Abstract: A pair of stacking gates or doors has a trailing gate and a leading gate which roll along parallel tracks between a retracted position with the gates approximately side-by-side and an extended position with the leading gate further from the retracted position than the trailing gate. Flexible roller chains are used to retract and extend the gates. A retraction chain has one end connected to an anchor fixed between the gates, is wrapped around a rear idler sprocket on the rear of the trailing gate, and is connected at the other end to the leading gate. An extension chain has one end connected to the fixed anchor, is wrapped around a front idler sprocket near the front of the trailing gate, and is connected at the other end to the rear of the leading gate. As the trailing gate is moved, the idlers move, changing the lengths of the reaches of chain and moving the leading gate twice as far as movement of the trailing gate.