This trains the application of koubu and baibu stepping, the application of the body technique, the method of coiling the hands. This develops the vital principle of 'crossing', the same as done with a spear. If you can get your arm crossed with the opponent, then you can control and get in. So do not do this drill to heavily, it is a way of defending and getting in. You can combine almost any technique with crossing.
1. Sit in mabu facing each other with the arms connected. Circle the arms, keeping them connected and straight. Change arms and direction at will, there is no fixed pattern. Keep the power mid-weight, not too heavy (this is not yazhang partner training). Switch sides every 1 or 2 circles, going in the same direction. Change directions occasionally. Press slightly into your partner rather than circling in empty vertical circles. If you are following, make sure you are following, not just going along. Do not go too fast. To take the lead, bring the other arm in at a natural place and continue to circle as you gradually switch arms.
2. Add stepping with the circling as you become more comfortable. Use koubu and baibu to position yourself. If you step well, when you cross arms you are already in a good position for a zhuangzhang with the body.