Endless belt is merely the mechanic advantage of the wheel. The shorter movement of the inner wheel (HANDS) increases the surface speed of the OUTER circle (Clubhead) so it can still in rhythm and maintain its Pace with the inner circle of one revolution. It is a whipping action of the clubhead (outer circle) around the hands (inner circle). This of course increases clubhead speed.
In nature any increase in surface area will produce an increase in surface speed to maintain its original Pace. This action with air over a wing produces LIFT called Bernoulli's law by producing a difference of pressure on the shorter side of the wing - in this case the outter side of the foil that cause an increase in air speed is the clubhead and the short flat side of the wing is the hands which maintains its Pace.