Page 22 - Rollingbearings

A.1 Bearing basics

Bearing basics

A.1 Why rolling Ball and roller
bearings
bearings?

The two basic types of rolling element
Rolling bearings support and guide, with distinguish the two basic types of rolling
minimal friction (ig. 1), rotating or oscillating bearing:
machine elements – such as shafts, axles or
wheels – and transfer loads between machine • ball → ball bearing
components Rolling bearings provide high • roller → roller bearing
precision and low friction and therefore enable
high rotational speeds while reducing noise, Balls and rollers are different in how they
heat, energy consumption and wear They are make contact with the raceways
cost- effective and exchangeable machine Balls make point contact with the ring
elements that typically follow national or raceways (ig. 2) With increasing load acting
international dimension standards on the bearing, the contact point becomes Fig. 2
an elliptical area The small contact area Point contact
provides low rolling friction, which enables
ball bearings to accommodate high speeds
but also limits their load-carrying capacity
Rollers make line contact with the ring
raceways (ig. 3) With increasing load acting
on the bearing, the contact line becomes
somewhat rectangular in shape Because of
the larger contact area and the consequently
higher friction, a roller bearing can accom-
modate heavier loads, but lower speeds,
than a same-sized ball bearing

Fig. 1 Fig. 3
Why rolling bearings? Line contact

Sliding friction Rolling friction Rolling bearing

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