Question about RD4B

Does a RD4B system have a vertical path or does it change direction as it goes up and down?

Be aware that you are posting this in a Vex IQ forum, I am guessing you intend this to be in an EDR forum. To the best of my knowledge, a double reverse 4 bar linkage should move in a relatively straight line vertically. Each of the 4 bar linkages move in an arc, but the output of the arm stays normal (perpendicular) to the ground. The opposite arc should cancel out any linear movement in the horizontal plane resulting in straight vertical movement.

As with most things, try it, document the results in your engineering notebook.


A DR4B doesn’t have a perfect vertical path but the movement horizontally is minimal as the arcs of the 2 4 bars counter each other out leading to that near perfect vertical movement. The difference between length of the 2 stages is what would cause the movement horizontally. So take that into consideration


Please, consider reading this excellent tutorial about building DR4B linkages:


I actually just downloaded this as soon as i saw it! Thanks for the recommendation!