Patent ID: 7730707

Claim:
An extendable header for a harvesting machine having: a frame; a cutterbar mounted on the frame operable to cut standing crop, the cutterbar being adjustable relative to the frame in a fore-and-aft direction; a reel rotatably supported between a pair of reel arms pivotally mounted on the frame and operable to sweep crop material towards and over the cutterbar; a hydraulic cylinder extending between each reel arm and a corresponding side wall of said header frame to effect a generally vertical movement of said reel; and an interlock mechanism operably interconnecting the cutterbar and the hydraulic cylinder at each side of the header for adjusting the vertical position of the reel in response to a fore-and-aft movement of the cutterbar to avoid interference between the reel and the cutterbar, said interlock mechanism including a linkage mechanism on each side of the header, wherein each linkage mechanism comprises: a body connected to the cutterbar and extending along a corresponding side wall of said header frame, said body following the generally horizontal movement of the cutterbar; and interconnecting means between said body and the hydraulic cylinder at each side wall of the header frame, said interconnecting means comprising guiding means for guiding the hydraulic cylinder in a generally vertical movement, and the body in a generally horizontal movement, said body further comprising adjustment means for effecting said vertical movement of the hydraulic cylinder in relation to said horizontal movement of the cutterbar, wherein said body is a plate with a wedge-defining slot or groove applied into the body, said wedge-defining slot or groove having a shape adapted to lift or lower the hydraulic cylinder accordingly as the body is moved forwardly or rearwardly, wherein said adjustment means includes a wedge-like or generally triangular shape applied along an edge or a side of said body, or into said body, along or into which the hydraulic cylinder is moved vertically as the body moves generally horizontally, said triangular shape being adapted to lift or lower the hydraulic cylinder accordingly as the body is moved forwardly or rearwardly.