| 摘要 |
A retractable mailbox assembly includes three concentric cylinders with the outer mounted underground and the middle and inner cylinders telescopically mounted to rise out of the ground in response to air pressure with the middle cylinder mounted to rise linearly a predetermined height and latched at that height by magnetic latches and the inner cylinder mounted to rise an additional predetermined height beyond that of the middle cylinder to permit a rotatable mailbox pivotally mounted at the top of the inner cylinder to be opened by a rack and pinion mechanism to permit depositing or withdrawal of mail. Air pressure to raise the middle and inner cylinders is transmitted from water cooled air storage means, illustratively a plurality of storage pipes, through an air diffuser controlled by a pneumatic solenoid valve. The pneumatic valve is controlled by a time delay relay of a switching system which is actuated in response to a signal transmitted from either a mailman's transmitter or a user's transmitter to thereby open the mailbox and retain it open for a predetermined period of time determined by the time delay relay. At the end of that predetermined period, the relay actuates a compressor which evacuates the interior of the cylinders and pumps air back into the storage means thereby closing the mailbox and retracting the inner and middle cylinders into the outer cylinder. Make-up air during and after retraction is admitted through a suitable check valve. The switching system also includes signaling means for signaling the user that the mailbox is being or has been serviced by the mailman. It further includes signaling means for signaling the mailman that mail has been deposited by the user. Drainage means is provided for draining water from the bottom of the outer cylinder into a suitable underground drain.
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