DMU Kinematics: U-Joint- what it cross pin axis direction

[supergee]

Hi everybody,

One question that is REALLY bothering me: what is cross pin axis diection in DMU Kinematics U-joint definition? I have no Idea what it means but I hear from some of my customers that it created problems when the wrong one is selected.

 

[supergee]

... so nobody has any answer or nobody cares????

 

[KevinDeSmet]

For what it's worth, but I admit the description is a little vague..

http://catiadoc.free.fr/online/kinug_C2/kinugbt0605.htm

 

[supergee]

First and foremost, thank you KevinDeSmet for taking the time to answer.

Unfortunately, I already had found this document and, as you can see, I doesn't says a lot about it.

I was wondering if anyone had any better explanation.

Again, I appreciate the time you took to answer.

 

[jackk]

If this REALLY bothers you, why don't you do some research on Universal Joints? Or even better, ask your customer to show you the problems it creates and learn from them while you are helping them (I assume you will be submitting a Problem Report to Dassault).

A Universal Joint is simply two Revolute Joints based on a common center piece consisting of two cylinders. This center piece is what CATIA calls the "cross pin", two pins forming a cross ("+"). CATIA Kinematics makes defining a U-Joint simple by not requiring the cross pin to be modeled, but it's orientation must be specified. The cross pin axis direction is a line that is parallel to the centerline of one of the pins in the center piece, and normal to a centerline of one of the rotating shafts