Patent ID: 7866132

Claim:
A harvesting head for an agricultural combine, the harvesting head comprising: a frame ( 106 ) that extends laterally and has a leading edge; a conveyor means ( 108 , 110 , 112 ) mounted on the frame ( 106 ) to carry cut crop to a feederhouse ( 102 ) of the agricultural combine; a reciprocating knife ( 132 ) fixed to a leading edge of the frame ( 106 ); a reel ( 122 ) disposed above the reciprocating knife ( 132 ) to convey crop material to the conveyor means ( 108 , 110 , 112 ); at least first, second and third reel support arms ( 114 ), ( 116 ) and ( 118 ), respectively, being coupled between said frame ( 106 ) and said reel ( 122 ); at least first and second hydraulic cylinders ( 124 ) and ( 128 ), respectively, having first ends pivotally coupled to first and a second ones ( 114 , 118 ) of said reel support arms ( 114 , 116 , 118 ) and having second ends pivotally coupled to said frame ( 106 ) to support and vertically position the reel ( 122 ); at least a third hydraulic cylinder ( 134 ) and a fourth hydraulic cylinder ( 138 ); and a hydraulic height control circuit comprising at least first and second closed hydraulic circuits respectively including said third hydraulic cylinder ( 134 ) being hydraulically coupled to said first hydraulic cylinder ( 124 ) for effecting extension and retraction of said first hydraulic cylinder ( 124 ), and including said fourth hydraulic cylinder 138 being hydraulically coupled to said second hydraulic cylinder ( 128 ) for effecting extension and retraction of said second hydraulic cylinder ( 128 ), with said extension and retraction of said first and second hydraulic cylinders ( 124 ) and ( 128 ), respectively effecting raising and lowering of said first and second ones ( 114 ) and ( 116 ) of the first, second and third reel support arms ( 114 , 116 , 118 ).