Electronic – What do the numbers mean on a three-position switch

schematicsswitchessymbol [~]wiring

I'm having trouble understanding how this instrument switch works.

Image of instrument lighting switch assembly

Here is the schematic illustrating the three switch states:

extract of schematic showing instrument lighting switch

How do I interpret these numbers?

If I were to guess, I'd say that the two relays are shown in the open position (NVG):
enter image description here

On closes the top relay:
enter image description here

Off closes the bottom relay:
enter image description here

I don't have any confidence in my guess though.

Also, I don't understand why there are two junctions not connected to anything:
enter image description here
Hopefully this is standardized, and not specific to my wiring diagram.
I couldn't find the numbers referenced anywhere on the sheet.

Best Answer

The most likely conclusion is:

  • The dotted line indicates that internally the two switches are mechanically linked. meaning that they switch over at roughly the same position and instant.
  • Each switch has three possible settings:
    • NVG: 2-3 and 5-4
    • ON: 2-1 and 5-6
    • OFF: 2-none and 5-none (in the photo this is the top position)

Since nothing is connected to 4, the 5-4 connection is not needed, but the designer probaby chose an off-the-shelf product.

Technically, you would call this a double-pole, triple-throw, top-off switch