Definition of caster

The caster is a general term, including the movable casters and the fixed casters, which are also known as the universal wheel, whose structure allows for 360-degree rotation; Fixed castor also called directional casters, it has no rotating structure, cannot turn is usually two kinds of casters are generally use collocation, such as the structure of the trolley is in front of two directional wheel, behind near the armrest is driven by two wheels.