Thanks Dennis.

Reading about solenoids as used in landing gear here:
http://saginawwings.com/monty-answerman/relay.htm

this excerpt shed some more light:

"The intermittent [solenoid] contacts are made to break large starter motor
currents and therefore has a lower resistance coil which makes more force
to "snap" the main contacts open and closed."

Neil.

On Tue, Oct 20, 2015 at 8:41 PM, Dennis Haynes <d23haynes57@hotmail.com>
wrote:

> These "ignition" solenoids, (relays) are common for trucks, busses, RVs,
> industrial equipment etc. For these applications there are many things that
> need high current control including manifold pre-heaters and glow plugs to
> get engines started to air tank drain valve heaters to keep them from icing
> up in winter. They are for continuous duty.
>
> The duty refers to the coil design. Relays designed for starters that do
> have built in solenoids such as those found on older Fords are designed for
> short term operation, under a minute and to operate under lower voltages
> during the starting process where battery voltage may drop as low as 8-10
> volts. Continuous operation of these starter relays at >13 volts usually
> does them in around 5 to 10 minutes. If really unlucky the melt down will
> short the coil out and since most do not fuse these coil circuits you will
> get to deal with other damage. Use the alternator warning light circuit as
> is often done on a Westy and you also get to replace the alternator and
> that blue wire.
>
> Dennis
>

--
Neil n

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