These are the machines which carry a
load by placing round elements between the two pieces.
The relative motion of the pieces causes the elements to
roll with little amount of sliding.
Rolling-element bearings have the advantage in terms of
cost, size, weight, carrying capacity, durability,
accuracy, friction, and so on. Other bearing designs are
often better on one specific attribute, but worse in
most other attributes. There fore, roller bearings
should be chosen according to the requirement of the