Abstract: A baggage caster is composed of a wheel frame, a wheel, and a retrieving mechanism. The wheel frame is fastened pivotally with a baggage shell such that the wheel frame is capable of swiveling between a retraction position and an extraction position. The wheel is fastened pivotally with the wheel frame such that a plummet of the pivot center of the wheel does not coincide with a plummet of the pivot center of the wheel frame at such time when the wheel frame is located at the retraction position. The wheel frame is therefore capable of swiveling to remain at the extraction position when the baggage shell is exerted on by a load. The retrieving mechanism is intended to provide the wheel frame with an elastic force to enable the wheel frame to return to the retraction position when the baggage shell is relieved of the load exerting thereon.

Abstract: A caster assembly of a shopping bag is composed of a base for holding the shopping bag, two support frames fastened pivotally with the base such that the support frames can be folded and unfolded, two elastic elements enabling the support frames to return to a folded position from an unfolded position, two casters fastened pivotally with the support frames, and a locating member fastened pivotally with the support frames such that two arms of the locating member are located between the base and the support frames at such time when the locating member is folded, and that the arms of the locating member push the support frames to spread out at such time when the locating member is unfolded.