GB801625A - Improvements in or relating to means for regulating the working depth of agricultural implements - Google Patents

Abstract

801,625. Tractor power-lift linkage mechanisms. INTERNATIONAL HARVESTER CO. OF GREAT BRITAIN, Ltd. March 15, 1956 [May 17, 19551. No. 14229/55. Class 79(1) In a tractor having an implement attaching linkage including upper and lower pivoted links 3, 4 and power lift means connected to the linkage, the working depth of an implement 1 attached to the linkage is regulated by spring means 12 which are arranged to provide a lifting force on the linkage when the tractor pitches rearwardly, and lost-motion is provided in the link 3 so that the tractor can pitch forwardly without exerting a lifting force on the implement through the link 3. The upper link 3 is telescopic, having a part 3b slidable in a part 3a, the latter having slots 3d engaged by.a transverse pin 3c on the part 3b, and a pair of lower links 4 are connected by lifting links 11 to lifting arms 10 on a shaft 9, rockable by hydraulic or other lift means. An arm 15 secured on the shaft 9 engages a member 14 of the spring means comprising the compression spring 12 in a housing 16 having a screwed cap 17 and adjustable axially relative to the tractor hydraulic lift housing 13 by means of a screw 18 and handwheel 19. In the normal working position of the tractor and implement shown, the spring is fully compressed and solid. When the tractor pitches rearwardly the spring 12 expands and maintains support of the linkage with a progressive reduction of the proportion of the weight of the implement which is transferred to the tractor rear wheels 20. When the tractor pitches forwardly, the link 3 which is normally under compression extends so that lifting force is not exerted on the implement through the link 3, so that the working depth of the implement is maintained. The spring means adjustment, for the working depth and the lowest, point of the implement, is effected when the linkage is raised by the power lift.