JUNEAU (AP) The state ferry Taku will be out of commission until Monday, as maintenance workers repair damage from a mechanical problem that occurred earlier this week.
The Taku was in Chatham Strait Monday and headed to Sitka when the crew found that a bearing in its drive mechanism had overheated. The drive mechanism transmits the diesel engine's power to the propeller.
The starboard main shaft thrust bearing also was damaged. That bearing, which is part of the ship's reduction gear, handles the thrust generated when the propeller spins.
''The nut on the thrust bearing came loose and it wasn't handling the thrust of the propeller,'' said George Poor, senior port engineer for the Alaska Marine Highway System.
As a result, the first bearing had to carry the thrust bearing's load, and it failed, he said.
The Taku began having problems with its shaft clutch assembly last week as it sailed from Auke Bay to Haines and Skagway. The Aurora, a smaller ferry, was brought up to cover the Taku's weekend Lynn Canal runs.
The Taku is the third of the Alaska Marine Highway System's seven Southeast ferries to be sidelined in the past month. A generator fire hit the Columbia as it sailed through Wrangell Narrows on May 28, and the Kennicott hit a rock outside of Wrangell on June 3. Both are back in service.
Lufkin Industries, a Texas company that manufactures bearings used in the Taku, said there have been problems with the bearing loosening.
''It's not a maintenance issue. It's a design fault which we're now going to correct. We're going to modify it so it can't ever come loose again,'' Poor said.
He said the Taku is the system's only ship that uses that model of reduction gear.
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