Forage Harvester Orientation Mechanism to Reduce Particle Size Variation

Abstract

A third set of feed rolls, one of which contains a cam-actuated combing mechanism, was placed between the normal feed rolls and the cutterhead of an experimental forage harvester. This mechanism was intended to orientate stems of forage, such as alfalfa, before being commutated by the cutterhead and thereby reduce particle size variation. When the 1:1 combing ratio was used as a control, the combing mechanism reduced the percent longs, shortened the geometric mean length, and lowered the geometric standard deviation of the particle size distribution. Increasing the combing ratio was beneficial up to the limit of 3:1. The percent longs were reduced by up to 48%, the geometric mean length was reduced by up to 29%, and the geometric standard deviation was reduced by up to 15% with a combing ratio of 3:1. However, the control forage harvesters consistently produced chopped material with fewer percent longs, shorter geometric mean length, and lower geometric standard deviation than the experimental machine. This may have been at least partially due to non-uniform feeding from the pick-up of the experimental machine. Net specific energy requirements of the combing mechanism and clean-off roll were less than 0.24 kWh/t.