| 摘要 |
Wheel structures are made removable from the body which they support. Each wheel structure includes a solid wheel which is normally imperforate between the hub and the rim and an axle on which the wheel is rotatably secured. The web of each wheel between the hub and the rim is provided with apertures complementarily formed relative to the axles for receiving the axle or axles of another wheel or wheels therethrough to permit nesting the wheel structures.
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