| 摘要 |
An adjustable support device includes a base that includes a plurality of rolling element receiving cavities, a plurality of rolling elements that interface with the rolling element receiving cavities, and an external sleeve coupled to the base for adjustable vertical positioning of the external sleeve relative to the base. Each of the rolling element receiving cavities is positioned and oriented to interface with a rolling element disposed between the base and the support surface. The external sleeve can be placed in a first vertical position relative to the base where the rolling elements do not contact the support surface, and in a second vertical position relative to the base where the rolling elements do contact the support surface. A rimguard may be rotatively coupled with the external sleeve so that as the external sleeve is rotated to the first vertical position.
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