pic: Team 148 - 2011 - Raptor

[Adam Freeman]

Originally Posted by Chris is me

I've never learned much about arms and I don't understand the advantage or disadvantage of either system, other than CG placement.

When we did it in 2007, it was specifically for CG purposes. I did not want to mount a gearbox near the top of the arm. I also did not want to run chain from the gear box to a sprocket at the top of the arm.

There is also a design elegance to doing something different than running chain.

I can tell you there are advantages and disadvantages to it. CG is probably the biggest advantage...other than 4 bar linkages are always cooler. In my mind the biggest disadvantage is the amount of packaging room required to allow the push link and connecting link to swing in the bottom of the robot.

In 2008 we wanted to use a double 4 bar, but could not get it to package... so we mounted a sprocket to the arm and ran a long strand of chain.