Abstract: A roller carriage has a carriage bottom below which a plurality of wheels is mounted, at least one of the wheels being mounted swingably about a substantially vertical axis of swing. The roller carriage moreover has retention device to retain the swingable wheel or wheels on an overlying roller carriage, the wheel retention device being constructed as a substantially horizontal guide track which extends along at least part of a circle. The guide track forms two engagement areas which restrict the movement of the swingable wheel or wheels of an overlying roller carriage.