To lock and unlock an upper door and a front-surface door by following the operation of a cylinder via a through hole being formed on the front surface of an upper door and then by allowing the tip of a key piece to penetrate through a long hole being formed on the lower surface of an upper door and to be engaged to or disengaged from a hook hole being provided on the upper surface of the front- surface door.
When an upper door 5 is to be locked, the upper door 5 is closed, a key is inserted to a key hole 13 via a through hole 16, a key piece 12 is rotated until it is set to a vertical, lower position, and the tip of the key piece 12 penetrates through a long hole 14 being provided on lower surface of the upper door and is engaged to a hook hole 15 being provided on the upper surface of a front-surface door 3. On the other hand, when the upper door 5 is to be unlocked, the key being inserted to the key hole is rotated by 90° so that the key piece 12 can be removed from the long hole 14 and the hook hole 15. Furthermore, two front-surface doors 3 are slightly overlapped at the center part of a low-temperature storehouse, and a hook hole 16 is provided in the upper one of two front-surface doors 3 and then the key piece 12 is engaged, thus simultaneously locking and unlocking the upper door and two front-surface doors with one key.
MIYABAYASHI KIMIO
WAKUI TOSHIYUKI
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