The Old Three Techniques

The second stage of push hands that I was taught is called "The Old Three Techniques."

It consists of:

Lu (Roll Back),
An (Push), and
Zhou (Elbow).

It's a simple game of rock-scissors-paper:

Respond to Push with Roll Back.
Respond to Roll Back with Elbow.
Respond to Elbow with Push.

Following from the Primary Two Techniques (Respond to Push with Roll Back, then apply Push), this provides the next level of complexity in training. You practice each level of complexity until it is subconscious before moving on. This is the point of these exercises; training your instincts.