| 摘要 |
A movable compartment having a pair of mounting members spaced laterally from each other, each one having a pair of tracks at its sides, a pair of supports associated with the mounting members, each support having a pair of tracks at its sides, a box secured at each of its sides to one of the supports, ball bearings positioned between the mounting members and the supports lying in the tracks therein and means retaining the ball bearings in that position whereby the box is movable with respect to the mounting members through the ball bearings rolling in the tracks in the mounting members and the supports.
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