A fifth-wheel trailer is one that has a hitch that connects to the
towing vehicle at a point above the rear axle of the towing vehicle -
not at a point on the rear of the vehicle as with a pull-behind trailer.
For example, this is a 5th wheel:
http://www.theironworker.com/Fifth%2...%20Trailer.jpg

My question concerns position of the point of attachment, let's say, the
position of the king pin. For normal pulling of the trailer, where is
the best point to have the king pin? Should it be directly over the axle
of the towing vehicle or should it be ahead of the axle? If ahead, by
how much? In what ways does handling change if the position of the king
pin is changed?

This page http://www.etrailer.com/faq/fifthwheelfaq.asp discusses using
a slider arrangement to move the king pin for maneuverability. It doesn'
t discuss the optimum position for towing.

Instructions that came with a hitch say to mount 0 to 6 inches ahead of
the axle, but provides no further information.

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|||||||||||||||| Nehmo Sergheyev ||||||||||||||||