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Overspeed
edit"As the ratio was perhaps 1000:1 and the main engine ran at 60 rpm, this would otherwise have been a disastrous overspeed." I think someone at http://www.nmes.org/barring.html is getting a bit excited. A single-start worm-gear, as these are - to get the required reduction, is not reversible: the wheel cannot turn the worm. So you would not overspeed the barring engine at all. If anything had to break you would probably strip teeth or snap mounting bolts. Actually I don't think even that would happen. As the main engine started to run, if the barring gear did not disengage it would more likely just prevent the engine from accelerating. Globbet (talk) 17:18, 10 July 2009 (UTC) Comments revised - Globbet (talk) 15:59, 28 July 2009 (UTC)
- There are two reduction ratios in effect: the worm ratio (let's say 1:50) and also the ratio of the barring engine's pinion to the flywheel's teeth (maybe 8:160 for the Science Museum engine in the photo). That's 1000:1 overall. Andy Dingley (talk) 01:44, 30 July 2009 (UTC)
- Indeed. I altered the comment above when I realised that was what was meant. A single start worm wheel still won't turn the worm, though. Globbet (talk) 10:09, 30 July 2009 (UTC)
Images required
editThe article needs a good image (I've seen some poor ones on Commons) of a flywheel with the characteristic central row of external square holes. An image of a fixed roller fulcrum for manual barring would also be useful. Andy Dingley (talk) 16:12, 28 July 2009 (UTC)
- You have prompted me to upload these. There are about 10 more to come when I get time. Globbet (talk) 01:08, 30 July 2009 (UTC)
- Thanks, this will be handy for another article (manyana!). It's not a Watt governor, it's a Porter governor, with a central loaded weight. I've been needing a decent photo of one. Andy Dingley (talk) 01:35, 30 July 2009 (UTC)
- Correction noted. Ta. Globbet (talk) 10:09, 30 July 2009 (UTC)
- Thanks, this will be handy for another article (manyana!). It's not a Watt governor, it's a Porter governor, with a central loaded weight. I've been needing a decent photo of one. Andy Dingley (talk) 01:35, 30 July 2009 (UTC)
Not Obsolete
editThis article shows clear signs that Andy Dingley created it after a visit to the Bolton Steam Museum. Mr. Dingley left the museum with the mistaken impression that the barring engine he saw there was as obsolete as the large stationary steam engine he saw there. Just as the steam engine that drove the Titanic was a Huge Marine Engine and had a barring engine, so are the Marine Diesel Engines that drive the supertankers, and the giant container ships. These engines also need barring engines, for the same reasons that the steam engines did. I found a half dozen manufacturers today with a simple search for Barring Motor. Nick Beeson (talk) 02:54, 11 April 2021 (UTC)
Another use
editWhen I worked for a generating organisation, unused turbines and generators were kept on a barring engine all the time they were not in use. The purpose was to keep the long shaft straight, otherwise it would start to bend under its own weight. These were large (750MW) steam turbines and generators. Wom the Bat (talk) 08:00, 14 June 2022 (UTC)