Sykes unloading in Grand Haven

[Brent]

3AE is correct. The other reason is so the blades won't develope hot spots and also so the oil to the bearings is circulated. If the oil is not circulate the bearings can develope dry spots and wipe the bearings.

[BeeZee]

Thanks for the information on the propeller.

[standuffer]

Great explanation 3AE.

[3AE]

Steam turbines are always kept rolling except during winter layup. The engines are hooked to an electric motor called a jacking gear and since there are no clutches (direct connection to the propeller via reduction gear) the propeller turns over slowly also. This is done because if the rotors are not kept turning when they are hot then they can sag between the bearings under their own weight thus destroying them. Also, for an hour before any steamship leaves port the engineers warm the engines up by rolling them 5-10 RPM ahead. This allows the steel to slowly and uniformally expand. Tolerances within a turbine between blades spinning at 6,000 RPM and the stationary casing are only 2-3 thousandths of an inch.

[Guest]

Likely, the turning gear was in.

[BeeZee]

You can visit here,

http://www.grandhaventribune.com/harbor-cam

Look at the propeller. It must be free wheeling as the current is revolving it around.