Article transporting apparatus and method of operating the apparatus

An article transporting apparatus comprising:

• a plurality of article transporting movable bodies movable along a single track between a plurality of article transfer locations;
• and
• operation controlling means for controlling operations of the movable bodies for causing the bodies to effect article transporting operations in accordance with an article transport request information;
• wherein said operation controlling means selects a movable body from the plurality of movable bodies for an article transporting operation based on an operation condition configured to cause the movable bodies to have substantially the same past operation histories so as to have a same timing for replacing a replaceable part for each of the plurality of movable bodies and moves the movable body or bodies, that is/are not selected based on the operation condition, out of an article transporting movable area in which the selected movable body is moved for effecting the article transporting operation,
• wherein the operation condition involves comparing a past operation history of one of the plurality of movable bodies with a past operation history of another of the plurality of movable bodies;
• and
• wherein the operation controlling means selects for an article transporting operation a movable body having a smaller past operation history based on the comparison.