COMBINE HEAD RAISE AND LOWER RATE CONTROL

A control system for controlling the height of a harvesting head on a combine is disclosed herein. The control system includes operator controlled signal generators which permit an operator to independently set the maximum velocity at which the harvesting head is raised and lowered. The signal generators are connected to the system controller which controls the operation of a hydraulic valve which controls hydraulic lift cylinders which raise and lower the harvesting head. The hydraulic valve is controlled with a pulse-width modulated signal. The width of the pulse is related to the direction the head is being moved (raised or lowered), and the maximum speed at which the head is to be moved. To reduce jerking upon initiation of head movement and termination of head movement, the controller determines acceleration and deceleration rates for head movement initiation and termination. The acceleration and deceleration determinations are based upon the signals produced by the signal generators.