Bearings: Purpose, Loads, Materials, and Types

Vocabulary flashcards covering the definitions, load types, materials, and classifications of bearings as described in the lecture notes.

Slenderness Ratio

A calculation represented by $\frac{FL}{D}$ (where $FL$ is Free Length), where a higher ratio indicates a greater risk of buckling.

Bearing

A machine element that constrains relative motion to the desired motion and reduces friction between moving parts.

Axial Load

Also known as thrust or longitudinal loads, these forces act along the supported shaft by pulling or pushing it.

Radial Load

Also known as journal loads, these forces act at right angles to the shaft, such as vertical weight on a horizontal shaft.

Plain Bearings

Sleeve or sliding bearings that have no moving parts and consist of a plain cylinder or flat washer surface.

Rolling Element Bearings

An assembly comprising hardened rolling components, such as balls or rollers, that roll within inner and outer races.

Races

The inner and outer cases of a rolling element bearing assembly.

Self-Lubricated Metals

Dry-powdered metals containing fluid or solid lubricants in their pores, which are released when heated; examples include graphite and molybdenum disulphide.

Synthetic Bearings

Bearings often made from synthetics that are frequently lubricated with water to act as a coolant, as they tend to retain heat.

Clearance

The essential space between the stationary part and the rotating part in a plain bearing required to work efficiently.

Pivot Bearings

Also known as axial bearings, these are specifically designed to accept forces in a longitudinal direction.

Anti-Friction Bearings

A group of bearings, including ball and roller types, named for their ability to almost entirely eliminate friction.

Cage

Also referred to as a retainer, this component is used to align and separate rolling elements within a bearing.

Point Contact

The type of contact occurring in ball bearings, where the bearing presses into the race at a tiny area; unsuitable for heavy oscillating loads.

Line Contact

The type of contact occurring in cylindrical rollers against the races, allowing them to carry more radial load compared to ball bearings.

Floating Position

A non-locating bearing position that accommodates thermal expansion by allowing axial displacement of the shaft relative to the housing.

Needle Roller Bearings

Bearings featuring long, thin rollers that provide a compact cross-section and high radial load capacity relative to their sectional height.

Spherical Roller Bearings

Self-aligning bearings that accommodate minor angular displacements between the shaft and housing.

Tapered Roller Bearings

Bearings capable of combined radial and thrust loads that use a natural pumping action to force particle contaminants out of the contact area.

Air Bearings

Bearings that utilize a thin film of pressurized air to provide a zero-friction interface between non-contacting surfaces.

Thrust Washer

A component designed for use in plain bearings to handle purely thrust loads.

Thrust Bearings

Bearings designed to bear thrust loading along the axis, such as those used in variable pitch propellers to bear centrifugal force.