| 摘要 |
<p>The appliance has a standing board (1) with a central ball bearing ring (2) enclosing a support ball (3), and a steering device consisting of a non-centrally located steering roller or ball (4). The device is non-functional, and the roller/ball is suspended to be out of contact with the ground, when the boards is horizontal. The torque required to turn the steering roller/ball is larger than the torque required to turn the support ball.</p> |
