The development of an on-off control system for automatic swather and combine height-of-cut adjustment

Abstract

This thesis describes the development of an on-off control system which can be used for automatic height-of-cut adjustment on both swathers and combines. The system was designed to be compatible with the hydraulic and electrical systems already present on most grain harvesting machinery. It can be pre-set by the operator, so that cutter bar movement varies between any desired maximum and minimum positions. A separate investigation was conducted to determine some of the physical properties of grain plants. The results of this investigation were applied to the design of the sensing elements in the control system. The performance of the system was determined in the laboratory by mounting grain plants of different heights in a narrow strip around the circumference of a large rotating table. The results obtained from the laboratory study showed that the operation of this system was satisfactory for all practical combinations of ground speed, grain height and density of plant population. A more complete system was then constructed and mounted on a pull-type swather. Field tests showed that this automatic control system performed satisfactorily and could have a number of practical applications.