On Thu, 01 May 2008 19:05:20 -0600, wrote:

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

If you use starter solenoids, you'll need four of them if you want it
to run in both directions. The switch can be a SPDT center off or
DPDT center off toggle switch. The solenoids would be arranged in an
H with top of the H going to + battery and bottom of H going to
ground or - battery with the motor being the crossbar of the H.

-----------
| |
S1 S3
|--M--|
S4 S2
| |
-----------

The switch would then energize diagonally opposed pairs of solenoids
S1 and S2 or S3 and S4, one set for up and the other set for down.