Whereas the first and second accumulators can be neatly summed up in one line (i.e. bending / extending the right arm, and cocking / uncocking the left wrist), the third power accumulator is a little more complicated. For a start, it’s an accumulator that doesn’t accumulate. It works by maintaining its “in line” condition.(1)

That “in line” condition, in Mr Kelley’s words, is where “...the entire left arm, the clubshaft and the back of the left hand are ALWAYS positioned against the same flat plane- the plane of the left wristcock motion.”(2)

Going back to the lever assemblies concept, I’d told you the third power accumulator, like the second, is responsible for providing force, and therefore motion, to the secondary lever assembly, where the left wrist is the fulcrum and the clubhead the weight.(3)

At this point we know the third power accumulator is not horizontal wrist motion; the bending and arching of the left wrist, because that would take the third accumulator “out of line”, off the aforementioned flat plane created by the left arm and clubshaft. It’s not perpendicular wrist motion either, because that is the second accumulator of cocking and uncocking the wrists. The third power accumulator is the last wrist motion available to us: rotational. The third power accumulator works by first rotating the wrists clockwise(4) during the backstroke and then rotating them anti-clockwise(5) near the bottom of the downstroke, through the ball. Because the third accumulator’s role is to provide motion to the secondary lever assembly, all rotation is around the axis of the left wrist. The third accumulator is the last of the four accumulators to be released.(6)