I'm trying to wire a Freightliner to operate the tarp motor.

The diagram I was given, suggests the machinist who provided
it, is not or should not be looking to quit his day job

jpg of his sketch has been ul-ed to the dropbox @ 1Schem.jpg

Switch I was directed to purchase, will switch polarity, but
will not carry the load.

Relays are starter solenoids.

Thanks

gary