are special not only because the size and the number of rolling elements, but their presentation too. Sometimes there is no housing on the bearing and the needle rollers are exposed. This type of thrust bearing can handle high axial and shock loads but radial load.
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