[Yoda]

...how do you make an active right triceps only stretch the left arm in swinging and actually drive or move it in hitting?

Thanks for your insightful posts, Coop. You've got everybody thinking and learning. As it should be!

Regarding your question...

In addition to Clubhead Lag Pressure (Acceleration Control per 6-C-0-3), there are two types of Thrust: Non-Accelerating and Accelerating. Extensor Action is a Non-Accelerating Thrust that supplies Power Package Mass (6-C-0-2). Used by both Hitters and Swingers, it stretches the Left Arm (in the direction it is pointing -- Below Plane) but does not cause it to move. Hence the modifier Non-Accelerating.

On the other hand, the Hitter's #1 Power Accumulator -- Right Triceps/Elbow Drive-Out -- is an Accelerating Thrust (6-C-0-1). Applied On Plane against Pressure Points #1 and #3, it does move the Left Arm. In fact, it moves both the Arm and the Club (the entire Primary Lever Assembly). You could say that the Accelerating Thrust (Right Arm Drive) Pushes the Non-Accelerating Thrust (Power Package Mass) Down Plane through Impact to the end of the Follow-Through.

Swingers use the Right Triceps to produce only the Non-Accelerating Thrust of Extensor Action. Centrifugal Force -- that phenomenon induced by rotation that causes the Club to seek its In Line relationship with the Left Arm -- provides the Acceleration Thrust (6-C-0-4).