# Electro Magnetic Coupling (Federal SN Co)



## Nigel Wing (Sep 26, 2006)

As an apprentice electrician at Silley Cox & Co. Falmouth, between 1959 - 1964, I remember several Federal SN ships having two Main Engines, coupled to a single screw, via an electro magnetic coupling, (Surrey) for example.
The unpleasant task of cleaning the electrical coils on this gear, normally occured during drydockings, and I became involved on more than one occasion.
I have often wondered how it worked, and whether one Main Engine could be coupled/uncoupled as necessary.
If anyone can reply with a simple explanation I would much appreciate this, it was probably simple, but as an apprentice sometimes enough attention was not paid.
Cheers.
Nigel.


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## J Boyde (Apr 7, 2005)

I was 4th on the Wairata, she had two Nordberg engines coupled through magnetic couplings on to reduction gears finishing up with a single shaft. Manouvering, normaly, one engine ahead, one astern. When the ship was to be started the telgraph would indicate direction, ie, ahead or astern. On her it was a matter of putting a switch (like a big knob) If ahead. it was pushed forward. If astern, backwards. Very simple to manouver. Use the a throtle on whichever engine was required. Double ring, (popular move in Bombay) Full power to the required direction, then stop the other then start in the direction required, then couple the two together. The power had to be agusted to that both engines had the rame revs. Her running speed was 72 rpm, for around 14 knots. 
Hope this helps, like the ship, I too and getting old and do miss things.
Jim B


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## CONDOR (Jun 26, 2009)

I was engineering officer on a US Navy ship. 6 large 16 cyl. diesel engines. 3 diesels connected to each shaft (2 shafts), through a electro magnetic coupling, which then connected to a speed reduction gear, and thence to the propulsion shafts. Great for maneuvering, with some engines running ahead and some in reverse. Quick connect disconnect thruough a simple throw of a hand toggle switch. It was rumored that you could even start a dead engine by energizing the coupling taking power from an On Line engine, but we never dared tried that. CONDOR


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## jim garnett (Sep 13, 2009)

Nigel Wing said:


> As an apprentice electrician at Silley Cox & Co. Falmouth, between 1959 - 1964, I remember several Federal SN ships having two Main Engines, coupled to a single screw, via an electro magnetic coupling, (Surrey) for example.
> The unpleasant task of cleaning the electrical coils on this gear, normally occured during drydockings, and I became involved on more than one occasion.
> I have often wondered how it worked, and whether one Main Engine could be coupled/uncoupled as necessary.
> If anyone can reply with a simple explanation I would much appreciate this, it was probably simple, but as an apprentice sometimes enough attention was not paid.
> ...


i served for two years on a C1A vessel la estancia/montcalm.It had two sulzer engines coupled to one shaft via manetic couplings and recduction gear.Yes the engines could be uncoupled by simple switches 
on the contol panel.During manoeuvering one engine was run in the ahead direction and the other astern.
It made things very simple and saved a lot of compressed air.See wikipedia C1A vessels.

Jim garnett


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## billmaca (Jan 14, 2006)

The Wiamati Union Steam NZ had a similar setup


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