"basskisser" wrote in message
om...

About the z axis. Are you saying that, seeing how in
the x direction, the fulcrum point isn't at the CG,

This was clearly stated by the reference that there was tongue weight.

that if we move
the cg up, or down, in the z direction, that the resultant resistance
on the hitch doesn't change?

It was clearly stated that the trailer was level. Hence, the center of
gravity and the center of mass lie on the same spot with reference to the X
axis.

Really?

Really.

So, you are saying that there
won't be a moment induced in the z direction?

You keep making statements that I can't believe a professional engineer
would make.
A moment induced in the z direction? That makes no sense at all.
You can have a moment about an axis, not in the direction of an axis. If
you meant to say a moment about the Z axis, then this would have to come
from an acceleration force in either the translational (forward/backward)
direction or lateral direction. As I said before, adding acceleration to
the problem changes it into a dynamcis problem.

If you meant to say a moment about the Y axis (which is the axis parallel to
the axel, and what provides tongue weight) then for any given condition
("level" in this case) you don't need to know where the center of mass lies
in the Z direction. On the other hand, if you wanted to know how the tongue
weight would change when the rig went up or down hills then you would need
to know where the center of mass is.


And are you thus saying
that the moment won't change as the distance from the fulcrum to the
CG changes?????

It is only required to know the tangential distance from the fulcrum.
Again, it was stated that the trailer was level.

Hint, moment is given thusly: pound/inches,
kip/inches, pound/feet, kip/feet, etc., etc.

You are wrong. Look it up again.

Moment it the product of the tangential force and the lever arm. You
multiply, not divide. By convention the units are stated in the order of
"legth" and "force" such as foot-pounds (that's a hyphen, not a subtraction
symbol).

So, yes or no, does this
torsional load change when the distance from the fulcrum to the CG
changes?

Only if it changes the tangential distance. If the trailer is level, you
can raise the load as high as you want and it won't change the moment about
the axel.

You keep saying that you are an engineer and know this stuff. Yet you refuse
to back up anything you say with equations, calculations or examples. It
should be simple: take the original example, make what ever assumption you
want for the location of the center of mass in the Y and Z direction and run
the calculations. Then create another example, with everything the same
except a different Y and/or Z distance for center of mass (leave the X
direction alone) and run the calculations again.

Rod