Definition
A force applied to a bearing in a direction perpendicular (at right angles) to the shaft's axis of rotation. The bearing supports this sideways load while allowing the shaft to spin freely.
Plain English
The sideways push on a bearing — pressing in toward the center of the shaft rather than along its length. The bearing holds the shaft steady against this side-to-side force while it turns.
Context Anchor
Seen in aircraft engine and propeller maintenance discussions about shafts, bearings, and the loads those bearings must support.
Derivation
Radial' comes from the Latin radius, meaning 'spoke of a wheel' or 'ray.' A radial load points outward from (or inward toward) the center of the shaft, just like spokes radiate from the hub of a wheel. This contrasts with an axial load, which acts along the length of the shaft.
Why Pilots Care
Bearings are designed for specific load types. A bearing built mainly for radial loads can fail if subjected to heavy axial loads, and vice versa. Understanding which loads act on which bearings helps when reading maintenance manuals and inspection findings.
Analogy
Think of a bicycle wheel hub. The rider's weight pushes down on the axle from the side — that downward push is a radial load on the hub bearings.
Intuition Check
Do not read “bearing” here as a compass direction. In this term, a bearing is a mechanical part that supports a rotating part. “Radial” here does not mean a VOR radial or a radial engine; it means across the radius of a rotating part.
Example Sentence 1
The main bearings in the crankshaft carry the radial bearing load created by the pistons pushing down through the connecting rods.
Example Sentence 2
Excessive radial bearing load from an unbalanced propeller can shorten bearing life in the engine.