Patent ID: 7603837

Claim:
A height control system for a header of a work machine, comprising: header support apparatus connecting a header to a frame of a work machine, the apparatus including first and second height control cylinders disposed in supporting relation to opposite first and second end portions of the header, respectively, the height control cylinders, each having a body portion and a movable rod extendible therefrom, being controllably variable in length for supporting the first and second end portions of the header at selectable heights relative to the frame, respectively, each of the height control cylinders being connected to the frame by a connection which allows the height control cylinder and the end portion of the header supported thereby to be lifted from a selected height without changing the length of the height control cylinder; and an operator control system in connection with the height control cylinders and operator controllable for individually or jointly varying the lengths of the height control cylinders for positioning the end portions of the header at one selected height or different selected heights relative to the frame, at least one lift cylinder connected between the frame and the header support apparatus and controllably variable in length for lifting the header from a selected height and lowering the header thereto without a change in the lengths of the height control cylinders, and the control system configured to have a lift mode wherein the rod of the at least one lift cylinder is actuated to apply an upward force to the header such that the height control cylinders and connected header are moved upwardly from the selected height established by the height control cylinders, the rod of each height control cylinder maintaining a fixed extended length from the body and upon removal of the upward force to the header by the lift cylinder, the header and height cylinders return to the selected height.