Abstract: A material reduction machine includes a prime mover driving a cutting mechanism. A drive system receives a signal to initiate rotation of a cutting mechanism. A sensor senses a machine load parameter and reports a signal to a controller operatively coupled to the clutch to control sequential engagement cycles from the engine to the cutting mechanism. The controller utilizes a stored first disengagement threshold value for stopping a first engagement cycle and continues monitoring the signal as the machine load parameter increases momentarily after reaching the first disengagement threshold. The controller determines and adopts a second disengagement threshold value based on observation of the machine load parameter indicative of maximum load during the continued monitoring after the first disengagement threshold is realized, and further being based on a stored correction factor. The second disengagement threshold value is used for a second engagement cycle.