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Mantle Changer
| The mantle used in large open-sea lighthouses has a useful life of approximately five weeks and has to be changed at regular intervals. In 1917 Gustaf Dalén came upon the idea for an automatic mantle changer which allows the lighthouse to be left unmanned for long periods. The first candidate was the Skoghall lighthouse on Lake Vänern. Before large open-sea lighthouses can operate totally without manual intervention, lens rotation must also be automated. | 
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| The rotation apparatus utilizes the small movement which arises in the membrane of the Dalén mixer when the acetylene rushes in and out. Using a system of links the movement of the membrane is transformed into a rotating movement which operates the lighthouse lens system. This reduces the need of supervision to a minimum. Some AGA lighthouses only needed to be checked once a year. |
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