A correspondent on another list asked this:-
"I once had some involvement with a seagoing tug that had an enormous 5 cylinder Caterpillar diesel. It was a valved two stroke with a compressed air receiver which was used for starting. To go astern the engine was stopped and re started in reverse. I vaguely remember a reversing lever connected into the camshaft drive, but after sixty years I'm no longer certain what it did. Perhaps someone could tell me?"
Regards,
Kim Siddorn.
same as the deutz and all the others with a reversing camshaft
Usually, the camshaft has two sets of cams, one for forward running and one for reverse. The camshaft is moved axially to change from one to another, usually the followers are lifted bodily upwards to clear while it is moved .
Another method is to have the camshaft driven through an intermediate shaft which can be reversed. The engine starting air also has to be changed, so the starting air cams are reversed at the same time.
J W M Sothern or John Lamb both have books on Marine Diesels giving drawings of the various types of reversing gear along with details of the lock-out devices that prevent the change-over being effected while the engine is running etc etc.
See also the film "San Demetrio London" to see this done in practice.
Peter
-- Peter & Rita Forbes Email: snipped-for-privacy@easynet.co.uk Web:
After 60 years, the memories are a bit faulty. Caterpllar never made engines fitting that description, especially
60 odd years ago.Tom
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