Flatbed trolley consisting of foldable bed and casters

A flatbed trolley comprising:

• a bed rotating shaft;
• and
• a bed unit placed parallel to the ground so that an item is loaded thereon;
• wherein the bed unit is connected to the bed rotating shaft via a bed hinge unit;
• wherein the bed unit comprises a front bed part and a rear bed part;
• wherein the bed hinge unit comprises a front-bed-part hinge and a rear-bed-part hinge;
• wherein the front bed part is connected to one side of the bed rotating shaft via the front-bed-part hinge and is configured to rotate downward about the bed rotating shaft;
• wherein the rear bed part is connected to the other side of the bed rotating shaft via the rear-bed-part hinge and is configured to rotate downward about the bed rotating shaft;
• wherein the front bed part comprises on a lower portion thereof one or more front-bed-part caster units;
• wherein the front-bed-part caster unit comprises a front bed part caster and a front bed part caster hinge;
• wherein the front-bed-part caster unit is connected to the front bed part and the front bed part caster hinge, and is configured such that the front bed part caster protruding vertically from a lower surface of the front bed part is foldable while rotating toward the lower surface of the front bed part;
• wherein the rear bed part comprises on a lower portion thereof one or more rear-bed-part caster units;
• wherein the rear-bed-part caster unit comprises a rear bed part caster and a rear bed part caster hinge;
• wherein the rear-bed-part caster unit is connected to the rear bed part and the rear bed part caster hinge, and is configured such that the rear bed part caster protruding vertically from a lower surface of the rear bed part is foldable while rotating toward the lower surface of the rear bed part;
• wherein when the bed unit is unfolded horizontally, the front bed part caster and the rear bed part caster protrude vertically from the lower surfaces of the front bed part and the rear bed part, respectively;
• wherein, when the front bed part and the rear bed part of the bed unit are rotated and folded about the bed rotating shaft so that they come into contact with each other on an inner lower side, the front-bed-part caster unit and the rear-bed-part caster unit are rotated and folded beneath the front bed part and the rear bed part, respectively, so that the bed unit is folded in half and simultaneously the front bed part caster and the rear bed part caster are also automatically folded and concealed between the folded front bed part and rear bed part;
• and
• wherein the bed hinge unit connected to the bed rotating shaft comprises a bed hinge locking bar that locks the bed hinge unit to prevent the bed unit from being folded when the bed unit is unfolded and used, and unlocks the bed hinge unit only when necessary to allow the bed unit to be folded.