轮(Wheel)
平面，圆形框架或圆盘，构造为围绕其圆周在中心轴上旋转。车轮用于将旋转运动转换为平移运动，并通过摩擦力在接触面和行驶通道之间传递力。
英文介绍
Flat, circular frame or disk, constructed to revolve on a central axis around its circumference. Wheels are used to transform the rotary motion into a translatory motion and transfers the forces between contact surface and travelway via frictional forces.