Masterswitch details

[ShawnD2112]

Hello! I'd like to ask the help of the assembled exeprtise here about the
details of the standard two-sided Cessna masterswitch.

I'm rewiring my Pitts to put a B&C alternator in it. I've got a two-sided
switch and can't remember which side is the battery side and which is the
alternator side. Also, there are two contacts on a couple of points on the
switch and i'm not entirely sure what they're for.

So, does anyone know where I could get a schematic of the workings of this
type of switch? If not, how about just a good explanation of how it works.
Failing that, I'd just be happy to be reminded of which is the battery and
which is the alternator side. Basically, any info anyone can provide will
be greatly appreciated!

Cheers,
Shawn
Pitts S-1D, G-BKVP

[Mike Granby]

The side that can be switched on by itself is the battery; the side
that is physically interlocked to turn both sides on when activated is
the alternator. The idea is that you can have the battery on without
the alternator, but you can't have the alternator on without the
battery.

The battery side controls the coil of the master solenoid, and thereby
connects the battery to the main power bus. The alternator side
switches the power to the alternator field coils, typically via the
voltage regulator and over-voltage relay, and thereby effectivly
switches the alternator on or off.