"basskisser" wrote in message
om...


Yep, if you are not including the hitch in the calculations,

By "hitch" do you mean the draw bar portion that is rigidly mounted to the
tow vehicle, the actual ball joint, or the tongue assembly that is a rigid
part of the trailer?

Steves primary argument here is that you must consider the added weight of
the tongue extension. Please explain what your statement is inferring.

then yes.
What YOU seem to have not included, which would make YOUR analysis
fatally flawed, is the fact that the fulcrum point is NOT the CG,

Huh???

If the fulcrum point was at the center of gravity then the trailer would be
in perfect balance, I.E., no tongue weight.

and
ADDITIONALLY, you've done NOTHING about the fact that the fulcrum is a
long ways from the CG in the Z direction.

First off, if you are going to make this a multi-demensional problem, it
would be more accurate to refer to the "center of mass" instead of "center
of gravity".

All the discussions thus far have been a static problem."Static" is any
constant velocity situation. Note that Steve already defined a "given" as
the trailer was level, so for the purpose of discussion ignore going up or
down hills. As such, the Z axis is not a factor in the equations. The
center of mass will be somewhere above the center of gravity.

If you want to turn it into a dynamics problem then things get a bit more
complicated. Determining how the tongue weight will vary in an accelerated
frame of reference would require knowing where the center of mass is with
respect to the axel and hitch (ball joint). While you are at it, you might
as well consider the third dimension as well: if the "X" axis is for-aft,
the "Z" axis is up-down, then the "Y" axis is across the beam. If the
center of mass is not on the center line of the hitch then there will be a
moment about the hitch when the rig accelerates.

But that is irrelevant for the discussion at hand, which was limited to the
statics problem, which is pretty much a simple textbook exercise. If you
want to turn this into a full blown engineering project, give us the
necessary information and we can analyze it and tell you how the rig will
respond. But before you do that, why don't you demonstrate that you can do
the simple problem first?

Rod McInnis