"Tim Wescott" wrote

I expect that what you will see is that in one extreme the hook up
will be

Motor A -- battery +
Motor B -- battery -

and in the other it'll be

Motor A -- battery -
Motor B -- battery +

And in the middle it'll be nothing connected at all.

I can't imagine any other way (but then, sometimes my imagination
fails
me).
Tim Wescott,

My father tended to wire three-way light switches such that the power
went through the bulb one way, and around it the other (not for
long!). I couldn't properly explain the right way well enough that
he'd remember. Now they have the diagram on the box.

I had three-way and four-way light switches as a problem in college
physics class. Four-way light switches are wired the same as motor
reversing switches, often internally. They lack the center OFF
position.

jsw