1956 Mack Lt Series Parallel Switch

[rflegel]

I'm looking to find a supplier for an OEM style series parallel switch for my friend's 1956 Mack LT. What is existing is installed in the passenger seat box near the drivers seat and looks nothing like what i am finding available. The two main terminals are on the end of the switch whereas the terminals on newer models seem to be around the sides if the housing.

Can these still be purchased or would we need to convert to the newer style?

Thanks in advance for any help!

[vanscottbuilders]

The series parallel switch is available from Mack, I believe.

And, if not, I do have a good one from a truck converted to a 12 volt starting system.

Let me know if you need it.

Paul Van Scott

[rflegel]

Thanks for the reply Paul,

I'll let my friend know. It appears as though the switch is not faulty after all. I did some cleaning of terminals and charging of batteries and the problem seems to have resolved.

Sounds like many are converting to 12 volt. Is this due to problems with the switch, or other practical reasons?

Thanks again for the reply.

The series parallel switch is available from Mack, I believe.

And, if not, I do have a good one from a truck converted to a 12 volt starting system.

Let me know if you need it.

Paul Van Scott

[vanscottbuilders]

The series parallel system and switch are pretty dependable.

Usually a little terminal cleaning and good batteries will do the trick.

As far as I know, there is no real reason to convert to 12 volt, if you understand what the old system is doing.

24 volts and all of the battery's available cranking power are provided, through the series parallel switch, directly to the starter, only.

Everything else in the truck's electrical system is run on 12 volts.

Most newer 12 volt trucks are negative ground, whereas many of the older trucks, particularly Macks,

are positive grounded electrical systems.

The conversion to 12 volts with negative ground does make your system compatible with most other vehicles, and reduces the chances for cross-connections when jumping batteries. A 12 volt system is more commonly understood today. So it's safer.

If you were doing restoration work or electrical work to the truck, you might consider the change.

Starter motor efficiency and battery technology have improved in the past sixty years.

Today a 12 volt starter and two good 12 volt truck batteries are more than enough power to start your diesel.

Paul VS

[rflegel]

Thanks for the information Paul.

This is a positive ground system and has been setting for quite a spell waiting to be revived. It is a logging truck that has passed from father to son. I'm sure it is my friend's plan is to keep the Mack the way his father had it. I knew his father, but now I'm just along for the ride, assistance and a kind word as needed.

Thanks again!

Rick