The Stovebolt Site Forums The Shop Area The Electrical Bay Polarity reversing switch ('46 half ton) purpose?

I am trying to understand the purpose of a starting motor polarity reversing switch shown in the shop manual wiring diagram. The switch has 3 terminals. Two leads come from the distributor and one from the coil. From there they go no where else.

I checked diagrams for the '37 half ton and later year models nothing similar is shown. After '48 it appears nothing similar was used or maybe a resistor block?????

The Master Parts Catalog (1929-1950) shows that these were used from '41-42 and '46-48. Different part numbers are shown for each block of years.

What is the purpose?

Is it necessary?

Can I substitute a resistor block instead?

My 2¢,

The polarity reversing switch was used to increase the life of the points, so the build up was not just on one side of the points. That's my understanding, although I could be wrong about this! I know the points on Model T coils have a longer service interval when the car is run on MAG (AC), instead of BATT (DC).

I don't think most people use them anymore. If you've got one, it would be cool to wire it up.

I could be all wrong about this!

If I am, someone will point (hahaha, get it?) it out.

Well, at least it showed up that time!

I found additional info.

Yes, the switch was used to prolong the life of the points. It was used in trucks and cars from '41 to early '48. The switch was bolted to the top of the starter and was part of a unit that had a spring loaded connector lever. One end was connected to the stomp starter switch.

As I understand it the engine will operate fine with or without the switch, but if the year correct distributor (1110090) is used, it needs to be grounded.

They stopped using it because it introduced another point of failure without any benefit. Most people remove them.

If the switch was not used was a resistor block used in its place?

No but you would need to supply a ground connection for the distributor.

Is the truck still six volts?

Truckernix--thank you.

Mr. Lang--it is a 6v system. But, I discovered yesterday the coil is a 12v, so I need to order a new one.

If I understand correctly, not having the polar reversing switch (PVS) should not matter either with the 6V or 12V??? I ask, just in case I change my mind later and convert to 12v.

I also found that the stomp starter, date (June 1946) and part number "period" correct does not have the three bolt holes that would have been used to fasten the PVS to the starter. My guess is the truck, for whatever reason never had one???? Given this was assembled soon after the War, maybe it was a hold over part from pre-1941 inventory???? I understand that was a fairly common occurrence for a variety of parts.

I'm still climbing a steep learning curve with ALL this stuff, so I Thank You Guys!