The 333A tutorial was already linked by DougMoyers, but I included it here to have a nice collection of links for you.
Double Reverse Four Bar (DR4B or RD4B) - PSig
The Kepler Electronics Guide To The DR4B - Kepler yt
The 333A tutorial was already linked by DougMoyers, but I included it here to have a nice collection of links for you.
Double Reverse Four Bar (DR4B or RD4B) - PSig
The Kepler Electronics Guide To The DR4B - Kepler yt