| 摘要 |
A base for receiving a seat comprises a longitudinally extending chassis having a front end, a rear end, a central portion positioned therebetween and opposed sides extending longitudinally between the front and rear ends; at least one drive wheel mounted below the central portion; a plurality of rotatably mounted wheels positioned around the chassis and mounted at a fixed distance below the chassis; and a biasing member associated with the at least one drive wheel to bias the at least one drive wheel to engage the surface on which the base is situated and reduce the weight supported by the rotatably mounted wheels whereby the rotatably mounted wheels support sufficient weight of the base and the unoccupied seat to define a stable platform. |
