The present invention relates to a dynamic pressure-type liquid bearing unit which can prevent lubricating oil from flowing outside by discharging air that is trapped in the bearing. In one embodiment, the switching wheels are vertically displaceable relative to the chassis, and in a second embodiment, the chassis and the switching wheels are vertically displaceable as a unit relative to the vehicle support wheels and the monorail. On-demand service usage data is updated to indicate usage of the on-demand services by the users.